Symposium on the treatment of human amoebiasis II. The treatment of intestinal amoebiasis with emetine bismuth iodide, glaucarubin, dichloroacet-hydroxy-methylanilide, camoform and various antibiotics

114 II.

THE

BISMUTH

TREATMENT

OF

INTESTINAL

AMOEBIASIS

WITH

EMETINE

IODIDE, GLAUCARUBIN, DICHLOROACET-HYDROXY-METHYLANILIDE, CAMOFORM AND VARIOUS ANTIBIOTICS BY

A. W. WOODRUFF, S. BELL AND F. D. SCHOFIELD *

Department of Clinical Tropical Medicine, London School of Hygiene and Tropical Medicine, and Hospital for Tropical Diseases, London. Since the second World War the search for new amoebicides has been intensified and has led to the preparation of several substances showing high degrees of activity in laboratory animals. Therapeutic trials with these drugs and with certain antibiotics are here reported and their efficacy compared with that of emetine bismuth iodide (E.B.I.) used alone and in combination with other drugs. I n this country, circumstances are favourable for such trials as the chance of reinfection is small. Relapses therefore are almost certainly true relapses, not reinfections. METHODS

All patients were admitted to the Hospital for Tropical Diseases, London, after diagnosis, and were treated in bed. With the object of determining when the amoebae or cysts disappeared, stools whenever possible were examined daily throughout treatment. The groups and the numbers of patients whose stools were examined in this way are specified. Stools were examined microscopically at the conclusion of treatment in all cases. Following discharge from hospital the patients were asked to re-attend at monthly intervals. In practice it was found that many who remained in London and district after treatment attended regularly for 2-3 months, and thereafter were willing to attend at longer intervals. In the studies of glaucarubin,, dichloroacet-hydroxy-methy]anilide and fumagillin, Entamoeba histolytica cysts present were measured with an eyepiecemicrometer. In the absence of evidence that the small race of E. histolytica is affectedby amoebicides differently from the large race, and because there is no experimental proof that the small race is not pathogenic (HOARE, 1952), infections associated with both forms of the parasite or their cysts were treated but were observed separately. Patientswere drawn from most countries of the world, the majority however had acquired their infection in India or tropical Africa. The majority of the patients were suffering from alimentary symptoms at the time of treatment, the minority were found at routine examination to be harbouring the parasites. All had suffered from dysentery oi" diarrhoea while abroad. Routinemicroscopy of faeces was used throughout for detection of parasites. In addition to routine microscopy, a concentration technique * This work was made possible by a generous grant from the Hospital for Tropical Diseases Research Fund which enabled the valuable services of Mrs. A. Walshe to be obtained. We wish to express our thanks to the Hospital authorities for this grant, to Mrs. Walshe for her help, and to Sir Neil Hamilton Fairley and to Sir George McRobert for allowing us to include many of their cases in the study. We are grateful for the co-operation and assistance of Dr. D. S. Ridley, Dr. W. H. Jopling, many members past and present of the medical and nursing staff of the Hospital for Tropical Diseases, and to Mrs. J. de Wardener for secretarial help. To the Medical Research Council, Messrs. MerckSharp and Dohme, Messrs. Boots Pure Drug Co. Ltd., and Messrs. Parke-Davis and Co. Ltd. we are indebted for much valuable information and for supplies of drugs.

A. W. WOODRUFF, S. BELL AND F. D. SCHOFIELD

11~

(RIDLEY,this issue p. 133) was used in examining stools in the glaucarubin and dichloroacethydroxy-methylanilide trials. EMETINE

BISMUTH

IODIDE

In view of the conflicting opinions held regarding the drug and of the criticism to which it has been subjected in America (ANDERSON et al., 1953), it was decided to assess its efficacy in the conditions outlined. Emetine in one form or another has been the basis of most of the complex regimes used in recent years for the treatment of amoebiasis, and there is no doubt in the minds of many physicians that it is the most effective of the several remedies employed. If a complex, long treatment is of no greater value than a simpler, short one, it is of importance both to patient and doctor that the fact should be known. Moreover, if amoebic infections are treated with a combination of a powerful and a feeble amoebicide, the probability is that the results will be no better than if the powerful amoebicide alone is used. These considerations prompted the decision to compare the results of treatment with emetine bismuth iodide alone, with those following its use in combination with various other drugs.

Dosage and results. The standard course of E.B.I. used was 3 grains nightly for 10 nights, each dose being preceded by a sedative. This course was given to 64 patients all of whom were followed up on one or more occasions, the average number of such follow-up attendances being 1.83 per patient. The first follow-up examination was made 1 month after completion of treatment and subsequently at monthly intervals. Of these 64 patients, one has relapsed. Emetine bismuth iodide was followed by courses of one or more other drugs in 156 cases and among these a similar follow-up in which the average number of attendances per patient was 1.92, has revealed five relapses (Table I). Of those who relapsed, two were treated with a further course of E.B.I. combined with aureomycin 2 grammes daily for 10-12 days. Examinations 1 month and 2 months after completion of treatment revealed no further relapse in either case and in one case an examination at ¢ months was also negative. A third patient was re-treated with courses of E.B.I. and diodoquin and re-examination 1 and 2 months, and 2 years after the second treatment, revealed no persisting infection. A fourth patient who had repeatedly relapsed after treatment with E.B.I., aureomycin and terramycin, was eventually cured by a course of fumagillin.

Conclusions. It is possible that the smaller number of relapses following E.B.I. given alone is attributable to chance, the results however suggest that courses of E.B.I. followed by the other drugs used are no better than courses of E.B.I. only. If all the cases treated with E.B.I. are added together, there were six relapses among 220 treated, a relapse rate of approximately 3 per cent. It is not supposed that the follow-up which has been possible has revealed all the relapses that have occurred. In comparable series treated with other drugs however, results have been obtained which are inferior to those following treatment with E.B.I. DOBELL (1918) found 3 grains of E.B.I. daily for 12 days to cure about 90 per cent. of carriers of E. histolytica, a figure which appears not to be an overestimate. In a series of 116 cases treated with E.B.I., MANSON-BAH~ (1961) reported a relapse rate of 6.1 per cent. It is certainly safe to say that E.B.I. is a very good drug, and o t h e r s - to be better than i t - must be excellent.

116

TREATMENT

OF

INTESTINAL

AMOEBIASIS

TAnLE I. Results of treatment of intestinal arnoebiasis with emetine bismuth iodide (E.B.I.) alone and in combination with other drugs. T h e basic course of E.B.I. in all cases was 3 grains nightly for 10 nights. Follow-up results at end of : m

1 ruth.

2 mths.

09

~

3 mths.

09

4 mths.

5 mths.

"13 09

~J o9

a ~1£,1

09

d

d

Z

Drug

d

d

Z

d

Z

S Z

Z

•

O

Z

- - i

E.B.I. grains 3 daily for 7 days ,, + diodoquin 0.6 gramme thrice daily for 21 days ,, + diodoquin + carbasone grains 4 twice daily for 10 days ,, + emetine grain 1 for 2-4 days ,, + oxytetracycline 2 grammes for 10 days Basic course of E.B.I. with various combinations of carbasone,chloroquine, oxytetracycline, penicillin, diodoquin, sulphaguanadine and aureomycin

54

641 32

0

37

1

15

0

11

0

4

0

89

891 21

0

55

1

21

1

15

0

8

0

4~

431 8~

6 2

1 0

53 4

0 0

2( l

1 0

15

0 0

7 1

0 0

3

31

2

0

2

0

3

0

13

131

6

0

11

0

8

0

8

0

1

0

Totals

20 2 2 0 ] 69

1

16C

2

74

2

54

0

21

0

Follow-up results at end o f :

6 mths.

7 mths.

8 mths.

9 mths.

10 mths. 11 mths.

09

i

¢h

.2

N

o9 o

Z

Drug E.B.I. grains daily for 7 days ,, + diodoquin 0.6 gramme thrice daily for 21 days ,, + diodoquin + carbasone grains 4 twice daily for 10 days ,, + emetine grain 1 for 2-4 days ,, + oxytetracycline2grammes for 10 days Basic course of E.B.I. with various combinations of carbasone,chloroquine, oxytetraeycline, penicillin, diodoquin, sulphaguanadine and aureomycin Totals

0

4

13

]

13

1

13

6

13

Z 0 1

0

z° 0

1

0

0

2

0

2

0

4

0

1

13

1

0

2

0

A.

"W. W O O D R U F F ~

S.

BELL

AND

F.

D.

117

SCHOFIELD

TABLE I (continued). Follow-up results at end o f :

12 mths.

13 mths. 16-28 m.

2 years

4 years

¢

? (

2

(

Drug E.B.I. grains 3 daily for 7 days ,, + diodoquin 0.6 gramme thrice daily for 21 days ,, + diodoquin + carbasone grains 4 twice daily for 10 days ,, ÷ emetine grain 1 for 2 - 4 days ,, + oxytetracycline 2 grammes for 10 days Basic course of E.B.I. with various combinations of carbasone, chloroquine, oxytetracycline, penicillin, diodoquin, sulphaguanadine and aureomycin Totals

2

0

1

0

1

0

1

0

3-

0

1

0

1

0

2

0

ANTIBIOTICS IN INTESTINAL AMOEBIASIS CHLORAMPHENICOL

At an early stage in these investigations, the amoebicidal activity of the then recentlyintroduced chloramphenicol was evaluated. Three patients were given 2 grammes of the drug daily for 7 days, two were given 4 grammes daily for the same period, and one was given 2 grammes daily for 14 days. Three of these six patients had been passing E. histolytica trophozoites, and the remainder, cysts. Vegetative forms seemed to disappear from the stools of two of the three patients in whom they had been present, but in the stool of the patient who was treated for 14 days, E. histolytica cysts were detectable throughout this period. Stools were examined daily in this trial, and in those which eventually became free from parasites, amoebae disappeared on the 8th and 5th day of treatment respectively, and cysts on the 4th day and 2nd day respectively. All except one of the six patients had E. histolytica cysts in the stools 1 month after completion of treatment (Table II). In view of this high relapse rate it was concluded that the drug has very little value as an amoebicide in man.

118

TREATMENT

TABLE II.

OF

INTESTINAL

AMOEBIASIS

Results of treatment of intestinal amoebiasis with chloramphenicol.

Follow-up results at end of : n

2mths.

mth.

Dosage

2, }. ~ }. ex: nir d

No. relapsed

No. foll v'd l } treated --

4 mths.

No. examined

No. relapsed

No. examined

1

1

-

1

0

1

No. relapsed

-W--

2 grammes daily for 7 days 4 grammes daily for 7 days

1

2 grammes daily for 14 days

1

1

AUREOMYCIN

Aureomycin was similarly tried in six patients in whom E. histolytica cysts were present in the stools. The dosage used was 2 grammes daily for 10 days. Stools were examined daily during the course of treatment, and in all, cysts were no longer detectable by the 6th day, the average time taken for them to disappear being 5 days. In three, however, cysts were again found in the faeces when the patients returned 1 month after completion of treatment, a result which compared so unfavourably with experience with E.B.I. that it was considered unjustifiable to continue the study of aureomycin alone as an amoebicide in man. OXYTETRACYCLINE

Trials with oxytetracycline were carried out, following encouraging American reports and particularly that of MOST et al. (1950), who reported terramycin 100 per cent. effective against amoebiasis. In MOST'S series of 200 patients, 2 grammes of the drug daily for 10 days were given to patients whose weight was greater than 75 lb., and 1 gramme daily for a similar period to those weighing less than 75 lb. The patients were followed up for 6 months. BARGEN(1951) also found terramycin highly effective. In this series, 17 patients were treated and it was possible to follow up 14, two of whom relapsed (Table III). Cysts of E. histolytica were present in the stools of 15 patients, the remaining two had vegetative forms present. In all except one patient, stools were examined daily during the trial and among those passing cysts and treated with either 1 gramme or 2 grammes of the drug daily, cysts were no longer detectable after the 4th day of treatment. There was no apparent difference in the rate at which cysts disappeared with either dosage. One patient with trophozoites originally present in the stool, was treated with 1 gramme daily, the amoebae immediately disappeared but a relapse took place 1 month after completion of treatment. The second patient with trophozoites in the stool had previously relapsed following treatment with E.B.I. and glaucarubin. He was cured by a course of 24 grammes oxytetracycline given over 12 days. The relapse rate in this series was similar to that found by ELSDON-DEW et al. (1952). After administering 1 gramme oxytetracycline daily for 15 days to patients passing trophozoites of E. histolytica, they reported two relapses 1 month after completing treatment among 20 patients followed up, and one relapse among five patients a month later.

A. W.

TABLE III.

-~VOODRUFF,

S.

BELL

AND

F.

D.

119

SCHOFIELD

Results of treatment of intestinal amoebiasis with oxytetracycline. Follow-up results at end of : I mth.

2 mths.

3 mths.

4 mths.

5 mths.

6 mths.

5 Z

~ Z

5 Z

d Z

5 Z

d Z

d Z

0

0

0

0

o

0

0

0

1

0

1

o

3

0

r [8 ,.a

~9

¢0

d Z

d Z

d Z

Z

1 gramme daily for 10 days

5

4

2

0

2 grammes daily for 10 days

12

10

8

1

Dosage

5 Z

3i

d Z

6 Z

1

0

0

4[

i

I I

i

I

FUMAGILLIN

Following assessment, in vitro and in monkeys, of the amoebicidal activity of fumagillin (ANDERSON et al., 1953), clinical trials in human amoebiasis have been made in various parts of the world, and 34 patients have been treated with the drug in the Hospital for Tropical Diseases, London.

Dosage. The daily dose given to all except two patients was 60 mg. This dosage was continued for 10 days in eight cases, and for 14 days in 24 cases. Two patients, one of whom was a child, received 30 mg. daily for 14 days. Toxicity. Toxic effects were noted in 11 out of 34 cases. In four, heartburn and nausea occurred after meals throughout treatment. In a further four patients there was fine desquamation and itching of the palms of the hands at the end of treatment, and two patients also had erythema of the forehead, followed by desquamation. These effects persisted for a maximum of 2 weeks. Three patients had both " indigestion " and desquamation of the hands, and one of these also had pruritus ani. Another who had an active dermatophytosis of the feet developed severe cheiropompholyx of the hands and generalized pruritus with erythema. One patient developed nephritis on the day after completing treatment. The urine contained protein, scanty red cells, many hyaline casts and some granular casts, it had been normal before treatment and returned to normal in 4 days. This patient complained of headache but there was no rise of blood pressure. The patient's stools had originally contained E. histolytica cysts, and later a relapse occurred. Following this experience the urine of the remaining 17 patients in the series was examined daily during treatment and for as long afterwards as they remained in hospital, but no abnormality was found.

120

T R E A T M E N T OF I N T E S T I N A L A M O E B I A S I S

Results. It has been possible to follow up 27 of the 34 patients treated (Table IV). Of these one who originally passed E. histolytica cysts, relapsed ; of three patients who had E. histolytica trophozoites in the stool, however, two failed to respond to the drug. An average of 4.1 stools per patient were examined following completion of treatment. One patient who had had E. histolflica cysts in the stools almost continuously in spite of treatment with E.B.I., aureomycin and oxytetracycline in full doses, was rendered apparently free from infection by a course of fumagillin. Subsequent examinations on seven occasions have failed to reveal evidence of persisting infection. In four patients, the stools contained cysts of the small race of E. histolytica. In all these the infection was apparently eradicated by fumagillin. Conclusions. The results confirm the report of the efficacy of the drug in infections in which E. histolytica cysts are present in the stools (MCHARD¥, 1953). It proved so ineffective in cases of acute amoebic dysentery, however, that its use for this condition was discontinued. A similar finding was reported by ELSDON-DEw et al. (1953). This, the high incidence of dermatitis and other side effects following its administration, and the fact that it is no more effective than E.B.I. in cases in which E. histolytica cysts only are present in the stools, render it of doubtful value as an amoebicide in man. Results of treatment with fumagillin of patients passing E. histolytica cysts. Two out of three additional patients who had E. histolytica trophozoites in the stools failed to respond to the drug.

TABLE IV.

Follow-up results at end of : 1 mth.

2 mths__ 3. mths__ 4__mths__

dldidldld

d

Dosage 60 mg. daily for 14 days

21

18

60 mg. daily for 10 days 30 mg. daily for 14 days Totals

2

2

1

0

-

-

1

,8 o t o 6 1

mths.

5

mths__:_.$

TT 2 6 Z

6 Z

9

0

1]

0

3

3

0

i

0

0

C

1..

0-iT-

CAMOFORM In 1953 a substance now known as camoformwas synthesized by Parke Davis and Co.

A. W .

W OODRUFF~

121

S. B E L L A N D F. D. S C H O F I E L D

Ltd. as part of a search for new amoebicides. It is 6 : 6~-diallyl-~, c~lbis (diethylamino)4 : 41-bi-o-cresol, and was found to be amoebicidal at a dilution of 1 in 12,000 in an eggyolk infusion to which 0.5 per cent. liver extract had been added. The makers who had conducted toxicity trials in laboratory animals and man, and found no serious side effects, suggested daily doses of 1-3 grammes. An initial dosage of 1.5 gramme daily for 7 days was therefore given, and 2 months after having this amount one patient relapsed. The dosage was therefore progressively increased and no toxic effects were experienced. One patient, however, relapsed a month after completing a 10-day course in which he had taken 20 grammes of the drug (Table V). All the patients prior to treatment were passing E. histolytica cysts in the stools. Stools were examined daily during treatment in four cases, and in none did the cysts remain detectable after the 3rd day. TABLE V.

Results of treatment of intestinal amoebiasis with camoform. Follow-up results at end of :

1 mth.

2 mths.

3 inths.

4 mths.

i

5 mths.

09

c~

Dosage 1.5 gramme daily for 7 days

2

1

1.5 gramme daily for 10 days

1

0

0 i

o

0

2 grammes daily for 7 days

2

2 grammes daily for 10 days

0

-

0

Of 14 patients treated, 12 were followed for at least a month after treatment, and of these three relapsed. These results are less satisfactory than those of BARRIOS (1954) in Peru. Following administration of 1.5 gramme daily until an average total of 17 grammes had been given, he found that in follow-up periods of 1-7 months there were no relapses among 20 patients treated. HOEKENGAand BATTERTON (1954) reported an apparent cure rate of 85 per cent. in a series of 20 patients. GLAUCARUBIN

In 1954 in the laboratories of Messrs. Merck-Sharp and Dohme International an amoebicidal substance, now known as glaucarubin, was successfully isolated by HAM et al. (1954) from Simarouba glauca, a plant whose bark and roots had long been known in the tropical Americas to benefit dysentery. Glaucarubin has the chemical structure ~-methyl-c~hydroxybutyric acid combined with hexahydroxylactone. Rats and mice tolerate the drug well, rats taking 50 mg./kg, daily for a year remained well. Dogs having 8 mg/kg, daily were well at the end of 6 months, but they temporarily suffered from anaemia and leucopoenia

122

TREATMENT

TABLE V I .

OF

INTESTINAL

AMOEBIASIS

R e s u l t s of t r e a t m e n t of i n t e s t i n a l a m o e b i a s i s w i t h g l a u c a r u b i n . Follow-up

1 mth.

~3

2 mths.

n2

o

go O

~

o

d

Z

Dosage 1.0-1.9 m g / k g , daily f o r 10 d a y s 2.0-2.9 . . . . . . 10 ,, 3.0-3.9 . . . . . . 10 ,, 4.0-4.9 . . . . . . 10 ,, 5.0-5.9 . . . . . . 10 ,, 6.0-6.9 . . . . . . 10 ,, 7.0-7.9 . . . . . . 10 ,, 8.0-8.9 . . . . . . 10 ,, 9.0-9.9 . . . . . . 10 ,, 10 m g / k g , daily f o r 10 days

Dosage 1.0-1.9 m g / k g , daily f o r 2.0-2.9 . . . . . . 3.0-3.9 ,. . . . . 4.0-4.9 . . . . . . 5.0-5.9 . . . . . . 6.0-6.9 . . . . . . 7.0-7.9 ,, .... 8.0-8.9 . . . . . . 9.0-9.9 .... 10 10 m g / k g , daily f o r Totals

2

10 days 10 ,, 10 ,, 10 ,, 10 ,, 10 ,, 10 ,, 10 ,, 10 ,, days

Z

0a

Z

Z

4 4 1!

1 2 2 0 0

2 .~ 1(

(

0

",

1

0

~"

1

1

0

-

66

3.=

6

2,

7

7

Totals

6 Z

12 22 7 4 6 2 3 2

results at end of :

-

3mths.

4mths.

5mths.

123

A. W. WOODRUFF~ S. BELL AND F. D. SCHOFIELD

between the 1st and 5th month of treatment. blood picture in patients during this trial.

Special attention was therefore paid to the

Dosage. The dosage initially used was 1 rag. per kg. of patient's body weight daily for 10 days. A lO-day period of treatment has been used throughout the trial with this drug, and whenever it has been found that a patient has relapsed, the dosage given to future patients has been increased. In this way a daily dosage of 10 rag. per kg. body weigtlt has been reached. Side

effects.

Some patients having more thap. 8 nag. per kg. body weight have complained of nausea. The white blood cells have been counted before and after treatment in 26 patients. Before treatment the mean was 7,440 per c.mm. standard deviation (S.D.) ~_ 1,810, range 4,10010,950. At the conclusion of treatment, the mean was 6,710 per c.mm., S.D. ± 1,860, range 4,400-10,600. The standard error (S.E.) of the difference between the two means is 0.5069, the difference is therefore not statistically significant. Results.

Of 76 patients treated with various amounts of the drug, it has been possible to follow 66 for at least 1 month, and of these 17 have relapsed giving an over-all relapse rate of 25.7 per cent. In Table VI details of dosage and of the follow-up study are shown, and it will be noted that among the 25 followed after having daily doses of more than 4 rag. per kg. body weight, the relapse rate is only 12 per cent. The number of follow-up examinations was approximately the same in those having less, as it was in those having more, than 4 rag. per kg. body weight, the average being 2.1 in the former and 2.0 in the latter. Stools were examined daily during treatment in 50 cases, and in 43 E . h i s t o l y t i c a cysts were sufficiently numerous to permit assessment of the day on which they were apparently eradicated. This ranged from the 2nd to the 10th day of treatment, the mean being the 4th day. The relapse rate in relation to the form of parasite found is shown in Table VII, from TABLE VII.

Relationship of relapse rate following treatment with glaucarubin to form of E . originally present.

histolytica

Totals Percentage of relapses

No,

No.

No.

treated

followed

relapsed

9

9

1

11.1

cysts

26

21

6

28.6

. . . .

(small race) cysts

32

28

6

21.4

. . . .

(large and small races) cysts

9

8

4

50.0

76

66

17

25.7

E . histolytica ,,

Totals

,,

(large race) trophozoites ,,

,,

124

TREATMENT OF INTESTINAL AMOEBIASIS

which it will be noted that there is no marked difference in the response to the drug of infections associated with the presence of either large or small races of E. histolytica cysts. It will also be noted that the drug is active against E. histolytiea trophozoites, and that of nine patients in whom these were found only one relapsed.

Conclusion. It is understood that glaucarubin will be cheap to produce ; this, its freedom from toxicity and its satisfactory amoebicidal activity in doses of 4 mg. per kg. body weight and over, suggest that it may be a useful drug in the treatment of intestinal amoebiasis.

DICHLOROACET-4-HYDROXY-N-METHYLANILIDE

In carrying out an extensive screening programme for the detection of amoebicidal activity in new organic compounds, a series of substituted anilides was recently synthesized and investigated in the laboratories of Messrs. Boots Pure Drug Co. Ltd. One, dichloroacet4-hydroxy-n-methylanilide, showed particularly high amoebicidal activity in vitro and in vivo, and was almost completely free from toxic effects. Doses of 200 mg./kg, of body weight daily for 2 weeks were well tolerated by rats, and in cats 500 mg./kg, body weight produced only vomiting.

Dosage. The initial dosage employed in assessing this drug was 2 mg. per kg. body weight daily for 10 days, and this has been progressively increased to 21 mg. per kg. body weight daily for a similar period.

Side effects. No side effects nor toxic reactions of any kind have been observed, and no significant effect on white blood cells has been revealed by white cell and differential counts before and after treatment. The mean before treatment in 26 cases was 7,660 cells per c.mm., S.D. -2: 2,860, range 3,000-12,800. After treatment it was 7,410 per c.mm., S.D. ± 2,800, range 3,700-14,200. The standard error of the difference between these means is 0.785, the difference is therefore insignificant.

Results. Of 45 patients treated, 40 have re-attended on at least one occasion a month or more after completion of treatment (Table VIII). Of these, 10 have been found to have E. histolytica or its cysts in the stools. Of 17 patients followed up after being treated with 12 rag. per kg. body weight or more daily for 10 days, however, only two have relapsed, giving a relapse rate of 11.8 per cent. To date, slightly fewer stools have on the average been examined from patients having more than 12 rag. drug per kg. body weight than have been examined from those having less than this amount, the numbers being 1.6 and 2.3 respectively. This difference, however, is clearly too small to explain the difference in the relapse rates between the two groups, which were 11.8 per cent. and 30.4 per cent., respectively.

A.

TABLE V I I [.

W.

WOODRUFF~

S.

BELL

AND

F.

D.

125

SCHOFIELD

Results of treatment of intestinal amoebiasis with diehloroacet-4-hydroxy-n-methylanilide F o l l o w - u p results at end o f :

1 mth.

2 mths.

3 mths.

4 mths.

¢h q~ °

©

6

2.0- 3.9 m g / k g , 4 . 0 - 5.9 . . 6.0- 7.9 . . 8.0- 9.9 . . 10.0-11.9 . . 12.0-13.9 . . 14.0-15.9 . . 16.0-17.9 . . 18.0-19.9 . . 20.0-21.0 . .

daily for . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

d Z

Z

Dosage 10 d a y s 10 ,, 10 ,, 10 ,, 10 ,, 10 ,, 10 ,, 10 ,, 10 ,, 10 ,,

Totals

Z

d Z

d 2;

3 0 0

2 3 4

1 1

1 3

1 3 2

5 5 5 4 5 6 7 4

5 5 5 4 4 4 5 4

2 3 2 2 2 3

1

1

1

0 0 0 0

3

3

2

45

40

21

3 1

6 2;

S Z

S 2;

d Z

d Z

1

1

0

1

0

0 0 0

4 3 -

1 0 -

3 3 1

0 0 0

1

1

0

1

0

0 0

2 2

0 0

1 1

0 0

0

-

-

11

0

1

2

1

1

0

.

6

20

3

15

.

.

1

.

Follow-up results at end of : -

5 mths.

d Z

Z

Dosage

-

-

-

7 mths.

8 mths.

9 mths.

d Z

d Z

d Z

c5 Z

6 Z

d Z

d Z

2 2 .

0 0

1 1 . .

0 0

1 1

0 0

d Z

b

2.0- 3.9 m g / k g , 4 . 0 - 5.9 . . 6 . 0 - 7.9 . . 8.0- 9.9 . . 10.0-11.9 . . 12.0-13.9 . . 14.0-15.9 . . 16.0-17.9 ,, 18.0-19.9 . . 20.0-21.0 . .

daily for . . . . . . . . . . . . . . . . . . . . . . . . ,, ,, . . . . . . . .

10 d a y s 10 ,, 10 ,, 10 ,, 10 ,, 10 ,, 10 ,, 10 ,, 10 ,, 10 ,,

.

.

1 1 1

.

i

.

0 0 0,

.

1

. 0

.

.

.

. .

. .

4 1 0 1

.

.

.

.

.

.

.

.

.

.

2

.

.

.

.

.

.

.

.

.

.

0

1

0

1

0

.

.

.

.

.

.

0

.

.

.

.

.

.

.

.

.

.

1

.

.

.

.

.

.

.

.

.

.

0

.

.

.

.

.

.

.

.

.

.

1

i

Totals

l

6 mths.

4

0

i

2

0

4

0

2

0

2

0

10

126

TREATMENT OF INTESTINAL AMOEBIASIS

Stools were examined daily during treatment in 25 cases. If those in which E. histolytica cysts were present are considered, there were 18 in which they were sufficiently numerous to permit observation of their disappearance. This ranged from the 2nd day to the 9th day of treatment, the mean being the 5th day. 'I'ABLE IX.

Relationship of relapse rate following treatment with dichloroacet-4-hydroxy-n-methylanilide to form of E. histolytica originally present. Totals No. treated

E.

histolytica (large race) trophozoites

,,

,,

,~

,,

cysts

. . . .

(small race) cysts

. . . .

(large and small races) cysts

Totals

No.

No.

followed

relapsed

• Percentage , of relapses

3

3

100

22

21

4.8

16

13

30.8

4

3

2

66.7

45

40

10

25.0

T h e relapse rate in relation to the form of parasite present in the stools is shown in Table IX. It appears that the drug is more effective in infections in which cysts of the large race of E. histolytica are present than it is in those in which only those of the small race are found. Time will no doubt show whether this apparent difference is real or is due to chance. Preliminary results suggest that the drug is of little value in cases in which there are E. histolytica trophozoites in the stools.

Conclusions. It is understood that dichloroacet-hydroxy-methylanilide like glaucarubin will be cheap to produce, and this, its freedom from toxicity and its effectiveness in infections in which the patient is passing E. histolytica cysts, suggest that it may prove to be a useful amoebicide. T h r o u g h o u t the study, efforts have been made to reduce the variables in each case, and to this end new drugs have been used singly instead of in combination. Under these conditions E.B.I. was found to be superior to any of the other drugs used, when amoebicidal activity and toxicity were taken into consideration. It is suggested, therefore, that at the present time, in spite of the introduction of antibiotics and other amoebicides, administration in hospital of a full course of the drug should be the basis of all treatment of intestinal amoebiasis, and that in its use lies the best hope of eradicating the infection. SUMMARY

(1) At the Hospital for Tropical Diseases, London, 417 patients suffering from intestinal amoebiasis have been treated and followed up under standard conditions. (2)

Emetine bismuth iodide was given in doses of 3 grains nightly for 10 nights to

A. W . W O O D R U F F , S. BELL AND F. D. SCHOFIELD

127

220 patients. In 24 with E. histolflica trophozoites in the stool, this was preceded by 1 grain emetine by injection on 3 successive days. Of all these patients, 3 per cent. are known to have relapsed. (3) T h e relapse rates following treatment with chloramphenicol and aureomycin was so high that after short trials it was considered unjustifiable to continue the drugs. (4)

Of 14 patients followed up after treatment with oxytetracycline, two relapsed.

(5) Of 27 patients whose stools had contained E. histolytica cysts and who were followed up after treatment with fumagillin, one relapsed. Many toxic effects including dermatitis and albuminuria were encountered. (6) Glaucarubin in doses of more than 4 mg. per kg. body weight was followed by a relapse rate of 12 per cent. among patients whose stools contained either E. histolytica cysts or trophozoites. (7) A similar relapse rate followed the use of doses of 12 mg. or more dichloroacethydroxy-methylanilide in persons whose stools had contained E. histolytica cysts. (8) It is concluded that emetine bismuth iodide is the most satisfactory drug at present available for the treatment of intestinal amoebiasis. REFERENCES ANDERSON,H. H., BOSTIeK,W. L. & JOHNSTONE,H. G. (1953). Amebiasis. Springfield, Ill. : Thomas. BARCEN, J. A. (1951). `7. Amer. reed. Ass., 145, 785. BARRIOS, H. (1954). Gastroenterology, 27, 81. DOBELL, C. (1918). Rep. Ser. reed. Res. Comm., 15, 28. ELSDON, DEW, R., ARMSTRONG,T. G. & WlLMOT, A. J. (1952). Lancet, 2, 104. - - - - , WlLMOT, A. J. & ARMSTRONC,T. G. (1953). Ibid., 2, 1180. HAM, A. E., SCHAFER,H. M., DENKEWALT~R,R. G. & BRI~K, N. G. (1954). `7. Amer. chem. Soc. 76, 6066. HOARE, C. A. (1952). Experimental Parasitology, 1, 411. HOEKENGA,M. T. & BATTERTON,D. C. (1954). Amer..7. trop. Med., 3, 849. McHARDY, G., BECHTOLD,J. E., WELeI-I, G. E. & BROWNE, D. C. (1953). Sth. med. `7., 46, 428. MANSON-BAI~R, P. (1941). Brit. reed.`7, 2, 255. MOST, H., TOBIAS,J. E., BOZICEVISH,J. & REARDON,L. V. (1950). Publ. Hlth. Rep., I~Zash., 65, 1684.

DISCUSSION Sir G e o r g e M c R o b e r t : We have listened with great pleasurc to two very fine papers. Dr. Adams has provided us with a concentrated distillate of his wide clinical experience ; Professor Woodruff's contribution may well become a classic. Until the end of the first decade of this century the treatment of amoebiasis was chaotic. Treatments waxed and waned, ipecacuanha had its votaries and detractors, ipecacuanha sine emetina had a vogue until one man, Leonard Rogers - - a former President of this Society and still, fortunately, with us and very a c t i v e - introduced emetine into clinical practice in the tropics, and order into the treatment of amoebiasis. In a very brief period of time, through Rogers' painstaking researches and advocacy, emetine and its products became established as the sheet anchor in the treatment of amoebiasis and have remained so ever since.

128

DISCUSSION

When discussing clinical subjects in this hall we are apt to think in terms of temporary visitors to the tropics, of soldiers and airmen, of administrators and men of commerce. Let me remind you that for the pestilence-stricken multitudes of the tropics, even emetine and its derivatives have proved to be too expensive - - rural and village dispensaries being unable to stock them. The introduction of antibiotics, with one treatment costing the equivalent of a half-year's earnings of an agricultural labourer in India, has no significance for the peasant in the tropics, even if the fermentation residues tried in Natal are put on the market. There is, therefore, no room for complacency, and the search for cheaper and better drugs for use in amoebiasis must go on. Tonight's speakers have not touched on hepatic amoebiasis. I wish to lay stress on the real danger of relying solely on antibiotics in the treatment of amoebic hepatitis and amoebic abscess of the liver. I have seen a number of cases of liver abscess which have gone from bad to worse under antibiotic therapy, regarded by its prescribers as " the very latest treatment." As antibiotic succeeded antibiotic, the patients steadily went downhill. In the field of visceral amoebiasis, emetine is unequalled for rapid effective action in nearly all cases, with chloroquine a good second--slower to come into action but capable of being used over a longer period. With increasing experience in the use of chloroquine in hepatic involvement, one is finding more and more patients who complain of visual disturbances. T h e y cease to be able to read their newspapers. The mechanism of this change, whether central or peripheral, should be further investigated. Dr. Adams has touched on the need for accurate diagnosis being established before treatment is instituted. May I enlarge on this point when the ever-increasing number of travellers and of temporary visitors to the tropics are being made to believe that it is impossible to visit Asia without picking up what is now popularly known there as " Amoebic "? In my years in the tropics I treated many subjects of amoebic dysentery, but it was not a serious problem and was certainly not a source of major worry to business firms. A day or two of diarrhoea was an occasional occurrence, after a railway journey or after dining out with a careless hostess, but a dose or two of kaolin and salts or - - later on - - of sulpha drugs put the great majority of patients right, the stools showing no signs of amoebae. Real anxiety exists now in business circles ; employees of some firms are demanding " amoebic danger money." It is now usual for travellers to purchase aureomycin and enterovioform at a drug store without consulting a doctor. This state of affairs is due partly to doctors undertaking practice in the tropics without adequate training in tropical medicine, partly to incompetent microscopy, but, above all, to high pressure salesmanship and extensive advertising In a - to m e - appalling article entitled "Conditioning the Medico" in a leading British national newspaper it was revealed how the methods of certain antibiotic salesmen had boosted the sales of antibiotics in America. Let us get back to common-sense honest therapy and do not let us treat an intestinal flux as amoebic dysentery unless it has been proved to exist by a trained and honest laboratory worker who knows how to identify the trophozoites of E. histolytica or the characteristic cysts. I distrust reports of precystic forms. I agree with Dr. Adams in his advocacy of rest in bed and in the need for eradication of infection from visitors from the tropics even if no symptoms are present. Like my colleagues at the Hospital for Tropical Diseases I have entirely abandoned the use of retention enemata. I prescribed them for many years but now believe that intense concentration on the colon for several hours day after day may help to establish a colonic neurosis, that the

DISCUSSION

129

strain on the nursing staff is very high, and that in all probability a better concentration of the drug can be obtained in the caecum by oral administration of the drug. Is there not a real danger of patients purchasing for themselves and using over long periods, as prophylactics, drugs containing arsenic and iodine ? I have seen one case of severe exfoliative dermatitis following self medication with stovarsol, and I believe that the thyroid function may be upset by the prolonged use of iodine-containing drugs. Can we recommend any drug for the prevention of amoebiasis in persons passing through the tropics ? I think the prophylaxis may be more dangerous than the disease. There should be some discussion on standards of cure. Many years ago Acton and Knowles in Calcutta laid down rigorous standards of c u r e - requiring large numbers of negative stools over a long period before pronouncing the patient free from infection. In our practice at the Tropical Diseases Hospital in London we are apt to lose touch with our patients after a few months, but all the medical consultants there feel considerable confidence in the concentration methods developed by Dr. Ridley using a much smaller number of stools than are usually required by Army and Air Force standards. Sir Philip M a n s o n - B a h r said he was delighted to listen to the two s p e a k e r s - Dr. Adams and Professor W o o d r u f f - - a n d also to Sir George McRobert, the opener of the Discussion. He agreed with every word they had said. The slogan now obviously was " Back to Methuselah " and we were now in the position of " as you were thirty years ago." It was a source of great satisfaction to him that things were so, because for 45 years he had studied amoebiasis, in particular, in various parts of the tropics, in war and in peace and here in England. He had kept accurate records through all these years and had made earnest endeavours to follow up his cases. In 1941 he summarized his experiences in the Lumleian Lectures of the Royal College of Physicians. The response that he got to his championship of emetine and E.B.I. on that occasion was disheartening and chilly, and he even had experienced difficulty in getting his paper published. The result of his life's work was to discover that general opinion was that the old trusted form of treatment had been out-moded. Emetine bismuth iodide was said to be " nasty stuff " and it was said that it upset the heart and could not be retained. Often it was dispensed in keratin-coated tablets known as emplets, which were passed unchanged through the bowel. Unfortunately, those that had been through the " amoebic mill " in 1914-18 had not been consulted about the treatment of amoebiasis in World War 1 and after. In 1944 he had published in the Lancet his technique of administering E.B.I. and the nursing and management of amoebic dysentery, as well as the dangers of administering E.B.I. in an unabsorbable form ; but his advice could not be carried out effectively because, as we have heard, of a shortage of the drug. Since then we have been flooded with antibiotic propaganda. All this has stimulated a wholesale and uncritical diagnosis of amoebiasis. The public had been led to believe that in India and East Africa, for instance, everyone is bound to contract amoebiasis. The term " amoebic " has come to have a sinister significance. You hear women saying at a party " I wouldn't have anything to do with him, Kitty, he is an amoebic " ; and actually at a social gathering it has been declared," We are all amoebics here." This is just pure "bogey," and amoebic dysentery is being depicted as the " Big Bad Wolf," but it was really nothing of the kind. The amount of misdiagnosis was unbelievable, and there was a dearth of trained technicians who knew their amoebae and had had a training in protozoology. The more he had travelled around latterly the more shocked he had become. In the consulting

130

DISCUSSION

room he had seen almost every known disease of the colon diagnosed primarily as amoebiasis and treated, sometimes for years, with e m e t i n e - gallstones and peptic ulcers were quite common, even arthritis of the spine, renal calculi and pregnancy have been referred as " amoebiasis." One was a lady who had had constipation, with an Entamoeba coli infection for 15 years, and had been under continuous emetine treatment. After cleansing enemata she had become a new woman. He regarded it as difficult to enumerate all the intricacies and unexpected surprises of amoebiasis. The E. histolylfca was a Puck-like creature and could pop up at odd moments. It had also the power of lying latent for long periods. He had had one lady patient who developed a liver abscess at 78, fifty years after the primary infection and a symptomless interval. In other cases the infection had been known to be present in the bowel for a similar period, so that the emaciation and debility this produced had been mistaken for carcinoma. But, he thought, the most tragic cases of all were those of colon carcinomatosis which had been mistakenly treated for amoebiasis until it was too late to operate. The facts and fallacies of the subject would fill a whole book. He was a whole-hearted believer in sigmoidoscopy and protoscopy, within reason, and they had paid him good dividends. He had been able to spot and diagnose amoebic lesions in the rectum and sigmoid which had been previously attributed to carcinoma, and to make the correct diagnosis by scraping the lesion and demonstrating E. histolytica ; but these procedures demanded prolonged practice and training on the part of the observer, and this is not always appreciated or understood. The question of symptomless carriers in this country and also abroad was a vexed one. He had seen genuine autochthonous amoebic dysentery of an acute type in London on two occasions when it had been mistaken for ulcerative colitis in certain large London hospitals. In both, the treatment had been immediately effectual. He was convinced that intestinal amoebiasis was a process of such infinite diversity that all degrees of invasion of the bowel wall could be encountered. Regarding the Bantu amoebic dysentery amongst Zulus in Durban, he had had the opportunity of seeing some of them and examining them by sigmoidoscopy. He was convinced that this was an extremely serious form of the disease with massive destruction of the bowel and extensive sepsis, and was quite distinct from anything he had seen anywhere else. T h e whole population was infected with a virulent strain of E. histolytica that attacked small children producing fulminant dysentery and in many, acute liver abscesses. Fulminating forms of amoebic dysentery had come his way, but were rare. He had every reason to believe that deaths from amoebiasis were relatively uncommon, and he had had only six in the first World War, although he had done hundreds of autopsies on dysentery patients. He believed that all " carrier " cases should be treated, because one could never be certain what would eventually happen, and because he believed that with the appropriate technique it could be shown that active invasion forms of E. histolytica were present in some portion of the colon in the bowel wall, and that they could live on the mucosa without seriously damaging it.

Group Captain W. P. Stature : I congratulate the opening speakers for their clear and concise expositions of the present position and for the very good sense contained in their remarks ; this, of course, is another way of saying that I agree with nearly all they said.

DISCUSSION

131

I would like to add my plea for a more moderate and rational attitude to the toxic effects of emetine. When I first entered the world of tropical medicine, we were constantly being warned of tile grave dangers of emetine, and I have heard the same battle-cry proclaimed on more than one occasion within this room. The emetine bogey has recently gained support from American work showing transient electrocardiographic changes during emetine treatment. How many other drugs in common use would be found to cause minor transient electrocardiographic changes if anyone bothered to look for them ? I have never seen any serious or permanent toxic effects in a patient treated with emetine and confined to bed. This exaggerated story of the toxicity of emetine has been largely responsible for the popularity of other less effective drugs. On visits overseas I am constantly finding relatively ineffective drugs being used instead of emetine, and am having to guide physicians back into the paths of righteousness after they have been led astray by some overseas practitioner. A lot of them, I am sure, think I am just old-fashioned. On the question of the difficulties experienced in Burma during the war and the apparent resistance of some cases to emetine, to which previous speakers have referred, we had some E.B.I. tablets analysed in 1944 and found them to be one-third of their reported strength. Several speakers have expressed the hope that the Services would be able to give figures for relapse rates after long-term follow-up. I regret that we are in much the same difficulty as you, since most of our patients are ex-overseas and due for release from the Service soon after discharge from the hospital. However, we are trying to improve the follow-up system and I hope we shall eventually be in a position to provide the necessary information. I have two pieces of evidence which give some support to Dr. Adams's opinion that asymptomatic amoebiasis is common in the tropics. We have carried out a 3-year survey of 180 Pakistani apprentices stationed in this country. Fifty-six per cent. showed E. histolytica cysts in their stools on one or more occasions, and 85 of these strains were tested for pathogenicity by R. A. Neal in the Wellcome laboratories. Only five gave a caecal count in rats of more than 2, and only one of the Pakistanis suffered symptoms referable to amoebiasis during the whole period. The other evidence is from our routine examination of patients invalided home from overseas. About 8 per cent. of these show E. histolyNca cysts in their stools. Many of them are patients in the Neuropsychiatric Centre, and these, if free from all physical symptoms, receive no treatment, as I consider the danger of producing a gut neurosis in such patients is greater than the danger from their cysts. Yet not one of these patients has returned to hospital with active amoebiasis at a later date. I am not, however, quite so confident as Dr. Adams that there is no need to treat asymptomatic cyst passers. We have all seen patients with liver abscess who have never had any symptoms of intestinal amoebiasis. By not treating symptomless cyst passers, are we leaving them open to the danger of developing a liver abscess ? Even his autochthoncus infections may not be completely free from danger. As a pathologist I applaud Dr. Adams's faith in that branch of the profession, but in 1918 Laidlaw reported the results of a special study made over a period of a year at Guy's Hospital, during which he particularly looked for signs of amoebiasis at autopsy He collected three cases in persons none of whom had ever been overseas, and none of the infections had been diagnosed during life. Apart from the neuropsychiatric patients already mentioned, we treat symptomless cyst passers with a 3-week course of diodoquine as out-patients, and have had very satisfactory results in those we have been able to follow up.

132

DISCUSSION

I join Sir George McRobert in taking issue with Dr. Adams on his advocacy of retention enemas. Evidence suggests that, even where lesions are visible in the lower bowel, there are usually many more out of enema range. Retention enemas are rarely given properly, and frequently reach little farther than the sigmoid colon. Furthermore, these are an unpleasant business for the patient. I have abandoned them for all but special cases such as one I saw recently. This patient's only complaint was of seeing blood on his stools which were normally formed. Sigmoidoscopy revealed numerous ulcers as far as his second valve of Houston, but a perfectly normal mucosa above this point. Microscopically there were numerous active E. histolylica. He, therefore, was ideal for treatment by enemas, but such a case is very rare. M a j o r - G e n e r a l A. S a c h s : I should like to add my own congratulations on the excellence of the two papers we have heard, and am in full agreement with what Dr. Adams has stated about treatment, except that in my own case I was treated with carbarsone without any ill effects. T h e r e is, however, one aspect which has not been covered, that is, the immediate post-treatment phase when the patient should be taught to live in symbiosis with his symptoms. I do not believe that it is generally realized how important this is, or how many cases have been wrongly diagnosed as relapses owing to a lack of appreciation of the fundamental pathology of the condition. I saw a n u m b e r of such cases in India, Persia, and Iraq which had been wrongly diagnosed as relapses, and the inefficiency of the drugs used blamed. T h e onset of the original symptoms in these cases was slow and insidious, and often months elapsed before a positive diagnosis was made. During this period there is damage to the gut wall with fibrotic changes, frequently commencing in the hepatic and splenic flexures of the colon. After treatment with emetine, etc., the patient is well enough until there is an indiscretion of diet ; e.g., a fatty bulky meal with a high cellulose content. This does, in some cases, lead to increased peristalsis followed by spastic colitis with an outpouring of mucus. Microscopic examination of this mucus does not reveal the presence of white or red cells or any protozoa - - it is in fact neither a bacillary nor an indefinite exudate. T h e specimens were also negative on culture. Strenuous exercise resulting in fatigue can also bring on similar symptoms which are very distressing to the patient. These symptoms after treatment can persist for as long as seven years. I feel it is of the greatest psychological importance to warn a patient that he may expect some bowel discomfort for quite a long time, and so prevent him from becoming introspective, then migrating from one doctor to another, and being the willing victim of unproved remedies that are so readily available for this type of patient. Dr. D. S. R i d l e y : T h e verdict on amoebicidal drugs is in the last resort determined by the search for Entamoeba histolytica in the stools, before and after treatment, yet there is at present no practical possibility of detecting it in all cases ; it is commonly estimated that six stool examinations on different days are required to find about three-quarters of all cases, and even six specimens are seldom possible as a routine. T h e object of investigation, therefore, usually has to be limited to the finding of as many cases as possible by as many technicians as are available, and in follow-up examinations a further limit is imposed by the number of specimens that the patient produces before he takes himself away ; acute cases fortunately are the least likely to be missed.

DISCUSSION

133

From this angle, the finding of the most cases from the fewest specimens in the shortest time, the formol-ether method of concentrating cysts has much to offer. It has been shown by Ritchie and others in the American Army, who described the method, that it is more efficient than zinc sulphate concentration. A simplified procedure, developed at the Hospital for Tropical Diseases, can be performed in no more than 5 minutes. Using this technique in an unselected series of 600 cases, the finding of E. histolytica cysts rose from a total of 23 cases by direct examination, to 51 after concentration ; this was comparable to the increase for other cysts or o v a - the totals being 144 positive results by direct examination, 300 by concentration. Comparing these results from single specimens with some earlier results from multiple examinations it was seen that, for an expenditure of 5 minutes, single concentrated specimens could be made to yield as many positive diagnoses as four or five specimens examined directly on different days. This concentration technique was used for the followup of the great majority of the cases in Professor Woodruff's series, and we have now adopted it as a routine. Its main advantage, however, over other concentration methods is that it concentrates all types of cysts and all ova without exception, and that it does so without causing distortion ; we have never found a cyst or ovum in a direct examination which has not been recovered by formol-ether concentration. Enthusiasm for concentration methods is modified by the consideration that they destroy vegetative amoebae and cellular exudate ; stools must be examined directly in many cases as well as after concentration. There is, however, a widely held belief that E. histolytica trophozoites are not to be found in formed stools. At the Hospital for Tropical Diseases, during 18 months' observation, not a single E. histolytica trophozoite was found in fully formed stool free of macroscopic blood and mucus ; examinations with results of the order of nil per thousand specimens are an uneconomic proposition, and though allowance must be made for the rather low incidence of trophozoites in our present material, it is safe to conclude that direct examinations should be limited as a general rule to loose or semi-formed stools, and to those that exhibit blood or mucus. This is not to say that present methods of finding amoebae are satisfactory. Failure to find trophozoites in chronic cases or relapses is now probably the most serious loophole in diagnosis and follow-up. It is in such cases that signaoidoscopy is occasionally successful when repeated direct stool examinations fail. REFERENCES RIDLEY, D. S. & HAWCOOO,B.C. (1956.) J. Clin. Path. in press. RITCHm, L.S. (1948.) Bull. U.S. Army Med. Dept., 8, 326. Colonel H, E. Shortt : I have listened with appreciation to the papers tonight, and from the attendance it is evident that many have been looking forward to an assessment by such well-known workers in this field of the present position of treatment of amoebic infection. It needs no emphasis, since most workers will agree, that the treatment of acute amoebic dysentery is an entirely different problem from that of a chronic and, possibly, symptomless infection. In this connection I have noted that in Professor Woodruff's series of infections both the large and small so-called races of E. histolytica were used indifferently, although admittedly the results were assessed separately. He quotes ".in view of the fact that it may give rise to the large invasive form and is therefore potentially pathogenic, infections with both forms of the parasite or their cysts were treated." But is this a fact or merely surmise ? If the latter, is the assessment of the effect of

134

DISCUSSION

drugs on a non-pathogenic parasite, or a parasite in a non-pathogenic phase, a reliable criterion of their value in a pathological condition ? Professor Woodruff used emetine bismuth iodide as his yardstick for comparison with other drugs. This was a good and practical procedure, but what has surprised me is the fact that, neither as a yardstick nor for comparison as an alternative treatment, has he mentioned the use of emetine by injection. My own experience, extending over a long time, has been that for the treatment of acute amoebic dysentery the drug which is the superior or even equal of emetine by injection has yet to be found. In any case he comes to the final conclusion that an emetine-containing drug is superior to all the newer remedies tried by him. With regard to Dr. Adams's paper there is hardly a statement made by him with which I would not entirely agree. His remarks about treatment instituted without adequate parasitic diagnosis are, as many of us know, only too true, and the subjects of " amoebic dysentery " from certain places abroad seem to constitute almost a majority of the population in these districts. These patients are often sorely disappointed if one cannot confirm the diagnosis in their cases, and one's reputation suffers in comparison with that of the previous medical attendant. He takes an unequivocal stand "on the subject of the needlessness of treatment in the Case of infections acquired in this country, and if these never give rise to even minor trouble one could only agree with him. This, however, raises the question as to whether the parasite responsible for these infections is, in fact, E. histolytica. I strongly endorse his opinion, that in acute amoebic dysentery, treatment with emetine hydrochtoride by injection is superior to any other form of treatment. With regard to the final eradication of infections, the choice of drugs is a large one and each will use those which have given him the best results. I myself have used one which I have heard condemned tonight I Professor B. G. M a e g r a i t h : I would like to say how much I agree in general with what has been said, especially by my colleague Dr. Adams and by Sir Philip. I wish to join issue with Professor Woodruff on one point - - and this may make me eligible for "amoebic danger money." I don't agree that the major problem of amoebiasis is its treatment. We have very efficient drugs, although we could do with cheaper ones. The major problem in amoebiasis, I think, is why and how the amoeba penetrates the gut epithelium ; why when several individuals are infected perhaps only one develops lesions ? Maybe this point will be discussed at the next symposium on amoebiasis. Dr. F. J. Wright commented on the apparent improvement in the clinical condition that may result from leaving the tropics, and raised the question as to the part played by environment and absence of repeated bacterial infections in establishing cure. Colonel L. R. S. M a c f a r l a n e : In spite of what Dr Adams has said, I feel I know something about amoebic d y s e n t e r y - my experience of it has, however, been an unusual and unfortunate one, as I was looking after prisoners of the Japanese in Siam. As emetine was often unobtainable, I have seen the behaviour of the disease untreated, and I am able to bear out Dr. Adams's statements. When we had any emetine we gave a small quantity of it to the patients most severely affected, in an endeavour to push them over the hill into the chronic stage. Where we had

DISCUSSION

13 5

no emetine, we tried a variety of other drugs and remedies, some quite fantastic, and including crude kurchi bark. The latter, incidentally, was not much use, but I did not see any of the psychotic complications referred to by Dr. Adams. In this way we apparently " cured " many patients, but again milder cases without treatment also apparently got better. Criteria of cure were difficult, and the Japanese difficult to convince. Many patients were free for months, only to become positive later. We were satisfied that in most cases the disease is self limiting, but were forced to the conclusion that it is doubtful if the parasite is ever completely eradicated. As regards non-pathogenic or differently pathogenic strains of amoebae, we had ample proof of this. Similar people in similar health reacted entirely differently as regards the severity of the disease. Some camps were notorious for particularly virulent " amoebic." One patient with no history of amoebic dysentery died suddenly from a heart attack following diphtheria. Postmortem his lower bowel was found to be full of ulcers. Another patient, completely symptomless, passed active E. histolytica for nearly 3 years. A word about acute amoebic dysentery : there has always been controversy about amoebic dysentery's being acute. A really acute amoebic dysentery without t r e a t m e n t passing up to 80 stools a day, once seen is never forgotten. I agree with the need for examination of stools by a competent parasitologist. To illustrate this - - recently I performed a histological examination for the Ministry of Pensions in a case of possible amoebic dysentery. The case-notes included the following laboratory report : " Active, precystic and cystic forms of amoebae." Dr. A d a m s (in reply) : A number of expressions have been used by contributors to this discussion which I personally very much dislike. These are the words " trophozoitepasser " and " cyst-passer " and, most objectionable of all, " cyst-carrier." I really do not know wherein lies the difference between a person passing cysts and a person passing amoebae, except in the consistence of the stools. By giving opium or some other const!pating drug to the person passing loose stools containing amoebae, the stools can be made solid and to contain cysts ; similarly, a person passing formed stools containing cysts can be made to pass amoebae by giving a small dose of a saline purge. Sir George McRobert and Group Captain Stamm do not like enemata. This is a matter of taste. I personally do - - for my patients - - because I find that in those who have an irritable bowel the increasing capacity to retain the enemata during the course of treatment inspires confidence in the result of the treatment. I hope that Sir Philip Manson-Bahr did not misunderstand me when I said that autochthonous cases of infection in this country never require treatment. They do so only on very rare occasions ; I myself have recorded one or two such cases in which acute amoebic dysentery has developed as a result of an indigenous infection. It was suggested by Dr. C. A. Hoare that in these cases, occurring in the great seaport of Liverpool, infections had been acquired with parasites imported by persons returning from the tropics. Group Captain Stamm has said that he found 8 per cent. of the individuals in a neuropsychiatric centre, repatriated from overseas, to harbour E. histolytica infections. I have already suggested that the infection-rate in the indigenous population of this country is at least 5 per cent., and it would be interesting to know what percentage of Group Captain Stamm's subjects took their infections out of the country and brought them back again, before their presence was disclosed. In reference to the use of the sigmoidoscope for diagnosis, I adhere to my previous

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statements that this is inferior in value to proper stool examination but, as Group Captain Stamm has said, there are a very few cases in which scanty lesions are limited to the lowermost portion of the rectum, and from these, parasites can be collected by scraping with great ease. Nevertheless, in even these cases parasites must reach the exterior and should be found in the stools though they probably are very localized on them. Major-General Sachs referred to the fibrosis which may occur in the flexures after attacks of amoebic dysentery, and the subsequent inconvenience that these may cause in the form of an irritable bowel with colic and the passage of mucus. I agree that this condition does occur in any form of colitis where there has been extensive destruction of the mucosa, and I would say it was particularly evident in severe cases of bacillary dysentery before the specific drugs became available, but much less so in cases of amoebic dysentery. If the new concentration technique referred to by Dr. Ridley is as simple and rapid to perform, and is as effective as he claims in producing parasites which are not damaged by the method of concentration, I personally shall be extremely glad to adopt it ; none of the concentration techniques at present advocated in my opinion is satisfactory for diagnosis, as most of them severely damage the parasites, and all of them take considerable time to perform. There is danger in undue reliance on a mechanical laboratory technique if it is imperfect. Colonel Shortt suggests that other forms of emetine may be equally as effective as E.B.I. in the eradication of intestinal amoebiasis. I can only say that during the war years, when very large numbers of subjects of amoebic dysentery were brought into Liverpool, we did use emetine injections, in place of E.B.I., and we also gave emetine hydrochloride by mouth in the form of " enseals " (Lilly) as an alternative to E.B.I., but found them to be less effective in ensuring sterilization. On the other hand, for many years we used emetine periodide by mouth in the form of auremetine (Martindale), instead of E.B.I., with satisfactory results. Finally, I have had an opportunity of seeing a great many ex-prisoners of war from the Far East, and I still see many of them when they are sent for what is called " a check up " at the Ministry of Pensions Hospital in Liverpool. I think that when these people suffered from any acute infections, including amoebic dysentery, in addition to the hardships, the avitaminosis, and the malnutrition which they had to endure in Japanese prison camps, they were prone to die. M y own experience is that those who came out of these camps alive made a very rapid recovery from their troubles, though many of them continued to harbour E. histolytica infections. Some cases of amoebiasis are still being disclosed on routine examination, though the persons involved now complain of no symptoms at all as a result of their infections. It may well be that they have come to live in a happier relationship with their parasites. Nevertheless I deem it expedient to eradicate these infections, as they may recrudesce. Professor Woodruff (in reply) : With regard to the treatment of acute amoebic dysentery mentioned by Colonel Shortt, I should like to draw attention to the fact that in my opening remarks I stated that our standard practice in such cases is to commence treatment with injections of 1 grain emetine hydrochloride administered daily for 3 days. This, as is generally recognized, rapidly brings the acute symptoms under control and from that point onwards the case in so far as treatment is concerned is similar to one which presents as a chronic infection. As Dr. Adams has stated, there are reasons for believing that the presence of

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cysts or of trophozoites in the stools of infected patients depends only on temporarily operating factors. Thus if a person whose stools had previously contained E. histolytica cysts should develop diarrhoea, the stools may then be found to contain E. histolytica trophozoites. As far as trials with amoebicidal drugs are concerned, therefore, it probably matters little whether the stool contains the cysts or the trophozoites. Trophozoites must in any case be present somewhere in the bowel to give rise to the cysts. It is, of course, well known that those who, possibly for years, have had E. histolytica cysts in the stools, may suddenly develop acute amoebic dysentery in which E. histolytica trophozoites will then be found in the faeces. Of our patients, the majority were treated because they had alimentary symptoms, the minority were found by routine stool examination to be infected, all had been abroad and almost all had had diarrhoea or dysentery while overseas. Although it is probable that amoebicides can be assessed as well in those passing E. histolytica cysts as in those passing E. histolytica trophozoites, an important consideration is that in the tropics as in the temperate zones the great majority of those infected are found to have cysts, not trophozoites, in the stools. Knowledge of the value of amoebicidal drugs in these cases is, therefore, of great importance. An indication that the cases we treated were no less di~cult to cure than cases encountered in the tropics, is the fact that with some of the drugs we used, notably camoform and the antibiotics, our results were inferior to those obtained by workers in the tropics. Infections in which large and small races of E. histolytica were present were not " used indifferently." Patients in whose stools the small race of E. histolytica was present, were treated, and the results of treatment in such infections were observed as an extension to the trials of the drugs' value in infection with the large race of the parasite. Results obtained in both types of infections are quite separately known as can be seen by reference to Tables VII and VIII. Colonel Shortt poses a highly misleading question in asking " . . . is the assessment of the effect of drugs on a non-pathogenic parasite, or a parasite in a non-pathogenic phase, a reliable criterion of their value in a pathological condition ?" This question falsely implies that the drugs were assessed only by their effect on he small race of E. histolytica whereas as can be clearly seen from the paper, while primardy studying the effect on the large race of E. histolytica, the opportunity was taken to observe their effect on the small one also, Regarding the pathogenic forms of E. histolytica, I understand that the current view as exemplified by Hoare (1949, 1952) is that there are two races of E. histolyti{a, and of these the minuta forms of the large race are potentially pathogenic and in certain circumstances may develop into the larger invasive forms, whereas the small race is non-pathogenic and can be separately designated E. histolytica hartmanni. Colonel Shortt has expressed surprise that we did not treat a series of patients with emetine given by injection. T h e reason for this, in brief, is that it is unjustifiable to use a drug generally recognized to be inferior to others in eradicating the infection. Emetine by injection is excellent for bringing acute symptoms of amoebic dysentery under control, but there is general agreement that it should be reserved for this purpose and for the treatment of hepatic amoebiasis. In my introductory remarks I stated that during the last war, one of the most important reasons why so much dissatisfaction was felt with the currently used methods of treatment of intestinal amoebiasis, was that to the majority of forces in the tropics emetine for administration by injection was the only drug available, and the results following its use were poor. At many hospitals it was not until 1945 that the much more effective emetine bismuth iodide could be obtained, and even then the supplies of it were strictly

13 8

DISCUSSION

limited. Payne (1945) also showed parenterally-administered emetine to be relatively ineffective in the disease. He reports that following its use, clinical cure is obtained in approximately 33 per cent. of cases, in a further 33 per cent. there is improvement with occasional relapses, and in the remainder there is either no improvement or else there are frequent relapses. Concerning the case mentioned by Dr. F. J. Wright in which diarrhoea regularly ceased when the patient returned to this country, and recurred regularly on the journey back to the tropics, I should like to ask whether psychological factors have been investigated in this and similar cases. Such a history would immediately suggest a psychological disturbance, possibly a conflict between a desire to live in this country and feelings that for moral, financial or other reasons, work in the tropics should be continued. Finally, concerning Professor Maegraith's statement that regarding amoebiasis the most important problems concern not treatment but the reasons why, on being infected, one person develops overt disease and another does not, I should like to say that this is not a problem which specifically concerns amoebiasis. Exactly the same sort of thing happens in typhoid and paratyphoid fevers, in brucellosis, cholera, bacillary dysentery, and in fact in almost all infections taking place by the intestinal route. The problem is, therefore, a general one, and this is a " Symposium on the treatment of amoebiasis." REFERENCES

HOARE, C. A. (1949). Handbook of medical protozoology.for medical men, parasitologists and zoologists. Bailliere, Tindall and Cox, London. (1952). Experimental Parasitology, 1, 411. PAYNE, A. M. M. (1945), Lancet, 1, 206.