Balantidial dysentery: A human case in Northern Ireland

549 TRANSACTIONS OF THE ROYAL SOCIETY OF TROPICAL MEDICINE AND HYGIENE. Vol. 51. No. 6. November, 1957.

BALANTIDIAL DYSENTERY:

A H U M A N CASE IN N O R T H E R N IRELAND BY

C. C O T T O N K E N N E D Y , M.A., D.M.*

Consultant Clinical Pathologist, Belfast City Hospital AND T./Major R. C. S T E W A R T , Mm., INCH., mA.M.C.

Late Senior House Officer in Clinical Pathology, Belfast City Hospital

Balantidial d y s e n t e r y - balantidiasis, ciliate d y s e n t e r y - is caused by infection with the protozoon, B a l a n t i d i u m coll. It remains a rare disease, although human cases have been reported from all over the world. MALMSTEN (1857) discovered B. coli in two patients suffering from chronic diarrhoea, one of whom died. In the first patient, he examined microscopically thin blood-stained pus from an ulcer in the rectum and noticed that it contained, as well as pus cells and red blood corpuscles, a large number of small living animals. After the ulcer had healed these same microscopic animals, to his surprise, were present in the faeces, showing that they " existed not only in the wound, but in other parts of the intestine." He tentatively named the organism, Paramaecium(?) coll. LEUCKART(1861) found a similar ciliate in the intestine of pigs, and considered it identical with that described by Malmsten in his human cases. He appreciated that it might be possible for the infection to be conveyed to man. Stein placed the organism in the genus Balantidium because of its clear relationship to Balantidium entozoon (Ehrenberg) of the frog, so that the name is now Balantidium coli (~[ALMSTEN, 1857) STEIN, 1862.

Hosts

Balantidia have been found in the intestinal contents of man and a large number of animals. According to AWAKIAN (1937) balantidia are widespread in the animal world : " man, monkeys, pigs, wild boars, sheep, horses, bovines, guinea-pigs, fowls, fish, turtles, frogs, cockroaches, etc." They have been reported from 33 different hosts. Domestic pigs are much the most important reservoir hosts as far as man is concerned ; investigations have shown that a large percentage throughout the world is infested with this parasite. Apparently Balantidium lives as a harmless commensal in the pig ; the latter appears to be unaffected and no pathological lesions have ever been demonstrated (WALKER, 1913 ; RaTCLIFFE, 1934; FRENKIEL, 1936; A~VAKIAN, 1937). DISTRIBUTION AND FREQUENCY OF OCCURRENCE The subject of this paper is only the third case to be described in the British Isles.

In

E n g l a n d MACKENZIE a n d BEAN (1938) a n d ROBERTSON (1943) r e p o r t e d the two p r e v i o u s * We wish to thank Dr. C. M. B. Field, Belfast City Hospital, for permission to publish this case. We are grateful to Professor B. G. Maegraith for suggesting treatment with fumagillin and kindly supplying the first batch of the drug. Our thanks are also due to Mr. A. McLean, M.R.C.V.S., who obtained the faeces for our survey of balantidial infestation among pigs at the Belfast abattoir ; and to Dr. V. D. Allison, Central Laboratory, Belfast, for reading the manuscript.

550

A CASE OF BALANTIDIALDYSENTERY

infections. Both occurred in patients in different mental hospitals. The first, a female, had never had contact with pigs ; whereas the male patient described by Robertson was in charge of the hospital piggery. The comparative rarity of balantidial dysentery in man was noted by SHEGALOW(1899), who stated that only 63 cases had been recorded up to that time. Recently, ARE£N and KOPPISCH (1956) in a review of the literature, affirmed that about 600 cases had been reported in which B. coil was the sole or main parasite causing colitis. The apparent incidence of B. coli infection in man shows a wide variation. The examination of large numbers of human stools in various parts of the world in the selected groups of those with, or thought to have, intestinal disease, seems to indicate that B. coli infection is comparatively rare (SERRA, 1931 ; PRIESTLEY, 1944; SHOOKHOFF, 1951 ; FORSYTH, 1954). ROBEI~TS(1949), in his protozoological and helminthological survey of three races in Nairobi hospital patients, examined nearly 80,000 stools and found " no more than six cases " of balantidial infection. In England DOBELL (1921) and his fellow-workers examined the faeces of over 3,000 persons who had lived all their lives in Britain. Almost all were healthy subjects not suffering from any intestinal complaint ; and although several species of protozoa were identified, no B. coli were found. Reports from certain regions of the world, however, make it clear that there the disease in man is not of exceptional rarity. These countries include Persia (STEWART, 1949; MCCAREY, 1952), Puerto Rico (ATILES, 1943 ; BURROWSand JAHNES, 1952), the Philippine Islands (BowMAN, 1911 ; WALKER, 1913), parts of Central and South America (AGmLAR, 1925 ; CRUZ, 1955) and in certain regions of Russia (KIPSCHIDSE, 1928 ; FERRI, 1943 ; STSHENSNOVITSH, 1943). During one rainy season in Guatemala, AGUILAR(1925) reported that 40 patients admitted to hospital had balantidial infection. This figure represented almost 10 per cent. of admissions. In his survey of intestinal parasites in over 2,000 of the population of Azerbaidjan, STSHENSNOVITSH(1943) found that 5.1 per cent. were infested with B. coli. Children

In children the disease appears to be even rarer than in adults. This is perhaps surprising in view of the unhygienic habits of young children, who early indulge in oral and manual appraisal of objects. 1918

A m o n g those who have reported infections in children are SHEGALOW, 1899 (1 case) ; DE BuYs, (1 case) ; HERMITTE, SEN GUPTA and BISWAS, 1926 (3 cases) ; SEItRA, 1931 (1 case) ; PAltONI,

1933 (1 case) ; LIu, 1941 (1 case) ; FERal, 1943 (11 cases) ; ATILES,1943 (4 cases) ; SHUN-SHIN, 1947 (7 cases) ; HALAWANIand EL KORDY,1948 (1 case) ; and ARE~.Nand KoPplSeH, 1956 (3 cases). On the other hand, SHOOKHOEE(1951), who had experience of 20 cases in children, stated that B. coli infection " has a predilection for children, and among children, for males." MODE OF INFECTION

Despite man's close contact with pigs in many countries, human balantidial dysentery is still a rare disease. From a review of the literature AREANand KOl~PISCH (1956) estimated that in more than 50 per cent. of cases there was a history of contact with pigs. It is probable that man is most often infected by fingers, food, drinking water or soil contaminated by pig faeces containing balantidia, usually in the encysted form. AGUILAR(1925) and CRAIG and FAUST (1943) drew attention to the possibility of infection from green vegetables, the latter pointing out the danger in the use of pig excrement as a fertilizer. The cysts may remain viable for weeks in moist faeces.

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551

P u b l i s h e d a c c o u n t s i n d i c a t e , h o w e v e r , t h a t it c a n n o t b e a s s u m e d t h a t all p a t i e n t s w i t h b a l a n t i d i a l d y s e n t e r y h a v e c o m e i n t o close c o n t a c t w i t h p i g s o r o t h e r s u s c e p t i b l e animals. T h e r e are m a n y r e p o r t s w h e r e no s u c h r e l a t i o n s h i p existed. ( F o r e x a m p l e , MACKENZIE a n d BEAX, 1 9 3 8 ; YOUNG, 1 9 3 9 ; MCCAREY, 1 9 5 2 ; FORSYTH, 1954). A l s o TSUCHIYA a n d KENAMORE (1945) f o u n d no h i s t o r y of c o n t a c t w i t h pigs o r e a t i n g o f u n c o o k e d p o r k in t h e i r r e p o r t o f a case. T h e y c o n s i d e r e d t h e p o s s i b i l i t y o f house-flies h a v i n g a c t e d as v e c t o r s ; a n d t h e y s u g g e s t e d this m i g h t h a p p e n a n y w h e r e w h e r e b a d s a n i t a r y c o n d i t i o n s a l l o w e d flies access to p o t e n t i a l l y i n f e c t e d p i g faeces. ASH a n d SPITZ (1945) a n d BLACKLOCK a n d SOUTmWLL (1948) w e r e also of t h e o p i n i o n t h a t t h e disease c o u l d b e t r a n s m i t t e d b y flies. I n t h e o u t b r e a k o f b a l a n t i d i u m i n f e c t i o n a s s o c i a t e d w i t h d i a r r h o e a a m o n g t h e p r i m a t e s at t h e L o n d o n Zoo, COCKBURN (1948) c o n c l u d e d t h a t p r o p a g a t i o n b y flies was t h e m o s t likely m e t h o d o f i n f e c t i o n a n d a c c o u n t e d for t h e s c a t t e r e d d i s t r i b u t i o n o f cases. CASE REPORT

Past History. The chiid (James C.) was first seen at another Belfast hospital in April, 1950. He was then aged 5 years, and for about a year had been suffering from diarrhoea and failure to thrive. He was small for his age, wasted and anaemic, with a protuberant abdomen. A diagnosis of coeliac disease was made. Dietary treatment was instituted and for a month or two he responded well at home on this r~gime, and then relapsed. T h e diarrhoea returned and varied in intensity, with periods of remission. On February 12, 1951, he was admitted to a provincial hospital ; he was having eight to 10 motions daily, with the passage of blood and mucus. A tentative diagnosis of tuberculous peritonitis was made and two days later he was transferred to the Belfast City Hospital. On examination, he was thin and wasted, with a protuberant, doughy abdomen and he looked anaemic. His weight was 39} lb. T h e following investigations were carried out : Mantoux test, negative. Blood count : Hb., 60 per cent. (8.88 g. per 100 ml.) ; R.B.C., 4,000,000 per c.mm. ; W.B.C., 11,400 per c.mm. E.S.R., 4 ram. after 1 hour (Westergren). X-ray examination of chest and abdomen (including barium rhea1 and barium enema) : no abnormality noted. Fasting gastric juice : no acid-and alcohol-fast bacilli detected on two occasions. Faecal fat : 17 per cent. of dried faeces (67 per cent. split, 33 per cent. u,asplit). Faeces : no intestinal pathogens were cultured initially, but Shig. sonnei was isolated later during an outbreak of dysentery in the ward. This infection disappeared rapidly with sulphonamide therapy. Sigmoidoscopy : no abnormality detected. As a diagnosis of coeliac disease had previously been made, he was put on a coeliac diet and the diarrhoea slowly improved. When discharged from hospital on June 23, 1951, on a fuil diet he was having two normal motions daily. This improvement did not last for more than a few months and at home he continued to have intermittent bouts of diarrhoea. On December 3, 1951, he was seen at the Out-Patient Department and appeared to be fairly welt, the diarrhoea having undergone a temporary remission. During the next 10 months the diarrhoea became persistent and there was some loss of weight. He was eventually readmitted to hospital on November 1, 1952. T h e diagnosis of coeliac disease was thought to be correct and he was treated with vitamin B complex and a gluten-free diet. His general condition improved greatly and in one month his weight rose by 4-} lb. to 47-} lb. X-ray examination of chest and both hips showed no abnormality. He was discharged on December 12, having two normal motions a day. T h e diarrhoea returned in a short time, however, and he was again admitted to the local country hospital and he remained there from February 3, 1953, for 5 weeks. The customary improvement with dietary treatment took place, to be followed by the familiar picture of relapse inside a few months. On August 11, 1953, he was readmitted to the Belfast City Hospital in poor condition. His weight was now 46} lb. : i.e., 1 lb. lighter than 8 months previously. He was more anaemic than before and his haemoglobin level was 40 per cent. (5.92 g. per 100 ml.). Culture of the faeces failed to reveal any intestinal pathogens. X-ray examination of both upper and lower limbs showed no bony abnormality. He was again placed on a strict dietary r6gime, and one pint of blood was transfused on August 20. He was discharged 4 days later, the haemoglobin now being 60 per cent. (8.88 g. per 100 ml.) and the diarrhoea improved. However, the familiar pattern of relapse was again repeated and he was readmitted to hospital on December 7, 1953. Several further investigations were made, with negative results. He was discharged in 15 days, and returned to have a sigmoidoscope examination on February 11, 1954. Apart from worms, adjudged to be threadworms, which were present in the rectum, no abnormality

552

A CASE OE B A L A N T I D I A L

DYSENTERY

was noted. Sigmoidoscope examinations were again carried out on February 25 and March 4, with similar findings. The Mantoux test remained negative, and the barium enema X-ray examination was again normal. No intestinal pathogens were isolated from the faeces. Ova of Trichuris trichiura were seen on what now appears to be the first occasion on vehich the faeces were examined microscopically, and the adult worms were detected by naked eye. (These latter were probably mistaken for threadworms when seen during the sigmoidoscopy). " Nyxolan "~ (aluminium 8-hydroxy-quinoline sulphate), 1 oz. four times daily, was given in an unsuccessful attempt to eradicate the whipworm infestation. He was returned home on March 6. The now familiar cycle of remission and relapse occurred, and on August 18, 1954, the child was admitted to hospital for the ninth time. His weight was 48{- lb. Haemoglobin level was 66 per cent. (9.77 g. per 100 ml.). E.S.R. : 6 ram. after ] hour (Westergren). Mantoux test (1 in 1,000) was strongly positive. X-ray examination of chest again showed no abnormality. Barium meal and follow-through X-ray examination : rapid passage through small intestine ; otherwise nothing abnormal noted. Faeces : no intestinal pathogens isolated ; ova of T. trichiura still present ; no active trypsin detected. Benzidine test for occult blood: positive. He was again treated with Nyxolan in the hope of eliminating the helminthic infestation, but without success.

History since B. coli was detected. On September 8, I954, one of us (R.C.S.) noticed a large highly motile ciliated protozoon in a direct microscopic examination of the faeces. This was recognized as B. coli and a diagnosis of balantidial dysentery was established. Once the diagnosis was known, the importance of examining freshly passed faeces soon became evident. M a n y specimens which showed large numbers of actively motile trophozoites on first examination contained none, or only a few sluggish forms, inside 30 minutes. On the other hand, in some samples motile balantidia persisted for up to 6 hours or even longer. All faecal specimens examined were unconcentrated. Stools at this stage, some six to eight a day, were fluid and offensive, with blood and mucus. Microscopic preparations showed numerous leucocytes and red blood ceils, and undigested food particles: ova of T. trichiura were constantly present. No cysts or vegetative forms of Entamoeba histolytica were ever found. On September 16, before the onset of any treatment, several encysted forms of B. coli were seen. This is a rare finding in balantidial dysentery in man, and they were noticed only on this single occasion. A m o n g others who have reported this occurring in h u m a n infections are YOUNG, 1939 ; HALAWANIand EL KORDY, 1948 ; ]~LACKLOCKand SOUTHWELL, 1948 ; and SHOOK~OFF, 1951. T h e child showed no indication of mental deficiency. An intelligence test established that he was slightly backward for his age ; but this was probably due to prolonged absence from school on account of chronic illhealth.

Source of infection T h e balantidial infection was almost certainly contracted in the unhygienic surroundings of the boy's home. He lives in a provincial town in Northern Ireland in a poor, dirty, narrow street on the side of a hill. T h e house itself is small and sunless ; five y o u n g children and the two parents are accommodated in the living room, kitchen and two bedrooms. T h e living room, when the house was visited on one occasion, was dark, dirty, untidy and malodorous. Crusts of bread lay scattered about, flies abounded everywhere in large numbers and a dog lay on one of the few chairs in the room. There was no running water in the house, the water being obtained from a p u m p in the street. Sanitation was primitive : a bucket latrine at the rear served the purposes of the household, and the excrement was * Hommel's Haematogen & Drug Co., London.

C. COTTON KENNEDY AND R. C. STEWART

553

buried in the garden. The house is considered fit for human habitation, although the occupants have been warned several times by the local health authorities regarding the unclean state of the premises. Opposite the house, 10 yards across the street, is a small yard where a neighbour keeps 12 pigs in three pens. The effluent from this yard, which is closed from the street by a wooden gate, flows through a grating to join the main sewer. Surplus washings from the pigsty are brushed from the yard towards a gutter in the street. The child's father, aged 38 years, is an unemployed labourer. He was in the army for a short time during the war ; he never served abroad, nor has he ever had any intestinal complaints. His wife, aged 40 years, has never been out of the country and also has never had any bowel trouble. The other members of the family, two boys and two girls in addition to the patient, aged 11 years, 8 years, 3 years and 1 year, are in good health, and apart from the usual childhood infections have never been ill. James, on the other hand, has never been well and his habits as well as his health have caused his parents considerable anxiety. He suffers from pica ; he is a known dirt-eater and on many occasions his mother has had to chastise him for eating dirt from the street with a spoon. A hole in the wall of the living room testifies to his habit of devouring the plaster. James is at school most of the day, but after hours he frequently gives a helping hand with the pigs across the street, and it is from this source that his infestation in all probability originated. Examination of several samples of faeces from these pigs showed both vegetative and cystic forms of B. coll. Dirt, both at the street entrance to the pigsty and on the street outside the house, also revealed active trophozoites. It is almost certain that the child was infected by eating dirt contaminated by pig faeces which contained B. coli. At present, in this town where the human balantidial infection occurred, the local urban district council has not adopted bye-laws relating to the keeping of animals in, or near, dwelling-houses, although many authorities in other areas prohibit the keeping of pigs within distances ranging from 26 feet to 150 feet. Faeces from the other six members of the family and from the pig owner and his son were submitted for examination, but no B. coli were seen ; however all eight specimens were found to contain ova of T. trichiura. TREATMENT

AND

PROGRESS

MANSON-BA~R (1944), who cited 19 different drugs and treatments for balanfidial dysentery, wrote, " At present therapy is purely empirical." KopPISCH and WILKING (1947) stated that no generally specific drug had been found. Treatment with piperazine hydrate, in the form of " Antepar " elixir,* 2 teaspoonsful b.d., was started on September 20, 1954, and continued for 7 days. The day after the onset of treatment an unusualIy large number of very active balantidia were seen in =the faeces (as many as 13 in one low-power microscopic field), but the drug failed to eliminate either the B. coli or the T. trichiura infestation. On the 3rd day of treatment one trophozoite of B. coli exhibited the comparatively rare bubble-like " oral plug " at the peristome. (McDONALD, 1922, considered that in all probability this protrusion effected closure of the cytostome, because it is a mobile structure and contains fibres of the neuromotor apparatus). e Burroughs Wellcome & Co., London.

554

A

CASE OF BALANTIDIAL

DYSENTERY'

It was decided to try treatment with fumagillin, and on 28 September, 1954, this was begun in the form of "Fumidil"*, 10 mg. daily, and continued for 10 days, without lasting beneficial effect. Trophozoites of B. coli were present in the faeces on the 1st, 5th, 6th and 10th day after treatment, and absent on the remainder of the 10 days. Active vegetative forms of B. coli continued to be present, and on October 13 a second course of Fumidil, 20 mg. daily, was commenced. This, however, had to be stopped on the 7th day because the child developed anorexia, a stye of the right eye, and a pustular rash on the face. Staphylococcus aureus was cultured from a pustule. Culture of the faeces showed that no staphylococci were present. T h e white cell count was normal. While the facial rash cleared, a stye appeared in the other eye. Vitamin B therapy was instituted, followed by " F e r r o m y n " t (ferrous succinate) tab. i,t.d.s, a week later. The haematological findings 2 weeks before the fumagillin treatment was started showed an iron deficiency anaemia, with an eosinophilia. Hb., 63 per cent. (9.32 g. per 100 ml.) ; R.B.C., 4,610,000 per c.mm. ; C.I., 0.68 ; P.C.V., 32 per cent. ; M.C.V., 70 c.microns ; M.C.H.C., 28 per cent. ; W.B.C., 10,100 per c.mm. ; E.S.R., 8 mm. after 1 hour (Westergren). Film : neutrophils 51 per cent., eosinophils 13 per cent., basophils 2 per cent., lymphocytes 31 per cent., monocytes 3 per cent. ; microcytosis -4-, poikilocytosis 4-, hypochromia 4-. On November 3, after treatment with Ferromyn (duration of treatment not recorded), the haemoglobin level had been raised only 6 per cent. to 69 per cent. (10.2 g. per 100 ml.). Trophozoites of B. coli were present in the stools on the 1st and 2nd day of treatment with the larger dose of fumagillin, and absent on the following 3 days, when the drug was stopped. Ova of T. trichiura were still present. Because toxic effects necessitated withdrawal, an accurate assessment of fumagillin in this condition cannot be made. It is quite common for the parasite to disappear for a few days from the faeces without treatment, only to return later. Fumagillin, therefore, may, or may not, have a balantidicidal action in vivo, but experience in this case suggested that it was unlikely to eradicate the infection, because 6 days after stopping the drug, active trophozoites reappeared in the faeces. T h e child recovered rapidly from the side-effects of fumagillin ; he was given a rest for 2 weeks, then treatment with stovarsol (acetarsol) was instituted. Stovarsol was chosen because of the beneficial results claimed for it by BERNARD and T~OMAS (1924), AGUILAR (1925), HERMITTE, SEN GUPTA and BISWAS (1926), LIu (1941), and ATILES (1943). In what appears to be the largest single group of cases of balantidiasis recorded, McCAREY (i952) in 9 months investigated 87 patients in Abadan, South Persia. H e claimed that stovarsol was a specific treatment. H e tried several other drugs without success, and thereafter 61 patients received stovarsol, all of whom were considered to have been permanently cured. Accordingly, 2 grammes t.d.s., was commenced on November 4, 1954, and maintained fer 5 days. In the rest period before stovarsol treatment was started, many specimens of faeces were examined and numerous B. coli trophozoites were seen, although they were absent for the 7 days before stovarsol therapy was instituted. On one occasion budding, in this species relatively rare and possibly a mode of reproduction, was observed. After stovarsol was given no further active trophozoites or cysts of B. coli were identified. On the 4th day of treatment a few dead forms were recognized. For 11 days after treatment was discontinued two or more freshly passed specimens of faeces were examined daily, and on no occasion was the parasite seen. Benzidine tests for occult blood remained negative. T h e patient returned home and he has been brought back to hospital three times since then, Abbott Laboratories, London. t Calmic, Ltd., London.

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in January and May, 1955, and again in December, staying until January 7, 1956. T h e follow-up period has thus been just over 14 months ; scores of freshly passed stools have been examined microscopically and no trophozoites or cysts of B. coli have been found. T h e 7". trichiura infestation has remained unaffected ; nor did it respond to 0.5 per cent. hexyl resorcinol retention enemata given on 5 successive days. The child's general condition has improved greatly and his weight on the last occasion had risen to 60 lb. The haemoglobin level in May, 1955, reached 90 per cent. (13.32 g. per 100 ml.), although in January, 1956, it was 83 per cent. (12.28 g. per 100 ml.). The eosinophilia was still present. Total serum proteins were 7.0 g. per 100 ml. (albumin 5.0 g., globulin 2.0 g.), The eleetrophorefic pattern was normal. He still has frequent motions, but apparently less than formerly. The stools vary in appearance and consistency ; they may be normal or loose, with or without mucus, although no blood is now present. COMMENT

DOBELL (1921) wrote : " It is now generally accepted that B. coli is a parasite proper to the pig, from which animal man may occasionally acquire an accidental infection. Swineherds and others particularly associated with pigs are especially liable to balantidiosis. In parts of the British I s l e s - e.g. in rural I r e l a n d - conditions conducive to infection are apparently not lacking : and one would expect human cases of balantidivsis to occur, from time to t i m e . . . It seems, therefore, somewhat remarkable that no human cases [in Britain] of balantidiosis are yet on r e c o r d . . . " In the British Isles where pig-breeding is on a large scale, where p o r k products form a large part of the diet, and where many persons must come into close contact with pigs, it is surprising that balantidial dysentery is almost unknown. Apparently human subjects are not easily infected ; if the protozoon can pass the barrier of the gastric juices perhaps a lowering of resistance on the part of the host becomes necessary before infection can take place. Or, if infection occurs, the carrier may remain free of symptoms. Another possibility is that balantidial dysentery is not in fact as rare as generally supposed, but that it is not being considered in cases of chronic diarrhoea where there is association with pigs. This applies particularly where the personal hygiene of the patient is defective. After the experience of the present case, it is felt that the disease may be far from rare. ~ If stools are to be examined for B. coli it is stressed that the faeces must be fresh and first examined under the low power of the microscope : if this is not'done the delicate, strikingly motile ciliate may be overlooked. BALANTIDIAL INFECTION IN PIGS

A high percentage of pigs is infected with B. coli. Healthy domestic pigs in many countries have been investigated and some of the findings are shown in the Table. Until this present article the incidence of balantidial infection in healthy domestic pigs in the British Isles does not appear to have been reported. JAMESON(1927), in his experiments on the cultivation of B. coli, obtained faeces from the caeca of freshly killed pigs in Cambridge, but did not record the n u m b e r infected. We acquired our material from the caeca of healthy pigs immediately after slaughter in the Belfast abattoir. Unconcentrated faecal suspensions * Since this case was reported, in the Public Health Laboratory Service's (Medical Research Council) weekly summary of the distribution of infectious diseases, based on reports from public health and hospital laboratories in England, Wales and Northern Ireland, dated 14th January, 1956, there appeared the following : " Swindon, For several weeks an organism resembling Balantidium coli has been found in the faeces of sporadic cases of diarrhoea in children. This week the organism has been found in the faeces of 3 children in 1 ward in a hospital."

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A CASE OF B A L A N T I D I A L DYSENTERY

TABLE. Balantidial infection in healthy domestic pigs. Author

Country

Number of pigs examined

Percentage harbouring balantidia

Shegalow, 1899

Russia

200

21.5

McDonald, 1922

U.S.A.

200

68

Ohi, 1923

Formosa

Kipschidse, 1928

Not stated

" More than 60 "

Russia

210

63.3

Knauff, 1935

Germany

480

65

Awakian, 1937

Russia

200

100

86

32

100

74

Roberts, 1949

[ Kenya I Kennedy and Stewart (this article) ] N. Ireland

were examined within 2 hours of death. Of 100 pig faeces examined 74 were infested with B. coli; of the latter 40 showed trophozoites only, while cysts alone were found in 12. Both trophozoites and cysts were present in the remaining 22. The finding of trophozoites alone more than three times more often than cysts alone was not expected. In cases where man is thought to have been infected from the pig, the infecting protozoon is usually considered to have been in the cystic state. The explanation may be that in pig droppings cysts are more numerous than in the caecum, the majority having been formed more distally in the intestine. In consequence there is a diminution in the number of vegetative forms in faeces which have been voided. Similarly, FRENKIEL (1936), in his survey of pigs slaughtered at the Lausanne abattoir, found cysts chiefly in the large intestine, while vegetative forms predominated in the caecum. EXPERIMENTS TO ASCERTAIN THE ROLE OF FLIES In these experiments pig faeces containing both cysts and trophozoites of B. coli were placed in a petri dish at the bottom of a large glass jar with a perforated lid (" mouse jar "). Flies were introduced and allowed to fly around and alight naturally on the faeces. When they had walked over the faeces for times varying from 10 minutes to 3 hours they were killed with chloroform, and their legs were removed and examined microscopically. In this way balantidia were demonstrated adhering to the legs, thus incriminating them as possible vectors in the spread of balantidial dysentery. Judging by these experiments, it is thus probable that in nature flies can act as mechanical carriers of B. coli, the protozoa being conveyed in the faecal material sticking to the flies' hairy legs. SUMMARY l) Balantidial dysentery in a 10-year-old boy, who had suffered from chronic diarrhoea for over 5 years, and had spent much time in hospital, is presented. This is only the third human case of balantidiasis reported in the British Isles. He was almost certainly infected by eating dirt mixed with pig faeces containing Balantidium coll.

C. COTTON KENNEDY-AND R. C. STEWART

557

2) A cure with stovarsol (acetarsol) is claimed. In a follow-up period of 14 months no further B. coli have been detected in the stools and the patient's general condition has very much improved. 3) In a survey of healthy pigs slaughtered at the Belfast abattoir the incidence of B. coli infestation was 74 per cent. 4) Experiments with flies suggested the possibility that they could act as mechanical carriers of B. coli. 5) Because balantidial dysentery usually occurs in insanitary surroundings, particularly where personal hygiene is faulty and where there is an association with pigs, it is suggested that in the routine investigation of such patients suffering from unexplained diarrhoea their faeces should be examined for B. coli. It is emphasized that faeces must be fresh and the parasite first sought by employing a low magnification of the microscope.

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A CASE OF BALANTIDIAL DYSENTERY

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