Experimental investigation of measles

EXPERIMENTAL

INVESTIGATION OF MEASLES

GEOFFREY I:~AKE,

M.D.

N E W BRUNSWICK, N . J .

A S L E S is of the most prevalent of human virus diseases, MEsince some 9 ~ per cent of people in civilized countries suffer from it at some time in their life. Yet, despite the fact that it is widespread and that prior to the use of sul2onamide drugs it caused a high mortality, particularly in young children, comparatively little work has been done with the agent or with the experimental disease in the laboratory. The reason for this is simple. Despite many attempts, the virus has been successfully transmitted only to p r i m a t e s - - p a r t i c u l a r l y Macaca mulatta. E v e n in these it is a mild disease with evanescent signs and symptoms which tend to disappear on animal passage. I n addition to this lack of a Satisfactory experimental animal and p a r t l y on account of it, no serologic reaction has yet been developed with the virus comparable to those proving such useful tools in investigation of o~her virus diseases. The many attempts which have been made to cultivate the virus of measles b y one or other of the techniques used for other viruses have been reviewed elsewhere. ~ I t will perhaps suffice to say that some authors have reported failures, while the claims to success of most of the others of cultivation on the membranes of the developing chick, in tissue culture, or in symbiosis with bacteria are open to doubt on one ground or another. In fact, up to 1938 only the results of Plotz, 2 with tissue, would seem to have been certainly successful. F o u r years ago we began a study of the cultivation oi this virus in the developing chick embryo and in tissue culture and have succeeded in growing it not only in tissue culture 3 and on the chorioal]antois, 4, ~ but also in the amniotic and allantoic cavities. Most of the cultivation has been made by the Burner technique on the chorioallantois. Of twenty-seven attempts to establish strains, seventeen, have been successful a n d one of those has been propagated through 120 passages during more than seventeen months. I t should be noted that cultivation has been possible in the absence oi any regularly occurring lesions in the chick or its membranes. At first indeed, the only way of assuring o~rselves that the strain was being successfully maintained was by inoculation of the egg material into monkeys. This produced characteristic measles, but the disease, never v e r y severe, tended to become even milder with the use of material from later passages. I t seems F r o m the Squibb Institute for Medical :Research. Presented at a Panel Discussion on ~Virus Infections. Twelfth Annual :Meeting of the American Academy of Pediatrics, Chicago, Nov. 5, 1942. 376

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0E MEASLES

possible that failures reported by other investigators may be explained in part by this lack of any striking evidence of the presence of the virus either in the embryo or in the monkey. Despite the lack of any such striking evidence, passage material which had been tested to exclude the presence of contaminating bacteria or other viruses was injected into children, originally in collaboration with Dr. Joseph Stokes, Jr., Dr. O. C. O'Neil, and Dr. E. P. Maris of the Department of Pediatrics of the University of Pennsylvania.~' 6, ~ The very mildness of the disease produced in monkeys, indeed, led us to hope that the disease in children might be milder than that seen in nature; while the fact that monkeys which had developed measles from egg-passage virus were immune to challenge inoculations with infected human materiaP, ~ suggested that the vaccination disease might produce a similar immunity in man. TABLE I ]:~ESULTS IN PHILADELPHIA PI%IO1%TO JUNE~ 1942 1%OUTE OF INOCULATION

t. / MODEIKATE

MILD

TYPE OF DISEASE M I N I M A L DOUBTFUL

NONE

Past H~story ~'ro~ Physidazns I n t r a n a s M drip Subc. Intradermal Inhalation spray

5

4

2

15 5

31 10

43 22

25 (14%) 45 (24%). 67 (36%) Past Histo.r~y Frown Parents I n t r a n a s a l ~lrip Subc. Intradermal Inhalation spray

2 2 4 (6%)

16 3 21 1

3 2 1

41 (22%)

6 (3%)

~t

5

5

5

18 2

4

19 4 2

8 (11%)

25 (35%)

9 (13%)

25 (35%)

The expectations have been at least partially ~ulfilled. Measles has been produced in the majority of children by the use of egg-passage material which gave in the monkey only mild and transitory disease, and human inoculation has thus confirmed that the virus of measles was being successfully propagated and that the mild syndrome in the monkey was indeed measles. Furthermore, the disease in children has been in almost every instance milder than the mildest eases of the natural infection. I shall describe in more detail the disease in the children and then refer briefly to the evidence now accumulating on the protection afforded by the vaccination against natural infection or challenge inoculation. Up to the end of June, 1942, 255 children, in twenty-seven groups, had been inoculated with egg-passage material in Philadelphia. It will be noted from the pooled results in Table I that the results have been broken down in several ways. The primary division depends upon the source of the negative history of previous measles which was obtained in every case. As might be expected, those children who had been ~ol-

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lowed by physicians since b i r t h gave a higher proportion of demonstrated disease 74 per cent with on!y ~ per cent n e g a t i v e - - t h a n did those in whom reliance had to be placed on the word of the p a r e n t s - 52 per cent @ositive and 35 per cent negative. The results are also given in terms of route of inoculation. The administration b y means of i n t r a n a s a l drip, which was used in earlier work, gave poor results--30 p e r cent positive a n d 36 p e r cent n e g a t i v e - compared with those following the later-adopted methods of i n t r a d e r m a l inoculation', in which 80 p e r cent were positive, or inhalation of a finely divided spray, in w h i c h 98 per cent were positive. The degree of reaction has also been indicated, and Table I I shows the basis on which such division into moderate, mild, minimal, and doubtful has been made. In this earlier work, cases in which the children showed no Koplik spots were termed doubtful, even though morbillif o r m rash a p p e a r e d at about the right time a f t e r inoculation. Of partieular interest is the fact t h a t even in the patients with the most severe eases cough was almost always absent and malaise was mild and transitory. TABLE I I CL.a.SSIFICA~TION OF ]~E2~CTIONS

Exanthem Enanthem MalMse Cough Nasopharyngitis Conjunctivitis Temperature

MODEt~ATE

MILD

/v[INIMAL

DOUBTFUL

Typical but rarely florid Present Mild l%are Moderate

Light

Light

Light

Present with pho~ophobia 102 ~ F. or higher

Present Present Slight or none None None None Mild Very mild

None None None Very mild

Present with- Slight out photophobia 100.8 to 101.8~ Under 100.8~ :P. F.

Slight Under 100.8~ 1~.

I t was i m p o r t a n t to determine whether the mild vaccination disease would revert to the n a t u r a l l y severe t y p e on passage to another child. Thirty-five p r e s u m a b l y susceptible children were exposed to the inoculated groups. Of these, sixteen showed nothing, six gave a doubtful response, and thirteen showed a disegse identical with t h a t in the inoculated children. Of these thirteen, three had moderate, one mild, and nine minimal response. Thus one h u m a n passage did not change the character of the vaccination disease. Since J u l y 1, 1942, two other more extensive studies have been in progress u n d e r the auspices of the Commission on Measles and M u m p s of the B o a r d f o r the Investigation and Control of Influenza a n d Other Epidemic Diseases in the A r m y . Tables I I I and I V show the results to date. I n Baltimore, 827 colored children with negative history of measles derived f r o m the p a r e n t s have been vaccinated b y Dr. Hodes and Dr. Gellis, and 412 of these h a v e been carefully followed. Of these,

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145 have shown definite signs of mild measles and it must be recognized that many light and transient rashes may well have been missed in these negro children, s In Philadelphia 199 susceptible white children, followed from birth by physicians, have been vaccinated by Dr. Stokes and Dr. Marls, and 172 of these have been carefully followed. In this ease 131 have shown definite signs of mild measles. Both of these latter groups have shown a low incidence of Koplik spots, sixteen per cent and 25 per cent, respectively, due perhaps to further modification in the virus after prolonged passage in the chick embryo. In all, a total of 1,281 children have been vaccinated without harm in any instance. Of these, 839 have been carefully followed and 450, or 54 per cent, have shown definite signs of modified disease. TABLE III ]~ALTII~[01%EI~ESULTS

Children showing some s i g n s o f mea.sles

9 TO 18 Me. 48 of 103 (46%)

18 ~O. TO 2 "zl~. 26 of 57 (45%)

2 TO 3 YR. 31 of 93 (33%)

3 TO 4: Yi~. 19 of 58 (33%)

4 TO 5 YR. 18 o f 49 (36%)

5 ~20 6 u 3 of 17 (18%)

Only 16 per c e n t of the 412 children i n o c u l a t e d a nd checked showed K opl i k spots. All i n o c u l a t i o n s were b y the i n t r a d e r m a l ro, ute.

TABLE I V LATE1% PHILADELPHIA RESULTS

Children showing some s i g n s of m e a s l e s

6 to 18 M:O. 61of79 (77%)

18 ~o. ~o 2 Yl%. 10of19 (53%)

2 TO 3 YI%. 14:of18 (78%)

3 TO 4: Yl%. 18 of 21 (89%)

4: TO 5 YR. 7 of 7 (100%)

5 Ym AND OVEI~ 21of28 (75%)

Only 25 per cent of the 172 children i n o c u l a t e d and checked showed Koplik spots. All i n o c u l a t i o n s were by the i n t r a d e r m a l route.

Only meager data are yet available on the protection produced by vaccination. Twenty-four children were given challenge inoculations with blood from active cases of measles which produced typical disease in control children and monkeys. This severe test of immunity produced measles in ten of the twenty-four. Twenty-two children have been intimately exposed to the natural disease of which four have developed measles, three have shown a mild syndrome of questionable nature, and fifteen have remained well. Of particular interest in the latter group was one school where seven vaccinated children remained free of measles despite repeated exposure. Seventy per cent of thirty-five unvaccinated children in this school developed the disease. 7 SUMMARY

It has been possible to cultivate the virus of measles in the developing chick embryo. Such egg-passage material injecte4 by appropriate

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routes produced measles of mild character in 80 p e r cent of known susceptible children. There is evidence that this mild disease affords some protection against the n a t u r a l infection and t h a t it is not enhanced in virulence by at least one h u m a n passage. REFERENCES 1. Shaffer, 3s t 0" Rake~ G., Stokes, Y., J r , and O'Neil, G. C.: J. Immunol. 41: 241, 1941. 2. Plotz, N.: Bull. Aead. de rngd. Paris 119: 598, 1938. 3. Rake, G, Shaffer~ M. I~., and Jones~ If. P.: J. Infect. Dis. 69: 65~ 1941. 4. Rake, G., a~d Shaffer, M . F . : Nature'144: 672, 1939. 5. t~ake, @., and Shaffer, M. F. : ;[. Immuno]. 38: 177, 1940. 6. Stokes, J., Jr., O'Neil, G. C., Shaffer~ M. F , Rake, G., and lVfaris, E. P.: J. PED~AT. 22: 1, 1943. 7. lV[aris, E. P., ~ak% G., Stokes, J , Jr., Shaffer, M. F., and O'Neil~ G. C.: J. PEmAT. 22: 17, 1943. 8. Nodes, tt. L., and Gollis, S. : To be published.