DEVELOPMENTAL MEDICINE AND CHILD NEUROLOGY. 1972, 14

and other virus infections. In areas where sickle cell disease is prevalent, thrombosis of cerebral veins or sinuses may lead to irreversible brain-damage.

Febrile convulsions are an important aetiological factor, inasmuch as their management at home usually includes the administration of herbal medicines, the toxic nature of some of which is well known in paediatric practice in these areas. Where malaria is endemic, malarial convulsions may be responsible for as much as 50 per cent of all febrile convul- s iomS Some of these children will have cerebral malaria, a serious disease which produces brain-damage in a fair proportion of those who survive it.

Post-natal accidents, including road traffic accidents, are fast becoming important factors in the genesis of cerebral palsy in the developing countries.

Cerebral palsy is an important paediatric and social problem in developing countries. It will become more so when the present flood of infectious and parasitic diseases is stemmed, unless the expansion in the maternal and child health services keeps pace with the general health expansion programmes. Several areas have been identified as important causes of cerebral palsy, but it would appear that more deliberate research is needed into the aetiology of neonatal jaundice in some parts of Africa, where the cause is reported ‘unknown’ in as much as 70 per cent of cases in certain areas2

Department of Child Health, University of Ghana Medical School, P.O. Box 4236, Accra, Ghana.

Y. ASIRIFI

REFERENCES 1 . Ingram, T. T. S. (1964) ‘Cerebral palsy. Part I.’ British Medical Journal, 2, 1638. 2. Animashaun, A. (1971) ‘Aetiology of cerebral palsy in African children.’ African Journal of Medical

3. Basu, B. (1967) ‘Cerebral palsy in childhood.’ Journal of the Indian Medical Association, 49, 477. 4. Rahimtoola, R. J. , Masjid, 1. (1968) ‘Cerebral palsy in children.’ Pakistan Medical Review, 2, 25. 5 . Udani, P. M. (1963) ‘Cerebral palsy. (A study of 100 cases.)’ Indian Journal of Child Health, 12, 755. 6. Lesi, F. E. A. (1967) ‘The incidence of prematurity in Lagos, Nigeria.’ West African Medical Journal, 16,

Science, 2, 165.

132. 7. Malamud, N., Itabashi, H. H., Castor, J., Messinger, H. B. (1964) ‘An etiologic and diagnostic study of

8. Asirifi, Y. (1971) ‘Convulsive seizures in African children.’ Ghana Medical Journal, 10, 170. cerebral palsy.’ Journal of Pediatrics, 65, 270.

SMALLPOX VACCINATION-DEVELOPMENT AND DISCARD

WOULD-BE protective public health measures such as vaccination may reach a stage when their continued implementation has more adverse than useful effects. In this context, a recommendation was made in July, 1971, that the routine vaccination of children against smallpox should be discontinued within the United Kingd0m.l Continuation of the practice of vaccination or re-vaccination was, however, advised in the following circumstances : ( 1 ) for contacts of cases or suspected cases of smallpox, i.e., the ring system of creating

an immune barrier around an outbreak; (2) for persons, including children, about to travel to smallpox-infected areas; and (3) for doctors, nurses, ambulance workers and all health service personnel whose

duties might bring them into contact with a smallpox patient. In the light of these recommendations, it is useful to look at (a) smallpox generally for

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its effects, including severity, to see why protective measures have been necessary; (b) vaccination as a method of protection; and (c) the reasons for discarding it now as a blanket mode of protection while advocating its retention on a limited scale.

As a disease, smallpox has an ancient origin and has occurred frequently in many countries. It tends to be severe in its effects, often disfiguring, and the major variety (variola major) has a high mortality rate. It is strictly a human disease, though there are animal counterparts and it has been transmitted to monkeys experimentally. It is caused by a virus of the pox group of a single antigenic type. Recovery is followed by a durable immunity. Infection takes place by inhalation, with the primary focus in the lower respiratory tract. Spread from aerosol dissemination has been reported,2 as in the incident in Meschede, Germany, when 17 secondary cases developed in a hospital though none of them had been direct contacts of the primary case.

Smallpox has been prevalent in Europe since the Middle Ages. It has been known in Britain since the 16th century, remaining endemic until 1935 when a solitary doubtful case was reported. At that time, a diagnosis could be made only on clinical grounds. Although still frequent, early this century the disease was mainly of the mild variola minor or alastrim type, which had been specifically recognized earlier in South America and parts of Africa on account of its negligible mortality. However, it was also recognized that, although even variola major could give rise to a mild illness in a partly immune person, spread to a fully susceptible person resulted in severe illness.

Between 1936 and 1968 in Britain, the disease was introduced from abroad 41 times. In 33 instances, secondary spread occurred to 518 persons of whom 78 died. To begin with, entry was by sea, usually from the Far East, and surveillance and quarantine were easier because the disease became apparent during the voyage so that the immediate contacts were known. Latterly, entry has been by air, and passengers often reached their final destinations before becoming ill. During this period, points to be noted were that possession of a valid international certificate of vaccination or re-vaccination against smallpox became essential for travellers, that laboratory confirmation of a diagnosis of smallpox had evolved into a precise and rapid technique, that patients were not infectious until the rash appeared, and that both the primary and secondary cases had occurred almost entirely in adults. Therefore, if these cases had been vaccinated in childhood but not since, their immunity would have waned almost completely after a lapse of 15 years or more.

It has been known for centuries that an attack of smallpox results in a lasting immunity. Early attempts at protection included the practice of variolation-transfer of smallpox material to a susceptible person-but this was a method likely to have, and which sometimes did have, adverse effects. JENNER had observed that persons naturally infected with cowpox, a mild pox disease of dairy herds, were immune to smallpox. In 1798 he reported that persons inoculated with cowpox material also developed immunity to smallpox. From rather controversial beginnings, the Jennerian method became firmly established, particu- larly from the time that the vaccine lymph was prepared in calves or sheep by methods that ensured safety from bacterial and other contaminants, as well as potency. These methods are still largely followed.

The effectiveness of vaccination depends on the reaction obtained. A good primary take followed by obvious scarring will, in most instances, protect for 10 years or more. Re- vaccination needs to be done at shorter intervals because the amount of virus multiplication which can take place is so much less and it is this which stimulates the immune response.

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In these circumstances, there is protection for the individual. If the vaccine is so handled that it loses potency, e.g., by prolonged exposure in the liquid state to temperatures higher than 4”C, or if coverage of a population at one time is less than complete, then pockets of susceptible individuals remain and the disease is capable of smouldering until the time is ripe for an outbreak. Despite good vaccination programmes in many countries, the disease has been able to persist without difficulty. In the last few years, however, the World Health Organization has set in motion an ambitious programme of smallpox eradication. It has provided freeze-dried vaccine which remains fully potent, even at high ambient tempera- tures, until it is reconstituted and used. I t has provided training in surveillance and has encouraged countries in which the disease is endemic to mount vaccination and surveillance drives for its eradication. The success of these efforts is indicated by the spectacular fall in the number of countries reporting smallpox outbreaks and by the number of cases being reported by countries in which smallpox is still present. Though by no means eliminated yet, the total world incidence reported in 1971 amounted to only some 50,000 cases, of which half occurred in Ethiopia alone.3

The reduction in the number of cases of smallpox has highlighted the fact that vaccination itself is not entirely free from risk. In Britain between 1961 and 1970, there have been 133 cases of smallpox with 26 deaths; however, over the same period there have been 505 cases of complications following vaccination, with 33 deaths. These complications included 327 cases of generalized vaccinia (2 deaths), 57 of eczema vaccinatum (7 deaths), 9 of vaccinia gangrenosa (6 deaths), and 112 of postvaccinal encephalitis (with 18 associated deaths). In addition, accidental spread of vaccinia to other persons accounted for at least another 112 cases.4

It is on account of these various aspects of the smallpox problem that the routine vaccina- tion of children against smallpox is no longer recommended. Regional Virus Laboratory, The City Hospital, Edinburgh EHlO 5SB.

REFERENCES 1. Lancet (1971) ‘Smallpox policy reversed.’ ii, 305. 2. Gelfand, H. M., Posch, J. (1971) ‘The recent outbreak of smallpox in Meschede, West Germany.’

American Journal of Epidemiology, 93, 234. 3. Weekly Epidemiological Record (1972) ‘Smallpox Surveillance.’ Geneva: W.H.O., 47, 17. 4. Figures provided by the Department of Health and Social Security. Those for complications of vaccina-

tion are provisional.

A. D. MACRAE

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