From the authors' private laboratory, Pretoria, South Africa CLOSE co-operation between laboratory and public health service leaves few cases of "enteric" undetected in Pretoria. In all cases a laboratory diagnosis is carried out and an effort made to trace the source of infection. For South Africa, our population (68,000 whites and 40,000 natives and coloured) is relatively stable, and continuity in methods and comparability of results are assured by the fact that for the past 16 years all typhoid laboratory investigations have been performed in the same laboratory. In this way it has, for instance, been possible to show that in Pretoria paratyphoid infections are practically non-existent-a circumstance which greatly facilitates work on carriers. In these 16 years we have dealt with more than 3000 cases of enteric, of which several hundred were diagnosed by means of blood culture. In only two instances were paratyphoid bacilli found, and in both cases the infection could be traced to sources outside the town. During the same period we have detected nearly 60 carriers, and in every one of these typhoid bacilli were found, and not a single strain of paratyphoid bacilli.In this paper we give the experiences collected over a number of years in tracing carriers, and also some more recent observations on Vi agglutinins in carriers.INFECTION CHIEFLY SPREAD BY CARRIERS Although we can trace but a relatively small number of cases of enteric directly to a carrier, we regard the carrier as the chief source of infection in our midst. Large explosive outbreaks, such as one associates with water supplies, have never occurred. We do have smaller "outbreaks ", sometimes more than one in a year, and these are practically always traced to a carrier in a dairy. There are very numerous small dairies, and this fortunately limits the extent of such outbreaks. Case to case infections occur, but the majority of our cases of enteric are sporadic, and do not facilitate the search for a carrier. It is not unusual to get a single case in a household, and a carrier amongst the native servants. Here, as in dairy outbreaks, one is impressed by the large number of persons who are exposed to infection and do not become ill. There must be many channels of infection, leading from chronic carriers through ambulatory cases and " silent infections " to new sporadic cases, channels which always remain hidden, and may incidentally give rise to new chronic carriers.Improved sanitation may, in the long run, put a stop to the carrier evil, both directly, and by decreasing the production of new carriers. But that time is not yet, and it is doubtful whether such measures will ever reach the whole
Seven more carriers, all possessing appreciable quantities of Vi agglutinins, are added to those already known.Vi agglutination tests performed on 2526 inhabitants of the Transvaal, both native and white, showed that 5·3 % had similar quantities of Vi agglutinins.A fair number of these positive reactors were further examined for the presence of typhoid bacilli in their excreta, but the number of positive findings was very small.It is argued that there are a large number of typhoid faecal carriers who are such minimal excreters that the typhoid bacilli in their stools escape detection.We wish to thank Dr T. Lötter, Acting Medical Officer of Health of Pretoria, and his staff, for their kindly help in collecting the material for this paper. Our special thanks are due to Lieut.-Col. H. Nelson, Medical Officer of Health of Pretoria, now on active service, for his never-failing interest in our work which has been such a great encouragement.
The work began with efforts to isolate a type II Vi phage from local sewage. When this attempt failed, typing material was obtained from Dr J. Craigie and Dr A. Felix.The typing method was applied to 495 strains of typhoid bacilli, the technique laid down by Craigie being followed throughout.It was found that in South Africa the distribution of the various types of typhoid bacilli is different from that obtaining in other countries where this typing method has so far been applied.During further investigations of type F strains the fact came to light that by means of a simple biochemical test type F strains can be subdivided into two sub-types, which subdivision will be useful in further epidemiological work. No such biochemical subdivision was found possible in any other type.It did not prove possible to type all South African strains with the available phage preparations. Some of these strains must represent new types. Workers in other countries have had similar experiences and it will become necessary to compare all these unusual strains directly with one another in order to reach uniformity in nomenclature. It has already been possible to co-operate with workers in England, and they have been assisted by my finding that a strain, unique in England and supposed to have been brought there by a carrier, who had typhoid fever in South Africa 40 years ago, was endemic in South Africa.During the course of the work, two outbreaks of typhoid fever occurred in which the typing method proved most useful, not only for linking up a particular carrier with a particular outbreak, but also for excluding an already known carrier who was under grave suspicion.I have to thank Dr Craigie and Dr Felix for supplying material, and Prof. Pijper, of the Pretoria University, for placing laboratory facilities at my disposal. I thank all others for cultures received for typing.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.