Showing papers in "Transactions of The Royal Society of Tropical Medicine and Hygiene in 1952"

Zika Virus (I). Isolations and serological specificity

Abstract: 1. (1) The isolation of what is believed to be a hitherto unrecorded virus is described. The first isolation was made in April 1947 from the serum of a pyrexial rhesus monkey caged in the canopy of Zika Forest. The second isolation was made from a lot of A. africanus taken in January, 1948, in the same forest. The virus has been called Zika virus after the locality from where the isolations were made. 2. (2) Cross neutralization tests indicate that Zika virus is not related to yellow fever, Hawaii dengue nor to the FA and GD VII strains of Theiler's mouse encephalomyelitis virus. Neutralization tests with Zika virus and the antisera of some other viruses which are neurotropic in mice gave no evidence of any identity of these with Zika virus.

Zika virus (II). Pathogenicity and physical properties

Abstract: 1. (1) A description is given of the adaptation to mice of two strains of Zika virus. Zika is the name of a forest area near Entebbe, Uganda, where both strains of virus were isolated. One of the strains was isolated from a pyrexial rhesus monkey which was being employed as a yellow fever sentinel and the other was obtained from a batch of A. africanus. 2. (2) The signs of infection in mice are described. While mice of all ages tested are susceptible to intracerebral inoculations with Zika mouse brain virus, mice of 2 weeks of age and over can rarely be infected by the intraperitoneal route. Mice younger than 2 weeks are highly susceptible to intraperitoneal inoculation of the virus. 3. (3) Zika virus is highly neurotropic in mice and no virus has been recovered from tissues other than the brains of infected mice. 4. (4) Cotton-rats, guineapigs and rabbits show no clinical signs of infection after intracerebral inoculation of late passage mouse brain virus. 5. (5) Monkeys develop an inapparent infection after subcutaneous inoculation with mouse brain virus. After intracerebral inoculation one of five monkeys showed a mild pyrexia, the others showed no signs of infection. Viraemia during the first week after inoculation has been found in all monkeys tested and antibody has been demonstrated by the 14th day after inoculation. 6. (6) Of 99 human sera tested, 6 (6.1 per cent.)-have neutralized more than 100 LD50 of virus. Antibody has also been found in the serum of one of 15 wild monkeys tested. 7. (7) The size of Zika virus is estimated to eb in the region of 30 to 45 mμ in diameter. The virus may be preserved up to 6 months in 50 per cent. glycerol and up to 30 months after drying. It is susceptible to anaesthetic ether and the thermal death point is 58°C. for 30 minutes. 8. (8) Neuronal degeneration, cellular infiltration and areas of softening are present in infected mouse brains. Cowdry type A inclusion bodies have been found, particularly in the brains of young mice showing extensive lesions.

A health, nutrition and parasitological survey in a rural village (Keneba) in west Kiang, Gambia.

Abstract: 1. (1) As a preliminary to operations intended to eliminate the major parasitic diseases, a health, nutrition and parasitological survey was made in Keneba, a village of 710 inhabitants in West Kiang, Gambia, during 1950-51. 2. (2) The villagers depend for food very largely upon their cereals and foods of animal origin are rarely eaten. There is a marked seasonal variation in food supplies, giving rise to a regular “hungry season.” 3. (3) Body weights of adults were below those of racially comparable groups and the growth pattern of children was considered to-be probably sub-optimal. Clinical signs attributable to deficiency of vitamin B complex factors were found to be common. 4. (4) Malaria was found to be hyperendemic. P. falciparum predominated but P. malariae was seen in 8.5 per cent. of films. While some degree of immunity or tolerance is undoubtedly established, this appears to be a precarious one liable to break down under conditions of stress such as pregnancy. The inter-relationships of nutrition and malarial immunity are discussed. 5. (5) Approximately one-third of the population was found to be infected with A. perstans and one-third with W. bancrofti . Possible reasons for the absence of evidence of filarial infection in infants and young children are discussed and its apparent inverse relationship to malaria noted. 6. (6) Trypanosomal infection was found in 2.5 per cent. of the people. 7. (7) Hookworm infestation was found to be common, rising to over 90 per cent. in the 6 to 10 years age-group, but loads were generally light. Ascaris and Taenia were found infrequently. 8. (8) Anaemia was found to be almost universal, haemoglobin levels being lowest in the 2nd year of life. In males the levels were found to rise steadily with age well into middle life ; in females there was a marked fall during the child-bearing period. 9. (9) Some degree of “auto-agglutination” of the blood was found in all subjects. The characteristics of this clumping of cells are described. It was not cold-agglutination, nor was it related to anaemia. 10. (10) Hepatomegaly was observed very frequently in infants, often well below the age of weaning, and in children. Its incidence, associated clinical features and pathology appeared to differ from those of kwashiorkor (as defined). The possible aetiology of Gambian hepatomegaly is discussed and it is suggested that malaria, acting in conjunction with some other factor, probably nutritional and related to the constitution of breast-milk, may be the main cause of the condition. 11. (11) Notes on the entomology of the area are added. It was not possible to make exhaustive investigations of disease vectors during the survey year. The overall impression gained from the survey and from observation at all seasons of a year is that the health of Keneba villagers is, at the best, marginal and that the reserves necessary to meet any unusual physiological or pathological stresses are small.Immunity to the effects of a variety of parasites is hardly won and precariously maintained.Although this population has maintained itself for many generations the level at which it has done so is very low and it is clear that the combined forces of malnutrition and parasitization are among the major factors limiting progress and development.

Skeletal maturation in the hand A study of development in East African children

Abstract: A radiological investigation of the ossification and maturation of the carpal bones in 1,360 East African children of known ages has been described. The work has revealed that there is no difference in the order of appearance of the carpal ossification centres from that : commonly accepted for other races. The fact that skeletal maturation is more rapid in girls than in boys has been confirmed. The rate of skeletal maturation has been compared with findings of other writers on American children, and the African children investigated have been found to be from 1 1 2 to 2 years behind present American standards.

Uganda S virus; a hitherto unrecorded virus isolated from mosquitoes in Uganda. I. Isolation and pathogenicity.

Abstract: 1. (1) The isolation of what is believed to be a hitherto undescribed virus is recorded. Although the origin of the agent is uncertain, the evidence which has been presented indicates that it was isolated from one of the following species of mosquitoes: Aedes (F.) longipalpis, A. (F.) ingrami, A. (A.) natronius. 2. (2) Studies on the immunological relationship of Uganda S virus to other viruses are presented elsewhere (DICK, to be published); they indicate that Uganda S virus is not identical with any previously described virus. Neutralization tests have demonstrated antibody to Uganda S virus in high titre in 5.8 per cent. of sera from residents of Western Uganda and in the serum of one of six wild monkeys. 3. (3) The pathogenicity of Uganda S virus for mice, cotton-rats, guineapigs and for rhesus, grivet and redtail monkeys is described. The agent is highly neurotropic for mice only and has produced no clinical signs of infection in the other animals tested. Monkeys vary in their susceptibility to Uganda S virus as evidenced by the circulation of virus and development of antibody. 4. (4) Uganda S virus would appear to have a particle size of between 75 and 112 mμ. This estimate is subject to revision when other methods of size estimation have been applied. It would appear to be one of the more unstable viruses when in suspensions, but is readily preserved by desiccation. No studies have as yet been made on the susceptibility of Uganda S virus to chemicals, nor have attempts been made to cultivate it in chick embryos. 5. (5) Nothing is known of the natural history of the virus or of the disease, if any, which it produces in man or animals.

The treatment of typhoid fever with chloramphenicol; a clinical study of 330 cases of enteric fever treated in Egypt.

Abstract: 1. (1) Three hundred cases of typhoid and 30 cases of paratyphoid fever were treated with chloramphenicol in the course of a year in a hospital in Egypt. Most of the typhoid cases came from two large outbreaks; the circumstances attending these are briefly described. 2. (2) The clinical features and the clinical, bacteriological, serological and immunological response to treatment are described. Various schedules of chloramphenicol treatment were employed in an attempt to reduce the incidence of relapses; some patients received vaccine therapy in addition. The results of this investigation are described and discussed. 3. (3) The side-effects of chloramphenicol therapy are described and discussed, and also the complications of typhoid fever, in particular water and electrolyte deficiency. 4. (4) Some of the observations made and problems arising out of them are further discussed in more general terms.

A study of human malaria oocysts as an aid to species diagnosis.

Abstract: 1 (1) It is suggested that fuller and more accurate information would be obtained when malaria surveys are being carried out if both sporozoite and oocysts rates were known 2 (2) Experiments repeated by us on many occasions show that the minimum time required for the completion of the parasitic cycle in the mosquito varies considerably among the species P vivax has the shortest cycle and P malarie and P ovale the longest, with P falciparum a day or two longer than P vivax 3 (3) Any lowering of the temperature, even for a few hours during each 24-hour period of the incubation period, retards the growth of oocysts and in consequence may delay the completion of the cycle by several days 4 (4) It is considered that all species of human malaria oocysts can be diagnosed with some degree of certainty, at least to the stage of development before the dividing nuclei obscure most of the pigment 5 (5) Our descriptions of the pigment in the oocysts of human malaria refer to infections in Anopheles maculipennis atroparvus The mosquitoes were kept in the same insectarium and at the same constant temperature and humidity throughout the incubation period 6 (6) Day by day descriptions during the growth of the oocysts of all four species of human plasmodia are given The colour of the pigment, the number of grains of pigment, its arrangement and degree of coarseness are of value as an aid to diagnosis 7 (7) The measurements of the oocysts given in the table were arrived at after dissecting the mid-gut in Locke's fluid and adding a drop of fixative (Bles) just before flattening the gut with a cover-slip 8 (8) In some species of avian plasmodia the pigment in oocysts is very coarse, especially in P gallinaceum in which it is coarser than in any species of human Plasmodium 9 (9) At least in one human species of Plasmodium, P vivax, the pigment is indistinguishable in colour, number of grains and its arrangement, from at least one species of simian Plasmodium, P cynomolgi If there are areas where the distribution of these two species overlap, the percentage of mosquitoes infected, arrived at either by gut or salivary gland dissections, may be misleading if the work is being carried out to ascertain the oocysts or sporozoite rate for P vivax only 10 (10) Some drugs, though not gametocytocidal, may disarrange or even displace the pigment of gametocytes In areas where mass drug prophylaxis and treatment is being carried out, atypical oocysts may be found Pigmentless oocysts are difficult to identify and species diagnosis is impossible 11 (11) In a young oocyst the number of grains of pigment, its colour and arrangement in the cyst, resemble closely the pigment as it is seen in the female gametocyte in an erythrocyte It is therefore suggested that unstained, or very lightly stained, gametocytes of most species of human plasmodia will help in species diagnosis

Anaemias of Africans

Abstract: 1. (1) The anaemias of Africans in Kenya fall into the following types: (i) Microcytic hypochromic with non-dyshaemopoietic marrows; (ii) Microcytic hypochromic having dyshaemopoeitic marrows with giant stab-cells; (iii) Macro or normocytic with giant stab-cells; (iv) Macro- or normocytic with giant stab-cells and megaloblasts; (v) Sicke--cell anaemia; (vi) Haemolytic splenic anaemias. 2. (2) (i) responds to iron in any form, (ii) to a combination of iron and liver, (iii) and (iv) to all the known haemopietic substances as well as to penicillin, (v) responds to no form of treatment, (vi) to splenectomy. 3. (3) Sickle-cell trait grafted on to microcytic or megaloblastic anaemia is common and responds to the treatment for the appropriate anaemia. Methods are given for distinguishing between sickle-cell anaemia sui generis and sickle-cell trait grafted on to other types of anaemia. 4. (4) Giant stab-cells are regarded as definite evidence of dyshaemopoiesis and they respond slowly to haemopoeitic treatment. 5. (5) Megaloblasts, both typical, orthochromatic of the Ehrlich type, and the less typical intermediate forms, were common in our cases. 6. (6) Macrocytosis occurs without megaloblastosis, and megaloblastic marrows with normocytic blood pictures. Neither the marrow alone nor the peripheral blood alone is, therefore, a sound criterion for diagnosis or treatment. 7. (7) Mean corpuscular volume, even when reticulocytosis is taken into account, is not a satisfactory index of cell size, particularly diameter, and Price-Jones curves must be resorted to if a proper understanding of the relation between the variables M.C.V., M.C.D, M.C.A.T. and reticulocytosis is desired. Mean corpuscular volumes alone cannot, therefore, be used as a satisfactory means of diagnosing the anaemias. A series of Price-Jones curves is given, showing the variations in cell dimensions that occur at varius levels of reticulocytosis in both the hypochromic anaemias and the megaloblastic ones. 8. (8) A raised indirect van den Bergh is always present in the megaloblastic types of anaemia and is not related to malaria. As in pernicious anaemia, there appears to be an undercurrent of haemolysis in this type of anaemia, both in the African and the Macedonian cases. 9. (9) Peripheral bleeding due to intestinal parasites, or intravascular haemolysis due to blood parasites, cannot produce a megaloblstic marrow or giant stab-cells, and the presence of these abnormal cells in the marrow is indicative of disorders of haemopoiesis. Only a proportion of the anaemias of Africans in Kenya are due directly to parasitic infections. 10. (10) Raised temperatures are not uncommon in the heavy anaemias, especially the megaloblastic, as in pernicious. This is not necessarily evidence of infection, since the temperatures yield rapidly to treatment with such substances as liver, B12 and folic acid. Attempt to treat the temperature and not the anaemia may be disastrous.

Disordered gastro-intestinal function and its relationship to tropical sprue, coeliac disease and idiopathic steatorrhoea

Abstract: 1. (1) Studies of gastro-intestinal function in 10 cases of tropical sprue, 10 cases of coeliac disease and 24 cases of idiopathic steatorrhoea are described. 2. (2) All the cases showed delay and depression of intestinal absorption. 3. (3) Radiographic studies revealed excessive mucus secretion and decreased intestinal tone and motility in all three conditions. 4. (4) Pancreatic enzymes were normal. 5. (5) It is concluded that functional incapacity of the small intestine is the basic pathological fault in tropical sprue, coeliac disease and idiopathic steatorrhoea. 6. (6) Delayed and depressed absorption may cause a calorie deficit, increased growth of intestinal bacteria and modification of intestinal contents. These changes may be responsible for the main features of the syndromes observed. 7. (7) The relationship of possible primary aetiological factors to this basic intestinal fault is reviewed. Adrenal insufficiency, climatic factors and vitamin deficiency do not seem to be primary factors. Infection and hereditary factors may have a causative role in any of the three conditions. Rancid fats may be important in tropical sprue. Dietary wheat gluten is a factor of major importance in coeliac disease.

Acquired resistance to proguanil in Plasmodium knowlesi

Abstract: 1. (1) A high degree of resistance to proguanil was developed in a strain of P. knowlesi which was subjected to periodic exposure to the drug at varying intervals for one year. 2. (2) The effect was persistent even after 8 months during which time no further proguanil was administered during serial passages. 3. (3) The proguanil-resistant strain was found to be refractory to daraprim and bromoguanide but not so to sulphadiazine, M 3349 nor chloroquin.

Immunity to yellow fever nine years after vaccination with 17D vaccine.

Abstract: 1. (1) In November 1950, a yellow fever immunity survey was made at four places in the Toro district in the Western Province of Uganda. Three of the places were within, and one outside, the area where a mass vaccination campaign was made in 1941. Evidence is presented which indicates that there is a low endemicity of yellow fever and that no epidemic had occurred in the areas concerned during the past 9 years. 2. (2) The results of the surveys showed that at places in the area where vaccinations had been done, 77.2 per cent. of the sample of persons of 9 years and over were immune, while in the area where no vaccinations were done in 1941 17.5 per cent. were immune.It is believed that, in the latter area, there were a number of persons who had been vaccinated and that a number of non-vaccinated people who are now resident in the area where vaccinations were done. 3. (3) In the vaccinated area there was a significant difference in the immunity rates in the samples of children of 9 to 15 years (63.2 per cent.) as compared with that of adult females of 16 years and over (82.8 per cent.). While this difference may indicate a difference in the response of young children as compared with older children and adults to vaccination, it seems more likely that it is due to an excess of non-vaccinated children having been included in one of the samples. 4. (4) It is suggested that from the results of this study the validity of yellow fever certificates could be extended up to at least 9 years after vaccination, except in the case of children who were under 7 years when vaccinated.A further study is required in the case of the latter age group in which the age and residence of all the donors can be confirmed.

Ascorbic acid content of the milk of tswana women

Abstract: 1. (1) The ascorbic acid content of milk from 84 Tswana mothers of the Bechuanaland Protectorate was estimated. 2. (2) The mean content of samples collected during the dry season was 1.7 mg./ 100 ml.; of those collected during the rainy season, when indigenous fruit and vegetables are available, it was 2.9 mg./100 ml.; the mean content over the whole year was 2.4 mg./100 ml. 3. (3) In comparison with European and American findings and theory, the maternal output and infant intake of ascorbic acid are much below normal, but none of the mothers or babies showed any signs of ascorbic acid deficiency at any time whilst under observation.

The origin, fate and significance of the umbilical hernia in Nigerian children (a review of 1,300 cases).

Abstract: 1. (1) The results of a survey to determine the incidence, etiology and significance of umbilical herniae in Nigerian children are described. 2. (2) Ninety-seven per cent. of newborn babies were found to have the skin type of umbilicus. 3. (3) Umbilical herniae were found in 91 per cent. of a group of children aged from 1 month to 5 years, 64 per cent. in those aged 6 to 9 years and 46 per cent. in those aged 10 to 15 years. In a group of well-nourished adults, 14 per cent. were positive. In a malnourished group 27 per cent. were positive. 4. (4) The natural history of the umbilicus in the Nigerian child is discussed. The importance of the skin type of umbilicus and of a wide umbilical ring in the etiology of umbilical herniae is stressed. The harmless character of the condition is noted. 5. (5) The incidence of umbilical hernia in children in other parts of the world is briefly surveyed. 6. (6) It is concluded that umbilical herniae are very much more common in West African children, and probably all African children, than in children in other ethnic groups. 7. (7) It is suggested that this is due to two inherited physiological characteristics — the skin type of umbilicus and the wide umbilical ring.

Chemotherapeutic and other studies on the pre-erythrocytic forms of simian malaria (Plasmodium cynomolgi).

Abstract: 1. (1) A study was made of the chemotherapeutic reactions of the pre-erythrocytic forms of Plasmodium cynomolgi. 2. (2) Quinine and mepacrine did not destroy these forms; neither did chloroquin, although it possibly diminished the number of pre-erythrocytic forms developing, and it caused vacuolation in them. 3. (3) Proguanil given daily during the prepatent period suppressed the pre-erythrocytic forms but did not prevent the development of a latent infection; if given towards the end of the prepatent period it caused vacuolation of the parasites. Sulphadiazine, given throughout the prepatent period, incompletely suppressed the parasites. 4. (4) Pamaquin given daily during the prepatent period completely prevented the infection. 5. (5) Sporozoites were injected intraperitoneally into two immune monkeys and the pre-erythrocytic forms developed apparently normally; but the resultant parasitaemia of the blood was very small and brief. This confirms the view that in malaria the immune mechanisms are directed against the forms in the blood and not against those in the tissues. 6. (6) Prolonged search for pre-erythrocytic parasites less than 4 days old was unsuccessful. 7. (7) Sporozoites of Plasmodium vivax were injected into the liver of a rhesus monkeys but not infection could be detected.