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A relatively simple and specific test has been developed to distinguish eggs of Echinococcus from those of other morphologically identical taeniid species. A specific anti-Echinococcus oncosphere monoclonal antibody was produced which binds in an indirect immunofluorescence test to egg-derived oncospheres of E. granulosus but not to those of other taeniid species, such as Taenia hydatigena, T. saginata, T. pisiformis, T. ovis, T. multiceps, or T. taeniaeformis. Specific fluorescence was obtained with oncospheres of E. granulosus derived from either hatch/activated viable eggs using artificial intestinal fluid or from hypochlorite/detergent treated eggs. The potential use of this test in the study of the transmission of Echinococcus in Turkana, Kenya, is discussed.

The clinico-pathological effects of Schistosoma boviswere monitored in zebu calves for a year after exposure to 100 or 200 ccrcariae/kg body weight and were related to the number and reproductive activities of the parasites present. The disease was characterised by diarrhoea, weight loss or poor weight gain, anaemia, serum protein changes and eosinophilia. These changes were broadly related to the level of infection and were most prominent during the two months following patency when faecal egg counts were highest. Subsequently, the condition of most animals improved. This was associated with a marked reduction in faecal egg excretion which in turn was related to worm deaths, reduced worm fecundity and egg retention in the tissues.

A brief account is given of the geographical features of the Turkana area and of the events which led to the discovery that this part of Kenya had the highest incidence of clinically recognized hydatid disease in man anywhere in the world. Observations were made on the distribution of the disease following an aerial survey designed to determine the distribution of the people. It was found that the highest incidence of 198 surgical cases per 100,000 people per annum was in the north-western area bordering on the Sudan, Ethiopia and Uganda and this area was selected for the pilot control programme. By the development and assessment of better serodiagnostic methods combined with the use of a mobile ultrasound machine it has been shown that the true prevalence of hydatid disease in Turkana is between 5 and 10%. Studies on the parasite and its transmission have revealed that the species in Turkana is Echinococcus granulosus and that dogs and jackals are the main definitive hosts. Although goats, sheep, cattle and camels are all infected with hydatid cysts, dogs and jackals are also thought to be infected by scavenging on human corpses. In contrast to Masailand where wild carnivores and wild herbivores are infected, there is no wild life cycle in Turkana. The unusually high prevalence in man is thought to be due to the close intimacy of the Turkana with their dogs and to customs relating to the handling of dog faeces.(ABSTRACT TRUNCATED AT 250 WORDS)

A day blood smear survey for Mansonella ozzardi in the north coast communities of Trinidad recorded a prevalence of 4·8% in 4,488 persons examined. Prevalence rates were highest in the four westernmost communities, where the vector, Culicoides phlebotomus , is a severe nuisance problem. Prevalence rates increased with age and were higher in males than in females. Mean microfilaria densities were low in both sexes up to 50 years of age but in older males the density increased with age. Wuchereria bancrofti infections were detected in five of the ten communities surveyed.

1. 1) Eleven young males of the Kikuyu tribe in Kenya were found by muscle biopsy to be heavily infected with T. spiralis. It is probable that they contracted the infection from a wild pig. 2. 2) No previous record of the occurrence of trichinosis in either man or animal has been traced from any African country south of the Sahara. 3. 3) In eight of 10 survivors, muscle biopsies showed larval densities ranging from 420 to 2,800 per g. with an average of 1,849. A description is given of the clinical and laboratory findings in these patients. 4. 4) Specimens from 15 muscle groups in an untreated fatal infection showed an average larval density of 3,249 per g., ranging from 5,190 in the tongue to 1,850 in the sacrospinalis. There were 2,095 larvae per g. in the diaphragm. Very few previous observations on the distribution of larvae in the muscles of man have been traced; the widely held view that the diaphragm is the most heavily infected muscle in man is probably incorrect. A description is given of clinical, laboratory and autopsy findings in this case. 5. 5) Histological examination of postmortem material revealed universal myositis with muscle necrosis; in many sections a large proportion of the muscle fibres were replaced by larvae and cellular infiltration. The heart showed a moderately severe myocarditis. Muscle biopsies from the survivors showed heavy infections, but there was much less infiltration and less damage to the muscles. 6. 6) Treatment with prednisone was given alone or in combination with dithiazinine or diethylcarbamazine. Prednisone was rapidly effective in relieving symptoms, but neither of the other drugs appeared to have any effect on the course of the disease. 7. 7) Six patients were seen 15 months later; biopsies showed high densities of living encysted larvae with no sign of calcification. All the patients were well with no residual symptoms. 8. 8) The Kenya and a London strain of T. spiralis were compared. Morphologically the adult worms and larvae appeared to be identical. The Kenya strain differed markedly in its infectivity to rats; it produced very few adults and very few larvae with infecting doses which would have been expected to produce very heavy infections. 9. 9) The recent appearance of trichinosis in Kenya can probably be explained by previous failures in diagnosis, or to a relaxation of native taboos which prevented the people in the affected area from eating the meat of wild pigs. It is unlikely that the parasite has been recently introduced. Investigations have been started to discover the extent of trichinosis in man and animals in Kenya.

1. 1) In this preliminary note the results are given of the examination of 537 animals from the area in Kenya where Forrester et al. (1961) described an outbreak of human trichinosis. 2. 2) T. spiralis larvae were found in a dog (Canis familiaris) and a leopard (Felis pardus) collected near Kerugoya on the lower slopes of Mount Kenya. The dog had eaten part of a wild pig (Potamochoerus porcus) which was believed to be the source of the human infections. It is known that leopards also eat wild pigs. 3. 3) Four hundred and thirty-seven rodents and more than 50 carnivores which are known to eat rodents were examined; none was infected. 4. 4) T. spiralis larvae were found in a hyaena (Crocuta crocuta) from the Masai plains more than 100 miles from Kerugoya. 5. 5) Trichinosis is believed to be rare in the tropics. There are no previous records of infections in wild animals in Africa. Man probably contracts trichinosis in Africa when he intrudes into a cycle confined to wild animals. The incidence and distribution of the infection in animals is not yet known.

1. 1) Filariasis was studied in the village of Faza on Pate Island which lies 5 miles east of the northern part of the Kenya coast. The incidence of W. bancrofti in night bloods was 32 per cent. and in day bloods 4 per cent.; the average number of microfilariae per 20 c.mm. was 9.4 and 0.16. The highest parasite rates and densities were in the 16 to 20 age-group. 2. 2) A fortnight after mass treatment with diethylcarbamazine the W. bancrofti rate fell to 25 per cent. and the microfilarial density to 1.5. Eight months later the infection rate was 16 per cent. and the microfilarial density 1.1. 3. 3) Seven filarial species were found in animals. Monkeys (Cercopithecus aethiops) were infected with D. corynodes ; dogs, cats, and genets (Genetta tigrina) with W. patei and D. repens. Dogs were also infected with D. immitis and a Dipetalonema. Donkeys and cows were infected with Setaria sp. 4. 4) The commonest mosquitoes in houses were Ae. pembaensis, C. p. fatigans, and Ae. aegypti. Anopheles were almost absent from Faza ; only three A. gambiae were caught. 5. 5) Precipitin tests indicated that Ae. pembaensis feeds on monkeys, dogs, cats, cattle, goats and donkeys as well as man. C. p. fatigans and Ae. aegypti, though predominantly anthropophilic, also feed on animals. A number of C. p. fatigans contained avian blood. 6. 6) Over 15,000 mosquitoes were dissected at Faza. The filarial infection rate for Ae. pembaensis was 3 per cent. to 4 per cent. ; infective larvae were present in 2 per cent. to 3 per cent. Only 2 per cent. of Ae. aegypti were infected. After the diethylcarbamazine campaign the C. p. fatigans rate fell from 25 per cent. to 6.6 per cent ; the infection rates of the other mosquitoes were unaffected. 7. 7) In feeding experiments, only W. bancrofti and D. immitis developed well in C. p. fatigans. Ae. pembaensis proved a good experimental host of W. patei, D. repens, D. immitis, D. corynodes and the donkey Setaria. 8. 8) It was found possible to distinguish most of the infective larvae in mosquitoes, and these were studied in 187 mosquitoes found infected in nature. C. p. fatigans contained only W. bancrofti, and Ae. pembaensis only animal filariae.

2 calves have been experimentally infected with a Puerto Rican strain of S. mansoni. They developed mature infections and passed viable eggs in the faeces. The parasitological and pathological findings in these animals were compared with similar observations in 2 calves infected with S. mattheei. Further studies are necessary to assess the role of cattle as natural hosts of this infection.

Schistosoma mansoni infection in Cercopithecus species monkeys has been previously monitored for up to five years. This is an account of observations made during an autopsy on a male vervet monkey which had harboured the parasite for 15 years. Viable eggs had been recovered from the faeces throughout the infection, being hatched to observe the emergence of miracidia. Apart from a nodular appearance of the liver capsule, which was noted before the perfusion, and localized haemorrhaging in the large bowel there was comparatively little pathology attributable to the parasite. 86 worms were recovered from the mesenteries by perfusion. The distribution of worm eggs in the tissues was mainly in these two organs, although with the remarkably low incidence of granuloma it is likely that the schistosome infection would have been overlooked in a routine autopsy. It is stressed that these observations have been made on an individual animal, but it is felt that there is real significance with respect to the aetiology of natural transmission.

A simple and sensitive two-step enzyme immunoassay for Echinococcus antigen was developed, using peroxidase conjugated IgG fractions of rabbit anti-Echinococcus granulosus cyst fluid serum or of pooled sera from human hydatid patients, to assay samples of cystic fluid taken from patients with suspected hydatid cyst infections. The assay was 100% positive with nine proven human hydatid cyst fluids; in six patients with cysts where serology was negative, there was no evidence of Echinococcus antigen in the cyst fluid. This simple procedure is therefore of value in confirming or excluding the diagnosis of hydatid in cystic fluid obtained by biopsy or after surgery.

A species-specific indirect immunofluorescence test using an anti-Echinococcus oncosphere monoclonal antibody (EgOH6-4E5) was applied to identify Echinococcus oncospheres released from taeniid eggs collected in environmental soil and water samples, and from perianal or faecal samples of naturally infected dogs, in northern Turkana, Kenya. The specificity of immunodetection of Echinococcus eggs by specific fluorescence of Echinococcus oncospheres from naturally infected dogs was 100% when compared to Taenia hydatigena infections, and a sensitivity of 73% was obtained in the detection of dogs infected with Echinococcus using perianal Scotch tape swabs. Taeniid eggs were recovered from various soil samples inside Turkana manyattas (settlements) and from waterhole samples. Some oncospheres obtained from taeniid eggs recovered from all sampled areas, but particularly from inside Turkana huts (akai) and from water samples from open waterholes used by the people and their livestock, reacted positively with the Echinococcus 4E5 monoclonal antibody. The potential importance of contamination of such sites with Echinococcus eggs is discussed in relation to the transmission of echinococcosis in this hyperendemic region of northern Kenya.

“It is a remarkable fact that the dogs appear perfectly healthy” (Blackberg and Ashman, 1930).

Chronological lymphographic studies on 24 cats experimentally infected with a strain of Brugia pahangi revealed marked changes in the diseased lymphatics and nodes, which were detectable as early as the 15th day after infection, 8 uninfected cats were used as control. Significant findings were: (1) Marked nodal enlargement with occasionally visible filling defects, (2) Lymphatic dilatation—sometimes as much as 5 times as wide as the corresponding lymphatics in the uninfected limb, (3) Tortuosity of the dilated lymphatics, (4) Leakage of the contrast medium from the diseased lymphatics. Follow-up X-rays showed stasis of contrast medium in the affected lymphatics in some cats for as long as 6 weeks after lymphography. In selected cats that were autopsied, filarial worms were found in transverse and longitudinal sections of those lymphatics and nodes shown on lymphography to be diseased. These studies indicate that in endemic filarial areas it may be possible to detect early lymphatic involvement by lymphography which would then enable effective treatment of the patients, before the distressing and irreversible sequelae of filarial disease—chronic lymphoedema and elephantiasis—occur.

Publisher Summary This chapter discusses the role of wild animals in the transmission of cestodes of medical interest in Kenya. In Kenya, taeniasis is an important medical and economic problem; in some areas, infection rates in man approach 100% and the cysticercosis rate in cattle is around 30%. Cysts of T. solium are found occasionally in pigs in Kenya, but no adult worms have been found in man. There is a high incidence of hydatid infection in cattle, sheep, goats, and camels in Kenya, and the disease is an important medical problem in the Turkana district. A species of Diphyllobothrium was found in 14 out of 22 hyaenas in an area of Masailand where sparganosis is not uncommon in man. Dipylidium caninum is widespread in dogs and jackals and is seen occasionally in children. Hymenolepis nana infections are prevalent in rodents in Kenya, but it is uncommon in man.