The complex epidemiology of Rhodesian sleeping sickness in Kenya and Uganda. III. The epidemiology in the endemic areas along the lake shore between the Nile and the Yala swamp.

The endemic Rhodesian sleeping sickness belt along the shore of Lake Victoria between the Nile and the Yala swamp consists of two ecologically different areas: the Busoga belt and the Samia belt. The Busoga belt is a country of forest and forest relics, full of game, with a high density of Glossina fuscipes fuscipes but also inhabited by G. pallidipes, and with a people encroaching on the northern border who pass the forest on their way to the lake to catch and buy fish, but who seldom penetrate deep in the forest to hunt. The Samia belt is a country of dense bush in savanna, with less and smaller game, with forest, but with a relatively high density of G. pallidipes, and with a people who will not only pass the bush on their way to catch and buy fish at the lake, bur who also like hunting in bush and forest. From sex-, age-, seasonal and tribal incidence, from the incidence among different professions such as fishermen, fishmongers and cultivators, and from the differences in incidence encountered between the Busoga belt and the Samia belt, it is concluded: that nearly all women and children, most cultivators and part of the fishermen who contract sleeping sickness in these areas, become infected near their homes by G. pallidipes: this occurs mainly in the dense bush area. that most fishmongers, some cultivators and some fishermen become infected on their way to the lake shore, mainly by G. pallidipes; this occurs not only in the dense bush area, but also in the forest area. that fishermen, who become infected during trips, mainly contract their infection some distance away from the lake shore where they meet G.pallidipes. that transmission at the lake shore itself is rare and that G. fuscipes fuscipes only plays a minor role in the transmission of the disease in the areas under consideration. that man is not a good reservoir for Rhodesian sleeping sickness and that man-fly-man transmission is a rare occurrence. that game animals, particularly bushbuck and duiker, are the main source of infection for the flies which transmit the disease to man. that the sleeping incidence in man might merely be a reflexion of the incidence in the natural reservoir and that the factors influencing the latter will have to be studied to understand the former.

Studies on the vector of kala-azar in Kenya, VIII. The outbreak in Machakos District; epidemiological features and a possible way of control.

The epidemiology of kala-azar was studied in East Katangini, the area in Machakos District where the incidence of the disease had been highest during the epidemic years 1977-1979. A house-to-house survey showed that 19.3% of the homesteads had harboured kala-azar patients in the period 1977-1980, while 3.2% of the people had suffered from the disease. Significantly more males had had the disease than females and more children than adults, while the male patients came mainly from poorer homesteads. Significantly more kala-azar occurred in homesteads within 200 metres of a termite hill, while kala-azar seemed to occur particularly in homesteads near dry river beds. During a period of one year, sandflies were caught in a small focus of infection. They were still common in rock fissures, but were rare in other resting sites such as termite hills and huts. Particularly, the man-biting Phlebotomus martini was rare, as were other man-biting insects such as Anopheles gambiae. Very recently the farmers had begun to grow cotton which was sprayed regularly with insecticides stored mostly in the farmers' homes. As a result, the number of new patients in 1980 fell to four, and the longer the people had stored insecticides in their compounds, the lower was the recent kala-azar incidence in these homesteads. Presumably the insecticide treatments killed many sandflies and other insects, while the storing of insecticides protected the people inside their huts, although some patients probably became infected outside, probably near termite hills.(ABSTRACT TRUNCATED AT 250 WORDS)

Bancroftian filariasis in Kenya. V. Mass treatment given by members of the local community.

Diethylcarbamazine citrate was given for a total of 13 days to all people above one year of age in the following areas: (1) Mambrui, a town with a population of about 1300; (2) Jaribuni, a rural area with a population of about 1500; (3) The towns and villages on the islands off the north coast of Kenya with a population of over 20 000. The people were not weighed, but the daily dose was calculated according to age, being approximately 6 mg kg-1; drug taking was not supervised. The drug was mainly distributed by local people who also treated the side-effects; a doctor remained available in the background for consultation and advice. In Mambrui and Jaribuni, where baseline data had been collected, the number of infective larvae per 1000 vector-mosquitoes had decreased by more than 90% in the six to 12 months period after the campaign. Two years after the campaign, the microfilaria rate in Mambrui had dropped by 75%; in Jaribuni, a reduction of 75% was recorded in men, but in women it was only 48%. The overall rates after the mass treatment were 5.3 and 9.3% in Mambrui and Jaribuni, respectively. On the islands to the north, particularly good results were obtained in the village of Siyu, where the highest elephantiasis rate had been recorded; three years after the campaign, the microfilaria rate there had fallen to 3.6%, while none of 48 children under ten were found infected. The spectacular results in Lamu town may have been partly due to excellent mosquito control in preceding years. However, no control was achieved on the remote island of Ndau, probably because the treatment team left before the side-effects had disappeared, causing many people to stop the course of tablets. Thus, on the East African coast it is possible and cheap to control Bancroftian filariasis by mass treatment campaigns carried out by local, non-medical personnel.

The effect of repeated targeted mass treatment on the prevalence of schistosomiasis mansoni and the intensity of infection in Machakos, Kenya.

In a valley in Machakos District, Kenya, the entire population was surveyed in 1976 for the presence and number of eggs of Schistosoma mansoni in their faeces. All persons with 300 or more eggs g-1 faeces were then treated with a single dose of hycanthone, 1.5 mg kg-1 body-weight. A re-survey was carried out in 1977, followed by the treatment of all persons with 200 or more eggs g-1 faeces. After another re-survey in 1978, all persons with 100 or more eggs g-1 were treated. The final survey was carried out in 1981. It was found that the treatment of persons with a high egg output had a pronounced effect on the intensity of infection in the total population, but that, after a first considerable drop in the prevalence rate, further decreases were much smaller. Continuing moderate prevalence rates in very young children were an indication of continuing transmission.