Mutuku J. Mutinga

The isolation and identification of leishmanial parasites from domestic dogs in the Machakos District of Kenya, and the possible role of dogs as reservoirs of kala-azar in East Africa.

Two out of 288 sick and emaciated dogs from homesteads in the Machakos District of Kenya, where human kala-azar cases existed, were found to be infected with leishmaniasis. The leishmanial strain isolated from one of the dogs was characterized enzymologically and serologically and found to be identical with strains isolated from human kala-azar cases and Phlebotomus martini. The significance of these findings is discussed in terms of the general epidemiology of visceral leishmaniasis in Kenya.

Investigation of animal reservoirs of visceral leishmaniasis and the isolation of Leishmania major in Marigat, Baringo District, Kenya

Animals were trapped in Marigat, Baringo District to investigate animal reservoirs of visceral leishmaniasis in an endemic focus of the disease. Several species of rodents, carnivores and reptiles were captured. Specimens of spleen, liver and blood tissues were taken from the animals. The specimens were triturated into sterile saline and then cultured into NNN medium, and some of it injected into hamsters intraperitoneally. Skin biopsies were also taken and cultured in NNN medium. Slide smears of all the tissues taken were made stained with Giemsa stain and examined under the microscope for amastigotes. Four isolates of leishmanial parasites were made from a gerbil and three monitor lizards.

Vector—parasite relationships: the effect of Trypanosoma (Nannomonas) congolense on Glossina pallidipes

An electron microscope study was made on the infection by Trypanosoma (Nannomonas) congolense of the tsetse fly Glossina pallidipes. Infected flies showed many clear abnormalities in their gut cells and peritrophic membrane. These features are described and illustrated.

Insect pests of sunflower (Helianthus annuus L.) in Kenya

The pest complex of sunflower and its relative abundance and economic importance are discussed. A total of 80 insect species were collected—five of these were recorded on roots, 51 on stems and leaves and 29 on floral parts and developing seed. The major pests of sunflower commonly encountered in all the localities studied were Agrotis segetum Schiff, Agrotis ypsilon Hfn, Plusia orichalcea F., Nezara viridula L. and Heliothis armigera HB.

Epidemiological, investigations of visceral leishmaniasis in the West Pokot District, Kenya

Studies of the epidemiology of visceral leishmaniasis in the West Pokot focus have revealed that Sergentomyia bedfordi, S. antennatus and S. schwetzi are the most abundant sandfly species. The latter have been shown to feed mainly on lizards. Phlebotomus martini was encountered in termite hills in the ventilation shafts, and showed an even distribution among the termite hills throughout the district where kala-azar cases were detected. Investigations into the relationship between termite hills and the presence of kala-azar cases in various homes were carried out. All homes afflicted with kala-azar had a termite hill or hills within a 10-m radius. The period of time spent in own homestead by each kala-azar case was to establish if each kala-azar patient contracted the disease in the focus of investigation.

Some concepts of the interaction of Trypanosoma (Nannomonas) congolense and Glossina pallidipes

Light and electron microscope investigations were carried out on the infection with Trypanosoma (Nannomonas) congolense of laboratory-reared tsetse flies Glossina pallidipes. Trypanosomes became entombed in the peritrophic membrane (PM) to form intraperitrophic cavities which were more electron-translucent than the amorphous layer of the PM. A hypothesis is suggested that after migration anteriorly in the ectoperitrophic space, the trypanosomes become enmeshed in the PM during its formation in the proventriculus, and that the trypanosomes are extricated in the midgut as the PM advances towards the posterior end of the gut.

Diurnal and seasonal activity of unfed adult Rhipicephalus appendiculatus (Acarina: Ixodidae) in relation to some intrinsic and extrinsic factors—II. Factors affecting vertical distribution of ticks in the habitat

When marked adults of the tick Rhipicephalus appendiculatus were released into 25 ° 25 cm plots in the field, their vertical distribution in the habitat was assessed after recovery, by comparing the number of ticks on the vegetation with those on the soil surface. In the hot dry season, 73% of the ticks were recovered. Of these a third were on the vegetation and two thirds at the soil surface. Out of the 67% recovered in the wet season, only 15% were found at the soil surface and the rest on the vegetation. In the cool dry season, 75% were recovered with roughly equal proportions on the vegetation and the soil surface. This suggests that only a third of the ticks would be available to be picked up by the hosts during the hot dry season. Two thirds would be available during the wet season and only half were available during the cool dry season.

Partial protection of rats against Trypanosoma congolense by passive transfer of IgM

Abstract IgM produced during the declining phase of the first peak of parasitaemia in rats infected with an isolate of Trypanosoma congolense was isolated on a Sephadex G 200 column equilibrated against 0.05 M Tris HCl in 0.15 M NaCl buffer. Rats passively immunised with the anti-trypanosome IgM survived infection with the same parasite isolate for an average of 6.7 days more than the controls. Apparently passive transfer of IgM can only confer partial protection against trypanosome infection.