Sleeping Sickness Focus Research Articles

Sleeping sickness in Zaire: a nested polymerase chain reaction improves the identification of Trypanosoma (Trypanozoon) brucei gambiense by specific kinetoplast DNA probes

Blood samples collected in the sleeping sickness focus of Boma, Zaire, from human patients and domestic animals were analysed by polymerase chain reaction (PCR) for the presence of trypanosome DNA. The comparison of PCR and miniature anion exchange centrifugation technique (m-AECT) results clearly shows that in domestic animals mixed infections (Trypanozoon/Trypanosoma [Nannomonas] congolense) are more frequently diagnosed by PCR than by m-AECT. Trypanozoon positive blood samples were further analysed for Trypanosoma (Trypanozoon) brucei gambiense. For that purpose amplified minicircle kinetoplast DNA (minicircle kDNA) was differentiated in gambiense and non-gambiense by hybridization with DNA probes. To analyse blood samples, especially those with low parasite numbers, the amplification step had to be improved by a nested PCR. Subsequent hybridization was done with kDNA probes generated by PCR from blood samples which had been obtained from a human patient infected with T.(T.) b. gambiense and a pig infected with Trypanozoon. The hybridization results clearly show that at least two genotypes of Trypanozoon parasites occur in the sleeping sickness focus of Boma, Baz-Zaire. One obviously corresponds to T.(T.) b. gambiense and was present in humans and two domestic animals (pig, dog). The other genotype seems to be associated with T.(T.) b. brucei and could be detected only in the blood of domestic animals. This is the first time that field samples could be analysed by a technique which facilitates the molecular identification of T.(T.) b. gambiense without prior cloning, propagation, and/or isolation of the parasites. Therefore, this technique seems to be a promising tool to elucidate the significance of the animal reservoir for the epidemiology of the gambiense sleeping sickness in Africa.

Trypanosoma brucei rhodesiense: Characterisation of stocks from Zambia, Kenya, and Uganda using repetitive DNA probes

We have previously described a system for characterising the relationships between trypanosome stocks of the T.brucei group based on Southern blotting with repetitive DNA probes followed by cluster analysis of resultant banding patterns (G. Hide et al. Molec. Bioch. Parasitol. 39, 213–226, 1990). In this study, we extend this analysis to examine the relationships between trypanosome stocks isolated from major sleeping sickness foci in Zambia, Kenya, and Uganda. We show that the trypanosome strains responsible for disease in Zambia are quite distinct from those sampled from the Kenya/Uganda foci. Furthermore, the human serum resistant stocks isolated from the Kenya/Uganda foci which were isolated from man (or from animals) were found to form a tight group in the cluster analysis, while stocks isolated from nonhuman sources in the same area or stocks from elsewhere were found in separate groups. Thus, the human infective trypanosome strains found in these foci may have common origins and have, perhaps, arisen by clonal selection from a common

A new approach to community participation in tsetse control in the Busoga sleeping sickness focus, Uganda. A preliminary report

A process is described by which trapping technology is being taught to a rural community which has been affected continuously by an epidemic of sleeping sickness for over a decade. Through a systematic health education programme, people are actively involved in making and setting traps and in learning about the general characteristics of the tsetse fly and the disease. A mono-screen trap has been developed for community use and is being used to trap flies. This is the first time that this kind of community participation has been attempted in tsetse control--and this approach is discussed in relation to other approaches.

Prévalence des trypanosomoses des animaux domestiques dans le foyer de la maladie du sommeil de Fontem au Cameroun

Three hundred-fourteen domestic animals: 114 goats, 93 sheep, 67 dogs and 30 pigs in the Fontem sleeping sickness focus (Cameroon) were screened for infection with trypanosomes using parasitological and serological tests. Nannomonas was the only sub-genus detected in the animals with a prevalence of 28.3%. The card agglutination test (Testryp CATT) for trypanosomiasis showed a positivity rate of 38.2%, indicating that it allowed a better estimation of animal trypanosomiasis. The absence of trypanosomes of the sub-genus Trypanozoon seems to indicate that human African trypanosomiasis is not a zoonosis in this sleeping sickness focus.

La lutte communautaire contre une endémie tropicale: Croyances surnaturelles et pièges à tsétsé au Congo

Community participation in the control of tropical diseases is of major importance nowadays, particularly for sleeping sickness (Gambian trypanosomiasis). Indeed, the authoritarian measures used with success to control this disease during the colonial period are difficult to apply now. Moreover, in the Congo, cultural and financial restrictions are such that patients sometimes refuse treatment. Thus, it has become highly desirable for vector control to be carried out at the same time as the treatment of patients. Trapping tsetse flies (or Glossina) is an ingenious and effective anti-vectorial method which has been tested in 55 villages of the Congo. The blue-black pyramid trap used does not require insecticide impregnation, and is hung in the branches by means of a capture-bag containing diesel oil. These trials, conducted in the sleeping sickness focus of the Niari river, have demonstrated the feasibility of local communities taking over the responsibility for the traps, while at the same time revealing certain obstacles. Indeed, the efficacy of this method depends on the optimization of trapping. This involves the determination of strategic capture sites by periodically harvesting the flies and moving the traps in order to catch the maximum number of flies. It also involves regular maintenance of the traps (i.e. repairs, checking the capture bag, clearing vegetation...). However, although these activities would appear to be feasible at community level, they are not always carried out satisfactorily. This results in the insufficient viability of the traps and finally to the reinvasion of the treated area by the tsetse. This study presents aspects of the present-day Congolese socio-cultural environment characterized by the revitalization of traditional Bantou mysticism and religious worship. The possessors of the 'Vital Force' or Kundu (sorcerers and healers) are confronted at night in an 'over-reality' consisting of the visible reality together with innumberable beings and objects existing specifically in the invisible state. This nocturnal confrontation may modify the local balance of power and relationships, and is also thought to cause certain symptoms of sleeping sickness and other diseases. During the colonial period, Kundu was prohibited. Under the influence of the Christian church, and because of the progress of modern medicine, the power of the sorcerers and healers gradually decreased. Then, in the 1960s, the eruption of Marxism as an anti-religious theory, modified the balance of power once more.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects on non-target terrestrial arthropods of synthetic pyrethroids used for the control of the tsetse fly (Glossina spp.) in settlement areas of the Southern Ivory Coast, Africa

Side-effects of cypermethrin, permethrin, and deltamethrin applications for the control of tsetse flies were studied in a sleeping sickness focus near Bouafle, Ivory Coast (West Africa). The insecticides were applied by ground-spray on the surrounding vegetation of three villages. Each village was treated with one pyrethroid. Effects on the non-target arthropod fauna were observed by means of regular and multiple sampling before and after treatment in the sprayed villages and in an untreated control village. Malaise traps and pitfall traps were used. Apparently, the three pyrethroids had markedly different side-effects. The spiderAporoptychus lamottei, however, appeared to be affected by all treatments. This species is therefore considered as an indicator for side-effects of pyrethroids used under the given circumstances. In all affected taxa, except in the proctotrupoid genusCremastobaeus, recovery was observed within two months.Muscidae were markedly affected by deltamethrin. The selectivity of this insecticide for tsetse control is discussed.

Observations on an apparent population extension of Glossina tachinoides Westwood in Southern Ivory Coast

Recent entomological surveys in the Bouaflé sleeping sickness focus of the Ivory Coast have revealed that Glossina tachinoides is considerably more widely distributed than hitherto. Some flies were found in the fringing riverine forests of tributaries of the River Marahoué. However, the greatest concentrations were found in villages and settlements where domestic pigs were kept. The southern limit of G. tachinoides now appears to lie one half degree of latitude further south than that reported by earlier investigators. The authors think there is good evidence that G. tachinoides is extending its range eastwards and southwards through and beyond the Bouaflé area, and the epidemiological significance of this is briefly discussed.

Characterization of Trypanozoon stocks from the South Nyanza sleeping sickness focus in Western Kenya

220 Trypanosoma (Trypanozoon) brucei sp. stocks isolated between 1969 and 1983 from the Lambwe valley sleeping sickness focus in South Nyanza, Western Kenya, were characterized by isoenzyme electrophoresis using 12 enzymes. 12 different zymodemes of T. (T.) b. rhodesiense were isolated from patients during the 13-year period and identical stocks were also found in cattle, reedbuck ( Redunca redunca) and tsetse ( Glossina pallidipes). Cattle may have played an important role in maintaining and increasing peridomestic transmission of trypanosomes during the 1980 outbreak of sleeping sickness in the valley, even though they themselves suffered heavy mortality. Sleeping sickness in Lambwe valley is unlikely to have been introduced from elsewhere, since T. (T.) b. rhodesiense stocks isolated from the valley were different from those from neighbouring epidemic areas. Alternatively, the recent outbreak may have been caused by the increased transmission associated with an expanding tsetse population. The possibility that genetic exchange contributed to the biochemical diversity of the trypanosomes examined is discussed.

Ecology of tsetse flies in the preforested area of the Ivory Coast. Relation to human trypanosomiasis and possibilities for control

This paper gives the results of a tsetse fly research program in the preforested area of Ivory Coast. The main investigation tool was the Challier-Laveissière's biconical trap. The ecodistribution, resting and pupal sites of the principal tsetse species, G. palpalis, G. pallicera and G. nigrofusca were described in the T. b. gambiense sleeping sickness focus of Vavoua. Population dynamics, host preferences, activity cycles were compared between tsetse populations in plantations and village surroundings. Man-fly contact was of high intensity where human habitat is scattered in plantations but in village tsetse flies used to feed mainly on pigs. Resettlement of scattered populations can be considered as a preventive measure against sleeping sickness transmission. Experiments on tsetse flies control by insecticides along edges, associated with insecticidal impregnated screens, were considered as promising.

The experimental use of 'sentinel' goats to monitor trypanosomiasis in a Zambian sleeping sickness focus. Part I. The isolation of Trypanosoma brucei rhodesiense-like organisms from a 'sentinel' domestic goat.

The experimental use of 'sentinel' goats to monitor trypanosomiasis in a Zambian sleeping sickness focus. Part I. The isolation of Trypanosoma brucei rhodesiense-like organisms from a 'sentinel' domestic goat.

Sensibilité aux trypanocides et au plasma humain de souches de <em>Trypanozoon</em> isolées d’animaux provenant de foyers endémiques de maladie du sommeil au Nigeria

Twelve Trypanozoon stocks isolated from semi-nomadic cattle in known sleeping sickness foci of central and northern Nigeria were studied in terms of susceptibility to two trypanocides, diminazene aceturate (Berenil) and isometamidium chloride (Samorin) and human plasma. In infected small ruminants, three of the stocks were resistant to diminazene aceturate at does of 7.0 -14.0 mg/kg body weight (b.w.) while isometamidium chloride at doses of 1.0 mg/kg b.w. or higher failed to effect parasitological cure of infections with two of the diminazene-resistant stocks. The two isometamidium-resistant stocks were also consistently resistant to the trypanolytic action of human plasma. It is suggested that cattle are reservoirs of Trypanosoma brucei subspecies potentially infective to man and resistant to the therapeutic action of the known sanative pair (diminazene and isometamidium).