Annales de la Societe belge de medecine tropicale最新文献

The major risk factors associated with acquisition of T. b. rhodesiense sleeping sickness in the Busoga focus, S.E. Uganda were investigated using a case-control study. 122 cases and 244 matched controls were used in the study. For each case two age-, sex- and resistance controls (1 matched nearest neighbour control and 1 village control) were selected. Patients and controls answered the same questionnaire which had been developed and field tested before the field study started. A logistic regression model for a 1:2 matched case control design was fit to the data. The following factors were found significant: cases spent more time outside their village of residence than controls and visited more SS high risk areas than controls, more cases than controls collected firewood in the forests. Generally, cases had less domestic animals grazing near the places of man-fly contact, especially near water and firewood collecting and bathing points, and near farms and gardens, than controls. Cases had more antecedents of sleeping sickness in the family. Generally cases had a less well developed information network than controls, and belonged economically to a less powerful group. Based on these results we may conclude that the risk to develop T.b. rhodesiense sleeping sickness depends upon a multitude of economical, cultural and human behaviour factors. These factors should be taken into account in the planning and monitoring of sleeping sickness control programmes.

The movements of human populations towards the mining wealth of the northern parts of Sierra Leone are favorable to a high contact rate between onchocerciasis patients coming from the south-western area of this country and the vector species Simulium yahense and Simulium squamosum which assume the essential of onchocerciasis transmission in the above-mentioned mining area. In fact, the Onchocerca volvulus strains concerned by this contact seem to be more pathogenic than those locally transmitted. In order to assess the danger it could represent for the Onchocerciasis Control Programme in West Africa, we carried out the experimental study of transmission which may result from this contact when more or less infected onchocerciasis patients are involved. The results indicated that this transmission by S. yahense may reach high proportions only when heavily infected onchocerciasis patients are implicated. We took also notice of the low capacity of S. squamosum to transmit the O. volvulus strains from the south-western Sierra Leone, irrespective of the microfilarial load of patients. Thus, in the most favorable conditions of a high parasite-vector contact of the study, involvement of S. yahense and onchocerciasis patients with high skin microfilarial loads is the only occurrence to which a high risk of intensive transmission may be related. The authors consider that the probability of such a risk occurring will be drastically reduced, due to the considerable decrease of skin microfilarial loads in human communities which regularly have the advantage of ivermectin (Mectizan) mass treatments.

As part of the return of savanna migrants installed since a long time in forest regions, in the south of Sierra Leone, we carried out an experimental study about a cross-transmission between Simulium sirbanum from Missira (West-Mali) and the forest strain of Onchocerca volvulus in the south-west of Sierra Leone. This study will allow to know if there is a risk of onchocerciasis transmission recrudescence in relation to the reinstallation of these migrants in their native region. Because of the very high limitation to the forest strain of O. volvulus microfilariae output of the peritrophic membrane reduction with savanna black-flies and according to the very low mature parasite out put of S. sirbanum with this strain observed along this experimentation, the forest strain of O. volvulus from the south Sierra Leone appears maladjusted to S. sirbanum, the main vector of onchocerciasis in savanna regions. This observation implicates a very low intensity of transmission for this forest strain by savanna onchocerciasis vectors. The return of savanna migrants in their native region, installed in the south Sierra Leone since several decades, could not be, in a short time, an origin of onchocerciasis recrudescence in savanna regions of the Onchocerciasis Control Programme area cleaned by an effective vector control carried out since 1975 sustained now by a chemotherapeutic treatment reducing the human parasite reservoir. However, the preservation of this acquired necessitates an epidemiological supervision increased, because the interactions between the vector and the parasite for a long time could carry away a mutual adaptation and a sickness recrudescence.

Several studies recently done in Africa south of the Sahara have clearly demonstrated that pyrethroid impregnated bednets should actually reduce malaria inoculation rate due to Anopheles gambiae and therefore high Plasmodium falciparum parasitaemia and malaria morbidity, even mortality. Nevertheless some concerns were recently raised on an eventual shift in the usual behavior of this species induced by the presence inside the house of bednets treated with pyrethroid insecticide known to have a deterrent or excito-repellent effect, and which could therefore lead to a biting behavior earlier than usual. The current limited study, done in Djoumouna, a place well known for the very high density of An. gambiae, has shown that the temporary presence inside a house of a bednet impregnated with deltamethrin (12.5 or 25 ma a.i./m2) has not induced any shift in the biting cycle of this species, but it actually reduced by some 50% its biting rate noticed on human beings. It is worth underlining that all sporozoite infected specimens were actually caught after midnight. This biting behavior of An. gambiae could explain why impregnated bednets are so efficient in reducing man-vector contact and malaria transmission.

As part of research programme on malaria transmission in Sri Lanka, a study was made of man-biting anophelines at Nikawehera, a village on the border of the intermediate and dry rainfall zones. Weekly mosquito collections by night human bait (NHB) were performed inside and outside four fixed stations from October 1992 till March 1993. Houses in the village were treated with malathion by the Anti-Malaria Campaign in October and at the end of January 1993. An. culicifacies and An. tesselatus were the most abundant species. An. culicifacies was probably the only species responsible for malaria transmission. An. culicifacies densities varied between stations and reflected differences in availability of breeding places. An. culicifacies aggressivity is closely related to the rainfall pattern, increasing after the first monsoon rains in November and reaching a peak in late December--early January. Vectorial capacity, however, decreased during the first weeks of the rainy season. The maximum vectorial capacity was found in January. The night biting cycle of An. culicifacies showed a peak between 20.00 and 23.00 h. Since the introduction of electricity in the village, people go to bed later. This might reduce the impact of impregnated bednets on malaria transmission. The results show that malathion spraying as performed now is not very effective. The timing of the spray rounds should be improved. In order to limit malaria transmission, we suggest to advance the malathion spraying campaign of January with one month.

This study was conducted in the Guatemalan highland department of Sacatepequez, in a sample of 146 rural women insured by the Social Security system. It examined their health care behaviour when their children presented common childhood symptoms such as diarrhoea, fever, cough and worms. The mothers generally sought help and treatment advice from an older woman in the family, and did so more often for diarrhoea (82%) and fever (64%) than for cough (43%) or worms (28%). Obtaining advice in a pharmacy or from a drug seller ranked second (range: 8%-38%, depending on the symptom), before the procurement of professional help at a medical service (range: 8%-23%). Traditional healers were hardly consulted (range: 0%-3%). In the case of self-treatment the women predominantly relied on Western drugs: around 80% in diarrhoea and fever, and above 50% in cough. Herbs and traditional external remedies were little used, except in cough (27% herbs) and worms (58% external remedies). None of the mothers reported ORS as home treatment for diarrhoea. Problems of geographical or financial accessibility could not explain the low utilisation of the Western health care system. The acceptability of public services, however, was poor. Largely because the Social Security clinic did not prescribe the "potent" modern drugs mothers preferred for the treatment of childhood symptoms--at least, not for uncomplicated illness episodes. Women hence turned to the--partially informal--private sector, which unabashedly responds to their demands. Clear away the discrepancy between the "rational" needs perceived by the official health sector and the demands of the population is one of the bigger challenges to health care planning in transitional communities such as the one studied.

This paper gives an overview of what happened when a flat fee cost recovery system for pre-school children was introduced in a rural town hospital in western Mali: the preceding analysis, the implementation of the new scheme, the results and the problems. The most probable explanations for the problems are discussed. It is concluded that, in order to be successful and to attain its objectives, an initiative of this kind--in this environment--requires very careful preparation and commitment, management-wise as well as socially, in order to achieve a sufficient level of common understanding and consensus.

The Zumba focus of tegumentary leishmaniasis lies in the southwards Amazonian region of Ecuador. A clinico-epidemiological study has been carried out in the area on 83 patients attending health centers. All the biotopes suitable for sandflies, including dwellings, have been sampled from February to September 1992 by light trap and human bait catches. The number of sandflies caught amounts to 2,547. Anthropophilic sandfly fauna is poor and only three species have been recorded. Lutzomyia serrana abounds inside dwellings where it bites men even during daytime. The parasite was identified as an intermediate form between Leishmania panamensis and L. braziliensis. It will be described elsewhere. The high proportion of facial lesions suggests a domiciliary transmission for which Lu. serrana could be a good vector candidate.

Garlic (Allium sativum L.) and one of its major components, allicin, have been known to have antibacterial and antifungal activity for a long time. Diallyl trisulfide is a chemically stable final transformation product of allicin which was synthesized in 1981 in China and used for treatment of bacterial, fungal and parasitic infections in man. The activity of diallyl trisulfide was investigated in several important protozoan parasites in vitro. The IC50 (concentration which inhibits metabolism or growth of parasites by 50%) for Trypanosoma brucei brucei, T.b. rhodesiense, T.b. gambiense, T. evansi, T. congolense and T. equiperdum was in the range of 0.8-5.5 micrograms/ml. IC50 values were 59 micrograms/ml for Entamoeba histolytica and 14 micrograms/ml for Giardia lamblia. The cytotoxicity of the compound was evaluated on two fibroblast cell lines (MASEF, Mastomys natalensis embryo fibroblast and HEFL-12, human embryo fibroblast) in vitro. The maximum tolerated concentration for both cell lines was 25 micrograms/ml. The results indicate that the compound has potential to be used for treatment of several human and animal parasitic diseases.

Hyperreactive malarial splenomegaly (the former tropical splenomegaly syndrome) refers to a combination of splenomegaly, high antimalarial antibodies and high serum IgM content, a condition resulting from an aberrant immunological response to malaria. It has rarely been described in expatriates. We report the case of an 8 year-old Dutch boy who developed this syndrome 18 months after returning from Zaire. Treatment with mefloquine resulted in gradual improvement of all laboratory abnormalities. The spleen did not decrease in size, but became normal for age as height increased.