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G Hébrard

Publications and source records attributed to G Hébrard.

9 recordsLinked to original sources
PubMed1998

[Epidemiologic study of the main human intestinal nematodes in the middle west of Madagascar].

An epidemiological study of human intestinal helminthiasis was conducted during July and August 1995, in the middle west of Madagascar, with 4571 adults and children ranging from six months to 90 years, in 61 communities between Betafo and Miandrivazo. Faecal examination utilising the MIF concentration method revealed that ascariasis was the dominant nematodosis in the middle west with high prevalences in the high-altitude communities. Ascaris lumbricoides prevalences increase among children and women. Interesting more than 50% of the pattern, ascariasis is a public health problem and its association with infant malnutrition is statistically significant. Hookworm infection prevalence is higher in low-altitude communities, it increases among adults. The Trichuris trichiura prevalences were lower than the prevalences of ascariasis and hookworm infection in all of the communities. Important variations of the prevalences of intestinal helminthiasis are observed essentially in relation with climatic conditions.

Adolescent↗
PubMed1997

[Natural vector capacity level of Simulium damnosum s.l. (Diptera: Simuliidae) at the ecology station of Tai (Côte d'Ivoire)].

Several studies have been carried out on the transmission of Onchocerciasis by Simulium damnosum s.l. in the forest zone of Côte d'Ivoire. This study, carried out in 1979-1980 was devoted to determine the risk of onchocerciasis transmission inside and outside the rain forest of Taï (5 degrees 50' N-7 degrees 25' W). We present the vectorial capacity of S. sanctipauli in the region of Taï before massive flow of refugees from areas of Liberia without any control Programme. The results of micromorphological technics for determination of S. damnosum adults, showed that mainly females of S. sanctipauli were present. The studied populations had low parturity rates: 39.2% outside and 30.9% of parous flies inside the rain forest. The parasitic rates (0.4% of infectious females outside and 0.1% inside) and their parasitic loads (15 and 3 infective larvae per 1000 parous female respectively outside and inside the rain forest) were low, consequently their vectorial capacity with Onchocerca volvulus was almost non-existent in natural conditions. Before massive flow of refugees including persons carrying microfilariae, there were no problem of onchocerciasis within and outside the rain forest of Taï. However, the massive flow of refugees and the deforestation for growing crops can create situations favourable to the installation of more efficient vectors, increase man/vector contact and contribute to more intense onchocerciasis transmission. The monitoring of onchocerciasis transmission is necessary.

Animals↗
PubMed1997

[Window traps and displacement of adult Simulium damnosum s.l. along a line of breeding sites in a forest zone of Côte d'Ivoire].

The displacement of adult black flies along a line of breeding sites has been studied in savannah area and in pre-forest zone. This paper presents the results of studies carried out in forest zone of Côte d'Ivoire. Interception traps made with sticky window traps were vertically displayed cross the river. The results showed that the displacement of adult S. damnosum s.l. along a line of breeding sites is correlated with the river flow. In a period of low discharge, adult black flies present a marked tendency to fly up stream. But in period of heavy discharge, they do not show any tendency; they may fly ever up stream or down stream. They fly essentially at the water level during the period of low flow and at a height between 0.5 to 1.5 m during heavy flow of the river.

Animals↗
PubMed1987

[Ivermectin and the reduction of the rate of infection of simuliids in a forest focus of human onchocerciasis].

Eight patients from a forest onchocercian area "Grandes rivières", in Ivory Coast, were treated with a single oral dose of ivermectin (12 mg). The density of dermic microfilariae was estimated at days 0, 7 and 180; the mean numbers of ingested microfilariae and of developing larvae in the vectors S. soubrense-S. sanctipauli, engorged on the treated patients were recorded. Comparisons were made with non treated patients, having a similar density of microfilariae than the 8 treated patients at day 7. Results confirm the reduction induced by ivermectin of the dermic microfilarial density and the resulting reduction of the infection of the simuliids. Furthermore 7 days after treatment, a new phenomenon is demonstrated: for a similar dermic microfilarial density, simuliids take up a number of microfilariae 100 times lower from treated than from untreated patients. To explain this phenomenon, it is suggested that ivermectin induces a change in the microfilarial distribution in the layers of the dermis. Six months after treatment, this low uptake of microfilariae by the vectors had disappeared, and the infection rate of the engorged similiids was much higher than at day 7 although the dermic microfilarial density was similar.

Animals↗
PubMed1987

Antibody responses in forest and savanna onchocerciasis in Ivory Coast.

Three foci of onchocerciasis transmission (two forest and one savanna, respectively) in the Republic of Ivory Coast were chosen for a comparative analysis of Onchocerca volvulus antigens and of patients' antibody responses. Clear differences between frequency and intensity of ocular pathology existed between the forest foci and the savanna focus. We found heterogeneity of SDS-PAGE-separated components of female worms with respect to the mobility of three protein bands of the 100 KD region and to the ability of an 80 KD band to bind horseradish peroxidase. These variations were clearly not associated with the degree of ocular pathology. No differences in the composition of worm antigens were detected by immunoblotting. A variable with a possible relation to ocular pathology was the antibody response of patients: individuals from the savanna focus, where a high degree of ocular pathology is observed, tended to have a stronger and more differentiated IgG antibody response against O. volvulus antigens than patients from the forest foci. However, no antigens specifically recognized by patients from either forest or savanna were detected.

Adolescent↗
PubMed1985

Studies on the protein and antigen composition of individual female Onchocerca volvulus after collagenase digestion.

The composition of proteins and antigens of female Onchocerca volvulus from one focus of transmission was studied by SDS-PAGE and immunoblotting. Worms that had been exposed to collagenase digestion of onchocercomata for different periods of time and parasites of different age and status of reproduction were tested. Some O. volvulus antigens were found to be sensible to prolonged digestion (molecular weights: 18 KD, 21 KD, 24 KD) but the majority of the antigens was stable up to 64 hours of incubation at 34 degrees C. The composition of proteins and antigens varied with the age and the status of reproduction of the worms. Slight differences between individual filariae were found, even when worms of comparable age and status of reproduction were tested that had been exposed to nodule digestion for comparable time.

Animals↗
PubMedDate not supplied

[Drought and malaria decrease in the Niayes area of Senegal].

The Niayes is geographically characterized by an alternating succession of sand dunes and wet depressions, 20 km wide, which are behind the offshore bars from Saint-Louis to Dakar. Since 1970, the area has been affected by drought. The rainfall which was around 700 mm per year before 1960 has fallen below 500 mm during the last 30 years. In 1991 it was only 350 mm and in 1992, 260 mm. The vegetation has become impoverished in the depressions which are now more and more cultivated for vegetables. Entomological, parasitological and clinical studies on malaria were carried out in 1991 and 1992 in three villages and the results were compared with data gathered from 1967 to 1968 with comparable methods. The main points concerning the evolution of malaria are listed as follows. An. funestus, which was previously the predominant malaria vector, has almost disappeared. An. gambiae has regressed ahead of its sibling species An. arabiensis, a less competent vector. These changes in vector populations have led to lower malaria transmission and consequently a decrease of the endemicity. The children parasitic index, which was between 40 to 80% according to the localities in 1967, fell to 10% or less in 1991 and 1992. Finally, the incidence of clinical cases, calculated on a cohort of 100 children was only 4% in 1992, which is very low for an African endemic country. We conclude that drought and human activities have modified the environment such that malaria endemicity has seriously decreased. However, the risk of epidemic remains with the eventual occurrence of heavy rains. Therefore a surveillance of the area is needed to prevent a future epidemic.

Animals↗