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Biomedical subjects

D Fontenille

Publications and source records attributed to D Fontenille.

At least 91 records · Page 5Linked to original sources
PubMed1992

Malaria transmission and vector biology on Sainte Marie Island, Madagascar.

A 17-mo longitudinal malaria survey (November 1988-March 1990) was carried out on Sainte Marie Island, an area on the east coast of Madagascar which is frequently visited by tourists. During 706 man-nights of capture, 46,401 mosquitoes belonging to 32 species were caught. Sporozoite rates were determined by ELISA and incriminated Anopheles gambiae Giles s.s., An. funestus Giles, and An. mascarensis De Meillon as vectors of malaria. An. gambiae, the main vector, was highly anthropophilic but largely exophilic. Transmission by this species occurred mainly from November to April; the overall circumsporozoite antigen positivity rate was 1.7%, with a maximum of 3.2% in March-April. The nightly peak of transmission occurred between midnight and 0400 hours. The annual inoculation rate was calculated to be 100 infective bites per human, of which 92 were of Plasmodium falciparum. An. funestus played a minor role in transmission. An. mascarensis, an anopheline endemic to Madagascar, was incriminated for the first time, as a malaria vector. The sporozoite rate in this species varied from 0.4 to 0.9% as shown by both ELISA and salivary gland dissections. Parasite indices in humans up to 20 yr of age fluctuated during the year from 64 to 80%. Bed nets are recommended for malaria protection for the local population and tourists.

Animals↗
PubMed1992

Is Anopheles mascarensis a new malaria vector in Madagascar?

Anopheles mascarensis De Meillon, 1947, a mosquito that is native to Madagascar, is reported for the first time to act as a vector of Plasmodium falciparum malaria. From September 1989 to March 1990, 2, 499 An. mascarensis specimens from different regions of Madagascar were tested by an enzyme-linked immunosorbent assay (ELISA), using monoclonal antibodies against the circumsporozoite (CS) protein of the four human species of Plasmodium. The salivary glands of 237 specimens were also dissected. Fourteen of 1,864 specimens obtained from Sainte Marie island on the Malagasy east coast were found by ELISA to be positive for the CS protein of P. falciparum. In addition, two of 237 specimens that were dissected were observed to have sporozoites in the salivary glands. These sporozoites were identified as P. falciparum by ELISA. In the other regions studied, no positive specimens were found. Due to observed behavioral differences between east coast and highland populations of An. mascarensis, the possible presence of a species complex is discussed.

Animals↗
PubMed1991

Transmission and epidemiology of newly transmitted falciparum malaria in the central highland plateaux of Madagascar.

The recent reappearance of Plasmodium falciparum in the central highland plateaux of Madagascar has led to an important increase in both morbidity and mortality in the population. To understand the phenomena that originated this outbreak, and to evaluate the clinical and biological reactions of the population, we conducted entomological surveys during the whole malaria transmission season of 1988. In parallel, 41 individuals presenting with a malaria attack in January were given a curative antimalarial treatment and were followed weekly for 20 weeks, until the end of the transmission season, in June. During the follow-up, individuals presenting with a clinical malaria attack or with a parasite density above 5000 per mm3 of blood were again given antimalarial treatment. Overall, individuals presented with an average of 5.6 thick blood smears positive for P. falciparum, and 1.4 malaria attacks requiring treatment. Plasmodium falciparum prevalence rates gradually increased to 53.8% in April, one to two months after the observed peak of transmission, then decreased to 15.4% at the end of follow-up. The proportion of P. falciparum infections with clinical symptoms did not follow a similar temporal evolution and was significantly lower than at enrollment. Splenic rates gradually decreased from 29.3-2.6%, while anti-P. falciparum and anti-Pfl55/RESA antibodies increased. For the whole transmission season individuals experienced a mean 1.5 infective bites; the malaria vectors were Anopheles gambiae s. 1 and An. funestus. This study demonstrates that, in this population newly exposed to P. falciparum infections, almost all sporozoite inoculations lead to blood parasite infection requiring treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Longitudinal study on malaria transmission and biology of vectors in the island of Sainte Marie, on the east coast of Madagascar, from 1988 to 1990].

A 17-month longitudinal malaria survey was carried out in Sainte Marie Island, on the East Coast of Madagascar, from November 1988 to March 1990. During 706 man-nights of captures, 46401 mosquitoes belonging to 32 species were caught. Sporozoïte rates were calculated by Elisa. The malaria vectors were Anopheles gambiae sensu stricto, An. funestus and An. mascarensis. An. gambiae was the main vector. It was highly anthropophilic and partially exophilic. Transmission by this species mainly occurred from November to April, monthly sporozoïte antigene positivity rate varied from 0 to 3.85. The annual inoculation rate was about 100 infecting bites per man, in which 92 by Plasmodium falciparum. An. funestus intervened weakly in transmission. An. mascarensis, a malagasy endemic region anopheline is a newly discovered vector. The observed sporozoïte rate varied from 0.4 to 0.9 between September and March 1990. Parasite indexes in human fluctuated during the year from 64 to 80%. Because of the high level of transmission, recommendations for inhabitants and tourists are proposed.

Adolescent↗
PubMed1991

[Prevalence of antibodies to West Nile virus in youngsters from 5 to 20 years old in Madagascar].

In 1990 a serological investigation among 3,177 children (5 to 20 years old) sera has been conducted by the Pasteur Institute of Madagascar in several areas of Madagascar, in order to evaluate the prevalence of West Nile virus antibodies. 29.9% out of human sera tested by ELISA for West Nile IgG antibodies are positive, that shows a rather high level of West Nile virus circulation in Madagascar. Prevalence is increasing with age but no significant difference has been registered among prevalence according to sex. The diffusion of the virus appears lighter in Central Highlands.

Adolescent↗
PubMed1990

Malaria transmission and vector biology in Manarintsoa, high plateaux of Madagascar.

To evaluate the factors which determine the transmission level of falciparum malaria, entomological and parasitological surveys were conducted from October 1988 to February 1990 in Manarintsoa in the central highland plateaux of Madagascar. Mosquitoes were collected for 928 man-nights in pit shelters and indoor resting sites. Malaria vectors were Anopheles arabiensis and An. funestus, with no evidence of the presence of An. gambiae sensu stricto. Vectors were mainly exophilic and zoophilic. The index of stability was less than 1.5. The sporozoite rate was 0.11 for An. gambiae sensu lato and 0.47 for An. funestus. The transmission level was low, with an inoculation rate of 0.91 infective bites/person/year and an infection risk of 0.62. Malaria transmission occurs 7 months of the year in this area, from November to May. Human parasite rates fluctuated from 29% in October to 53% in May.

Animals↗
PubMed1990

[The Wesselsbron virus, a new arbovirus for Madagascar].

Wesselsbron virus, an African arbovirus group flavivirus, has been isolated in 1989 for the first time in MADAGASCAR from Aedes circumluteolus collected inside primary forest near the village of MAROVITSIKA. Serological studies in man using haemagglutination inhibition test have permitted to think that Wesselsbron virus have circulated quietly in MADAGASCAR. The detection of Wesselsbron antibodies in Lemurs sets the problem of the biological cycle.

Aedes↗
PubMed1990

[Use of monoclonal antibodies for the antigenic analysis of West Nile viral strains isolated in Madagascar. Contribution to the understanding of the epidemiological cycle].

The antigenic relationship of 53 MADAGASCAR West Nile isolates to each other and to the two prototype viruses (Eg 101 and G 2266) was assessed using monoclonal antibodies. In MADAGASCAR exist 5 antigenic groups: 4 which are much closer to the Egyptian strain Eg 101 than to the Indian, and antigenically distinct from South african H 442 strain. One other is closely related to Indian strain G 2266. Antigenic variations are observed in every periods of transmission cycle. Some differences between strains isolated in a same region are also observed. MADAGASCAR is an exchange place for West Nile virus through the instrumentality of migratory birds.

Aedes↗
PubMed1990

[Preliminary study on malaria transmission at the end of the rainy season in Mahitsy near Tananarive].

This survey carried out from March to June 1989, demonstrated the important part of An. funestus in malaria transmission, in MAHISTY, a village near the malagasy capital city. End of March, the number of An. funestus bites reached 6 per man per night, and only 0.75 for An. gambiae s.l. In March a mean of 23 An. funestus per room were found as indoor resting mosquitoes. One indoor resting An. funestus, caught in June, was positive against P. vivax by ELISA. Observed of 52 indoor-resting An. funestus was 100%. In this village, Plasmodium indexes were 60%.

Adolescent↗
PubMed1990

[Malaria vectors and their role in transmission, in Manarintsoa in the Highland Plateaux of Madagascar from 1988 to 1990].

To evaluate the factors determining malaria transmission level, entomological and parasitological surveys were conducted from October 1988 to February 1990 in MANARINTSOA, in the central highland plateaux of MADAGASCAR. Mosquitoes were collected during 928 man-nights of captures, in pit shelters and in indoors resting sites. The malaria vectors were An. arabiensis and An. funestus, with no evidence of the presence of An. gambiae s.s. The vectors were mainly exophilic and zoophilic. The index of stability was below 1.5. The sporozoite rate was 0.11 for An. gambiae s.l. and 0.47 for An. funestus. The transmission level was low: the inoculation rate was 0.91 infected bite per man and per year and the infection risk 0.62. Transmission occurs 7 months per year, from November to May. In the human population parasite rates fluctuated from 29% in October to 53% in May.

Altitude↗
PubMed1990

[Ecological factors in the renewed outbreak of malaria in Madagascar].

The new epidemic of malaria which spread on the Madagascar high plateau in 1986-1987 is due to the combination of several factors (some of which are analysed by the authors, especially those related to anopheles, parasite and man). The authors compare the situations on the high Plateau and on St Mary Island, on the East Madagascar Coast, where the malaria is stable. Concerning the vector, the most interesting fact is the come-back of Anopheles funestus on the high Plateau from which it had disappeared at the beginning of the fifties. In this area, An.arabiensis seems to be the only representative of the gambiae complex whereas it is An. gambiae s.s. in St Mary Island. The parasite is getting more and more resistant to chloroquine. Nevertheless, man seems to develop protection, but it is difficult to analyse the markers which would prove the protection. However, that protection was assessed, on the humoral and cellular level, against the peptides of the RESA (Ring Infected Erythrocytes Surface Antigen), the circumsporozoite protein and the antigen E.

Adolescent↗