Biomedical subjects

J Mouchet

Publications and source records attributed to J Mouchet.

131 records · Page 8Linked to original sources

PubMedDate not supplied

[Human diffusion of arthropod disease vectors throughout the world].

The present distribution of animals and plants throughout the world is the result of an evolutionary process involving tectonic, climatic and biotic factors. Humans, since their appearance, have contributed to the spreading of many species including disease vectors and pests. When humans left their native African home, they brought with them ectoparasites such as lice and acarids. During the neolithic era, humans were leading domesticated animals which carried their own parasites into new areas. Dwelling commensals, flea, bugs, triatomids, flies, and cockroaches followed human migrations. In the second millennium, sailboats transported mosquito species which were resistant and reproduced on board, including Culex quinquefasciatus, Aedes aegypti, and Ae. albopictus. Steamers further shortened the length of trips and allowed the transport of anophelines. The opening of the Tamatave-Port-Louis line was immediately followed by the transport of An. gambiae from Madagascar to Mauritius and Reunion, and epidemics of malaria occurred on the two islands which had been free of the disease. Also, An. gambiae was transported from Senegal to Brazil. Old tires destined for recycling carried Ae. albopictus to the USA, Brazil, and then Italy. The pandemic of the plague at the end of the nineteenth century was propagated from harbour to harbour by steamers carrying both infected rats and their fleas Xenopsylla cheopsis. Aircrafts have reduced the travel time so much that in less than two days an insect could reach every point of the world. As soon as the airports had been built on the islands of French Polynesia, they were all colonized by Ae. aegypti. The same phenomenon occurred with midges (Fig. 2). Also, the construction of the airport on a Galapagos Island coincided with the importation of the blackfly Simulium bipunctatum from the continent. In addition, infected malaria mosquitos imported from tropical countries reached Europe and contaminated airport employees and local inhabitants. Six cases of malaria were recorded during the summer of 1994 around the Charles de Gaulle Airport, north of Paris, suggesting that the anophelines could have been imported from West and Central African countries which are served by this airport. The serious threat of vector importation is moderated by the vector's difficulty in adapting to new conditions. However any prediction is questionable.

Animals↗

PubMedDate not supplied

[Particularities and stratification of malaria in Madagascar].

The first factor is the malaria parasite, for which the species P. falciparum and P. vivax are important. Secondly, the transmission determines the disease stability and challenges the host's immunity. The third factor is the human host, consisting of people of both African and Asiatic origin, the latter of whom are more susceptible to P. vivax. Human activities such as cultivating rice fields are of paramount importance for the proliferation of the vectors. The vectors A. gambiae, A. arabiensis and A. funestus are very similar to those of the African continent. These vectors are not endemic on Madagascar, suggesting that they were recently introduced to the island where 95% of the fauna species are endemic. On the Plateau and in the South, the rice fields provide most of the breeding places for A. gambiae s.l. and A. funestus. Five epidemiological belts are found in Madagascar which are very similar to their analogs on continental Africa (fig. 1). These facies include the equatorial belt on the east coast and the tropical belt on the west coast north of Morondava, the Plateau belt analogous to the southern African continent, the southern Madagascar belt which is similar to the Sahelian areas, and finally the zones above 1,500m, which are essentially free of malaria. The first two facies have a stable type of malaria, and in the following two, malaria is unstable. These areas include the Plateau, the area of the severe epidemics which occurred between 1985 and 1988 with more than 50,00 deaths. Malaria control is based on a variety of strategies to respond to the epidemiological heterogeneity of the disease. Spraying within the homes with DDT, used on the Plateau after 1988, was and still is very successful.

Climate↗

PubMedDate not supplied

[Malaria: research perspectives in medical entomology in Madagascar].

The entomological studies on malaria in Madagascar had especially concerned the behavior of vectors in relation to insecticides. The cessation of spraying within the homes and the absence of chloroquine allowed a re-emergence of malaria on the Plateau in the 1980's. This phenomenon pointed out the heterogeneity of the transmission on the island. It was necessary to define the entomological characteristics of the four principal facies of transmission in Madagascar. These studies provided the services of public health with the epidemiological basis to organize the measures of the battle and prevention of malaria. In the very populated countryside of the Plateau, the nature of the vectors, their density and their vectorial competence present large local variations. The entomological studies search to define the different human and environmental factors which modulate the transmission and constitute the risk factors of epidemy. This micro-epidemiological approach will facilitate the analysis and comparison of the clinical and biological results obtained in the different residences. The research on medical entomology will equally enable the proposal of plans for the fight against malaria adapted to the different situations.

Animals↗

PubMedDate not supplied

[Impact of changes in the environment on vector-transmitted diseases].

We have defined the relationship between infectious diseases and environmental conditions and considered the development of this relationship to its current situation, where human intervention is occurring more often and is becoming more aggressive. The increase in the transport of freight and passengers by air has allowed parasite vectors to spread quickly and easily over large distances. Every country can now be reached from any other country within a couple of days. Usually, foreign species are unable to establish themselves and to persist in the new environment; but the recent arrival of Aedes albopictus in Albania, Italy and the Americas is a cause for concern. Demographic pressure has increased the need for land and the exploitation of new areas leads to large changes in the vegetation. The classic example of this man-made damage is the destruction of tropical forest in Western Africa, but the destruction of herbaceous vegetation, such as papyrus, in East Africa, could also have serious epidemiological consequences. Streams and rivers have been managed for power production and irrigation. The use of dams, both large and small, and the culture of rice in paddy-fields produces large expanses of water which are suitable breeding grounds for mosquitoes and snails, the vectors of human diseases such as malaria and schistosomiasis in sub-Saharan Africa. They are, however, of lesser importance in Asia and the Americas. Urbanization imposes a set of very similar structures on a specific rural environment. The effect of these two factors on each other determines the pathologies associated with each town. The suburban area is a specific environment where both urban and rural diseases occur and are made worse by poor hygiene conditions (waste, sewage, etc.). However, not all man-made changes to the environment cause a deterioration in public health. Urban and agricultural development projects must consider these issues and should use medical and environmental studies to avoid causing epidemic-prone conditions or spreading endemic diseases. Currently, most studies are limited to listing the specific diseases in the target area and very few attempt to assess the possible consequences of changing the environment. Forecasting the consequences of changes in environmental management is of great importance, but it requires the development of multi-disciplinary teams in the field who must be involved in the planning and implementation of the projects.

Aedes↗

PubMedDate not supplied

[Chloroquine resistance and malaria control in Ivory Coast].

We present here data from the Ivory Coast on the susceptibility of Plasmodium falciparum to chloroquine, obtained since the first chloroquine-resistant strains were discovered in 1987. Susceptibility was assessed using the WHO 7-day field test. Almost all the tests were carried out in the capital, Adidjan, and in the southern forest zone. The frequency of chloroquine resistance was below 30% in most cases, the actual frequency differing between regions. The frequency of R3 chloroquine-resistant P. falciparum was very low. Such resistant parasites were found only on an oil-palm plantation and in the south west of the country, probably due to the free medical care available at both locations. In general, access to health care is limited. Fevers attributed to malaria are generally treated at home using plants or incomplete courses of chloroquine. Our data suggest that R3 chloroquine-resistant P. falciparum strains are selected by repeated high doses of chloroquine, rather than by low doses. Thus, symptomatic treatment of uncomplicated malaria and treatment at home with the "correct" medication may be more effective than systematic medication, for limiting the level of chloroquine resistance in the parasite. Pyrethroid-resistant Anopheles gambiae s.l. is present in West Africa and this may reduce the short-term effectiveness of impregnated mosquito nets. In the absence of R3 chloroquine-resistant P. falciparum, self-medication at home may be a practical and realistic way to treat malaria. However, more knowledge about the effectiveness of anti-malaria drugs, their use in various social, cultural and economic environments and the geographical distribution of insecticide-resistant vectors is required before effective strategies can be designed. However, it would certainly be of value to consistently check the quality of anti-malaria drugs and to try to improve the effectiveness of self-medication at home.

Adolescent↗