The authors, in a first part, show the general arthropods-viruses-vertebrates relationships and specially the different conditions of virus maintenance in the selvatic foci. Then they succinctly give the main characteristics of the vectors bioecology useful for understanding the epidemiology of arbovirus diseases of man and domestic animals. Thus diptera vectors of o'nyong-nyong and chikungunya fevers, yellow fever, dengue fever, Wesselsbron, Sindbis, and West Nile viruses, Rift Valley fever, sandfly fevers, bluetongue and african horsesickness are recorded. Lastly some attention is given to the range of virus-vector specificity and to the virulence variability of virus according to the vector.

Aedes↗

PubMedDate not supplied

[Sylvatic yellow fever in Africa recent advances and present approach (author's transl)].

Recent works carried out in west and central Africa resulted in numerous yellow fever virus isolations from sylvatic mosquitoes in the forest-savanna transitional zone. This virus was also obtained from monkeys, whereas studies on sequence and duration of the observed epizootics permitted a previsional approach of the yellow fever mechanisms in the same belt, the epidemiological importance of which was stressed ("emergence zone"). In the same course of research and publications, the prevalent part of the involved mosquitoes as virus-reservoirs was constantly emphasized ("reservoir-vector"). Recent investigations on transovarial transmission and yellow fever isolations from male mosquitoes caught in the field, provide decisive support to such a conception. It can explain that epizootics may be locally observed several years in succession, despite the fact that yellow fever virus circulation seems to be fundamentally of a dynamic character. Yellow fever virus was recently obtained from ticks and tick-eggs.

Africa↗

PubMedDate not supplied

[Arbovirus diseases in South America and Caribbean Islands (author's transl)].

Historically, yellow fever has dominated arboviral diseases in South America and the Caribbean and sylvatic cases still occur every year (more than 200 in 1979). The dengue, by the very large number of cases occurring in the area during successive epidemics--the most important being the last one in 1977-1978--is a serious problem for public health, an epidemic of hemorrhagic dengue being a constant threat. Encephalitides are the third syndrome of arboviral etiology observed in the South American subcontinent. Some which preferably attack horses have been known for a long time whereas the one due to the Rocio virus of an even graver prognosis, was recently discovered. These diseases present a large range of epidemiological forms. Dengue is an example of an urban illness transmitted from man to man through the mosquito, Aedes aegypti. But most of the viruses circulate between vectors and wild vertebrates in sylvatic cycle. For some viruses, both mechanisms can be involved. It is the case for Oropouche virus and yellow fever even if at present the urban form is the only recorded for the latter.

Animals↗

PubMedDate not supplied

[Determination of the free plasma fraction of drugs].

Explore the source record for details and available documents.

Centrifugation↗

PubMedDate not supplied

[The recycling of waste water and mosquitoes].

Recycling waste water in the Achères complex (North-West Paris) is based on both sophisticated industrial techniques and simple agricultural methods. The sewage farms and settling pools provide suitable breeding sites for more than ten mosquito species. Aedes caspius is the major pest for the local population. Moreover Culex pipiens (anthropophilic form) breeds in the sewers of the neighbouring towns. Mosquito control is based early ground treatment of breeding sites. Temephos and fenotrothion are used against A. caspius. Spherimos (Bacillus sphaericus) is used to control C. pipiens. The two insecticides have no adverse effect on humans or the environment and Spherimos is harmless. Aedes pest have been virtually eliminated. Urban Culex control is generally good despite being performed by less well trained municipal employees. In the areas treated by the specialized team of the SIAAP, pest mosquitoes have disappeared. The techniques used in the Achères complex do not require sophisticated equipment. Thus, if adapted to local ecological, epidemiological and financial conditions they could be transferred to developing countries.

Aedes↗

PubMedDate not supplied

[DDT and public health].

The availability of DDT led to a revolution in insect pest control. However, in the 1970's it was banned or its use restricted in many countries because it was accumulating in the environment. It was suggested that this could have a deleterious effect on human health. However, these effects, particularly carcinogenesis, have never been clearly proved in humans. Furthermore, accumulation is significantly lower in the tropical than temperature environment. DDT can therefore be continued to be used as a spray in houses, where it is sequestrated by mud walls. It is mainly used against anopheles (mosquitoes) for malaria control and phlebotomus (sand flies) for control of leishmaniasis. However, the value of DDT is restricted by the resistance of many vector species; and its excitatory-repellent effect which does not allow interruption of malaria transmission in highly endemic areas (for example Northern Cameroun).

Animals↗

PubMedDate not supplied

[Susceptibility of Anopheles gambiae to insecticides in the Ivory Coast].

Studies on the susceptibility of Anopheles gambiae to insecticides were carried out in rice field areas of Côte-d'Ivoire. An. gambiae larvae populations from Côte-d'Ivoire were resistant to DDT but susceptible to organophosphorous insecticides. Adult populations from the surroundings of Bouake were resistant to DDT and permethrin. Resistance to propoxur was strongly suspected. The knock-down effect of both deltamethrin and lambdacyhalothrin was delayed and strongly decreased. The control strain from Bobo-Dioulasso and populations from rice fields of Katiola located far from the city were still susceptible to the three pyrethroids. It is likely that resistance to pyrethroids in Bouake has been promoted by the intensive use of domestic aerosol sprays.

Animals↗

PubMedDate not supplied

[Rice: source of life and death on the plateaux of Madagascar].

Since the 17th century, Europeans travelling in Madagascar described the contrast between the fever-free Plateau and the fever-ridden coasts. The former were inhabited by people of Asiatic origins and the latter by African migrants. At the end of the 18th century, "Merina" kings developed land irrigation and rice cultivation, using manpower from the coasts. Since then, rice has become a monoculture covering most of the arable lands of the Highlands. The first malaria epidemic occurred in the Tananarive area in 1878, and rapidly spread throughout the Plateau. The mortality rate was high. A second epidemic in 1895 may have been a resurgence of the previous one. Subsequently, malaria became meso-epidemic despite control measures, mainly consisting of larvivorous fishes, quinine treatment and prophylaxis. In 1949, an eradication program was launched based on DDT house-spraying and chloroquine prophylaxis in children. It was very successful on the Highlands where malaria disappeared, in 1962. Spraying was cancelled and only three small foci remained under surveillance. In 1987 and 1988, a malaria outbreak devastated the plateau. Subsequently, intensive spraying operations brought the situation under control by 1993. The main malaria vector on the Madagascar Highlands is An. funestus. More than 95% of its breeding sites are in the rice fields just before the harvest and afterwards in the fallow lands. The vector peak and the corresponding peak of malaria cases occur between February and May, depending on the farming calender. The second but less important vector, An. arabiensis, breeds in the rice fields just after seeding when the surface water is sunlit. Although rice fields remain the main source of this vector, it also breeds in rainwater pods and borow-pits. Malaria vectors on the plateau are products of human activities of rice cultivation, which is the basis of the economy. The epidemiological importance of rice fields varies greatly from one country to another. In Southeast Asia, the rice fields harbor several anopheline species most of which are only vectors of P. vivax. In West Africa where malaria is holoendemic, they produce large populations of An. gambiae; however, the malaria pattern is unaltered and remains at peak levels. In the dry areas of southern Madagascar, the vector An. funestus and meso-hyperendemic malaria are restricted to areas of cultivated rice. In West and Central Africa, An. funestus is never found in rice fields even though it is common in marshes. In Madagascar, this vector breeds in irrigated rice fields. Because it is practically impossible to control anophelines in rice fields by chemical, biological and ecological methods on the Highlands of Madagascar, house-spraying remains the best method for mass malaria control. Bed-nets impregnated with pesticides may offer an alternative, but their use is resisted by the local population.

Agriculture↗