[Virus transmission in the tropical environment, the socio-ecology of primates and the balance of ecosystems].
We studied the contribution of non human primates to the transmission of yellow fever and HIV in the wild. We demonstrate the consequences of the modification of ecosystems on the emergence of new viral diseases and the reappearance of diseases believed to be eradicated. In the primary forest, the natural yellow fever cycle is limited to monkeys and mosquitoes living high in the canopy. Transmission to man is an anomaly, requiring the circumstances found in the forest and savanna contact zones, where man has changed the forest to a mosaic and decimated the simian population, favoring contact between mosquitoes and man. In these contact zones, the amaril virus circulates in episodic cycles. During each episode, most of the local monkeys are infected, and thereby acquire immunity. Yellow fever can only reappear subsequently when a sufficiently large new generation of non-immune young monkeys is available. Monkeys do not become ill when infected, presumably as a result of typical host-parasite cross selection having led to the development of a balance between the parasite and its host. AIDS is a transmissible viral disease which appeared recently. Various African non-human primates are hosts to SIV, a retrovirus closely related to HIV which causes AIDS in man. SIV-infected African monkeys do not develop AIDS. However, when used to infect species from other continents (for example Asian macaco monkeys) SIV can cause AIDS. Does pathogenicity appear during transmission of the virus from one primate host to another, and is this the case for human AIDS? Experimental inoculations, the demonstration of SIVagm in other species, the mosaic structure of the genome (implying cross species recombinations), and the high probability of cross-species transmission of the viruses in the wild all favor this idea. Possibly counterbalancing the pessimism about the development of an HIV1 vaccine in the near future, the non-human SIV models holds out some hope. The emergence of new diseases, such as Ebola, or diseases from other niches, and the reappearance of diseases believed to be eradicated, are frequent when man modifies the ecosystem, the structure and balance of which he does not control, and when he puts into contact species which have never met before.
Galat
G
G
Laboratoire de primatologie, ORSTOM, Dakar, Sénégal.
Galat-Luong
A
A
D016915:AIDS Vaccines; D000349:Africa; D000820:Animal Diseases / Q000635:transmission / Q000821:virology; D000818:Animals; D000835:Animals, Wild / Q000235:genetics / Q000276:immunology / Q000821:virology*; D001208:Asia; D001522:Behavior, Animal; D009033:Culicidae / Q000821:virology; D004195:Disease Models, Animal; D004199:Disease Vectors; D004463:Ecology; D017753:Ecosystem; D016679:Genome, Viral; D015658:HIV Infections / Q000635:transmission*; D000882:Haplorhini / Q000821:virology; D019142:Hemorrhagic Fever, Ebola / Q000635:transmission; D006801:Humans; D007110:Immunity, Active; D007303:Insect Vectors; D011323:Primates / Q000235:genetics / Q000276:immunology / Q000821:virology*; D011995:Recombination, Genetic; D016097:Simian Acquired Immunodeficiency Syndrome / Q000635:transmission; D015302:Simian Immunodeficiency Virus / Q000235:genetics / Q000472:pathogenicity; D014329:Tropical Climate; D014774:Virulence; D015004:Yellow Fever / Q000635:transmission*; D015047:Zoonoses / Q000635:transmission* / Q000821:virology
D016915:AIDS Vaccines