Résumé
An outbreak of Trypanosoma evansi in camels was detected for the first time on the French mainland, in October 2006, in a mixed farm (camels and ewes) of Aveyron Department, further to the importation of 5 camels in June 2006 from Canary Island (CI), Spain (CI are known to be infected and have regular surra outbreaks since 1994). One animal died prior to the identification of the parasite and 5 other camels were proved to be infected by microscopical observation of the blood or mice inoculation. All camels were treated in 3 instances at one month interval with melarsamine (Cymelarsan® 0.25mg/Kg IM), quinapyramine (Triquin® 3.75mg/Kg IM) and melarsamine again. A follow-up was made by microscopic examination of blood, CATT/T. evansi, ELISA T. evansi and PCR with specific primer for T. evansi. All animals became negative to all tests within 2-3 months after treatments. Parasites were not observed in sheep, but the sheep positive to any of the test were slaughtered to ensure the elimination of potential reservoir. In August 2007, one camel previously found infected, was positive again to all tests. It was immediately treated with quinapyramine and parasites disappeared. One month later it was treated with a double dose of melarsamine (0.5mg/Kg IM). All tests became and remained negative up to date, for one year. Origin of the infection, relapse/re-infection, was questioned. Re-infection was of low probability since there is no obvious reservoir of the parasite, but the hypothesis could not be rejected. Multi-resistance to melarsamine and quinapyramine is of very low probability since it has never been described. Finally the main hypothese is a relapse due to under-dosage of the chemicals and the refuge of the parasite in an extra-vascular focus (biological compartments of the organism where parasites are poorly exposed to the drugs and the host immune system). A retrospective study proved that the weight of this animal had been strongly under-estimated in December 2006 (250 Kg for 2 years of age) since it was 420Kg when it was weighted in September 2007. It is then hypothesised that the initial treatments killed the circulating parasites but that some trypanosomes could survive in extra-vascular foci and re-invaded the blood in August 2007. After one year of follow-up of this animal and a 2 years follow-up of the other 11 camels, the infection seems to be cleared from that herd. Robust diagnostic techniques certified prophylactic and curative treatments and quarantine regulation should be defined to accompany the importation of Camelids into France. (Texte intégral)