[Does 2003 summer heat wave modified prevalence of bovine helminthosis in southwestern France?].

The heat wave of 2003 summer had serious consequences on helminths prevalence and epidemiology. Comparison of 1917 cattle epg counts in southwestern France for years before and after showed that prevalence and mean numbers of Fasciola hepatica, paramphistomids, Dicroccelium lanceolatum and gastrointestinal strongyles eggs were significantly reduced. Nevertheless, the next year the epg counts were quickly increasing. Several factors may have induced a more or less long modification: strains of helminths may become adapted, a new spreading of intermediate hosts may occur with a modified ecology and finally moving of hosts and reservoirs may be amongst causes of epidemiological changes. Finally, after a heat wave the anthelmintic pressure may be maintained, as parasites seem quickly become adapted to a novel and modified environment.