[Migrant polyarthritis and EBV infection].
A twelve-years-old boy developed fever, pharyngitis and acute migrant polyarthralgia. An increasing ASO titre was observed, so that rheumatic fever was firstly diagnosed. Finally splenomegaly and positive IgG and IgM against Epstein Barr virus led to the diagnosis of acute EBV infection with polyarthritis. EBV infection should be considered into the differential diagnosis of migrant polyarthritis.