RESUMEN
In the final of November 1994, an outbreak of a febrile disease was observed in the Serra Pelada gold mine (5 degrees 35'S: 49 degrees 30'W) in the Southeast region of Pará State. Twenty samples were collected and sent to the laboratory of Arbovirus of Instituto Evandro Chagas. The tests showed that the disease was caused by Oropouche virus (Bunyaviridae, Bunyavirus, Simbu serological group). Between 8-22 December 296 serum samples were taken (54 from febrile patients, 16 paired samples and 242 from contacts and convalescent patients) of the 73 familiar groups. From febrile patients, ten Oropouche virus strains were obtained. From paired serum, six seroconversions were obtained and 242 other Oropouche infections were diagnosed by HI and MAC ELISA. The clinical-picture of febrile disease accompanied by severe bedache, chills, myalgia, photophobia retrobulbar pain and malaise was observed. Involvement of central nervous system was not observed. Based on the serological data, we estimated that in the outbreak of Serra Pelada around 5,000 cases occurred corresponding to a prevalence of 83 per cent.