Family Cluster of Mayaro Fever, Venezuela

A cluster of protracted migratory polyarthritis involving four adult family members occurred in January 2000 after a brief overnight outing in a rural area of Venezuela.Laboratory testing demonstrated Mayaro virus as the cause of the cluster.These results documented the first human cases of Mayaro virus in Venezuela.M ayaro virus (MAYV), the cause of Mayaro fever, is a member of the genus Alphavirus, family Togaviridae, and is closely related to Chikungunya, O'nyong-nyong, Ross River, Barmah Forest, and Sindbis viruses (1-3).Infection by these viruses produce similar clinical illnesses in humans (4-8).Mayaro fever is typically a denguelike acute febrile illness 3-5 days in duration, characterized by headache, retroorbital pain, arthralgias, arthritis, myalgias, vomiting, diarrhea, and rash (8).However, joint involvement in Mayaro fever may persist for several months and in some cases precede the fever.Moderate-to-severe polyarthritis, occasionally incapacitating, is a prominent feature of the disease (8).MAYV is enzootic in South America, where the suspected vectors are forest-dwelling Haemagogus mosquitoes, and the vertebrate hosts are marmosets and other nonhuman primates (8).Most human cases occur sporadically and involve persons who work or reside in humid tropical forests (8,9).Nevertheless, several small outbreaks of Mayaro fever have been described in residents of rural communities of the Amazon region of Brazil, Bolivia, and Peru (8-10).Airborne transmission has been reported among laboratory personnel (11).Although MAYV is enzootic in several South American countries, this report describes the first human cases of Mayaro fever in Venezuela.The cases occurred among members of the same family after a single day's exposure to a semirural forested area.The observations we report were made in response to the Ministry of Health's request to determine the cause of the cluster of cases.