Association of tonate virus (subtype IIIB of the Venezuelan equine encephalitis complex) with encephalitis in a human

Tonate virus, subtype IIIB of the Venezuelan equine encephalitis (VEE) comp lex, was first isolated in 1973 in French Guiana, South America. However, v ery little is known about its pathogenicity; it was considered to be respon sible for only mild dengue-like syndromes, In 1998, a 2-month-old boy livin g along the Oyapock river in French Guiana was hospitalized for fever and g eneralized status myoclonus, and despite treatment the patient died 72 h af ter admission. Testing showed the presence of IgM specific for viruses of t he VEE complex. A sensitive seminested polymerase chain reaction derived fr om a previous study was developed to detect viruses from the VEE complex, s ince no virus could be recovered from clinical specimens cultured on mosqui to cells or from intracerebral inoculation into newborn mice. The genome of a virus from the VEE complex was detected in postmortem brain biopsies, an d Tonate virus was identified by direct sequencing. This is the first repor ted case of human encephalitis due to Tonate virus.