Tahyna virus infection, a neglected arboviral disease in the Qinghai-Tibet Plateau of China.

Tahyna virus (TAHV) was first isolated from mosquitoes collected in the suburbs of Geermu city in the Qinghai-Tibet Plateau of China in 2007. Since then, TAHV antibodies have been detected in local livestock in Geermu, Qinghai. To determine whether the disease caused by TAHV was present in local residents, an investigation was conducted in the summer of 2009. During this investigation, ward inspections were conducted in rural clinics, and clinical information and specimens were collected from patients who complained mainly of acute fever. The collected samples were tested by serological and molecular methods. The results showed that four samples were positive for TAHV immunoglobulin M and had four-fold or higher levels of TAHV-neutralizing antibody titers between convalescent-phase and acute-phase, and that TAHV nucleotide sequences were detected in two acute sera. Clinical features of TAHV infection commonly included fever, accounting for 100%. Among all other symptoms, the one with the highest frequency was pharyngitis (80%), followed by malaise, inappetence, arthralgia, headache, and drowsiness. Follow-up surveys revealed that all cases recovered in 2-5 days after onset, and no serious or deadly cases were observed. This is the first time that the disease caused by TAHV infection has been reported in China. TAHV infection is another known mosquito-borne arboviral disease in China.