An outbreak of Influenza A virus in a hilltribe village of Mae Hong Son Province Thailand, 1997.

An outbreak of Influenza A virus occurred in a hilltribe village between July 18th and August 8th, 1997. The overall infection rate was 92.5 per cent. The household infection rate was higher in the crowded part of the village. The symptoms analyzed after all, were fever (100%), cough (99%), headache, myalgia (78.1%) and rhinorrhea (50.5%). The patients were self - recovery within 5-7 days. Isolation and Haemagglutination inhibition test (HI) were undertaken to identify the causative agent. The results were positive for influenza A/Wuhan/359/95(H3N2) - like strain. The outbreak did not spread to the town, possibly because of the differences in environmental condition. Predisposing factors of the village that may have influenced the outbreak were crowded living quarters, cold (8 - 10 degrees C) and moist weather, poor personal hygiene and improper sanitation.