An Epidemic of Acute Hemorrhagic Conjunctivitis in American Samoa Caused by Coxsackievirus A24 Variant

Between May 25 and July 5, 1986, an epidemic of acute hemorrhagic conjunctivitis affected an estimated 47% of the population on American Samoa. Coxsackievirus A24 variant was isolated from 18 of 22 patients. This is the first documented outbreak of acute hemorrhagic conjunctivitis due to coxsackievirus A24 variant outside of Southeast Asia and the Indian subcontinent. When this outbreak was compared with an outbreak on the island in 1981-1982 caused by enterovirus 70, conjunctival hemorrhage or injection and the severity of hemorrhage were less prevalent among cases in 1986, while upper respiratory and systemic symptoms were more common. Residents of traditional housing had significantly higher attack rates (48%) than residents of government housing (23%). Serum specimens collected from the residents of Samoa in 1985, before the outbreak, unexpectedly revealed the presence of neutralizing antibodies against coxsackievirus A24 variant. The presence of these antibodies correlated with protection against coxsackievirus A24 variant infection in this outbreak.