Investigating an outbreak of acute fever in Chuuk, Federated States of Micronesia

Abstract

Objective: In September 2012, there was an unexpected increase of acute febrile illness (AFI) in Chuuk State of the Federated States of Micronesia. At the same time, dengue outbreaks were occurring in two of the Federated States of Micronesia’s other three states. The cause of AFI was suspected to be dengue; however, by the end of October, only one of 39 samples was positive for dengue. The objective of the investigation was to establish the cause of the outbreak.

Methods: A line list was created and data analysed by time, place, person and clinical features. Reported symptoms were compared with the published symptoms of several diagnoses and laboratory testing undertaken.

Results: Of the 168 suspected cases, 62% were less than 20 years of age and 60% were male. The clinical features of the cases were not typical for dengue but suggestive of respiratory illness. Nasopharyngeal swabs were subsequently collected and found to be positive for influenza. Public health measures were undertaken and the AFI returned to expected levels.

Discussion: Clinical diagnosis of acute febrile illness (AFI) can often be difficult and misleading. This can mean that opportunities for preventive measures early on in an outbreak are missed. In any outbreak, descriptive epidemiological analyses are valuable in helping to ascertain the cause of the outbreak.