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

Damian Hoy,Thane Hancock,Helden Heldart,Prisca Assito,Adam Roth,Andita Meyshine,Yoster Yichiro,Mark Durand,Moses Pretrick,Kasian Otoko,Yvan Souares

doi:10.5365/wpsar.2014.5.3.005

Abstract

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. 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. 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. 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.

Highlights

Of the 168 suspected cases, 62% were less than 20 years of age and 60% were male
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
The Federated States of Micronesia is an independent nation in free association with the United States of America, consisting of more than 600 islands extending across four states in the North Pacific Ocean: Pohnpei, Kosrae, Chuuk and Yap.[1]

Summary

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. From 31 October to 2 November, an investigation was undertaken to establish the cause of the AFI outbreak. Members of the EpiNet team, doctors, dispensary nurses, laboratory staff, the dispensary coordinator and a small number of patients were interviewed. Analyses were undertaken to examine and describe the outbreak in terms of time, place, person and clinical features. Attack rates and clinical features were compared across the three sites as was the distribution of cases by age and sex. A line list of all suspected dengue cases was developed in Microsoft Excel using the Chuuk State Hospital emergency department register and the inpatient, outpatient and laboratory registers together

Results

Discussion

Conclusion