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Open Access Short Report

Serologic evidence of human orthopoxvirus infections in Sierra Leone

Adam MacNeil1*, Jason Abel1, Mary G Reynolds1, RR Lash1, Richard Fonnie2, Lansana D Kanneh2, Willie Robert2, Victor K Lungay2, Augustine Goba2, Lina M Moses3, Inger K Damon1, Kevin Karem1 and Daniel G Bausch3

Author Affiliations

1 Centers for Diseases Control and Prevention, Atlanta, GA, USA

2 Kenema Government Hospital, Ministry of Health and Sanitation, Kenema, Sierra Leone

3 Tulane School of Public Health and Tropical Medicine, New Orleans, LA, USA

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BMC Research Notes 2011, 4:465  doi:10.1186/1756-0500-4-465

Published: 28 October 2011



Orthopoxviruses, including variola virus, vaccinia virus, and monkeypox virus, have previously been documented in humans in West Africa, however, no cases of human orthopoxvirus infection have been reported in the region since 1986. We conducted a serosurvey to determine whether human exposure to orthopoxviruses continues to occur in eastern Sierra Leone.


To examine evidence of exposure to orthopoxviruses in the Kenema District of Sierra Leone, we collected and tested sera from 1596 persons by IgG ELISA and a subset of 313 by IgM capture ELISA. Eleven persons born after the cessation of smallpox vaccination had high orthopoxvirus-specific IgG values, and an additional 6 persons had positive IgM responses. No geographic clustering was noted.


These data suggest that orthopoxviruses continue to circulate in Sierra Leone. Studies aimed at obtaining orthopoxvirus isolates and/or genetic sequences from rodents and symptomatic humans in the area are indicated.