Chikungunya as a Cause of Acute Febrile Illness in Southern Sri Lanka

Ufuoma Akoroda,Robert Chua,Christopher W. Woods,Angelia Chow,Ajith Nagahawatte,Vasantha Devasiri,Truls Østbye,Wasantha Kodikaarachchi,Champica Bodinayake,John J. Strouse,Megan E. Reller,October M. Sessions,Lark L. Coffey,Duane J. Gubler,Yan'an Hou

doi:10.1371/journal.pone.0082259

Abstract

BackgroundChikungunya virus (CHIKV) re-emerged in Sri Lanka in late 2006 after a 40-year hiatus. We sought to identify and characterize acute chikungunya infection (CHIK) in patients presenting with acute undifferentiated febrile illness in unstudied rural and semi-urban southern Sri Lanka in 2007. Methodology/Principal FindingsWe enrolled febrile patients ≥ 2 years of age, collected uniform epidemiologic and clinical data, and obtained serum samples for serology, virus isolation, and real-time reverse-transcriptase PCR (RT-PCR). Serology on paired acute and convalescent samples identified acute chikungunya infection in 3.5% (28/797) patients without acute dengue virus (DENV) infection, 64.3% (18/28) of which were confirmed by viral isolation and/or real-time RT-PCR. No CHIKV/DENV co-infections were detected among 54 patients with confirmed acute DENV. Sequencing of the E1 coding region of six temporally distinct CHIKV isolates (April through October 2007) showed that all isolates posessed the E1-226A residue and were most closely related to Sri Lankan and Indian isolates from the same time period. Except for more frequent and persistent musculoskeletal symptoms, acute chikungunya infections mimicked DENV and other acute febrile illnesses. Only 12/797 (1.5%) patients had serological evidence of past chikungunya infection. Conclusions/SignificanceOur findings suggest CHIKV is a prominent cause of non-specific acute febrile illness in southern Sri Lanka.

Highlights

Chikungunya is caused by infection with chikungunya virus (CHIKV), a mosquito-transmitted Alphavirus, family Togaviridae, found in tropical and subtropical regions of Africa, the Indian Ocean islands, and south and southeast Asia [1]
Paired sera to identify acute Chikungunya virus (CHIKV) infections in those without acute DENVwere available from 797/1079 (73.9%) patients consecutively enrolled between February and November 2007
We sought to document whether CHIKV was an important cause of non-specific acute febrile illness in southern Sri Lanka in 2007 and to describe its epidemiological, clinical, and virologic features

Summary

Introduction

Chikungunya is caused by infection with chikungunya virus (CHIKV), a mosquito-transmitted Alphavirus, family Togaviridae, found in tropical and subtropical regions of Africa, the Indian Ocean islands, and south and southeast Asia [1]. In Asia CHIKV largely causes urban epidemics and circulates between humans and mosquitos (primarily Aedes aegypti, and Ae. albopictus); recent evidence suggests it may have a sylvatic cycle in Malaysia [2]. After a 40-year hiatus [4], >37,000 suspected cases of CHIKV were reported in densely-populated regions in the north, east, and western coastal belt of Sri Lanka in 2007 and a similar number in 2008 [5,6]. We sought to identify and characterize acute chikungunya infection (CHIK) in patients presenting with acute undifferentiated febrile illness in unstudied rural and semi-urban southern Sri Lanka in 2007

Methods

Results

Conclusion