Open Access Research article

Chikungunya outbreak in a rural area of Western Cameroon in 2006: A retrospective serological and entomological survey

Maurice Demanou1*, Christophe Antonio-Nkondjio2, Emmanuel Ngapana3, Dominique Rousset1, Christophe Paupy4, Jean-Claude Manuguerra5 and Hervé Zeller6

Author Affiliations

1 Laboratoire de Virologie, Centre Pasteur Cameroon, BP 1274, Yaoundé, Cameroon

2 Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale (OCEAC), Yaoundé, Cameroun

3 Comité National d'Epidémiologie du Cameroun, Yaoundé, Cameroun

4 Institut de Recherche pour le Développement (IRD), UR016, OCEAC

5 Institut Pasteur, Paris, France

6 Centre national de référence des arbovirus et fièvres hémorragiques, Institut Pasteur, Lyon, France

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BMC Research Notes 2010, 3:128  doi:10.1186/1756-0500-3-128

Published: 5 May 2010

Abstract

Background

Although arboviral infections including Chikungunya virus (CHIKV) are common in sub-Saharan Africa, data on their circulation and prevalence are poorly documented. In 2006, more than 400 cases of dengue-like fever were reported in Kumbo (Northwest Region of Cameroon). The aim of this study was to identify the aetiology of this fever and to define its extent in the area.

Methods

We conducted a cross-sectional seroprevalence survey one year after clinical investigations to define the extent of the infection. An entomological survey consisted of the collection and identification of mosquito immature stages in water containers in or around human dwellings.

Results

A total of 105 sera were obtained from volunteers and tested for CHIKV, O'Nyong-nyong virus (ONNV) and Dengue virus (DENV) specific IgM and IgG antibodies by enzyme-linked immunosorbent assays (ELISA). CHIKV infection was defined as the presence of IgM antibodies to CHIKV. There was serological evidence for recent Chikungunya infection, as 54 subjects (51.4%) had detectable IgM anti-CHIKV in their sera. Amongst these, 52 showed both anti-CHIKV IgM and IgG, and 2 (1.9%) had IgM anti-CHIKV in the absence of IgG. Isolated anti-CHIKV IgG positives were detected in 41 (39%) cases. No anti-ONNV and anti-DENV IgM antibodies were found amongst the sample tested. Out of 305 larvae collected in the different breeding sites, 87 developed to the adult stage; 56 (64.4%) were Aedes africanus and the remaining Culex spp.

Conclusions

These findings suggest that the outbreak of febrile illness reported in three villages of Western Cameroon was due to CHIKV. The issue of a possible persistence of anti-CHIKV IgM antibodies is discussed. Ae. africanus which was found to be relatively abundant among the raffia palm bushes probably plays a role in the transmission of CHIKV along the chain of sylvatic/domestic mosquito species in this rural area. Particular attention should therefore be given to arbovirus infections in the Central African sub-region where these infections are becoming an emerging public health threat.