Ongoing outbreak of dengue serotype-3 in Solomon Islands, January to May 2013

Abstract

Introduction: In January, 2013, clinicians in Honiara, noted a number of patients presenting with dengue-like illness. Serum from three patients tested positive with rapid diagnostic test.  Over the subsequent weeks an increasing number of cases was identified. DENV-3 outbreak was confirmed by viral isolation and by RT-PCR. This report describes the on-going outbreak investigation, findings, and response.

Methods: Enhanced dengue surveillance was implemented in the capital Honiara and provinces including training on dengue case definitions, data collection and reporting. Vector surveillance operations were conducted to identify implicated vector(s).

Results: From 3 January to 15 May, 2013, 5,254 cases of suspected dengue were reported (101.5 per 10,000 population), including 401 hospitalizations and six deaths. The median age of patients was 20 years (range 0 to 90) with most in adults. Eighty-six per cent of the cases were reported from Honiara. Both Aedes aegyti and Aedes albopictus were identified in Honiara. Outbreak response control measures included clinical update training seminars, vector control activities, implementation of diagnostic and case management protocols and a public communication campaign.

Discussion:This is the first large dengue outbreak reported in the Solomon Islands since the Second World War. Factors that might have contributed to this outbreak include a largely susceptible population, the presence of a highly efficient dengue vector in Honiara; a high density human population with numerous breeding sites and favoured weather conditions for mosquito proliferation. Although the number of cases has plateaued over since 1 April, continued enhanced nationwide surveillance and response activities are necessary.