Knowledge, attitudes and bite prevention practices and estimation of productivity of vector breeding sites using a Habitat Suitability Score (HSS) among households with confirmed dengue in the 2014 outbreak in Dar es Salaam, Tanzania.

Author summary Dengue fever is a viral infection transmitted by Aedes (Stegomyia) mosquitoes causing a flu-like illness that may develop into severe complications such as dengue haemorrhagic fever and dengue shock syndrome if the patient contracts two viral serotypes concurrently. Three dengue serotypes have been detected in Dar es Salaam (DNV 1, 2 and 3). There is currently no antiviral treatment or vaccine available against dengue so vector control and mosquito bite prevention remain essential to prevent transmission. Due to globalisation and rapid urban expansion, Dar es Salaam is experiencing regular dengue outbreaks. Without adequate vector control and public awareness, these will certainly continue to re-occur. During the dengue outbreak of 2014 we followed up 97 people with confirmed dengue. We went to their homes to ask them about their perception of dengue and to look at the suitability of their homes for vector breeding. We devised a tool to predict whetherAedes aegyptiwould be present in breeding sites based on the results of other authors in the region. The study proposes the use of HSS, a tool to be used to predict the productivity of Aedes breeding habitats, which correctly predicted the presence ofAedes aegypti75% of the time. The prediction will enable quick management of habitats before the rain begins. The study interviewed those who had confirmed dengue and identified a large gap in public knowledge of dengue fever: 84% of people interviewed thought bed nets can prevent dengue, 60% of the patients only became aware of dengue while in the hospital with the illness and 22% thought that dengue spreads from person to person. The public need to be aware of dengue prevention and management especially just before the rains. Most respondents owned mobile phones and the use of mobile phone messages might be a suitable means to raise awareness before possible outbreaks. Background The frequency and magnitude of dengue epidemics has increased dramatically throughout the tropics in the past 40 years due to unplanned urbanization, globalization and lack of effective mosquito control. The commercial capital of Tanzania, Dar es Salaam, is now experiencing regular dengue outbreaks. Three dengue serotypes have been detected in Dar es Salaam (DNV 1, 2 and 3). Without adequate vector monitoring and control, further outbreaks will certainly occur. Methods/Findings A case series study followed 97 individuals with confirmed dengue fever (NS1 and/or IgM on rapid diagnostic test and/or PCR positive) to their households in Kinondoni, Dar es Salaam during the 2014 outbreak from a random sample of 202 confirmed cases at Mwananyamala Hospital. Kinondoni wards of Manzese, Mwananyamala, Tandale and Mabibo had the highest number of confirmed cases: 18, 13, 13 and 9 respectively. Individuals were interviewed by questionnaire on dengue prevention practices and houses were inspected for mosquito breeding sites to validate a Habitat Suitability Score (HSS). This is a tool devised to predict the productivity of any potential breeding habitats (PBHs) before the rains begin. There were 12 /312 positive Aedes breeding habitats. Drums/barrels, flowerpots and tyres were the most common breeding habitats. The HSS correctly identified 9/12 of Aedes breeding habitats. Larviciding is already conducted in urban Tanzania for malaria control and the HSS may be a useful means to train individuals on productiveAedes aegyptibreeding sites should this program be extended to include dengue control. The population remains poorly informed about dengue transmission and prevention: 22% of respondents said dengue is spread from one person to another and 60% first heard about dengue when already sick. Less than 20% of respondents used personal protection and >80% thought bednets protected against dengue. Mobile phones were owned by almost all individuals followed up and have the potential of being the prime medium for dissemination of information on dengue prevention.