Dengue in the coastal regions of Tanzania - a ticking time bomb?

Dengue is an emerging mosquito-borne arboviral disease of international concern with an estimated 390 million cases and 22,000 deaths annually. In Tanzania, dengue outbreaks have been reported mainly from the coastal region of Dar es Salaam in 2010, 2013, 2014, 2018 and 2019, causing morbidity, mortality and economic impacts. Although it is known that dengue virus (DENV) is circulating in coastal Tanzania and is predicted to spread across the country, the government lacks a dengue surveillance system, has a limited control program and low diagnostic capacity. Consequently, infection rates of dengue in human and vector are unknown, risk factors for infection not identified and seasonal dynamics not recorded. This hampers the development of predictive models and in turn hinders the efforts of increasing diagnostic capacity, surveillance and preparation for outbreaks. We propose to carry out a pilot study in the coastal area of Dar es Salaam to 1) determine infection rates in humans and vectors 2) identify risk factors for infection 3) record seasonal dynamics. We will test human blood samples from febrile patients for current and past DENV infection and collect and test DENV vectors around their homes, while recording environmental and socio-economic data. This will provide evidence essential for the development of a country wide study looking at the temporal and spatial epidemiology of dengue in Tanzania to inform surveillance, diagnostic needs and vector control efforts.