Serological evidence of exposure to Rift Valley, Dengue and Chikungunya Virusesamong agropastoral communities in Manyara and Morogoro regions in Tanzania: A community survey.

Rule M Budodo,Blandina T Mmbaga,Richard S Mwakapuja,Jaffu O Chilongola,Sixbert I Mkumbaye,Pius G Horumpende

doi:10.1371/journal.pntd.0008061

Rule M Budodo, Blandina T Mmbaga + Show 4 more

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https://doi.org/10.1371/journal.pntd.0008061

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Abstract

Tanzania has recently experienced outbreaks of dengue in two coastal regions of Dar es Salaam and Tanga. Chikungunya and Rift Valley Fever outbreaks have also been recorded in the past decade. Little is known on the burden of the arboviral disease causing viruses (Dengue, Rift Valley and Chikungunya) endemically in the inter-epidemic periods. We aimed at determining the prevalence of the dengue, rift valley and chikungunya among humans in two geo ecologically distinct sites. The community-based cross-sectional study was conducted in Magugu in Manyara region and Wami-Dakawa in Morogoro region in Tanzania. Venous blood was collected from participants of all age groups, serum prepared from samples and subjected to ELISA tests for RVFV IgG/IgM, DENV IgG/IgM, and CHIKV IgM/IgG. Samples that were positive for IgM ELISA tests were subjected to a quantitative RT PCR for each virus. A structured questionnaire was used to collect socio-demographic information. Data analysis was performed by using SPSSv22. A total of 191 individuals from both sites participated in the study. Only one individual was CHIKV seropositive in Magugu, but none was seropositive or positive for either RVFV or DENV. Of the 122 individuals from Wami-Dakawa site, 16.39% (n = 20) had recent exposure to RVFV while 9.83% (n = 12) were seropositive for CHIKV. All samples were negative by RVFV and CHIKV qPCR. Neither infection nor exposure to DENV was observed in participants from both sites. Being more than 5 in a household, having no formal education and having recently travelled to an urban area were risk factors associated with RVFV and CHIKV seropositivity. We report a considerable exposure to RVFV and CHIKV among Wami-Dakawa residents during the dry season and an absence of exposure of the viruses among humans in Magugu site. In both sites, neither DENV exposure nor infection was detected.

Highlights

RVFV, DENV and CHIKV are endemic in Sub-Saharan Africa and cause sporadic and sometimes large epidemics in humans
Households with 5 or more members living in the same house were more likely to be seropositive for CHIKV IgM antibody as compared to households with less than 5 people [OR 3.5, (95%CI: 1.6–4.84), p
Our study is limited by the small sample size due to convenience and logistical factors, our findings provide valuable information regarding the rate of exposure to RVFV, DENV and CHIKV in the studied areas

Summary

Introduction

RVFV, DENV and CHIKV are endemic in Sub-Saharan Africa and cause sporadic and sometimes large epidemics in humans. The ecological drivers of the pattern and frequency of virus infections (and subsequent epidemics) in the different host species are largely unknown[1]. Many authors identified non-human primates, and birds as hosts/reservoirs for arboviruses [2,3,4]. Arboviruses are genomically variant, they share a common transmission mode through vectors, pathobiological mechanisms and cause overlapping clinical presentations[5]. DENV and CHIKV are principally transmitted by Aedes Aegypti mosquitoes, but occasionally they can be transmitted by Ae albopictus and Ae. Polynesiensis while RVFV is mainly transmitted by floodwater Aedes sp including Ae. Mcintoshi and Ae. Ochracius [6,7,8]. DENV and CHIKV are an increasing global public health concern due to their rapid geographical spread and increasing disease burden

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