Seroprevalence of Alphavirus Antibodies in a Cross-Sectional Study in Southwestern Tanzania Suggests Endemic Circulation of Chikungunya

Abstract

BackgroundTo date, Alphavirus infections and their most prominent member, chikungunya fever, a viral disease which first became apparent in Tanzania in 1953, have been very little investigated in regions without epidemic occurrence. Few data exist on burden of disease and socio-economic and environmental covariates disposing to infection.MethodsA cross-sectional seroprevalence study was undertaken in 1,215 persons from Mbeya region, South-Western Tanzania, to determine the seroprevalence of anti-Alphavirus IgG antibodies, and to investigate associated risk factors.Results18% of 1,215 samples were positive for Alphavirus IgG. Seropositivity was associated with participant age, low to intermediate elevation, flat terrain and with IgG positivity for Rift Valley fever, Flaviviridae, and rickettsiae of the spotted fever group. When comparing the geographical distribution of Alphavirus seropositivity to that of Rift Valley fever, it was obvious that Alphaviruses had spread more widely throughout the study area, while Rift Valley fever was concentrated along the shore of Lake Malawi.Conclusion Alphavirus infections may contribute significantly to the febrile disease burden in the study area, and are associated with several arthropod-borne infections. Their spread seems only limited by factors affecting mosquitoes, and seems less restricted than that of Rift Valley fever.

Individual and environmental risk factors for dengue and chikungunya seropositivity in North-Eastern Tanzania

“…A small number of sero-prevalence studies have provided limited information on the transmission and risk factors of dengue and chikungunya in East African countries [25,29,65]. For Tanzania, in particular, only one study [66] has investigated dengue transmission, and only one has, to our knowledge, investigated risk factors for chikungunya seropositivity [28].…”

“…Specifically, low income [46,47] and living in or traveling to endemic areas [48,49] have been singled out as risk factors. Socioeconomic status (SES) [28] and locality (rural areas) [30] have also been associated with increased risk of chikungunya virus infection. Notably, some of these risk factors (such as area of residence and housing quality) may vary between different geographical settings, even between neighboring areas in urban settings [50e52].…”

“…Environmental factors, including the presence of anthropogenic breeding sites for the primary vector Aedes (Ae) aegypti within the perimeters of residential areas have been associated with dengue seropositivity [52,56], whereas high vegetation density, elevation above sea level and presence of animals have been associated with chikungunya seropositivity [22,28].…”

Evidence of chikungunya virus infection among febrile patients seeking healthcare in selected districts of Tanzania

“…In Africa, chikungunya outbreaks have been reported in 25 countries [11]. In Tanzania, chikungunya has been reported in southern, southwestern, northern and central regions of the country [2,[12][13][14][15].…”

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“…It influences all age gatherings and both genders similarly, with an assault (rate of people who create sickness after contamination) of 40%-85%]. Different arbovirus are no doubt vital and are increasing more unmistakable quality as seen through an expansion in detailed action [17][18][19][20] and plague action of sicknesses, for example, dengue and Chikungunya [21][22][23][24]. Also, intestinal sickness should have been over-analyzed in various parts of Tanzania [25][26][27], mostly because of absence of differential pathogen analysis separated from jungle fever [28], including dengue and Chikungunya.…”