A Sero-epidemiological Study of Arboviral Fevers in Djibouti, Horn of Africa

Abstract

Arboviral infections have repeatedly been reported in the republic of Djibouti, consistent with the fact that essential vectors for arboviral diseases are endemic in the region. However, there is a limited recent information regarding arbovirus circulation, and the associated risk predictors to human exposure are largely unknown. We performed, from November 2010 to February 2011 in the Djibouti city general population, a cross-sectional ELISA and sero-neutralisation-based sero-epidemiological analysis nested in a household cohort, which investigated the arboviral infection prevalence and risk factors, stratified by their vectors of transmission. Antibodies to dengue virus (21.8%) were the most frequent. Determinants of infection identified by multivariate analysis pointed to sociological and environmental exposure to the bite of Aedes mosquitoes. The population was broadly naïve against Chikungunya (2.6%) with risk factors mostly shared with dengue. The detection of limited virus circulation was followed by a significant Chikungunya outbreak a few months after our study. Antibodies to West Nile virus were infrequent (0.6%), but the distribution of cases faithfully followed previous mapping of infected Culex mosquitoes. The seroprevalence of Rift valley fever virus was 2.2%, and non-arboviral transmission was suggested. Finally, the study indicated the circulation of Toscana-related viruses (3.7%), and a limited number of cases suggested infection by tick-borne encephalitis or Alkhumra related viruses, which deserve further investigations to identify the viruses and vectors implicated. Overall, most of the arboviral cases' predictors were statistically best described by the individuals' housing space and neighborhood environmental characteristics, which correlated with the ecological actors of their respective transmission vectors' survival in the local niche. This study has demonstrated autochthonous arboviral circulations in the republic of Djibouti, and provides an epidemiological inventory, with useful findings for risk mapping and future prevention and control programs.

Dengue in the Middle East and North Africa: A Systematic Review

“…aegypti breeding [1, 39, 43, 55, 95, 111, 123, 135]. Heavy rainfall has been implicated in DENV outbreaks in Sudan, Djibouti, and Yemen [12, 47, 143, 144], which may become increasingly unpredictable through climate change [145]. Armed conflicts and economic turmoil in Iraq, Syria, and Yemen may render these areas vulnerable to vector-borne diseases while diminishing surveillance and response [146].…”

Serological Evidence of Contrasted Exposure to Arboviral Infections between Islands of the Union of Comoros (Indian Ocean)

“…Yellow fever virus, CHIKV and RVFV assays were described elsewhere [13] and relied on the use of antigen derived from whole-virion particles in non-inactivated cell culture supernatants. They were operated in a BSL-3 environment.…”

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

“…Household factors including number of residents per room have been associated with increased risk of dengue virus infection [40] while for chikungunya, the number of residents in the general household [41] and community clustering have been associated with seropositivity [29]. Other factors like water storage [42], lower household income [43], living in rented housing, living near uncovered sewers, and living near open sewers and untreated water discharging directly into nearby ponds/lakes have been associated with dengue [44].…”

“…We observed an association between chikungunya IgM seropositivity and animal keeping; those with animals had higher odds of being seropositive. Animal keeping increases the density and survival of mosquito vectors by providing alternative and/or additional blood-sources and breeding sites [41,86,87]. Ae.…”