Prevalence of dengue fever virus antibodies and associated risk factors among residents of El-Gadarif state, Sudan.

BACKGROUND: Dengue fever, caused by dengue virus (DENV), has become one of the most important mosquito-borne viral diseases with a steady rise in global incidence, including the Sudan. Sporadic cases and frequent acute febrile illness outbreaks, compatible with Dengue fever, have been reported in El-Gadarif State, Sudan. However, diagnosis was based almost exclusively on clinical signs without confirmatory laboratory investigations. Despite the magnitude of the problem in El-Gadarif State, no information is currently available with regard to the epidemiology of the disease in this State. El-Gadarif State is one of the largest commercial centers in the Sudan. The objective of the present investigation is to estimate the prevalence of DENV antibodies, and determine the potential risk factors associated with seropositivity among residents of El-Gadarif State. METHODS: A cross sectional study was conducted in a total of 701residents randomly selected from all 10 localities in El-Gadarif State. The sera from the 701 residents were tested for the presence of DENV-specific immunoglobulin G (IgG) antibodies using a commercially available Anti-dengue IgG enzyme-linked immunosorbent assay (ELISA). RESULTS: Among the 701 residents, 334 residents (47.6%) were seropositive for DENV. Mosquito control (OR = 2.73, CI = 1.37-5.87, p-value = 0.001); low income (OR = 2.31, CI: 1.71-6.36, p value = 0.032); sleeping out-doors (OR = 3.73, CI = 2.63-6.23, p-value = 0.013), and localities were determined as potential risk factors for contracting DENV infection. CONCLUSIONS: The prevalence rate of DENV antibodies among residents of El-Gadarif State is significantly high (47.6%). Further epidemiologic studies including, distribution of mosquito vectors and implementation of improved surveillance are urgently warranted for better prediction and prevention of a possible DENV outbreak in El-Gadarif State, Sudan.

Rift Valley fever, Sudan, 2007 and 2010.

To elucidate whether Rift Valley fever virus (RVFV) diversity in Sudan resulted from multiple introductions or from acquired changes over time from 1 introduction event, we generated complete genome sequences from RVFV strains detected during the 2007 and 2010 outbreaks. Phylogenetic analyses of small, medium, and large RNA segment sequences indicated several genetic RVFV variants were circulating in Sudan, which all grouped into Kenya-1 or Kenya-2 sublineages from the 2006-2008 eastern Africa epizootic. Bayesian analysis of sequence differences estimated that diversity among the 2007 and 2010 Sudan RVFV variants shared a most recent common ancestor circa 1996. The data suggest multiple introductions of RVFV into Sudan as part of sweeping epizootics from eastern Africa. The sequences indicate recent movement of RVFV and support the need for surveillance to recognize when and where RVFV circulates between epidemics, which can make data from prediction tools easier to interpret and preventive measures easier to direct toward high-risk areas.