Retrospective Study On Rift Valley Fever in Selected States in Sudan With Reference to Spatial and Animal Patterns

Abstract

Background A retrospective study was performed in selected states of the Sudan that include Gezira state, White Nile, Blue Nile, Khartoum, River Nile and Sennar states in order to investigate the seroprevalence of Rift Valley Fever (RVF) from 2007 to 2016. The risk factors that identified for RVF were locality, species, and animal population. For example, locality and species were significantly associated with seroprevalence of RVF (P-value = 049)(P-value = 0.000) respectively, While animal population was not associated in Gezira state (P-value = .415) and χ2 value was (12.629), however it was significantly associated in other regions. The highest seroprevalence estimated for RVF was 0.7% in River Nile state, while lowest seroprevalence for RVF recorded was 0.01% in Khartoum and Sennar states, respectively. Methods The current study was carried out in selected states in Central Sudan to investigate the epidemiology of RVF. Also it was focused on livestock in particular sheep, goat and cattle. Study design was retrospective to investigate seroprevalence, risk factors and spatial and animal patterns associated with RVF from 2007 to 2016. Result Estimated seroprevalence of RVF was 0.15% (n = 905) in sheep, 0.20%( n = 776) in goats and 0.13%( n = 638) in cattle respectively. The risk factors that identified for RVF were locality, species, and animal population. For example, locality and species were significantly associated with seroprevalence of RVF (P-value = 049)(P-value = 0.000) respectively, While animal population was not associated in Gezira state (P-value = .415). Environmental risk factors i.e. annual temperature and annual rain fall were compared to RVF occurrence in study area with average mean of 29.0ºC and 398.8 mm Conclusion Rift valley fever is arthropod-born zoonosis disease. It affects livestock like sheep, goat, cattle and camel .it usually occurs following heavy rainfall and cause storm of abortion in pregnant animals. The principle vector of RVF is Mosquitoe and also it is transmitted through tissues of infected animal and human and also through of undercooked milk. In spite of there is no confirmed cases that can be transmitted from person to person by direct contact. It is characterized in human by influenza- like illness, in moderate cases can develop retinitis and eye infection and severe complication can cause hemorrhagic form with oozing of blood from natural orifices, the morbidity and mortality rate is varying from 5–100% in livestock, death rate can reach up to 10% and case fatality rate is less than one percent. The vaccination against RVF is used in case of outbreak and suspected cases in livestock; however there is no available vaccine for human usage. The current study is retrospective survey to investigate the seroprevalence, risk factor and spatial and animal patterns in selected states in Sudan. Estimated seroprevalence of RVF was 0.15% (n = 905) in sheep, 0.20%( n = 776) in goats and 0.13%( n = 638) in cattle respectively. The risk factors that identified for RVF were locality, species, and animal population. For instance, locality and species were significantly associated with seroprevalence of RVF (P-value = 049), (P-value = 0.000) respectively, While animal population was not associated in Gezira state (P-value = .415). Environmental risk factors i.e. annual temperature and annual rain fall were compared to RVF occurrence in study area with average mean of 29.0ºC and 398.8 mm respectively.