A survey of rift valley fever and associated risk factors among the one-humped camel (Camelus dromedaries) in Sudan

Abstract

BackgroundRift valley fever (RVF) is a mosquito-borne viral disease of domestic livestock and wild ruminants. In camels RVF may cause abortion among pregnant camels, but is most often asymptomatic among other camels. In this study, a seroepidemiological survey was conducted to determine the prevalence of RVFV antibodies and to identify the potential risk factors associated with RVFV seropositivity among the Sudanese one-humped camel (Camelus dromedaries) in Khartoum State, Sudan. A cross sectional study was conducted in Khartoum State, Sudan, in a total of 240 camels selected randomly from four localities. Sera sampled were tested for the presence of RVFV-specific immunoglobulin G (IgG) antibodies using a competitive enzyme-linked immunosorbent assay (c-ELISA).ResultsRVFV seropositivity was recorded in 23 out of 240 animals, prevalence rate of 9.6 % among camels in Khartoum State. Age (OR = 8.29, p-value = 0.04) and heavy rainfall (OR = 5.36, p value = 0.01) were recorded as potential risk factors for contracting RVF.ConclusionsOlder age and heavy rainfall were considered as potential risk factors for seropositivity to RVF. Surveillance for RVF among camels and distribution of mosquito vectors should continue to better understand the clinical signs associated with RVFV infection in camels and provide public health authorities an opportunity to anticipate and prepare for a possible RVF outbreak in Khartoum State, Sudan.

Serological evidence of Rift Valley fever infection and risk factors among one-humped camels (Camelus dromedarius) in Northern Nigeria

“…This age group is considered the age of maturity or adulthood for camels when they are released into the pasture for grazing and travel long distances where they may be exposed to infected mosquitoes and other hematophagous insects and hence the high positivity among this age group. This agrees with some authors, who all reported higher risks of older camels to Rift Valley fever infection like [22–23,32]. The camel owners give younger camels more attention and provide them with the necessary care which minimizes the risk of infectious diseases contraction like vector-borne diseases due to short distances covered.…”

“…It is a general observation that female animals stay longer than males in the herd. Therefore the longer the females stay in the herd, the longer they are exposed to risk factors associated with RVF [23]. This corroborates with the report by [41] in Mauritania and [40] in Tanzania regarding significant sero-positivity with female sex.…”

“…The higher prevalence reported could be attributed to the epidemics of RVF reported in these affected regions. In Sudan, [23] reported a prevalence of 9.6% in their studies and for the first time in Turkey, RVFV antibodies were reported in camels, with a prevalence of 1.3% [24]. Again, the areas in Sudan and Turkey had never experienced any epizootic of RVFV in livestock; however, antibodies were demonstrated, which may be an indication for a covert circulation waiting for the right environment for an outbreak to take place.…”

High seroprevalence of Rift Valley fever phlebovirus in domestic ruminants and African Buffaloes in Mozambique shows need for intensified surveillance

“…Abdalla et al . [63], when they evaluated the risk factors for RVFPV infection in Camels ( Camelus dromedaries ) in Sudan, and Blomström et al . [33], when investigated the seroprevalence of RVFPV in sheep and goats in Zambezia Province, obtained a similar result.…”

“…[33], when investigated the seroprevalence of RVFPV in sheep and goats in Zambezia Province, obtained a similar result. This is commonly seen in infectious diseases and for RVF it may be due to the longer exposure time of the adult animals in the herds, where they are in contact with potential mosquitoes vectors during several rain seasons, with increased risk of acquiring RVFPV infection through bites from infected mosquitoes [33,63]. Very little is known of the ecology of the mosquito vectors of RVFPV in Mozambique.…”