Rift Valley fever (RVF) is a zoonotic arbovirus - commonly infecting cattle, sheep and camels but having the ability to infect humans. Most outbreaks occur in regions of Eastern and Southern Africa but the virus is present in most of sub-Saharan Africa including Madagascar [1, 2]. Similar to the other arboviruses discussed the virus can be vertically transmitted from females to their eggs and this means that in times of high rainfall, periodic epizootic/epidemic cycles are likely [1]. When these occur, there are "abortion storms" with newborn sheep and cattle mortality approx. 90%. Mosquito vectors do not just include Aedes spp. - RFV has been isolated from more than 30 mosquito species including Aedes, Culex, Anopheles, Mansonia and Coquillettidia. These vectors, once infected, also lead to the observed human epidemics. A final route of transmission is percutaneuous or via aerosol exposure whilst slaugthering livestock or handling aborted foetal material [1].
- Bird BH, Ksiazek TG, Nichol ST, MacLachlan NJ. Rift Valley fever virus. Journal of the American Veterinary Medical Association. 2009 Apr 1;234(7):883-93. https://pdfs.semanticscholar.org/16a8/c4072aa9fbe04a32584d38572bc33413e9c3.pdf
- Centers for Disease Control and Prevention. Rift Valley Fever (RVF). 2016. Available at https://www.cdc.gov/vhf/rvf/index.html