Identification of potential vectors of and detection of antibodies against Rift Valley fever virus in livestock during interepizootic periods.
OBJECTIVE
To evaluate the prevalence of Rift Valley fever virus (RVFV) antibodies in livestock and presence of competent mosquito vectors of RVFV during an interepizootic period (IEP) in Kenya.


METHODS
208 sheep and 84 goats ranging in age from 4 months to 15 years, from 2 breeding herds.


METHODS
Blood specimens were collected from the sheep and goats during the 1999-2006 IEP in Rift Valley Province, and serum was harvested. Serum specimens were tested for IgG and IgM antibodies against RVFV by use of an ELISA. In addition, 7,134 mosquitoes were trapped in Naivasha, Nairobi, and Northeastern Province, and speciation was performed.


RESULTS
No animals were seropositive for IgM against RVFV. Of the animals born after the 1997-1998 epizootic, 18% (34/188) of sheep were seropositive for IgG against RVFV, compared with 3% (2/75) of goats. Seventy percent (8,144/11,678) of the mosquitoes collected were of the Culex subgenera; 18% (2,102/11,678) were Aedes spp.


CONCLUSIONS
Detection of IgG in the sera of sheep and goats born after the 1997-1998 epizootic and before the 2006 epizootic indicated that virus activity existed during the IEP. Detection of Aedes mosquitoes, which are competent vectors of RVFV, suggested that a cryptic vector-to-vertebrate cycle may exist during IEPs.
Rostal
Melinda K
MK
Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN 55108, USA.
Evans
Alina L
AL
Sang
Rosemary
R
Gikundi
Solomon
S
Wakhule
Lilian
L
Munyua
Peninah
P
Macharia
Joseph
J
Feikin
Daniel R
DR
Breiman
Robert F
RF
Njenga
M Kariuki
MK
D000330:Aedes / Q000821:virology; D000818:Animals; D000852:Anopheles / Q000821:virology; D000914:Antibodies, Viral / Q000097:blood*; D003465:Culex / Q000821:virology; D009033:Culicidae / Q000821:virology; D004199:Disease Vectors; D015511:Goat Diseases / Q000276:immunology* / Q000821:virology; D006041:Goats; D019660:Malvaceae / Q000821:virology; D012295:Rift Valley Fever / Q000276:immunology*; D012296:Rift Valley fever virus / Q000276:immunology*; D012418:Ruminants / Q000276:immunology / Q000821:virology; D012756:Sheep; D012757:Sheep Diseases / Q000276:immunology* / Q000821:virology
D000914:Antibodies, Viral