Genetic and serological evidence of Crimean-Congo Hemorrhagic Fever
Virus circulation in Ticks and Cattle in North Central Nigeria.
Abstract
Crimean - Congo haemorrhagic fever virus (CCHFV) is a tick-borne viral
haemorrhagic febrile disease that is highly pathogenic in humans with
enzootic cycle between tick vectors and animal hosts. Human infection
with CCHFV takes the clinical form of viral haemorrhagic disease, a
major health condition but with limited testing in Nigeria. In this
study, blood samples were collected from 333 pastoralists’ cattle in
North Central Nigeria and 1,470 ticks were picked from the animals. For
serology, Enzyme Linked Immuno Sorbent Assay (ELISA) was performed using
a double antigen multi species ELISA kit with sensitivity and
specificity of 98.9% and 95% respectively at 95% confidence interval
to detect IgG antibody to CCHFV in plasma. RT-qPCR virological technique
was used to identify viral antigen in ticks that were pooled based on
location and genus. Four species of ticks were morphologically
identified to parasitize cattle in the sampled location namely;
Rhipicephalus ( Boophilus) decoloratus (34.6%),
Hyalomma truncatum (32.9%), Amblyomma variegatum (24.6%)
and Rhipicephalus sanguineus (8%). The seroprevalence of CCHFV
was found to be 67%. In Kaduna state, 85 of 108 plasma samples tested
positive (78.7%) while in Plateau state 138 of 225 plasma samples
tested positive (61.3%). Of the 41 pools of tick tested for CCHF, one
(1) pool of 35 Rhipicephalus ( Boophilus) ticks (2.4%)
was positive for CCHF virus with qPCR cycle threshold of 31.88. Although
Hyalomma spp. is documented to be the main vector of
CCHFV, in the present investigation, Rhipicephalus (
Boophilus) species was identified to play a role as reservoir of
CCHF. The high seroprevalence of CCHF in livestock underscores the
public health risk associated with CCHFV at the human-animal interface
in Nigeria.