Seroprevalence, risk factors in cattle and molecular investigation in ticks of crimean-congo hemorrhagic fever virus (CCHFV) in central Malawi.

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Phonera, Marvin Collen
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The University of Zambia
Crimean- Congo Hemorrhagic Fever virus (CCHFV) is zoonotic, causing subclinical infections in animals but fatal infections in humans. The virus is endemic in Africa, Asia, and Eastern Europe and its distribution corresponds to that of its principal vector, Hyalomma ticks. In Malawi, no case of CCHF has been reported and there is no evidence of CCHFV circulation in the country despite the presence of Hyalomma ticks. This study aimed to investigate the epidemiology of CCHFV in traditional cattle herds and ticks in central Malawi. A cross sectional study was conducted in April 2020 in seven districts of central Malawi. Sera were collected from 416 randomly selected cattle (from 117 herds) and screened for CCHFV specific antibodies using a double antigen sandwich ELISA test. Ticks were collected from cattle and screened for the presence of the CCHFV genome using nested RT-PCR. Data on associated risk factors for CCHFV exposure in cattle were collected from cattle farmers using a structured questionnaire. CCHFV nucleoprotein specific antibodies of 46.86% (195/416; 95% CI: 42.02-51.82) was determined. This seropositivity was significantly associated (significance level: p-value <0.25) with cattle age sex, presence of ticks, district, type of grazing land, cattle herd size, and source of cattle. In a binary logistic regression model (significance level: (p-value < 0.05), cattle from Lilongwe West (OR 2.7; 95% CI 1.191- 6.037) and Ntchisi (OR 5.0; 95% CI: 1.383-18.111) were more likely to be infected with CCHFV compared to those from Mchinji. Cattle aged 25-48 months and >48 months, were two and three times more likely to be CCHFV infected (OR= 4.33; 95% CI: 2.196-8.533; OR= 4.229; 95% CI: 2.032-8.798), respectively compared to cattle of 1-12 months old. Female cattle were 2.5 times more likely to be CCHFV infected than males (OR= 2.478; 95% CI: 1.568-3.944). There was a strong association between cattle grazing in uplands and being CCHFV seropositive (OR=4.489; 95% CI: 1.799-11.2). Cattle infested with ticks were three times more likely to be CCHFV seropositive than those that had no ticks (OR= 3.206; 95% CI: 1.208- 8.509). Amblyomma variegetum, Rhipicephalus appendiculatus, Rhipicephalus (Boophilus) decoloratus, Rhipicephalus (Boophilus) microplus, and Hyalomma truncatum were identified from the collected ticks. CCHFV S-segment genome was detected in 64.44% (29/45) of the RNA pools extracted from the ticks. These results indicate higher exposure of cattle to CCHFV in the study area. Therefore, good cattle management practices and awareness of the existing risk rae required to reduce chances of contracting the deadly CCHFV among cattle-keeping communities
Thesis of Master of Science in One Health Analytical Epidemiology