A serosurvey of bluetongue and epizootic haemorrhagic disease in a convenience sample of sheep and cattle herds in Zimbabwe

Abstract

A convenience sample of sheep and cattle herds around the cities of Harare, Kwekwe and Bulawayo, located in the Highveld region of Zimbabwe, was used to estimate the sero-prevalence and sero-incidence of bluetongue virus (BTV) and epizootic haemorrhagic disease virus (EHDV) antibodies. A competitive enzyme-linked immunosorbent assay was used to identify serum antibodies against BTV and EHDV across three rainy seasons. The median sero-prevalence of BTV and EHDV antibodies in cattle was 62% (interquartile range [IQR]: 30–89) and 56% (IQR: 5–77), respectively. In sheep, the median sero-prevalence of BTV and EHDV was 41% (IQR: 19–63) and 0% (IQR: 0–21), respectively. Median sero-incidences of BTV and EHDV antibodies in cattle of 43% (IQR: 22–67) and 27% (IQR: 9–57) respectively were recorded. The median sero-incidence of BTV in sheep was 14% (IQR: 6–23). Based on these preliminary findings, animal health workers in Zimbabwe should continue to monitor the exposure rates of cattle and sheep to BTV and consider the possibility of strains emerging with increased pathogenicity. There are no previous published reports of antibodies against EHDV in Zimbabwe so the possibility of epizootic haemorrhagic disease existing in domestic livestock should now be considered by Zimbabwean animal health officials. Seroconversions to BTV and EHDV occurred predominantly at the end of each rainy season (March and April), which generally corresponds to high numbers of the Culicoides vectors. BTV isolations were made from three individual cows in two of the sentinel herds and all three were identified as serotype 3. This is the first time BTV serotype 3 has been recorded in Zimbabwe, although its presence in neighbouring South Africa is well documented.

Perspectives on the Changing Landscape of Epizootic Hemorrhagic Disease Virus Control

“…Detection of EHDV-2 genomes and antibodies in WTD and cattle in east-central Canada suggest a potential progression of the previously observed northern expansion of virus occurrence in North America [34][35][36][37]. Globally, evidence of EHDV circulation was recently documented for the first time in Ecuador (EHDV-1), Zimbabwe (serotype not determined), the island of Mayotte (EHDV-6), Trinidad (EHDV-6), French Guiana (EHDV-1 and -6) and Egypt (EHDV-1), all in samples (some from historical collections) taken from cattle [38][39][40][41][42][43][44]. The introduction of new serotypes has recently been detected in Israel (EHDV-1 and -6) and China (EHDV-7), also identified in cattle samples [45][46][47].…”

Serological survey of epizootic hemorrhagic disease in European bison in Poland in 2017-2018

“…Globally, EHDV has been reported in both domestic cattle and wildlife in North and South America, Africa, and Asia (8,9,13,14,23,40). It has also been found in countries neighboring Europe, such as Turkey (3).…”

Type-specific seroprevalence of bluetongue in India during 2018 and 2019

“…BTV seroprevalence of varying percentages was reported by several authors before [11][12][13][14][15][16][17]. In BT endemic countries such as India, high seroprevalence (>50%) is usually reported [18][19][20][21][22].…”