Epizootic hemorrhagic disease in yaks (Bos grunniens)

Abstract

An epizootic of hemorrhagic disease associated with Epizootic hemorrhagic disease virus serotype 2 (EHDV-2) infections in yaks from 5 herds occurred in Colorado between August 21 and October 3, 2012. Affected yaks presented with fever, lethargy, anorexia, dyspnea, and swollen conjunctivae. Ulcerated dental pads, mucoid sanguineous nasal discharge, petechial hemorrhages in multiple organs, pulmonary edema, and serosanguinous fluid in the thorax, abdomen, and pericardial sac were observed at necropsy. Blood and tissue samples from 8 yaks with similar clinical signs and necropsy findings were positive for EHDV-2 by reverse transcription polymerase chain reaction and 5 yaks were seropositive for EHDV. Tests for malignant catarrhal fever (Ovine herpesvirus 2), Bovine viral diarrhea virus, Bovine herpesvirus 1, Foot-and-mouth disease virus, and Vesicular stomatitis virus were negative. The findings indicate that yaks are susceptible to infection with EHDV-2 and exhibit the clinical signs, and gross and histologic lesions of hemorrhagic disease observed in other ruminant species.

Epizootic haemorrhagic disease

“…The tongue, salivary glands, forestomach, aorta, and myocardium, especially that of the papillary muscle of the left ventricle, are commonly affected. Similar lesions have recently been described in EHDV-infected yaks and brocket deer (13,14).…”

“…In temperate regions, infection is most common in the late summer and autumn when vector populations peak, whereas infection occurs year-round in tropical regions of the world. With global climate change, there appears to be a correlation between increasing ambient temperature and risk of EHDV infection (13). For example, the effects of subtle differences of ambient temperature on vector midges likely explain differences in the global distribution of BTV and EHDV in Europe and North America (4).…”

“…Although recognised earlier in the south-eastern United States, EHD was first described after a severe outbreak of the disease in white-tailed deer in New Jersey in 1955 (5). Epidemics of EHD continue to occur regularly in this species throughout much of North America east of the Rocky Mountains (1,2,6,7,8,9,10,11,12,13). The disease also occurs sporadically in American pronghorn antelope and bighorn sheep, and was documented recently in brocket deer in Brazil and captive yaks in Colorado (1,2,13,14).…”

“…Epidemics of EHD continue to occur regularly in this species throughout much of North America east of the Rocky Mountains (1,2,6,7,8,9,10,11,12,13). The disease also occurs sporadically in American pronghorn antelope and bighorn sheep, and was documented recently in brocket deer in Brazil and captive yaks in Colorado (1,2,13,14). Whereas EHD virus (EHDV) can cause a fulminant haemorrhagic disease syndrome in both experimentally and naturally infected white-tailed deer, similar infections of ruminant livestock and other wildlife species are generally subclinical or clinically inapparent (1,2,4,.…”

Generation of virus like particles for epizootic hemorrhagic disease virus

“…Although black-tailed deer, red deer, wapiti, fallow deer, roe deer, elk, moose, and bighorn sheep do not appear to be severely affected, they may seroconvert, indicating that they can become infected (MacLachlan and Osburn, 2004;Noon et al, 2002aNoon et al, , 2002b. Recently EHDV has also been isolated in yaks (Van Campen et al, 2013). Goats do not seem to be susceptible to EHDV infection and sheep can be infected experimentally but rarely develop clinical signs, and a recent study has excluded a role in transmission to more susceptible species (Kedmi et al, 2011a).…”