African Horse Sickness

Infectious Diseases of Working Equids

“…The pathologic findings associated with AHS infection in horses have been extensively described in other texts. 21 In the pulmonary form of AHS, the most striking pathologic finding is the diffuse, severe, subpleural, and interlobular edema of the lungs. Severe hydrothorax is common, with the pleural cavity containing large quantities of transparent, pale-yellow, gelatinous fluid.…”

“…The typical macroscopic lesions of AHS on postmortem are often sufficiently specific to allow a provisional diagnosis of the disease. 21 Virus isolation is currently the gold standard diagnostic test for AHS, although other serologic and molecular tests are now accepted by the OIE. Serotyping of AHSV isolates is performed using virus neutralization tests.…”

“…The disease is occasionally reported in countries in North Africa, from where it has also entered the Middle East and Spain. 21 Two countries on the African continent with large working horse populations are Ethiopia and Senegal. Outbreaks of AHS have been documented in Ethiopia, including reports of serotype 6 31 and serotypes 2, 4, and 8.…”

“…All 9 serotypes have been documented in eastern and southern Africa, with serotype 9 more widespread in the northern areas of sub-Saharan Africa. 21 Epidemiology AHSV is biologically transmitted by the Culicoides spp. Culicoides imicola and Culicoides bolitinos have been shown to play an important role in Africa.…”

The challenges posed by equine arboviruses

“…A mild form (horse sickness fever) involves oedema of the supraorbital fossae and fever and occurs in donkeys and zebra and horses that have some immunity or are infected with a less virulent strain [33]. The pulmonary form causes rapid respiratory failure and is associated with case-fatality rates that can exceed 95% [34]. The cardiac form causes oedema of the head and neck, progressing to dyspnoea, cyanosis, abdominal pain and heart failure and case-fatality rates are around 50%.…”