Common, emerging, vector-borne and infrequent abortogenic virus infections of cattle.

This review deals with the aetiology and the diagnosis of bovine viral abortion. While the abortion rates on beef and dairy cattle farms usually do not exceed 10%, significant economic losses because of abortion storms may be encountered. Determining the cause of abortions is usually a challenge, and it generally remains obscure in more than 50% of the necropsy submitted foetuses. Bovine viral diarrhoea virus and bovine herpesvirus-1 are the most common viruses causally associated with bovine abortions in farmed cattle globally. Rift Valley fever virus and bluetongue virus are important insect-transmitted abortogenic viruses. The geographic distribution of these two viruses is primarily dependent on the distribution of the insect vector, but direct transmission is possible. Recent global warming and subsequent insect vector expansion, coupled with the increase in international trade of animals and animal products, have been important factors in recent geographic advances of those two viruses. Bovine herpesviruses-4 and 5 in cattle, as well as other less frequent vector-borne viruses including epizootic haemorrhagic disease virus, Aino virus, Wesselsbron virus and lumpy skin disease virus, are discussed.