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Bovine malignant catarrhal fever (BMCF) is a fatal lymphoproliferative disease caused by a group of ruminant gamma herpes viruses including ''Alcelaphine Herpes Virus 1'' (AlHV-1) and ''Ovine Herpes Virus 2'' (OvHV-2) 〔〔Schultheiss PC, Collins JK, Spraker TR, DeMartini JC. J Vet Diagn Invest. 2000 Nov;12(6):497-502.〕 These viruses cause inapparent infection in their reservoir hosts, (sheep with OvHV-2 and wildebeest with AlHV-1) but are usually fatal in cattle and other ungulates such as deer, antelope, and buffalo.〔 BMCF is an important disease where reservoir and susceptible animals mix. There is a particular problem with Bali cattle in Indonesia, bison in the USA and in pastoralist herds in Eastern and Southern Africa. Disease outbreaks in cattle are usually sporadic although infection of up to 40% of a herd has been reported. The reasons for this are unknown. Some species appear to be particularly susceptible, for example Pére Davids deer, Bali cattle〔 and bison,〔 with many deer dying within 48 hours of the appearance of the first symptoms and bison within three days.〔 In contrast, post infection cattle will usually survive a week or more. ==Epidemiology== The term ''bovine malignant catarrhal fever'' has been applied to three different patterns of disease: *In Africa, wildebeests carry a lifelong infection of AlHV-1 but are not affected by the disease.〔 The virus is passed from mother to offspring and shed mostly in the nasal secretions of wildebeest calves under one year old. Wildebeest associated MCF is transmitted from wildebeest to cattle normally following the wildebeest calving period. Cattle of all ages are susceptible to the disease, with a higher infection rate in adults, particularly in peripartuent females. Cattle are infected by contact with the secretions, but do not spread the disease to other cattle. Because no commercial treatment or vaccine is available for this disease, livestock management is the only method of control. This involves keeping cattle away from wildebeest during the critical calving period. This results in Massai pastoralists in Tanzania and Kenya being excluded from prime pasture grazing land during the wet season leading to a loss in productivity. In Eastern and Southern Africa MCF is classed as one of the five most important problems affecting pastoralists along with East coast fever, contagious bovine pleuropneumonia, foot and mouth disease and anthrax.Hartebeests and topi also may carry the disease. However, hartebeests and other antelopes are infected by a variant, Alcelaphine herpesvirus 2. *Throughout the rest of the world, cattle and deer contract BMCF by close contact with sheep or goats during lambing. The natural host reservoir for Ovine herpesvirus 2 is the subfamily Caprinae (sheep and goats) whilst MCF affected animals are from the families Bovidae, Cervidae and suidae. Susceptibility to OHV-2 varies by species, with domestic cattle and zebus somewhat resistant, water buffalo and most deer somewhat susceptible, and bison, Bali cattle, and Pere David's deer very susceptible. OHV-2 viral DNA has been detected in the alimentary, respiratory and urino-genital tracts of sheep all of which could be possible transmission routes. Antibody from sheep and from cattle with BMCF is cross reactive with AlHV-1.〔 *AHV-1/OHV-2 can also cause problems in zoological collections, where inapparently infected hosts (wildebeest and sheep) and susceptible hosts are often kept in close proximity. *Feedlot bison in North America not in contact with sheep have also been diagnosed with a form of BMCF. OHV-2 has been recently documented to infect herds of up to 5 km away from the nearest lambs, with the levels of infected animals proportional to the distance away from the closest herds of sheep. The incubation period of BMCF is not known, however intranasal challenge with AHV-1 induced MCF in one hundred percent of challenged cattle between 2.5 and 6 weeks. Shedding of the virus is greater from 6-9 month old lambs than from adults.〔 After experimental infection of sheep, there is limited viral replication in nasal cavity in the first 24 hours after infection, followed by later viral replication in other tissues.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Bovine malignant catarrhal fever」の詳細全文を読む スポンサード リンク
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