A highly contagious epizootic disease of pigs, also known as classical (or European) swine fever. The causative agent is a virus in the genus Pestivirus. This disease is the subject of statutory controls in a majority of countries, and has been eradicated from many areas, including the United States, Canada, Australasia, and parts of Europe. Clinically and pathologically, it closely resembles African swine fever, which is caused by an unrelated virus. Animal virus Hog cholera can occur in European wild boar, but among domestic species only pigs are affected. Humans are not susceptible. The primary mode of transmission is by contact or proximity. Infected animals shed virus in all bodily secretions, including aerosols of respiratory mucus. The virus survival time in aerosol is short, and airborne transmission over long distances is not a factor. Virus may also be spread by contact with contaminated equipment and vehicles. It can survive for many months in frozen or refrigerated meat from infected pigs, and is not inactivated by mild forms of curing. Pigs of any age may be affected. There are typically a high fever, loss of appetite, and dullness. Other symptoms include blotchy discoloration of the skin (particularly the extremities), incoordination and weakness of the hindquarters, constipation followed by diarrhea, gummed-up eyes, and coughing. Death occurs within 4–7 days, and the mortality is usually high. The chronic form of disease is characterized by dullness, unthriftiness, capricious appetite, and variable degrees of coughing, diarrhea, and emaciation. There may be joint swellings and ulceration of the skin. Strains vary in virulence, and hog cholera may still be suspected when milder signs occur in epizootic form. Low-virulence strains may produce few signs apart from reproductive failure in sows or congenital tremors in their offspring. |
