By Attila Farkas, DVM, Carthage Veterinary Service
African swine fever is getting a lot of coverage in the media as outbreaks continue to occur across Asia and the European Union, while other foreign animal diseases are getting less “publicity” even though the introduction of these infectious agents would have similar economic effects and cripple the U.S. pork industry and exports. In modern day swine production, free trade agreements, free trade blocks, regionalization, increased international passenger travel and the constant evolution of infectious agents are among the factors affecting foreign animal disease prevention, control, management and recovery.
Classical swine fever is a highly contagious viral disease of swine that occurs in an acute, subacute and chronic form. In the acute form, the disease is characterized by high fever, severe depression, multiple superficial and internal hemorrhages, and high morbidity and mortality. These clinical signs are indistinguishable from other acute septicemic diseases. In the chronic form, the signs of depression, anorexia and fever are less severe than in the acute form, and recovery is occasionally seen in mature animals. Transplacental infection with viral strains of low virulence often results in persistently infected piglets, which constitute a major cause of virus dissemination to non-infected farms.
The hosts of CSF are the pig and wild boar. The disease has been eradicated in Australia, Canada and the United States. Modified live vaccines with no residual virulence for pigs have become available. In countries where CSF is enzootic, a systematic vaccination program is effective in preventing losses. CSF is not considered a zoonotic disease as humans are not susceptible to infection.
Vesicular stomatitis is a viral disease characterized by fever, vesicles and subsequent erosions in the mouth and epithelium on the teats and feet. Pigs, horses and cattle are naturally susceptible; sheep and goats are rarely affected. VS is recognized internationally as a reportable disease, and detection of this disease in the United States will lead to serious economic and regulatory repercussions, blocking international trade of U.S. animals. Interstate movement of animals is also impacted. Premises containing affected animals are quarantined until 21 days after the lesions in the last affected animal have healed.
While VS can cause economic losses to livestock producers, it is a particularly significant disease because its outward signs are similar to other FADs like foot-and-mouth disease and swine vesicular disease. The only way to tell these diseases apart is through laboratory testing. VS is a zoonotic disease — in humans it causes an influenza-like illness with fever, headache, muscular aches and blisters in the mouth.
FMD is a highly contagious viral infection of pigs, cattle, sheep, goats, water buffalo and cloven-hoofed wild animals. The disease is characterized by fever and vesicles with subsequent erosions in the mouth, nares, muzzle, feet or teats. FMD is considered enzootic in some Asian and African countries, but it is not considered to be a public health problem.
Swine vesicular disease is an acute, contagious viral disease of swine characterized by fever and vesicles with subsequent erosions in the mouth and on the snout, feet and teats. Pigs are the only natural host. SVD is considered a zoonotic disease, as accidental laboratory infection of humans has been reported. There is no vaccine available to combat this virus.
In order to keep these FAD infectious agents out of our farms, we have to continue general public awareness and the dedication to biosecurity measures. Implementing additional protective barriers such as refusing pork meat into your farms, implementing worker showers, wearing protective clothing/boot covers, having air filtration, and installing stations to wash and disinfect trucks and trailers have shown to be efficacious in keeping these pathogens out of swine barns. As an industry, we still procure some vitamins, amino acids, antibiotics and protein such as soybeans from countries where these FAD infectious agents are endemic.
Given the biosecurity of how these ingredients are stored and bagged, these ingredients represent a huge risk in the transmission of a transboundary disease. Utilizing feed mitigants and additional product hold times have been shown to be efficacious in inactivating the FAD infectious agents. Extreme caution should be taken when considering hosting someone on your farm from FAD-endemic regions and a five-day downtime should be observed before allowing them to enter the farm.
To detect FAD outbreaks early, suspicious signs of an FAD must be promptly reported to the state veterinarian. Private veterinarians in clinical practice are knowledgeable with the occurrences of domestic animal diseases and are likely to be the first to suspect the presence of an FAD. Prompt reporting of suspicious signs will enable responsible agencies to conduct an investigation, obtain a diagnosis and contain an FAD outbreak before it spreads. The economic and industrial losses due to the potential introduction of an FAD are too great and in order to protect the U.S. swine industry our No. 1 mission is to keep these infectious agents out of the United States.