Investigating Foreign Animal Diseases

Surveillance for and the investigation of suspected foreign animal diseases is a high priority for state and federal animal health regulatory officials, because the movement of animals and animal products, including semen and embryos, in international commerce could introduce disease and pests into our domestic animal populations. The introduction of a disease of foreign origin would threaten the U.S. share of international markets and would impose trade restrictions and costs for control and eradication. An economic study conducted in 2000 by the U.S. Department of Agriculture (USDA) estimated that the loss of equine exports due to the diagnosis of a communicable infectious disease of horses would have a total impact on the U.S. economy of 1.6 billion dollars.(1)

The Animal Plant Health Inspection Service (APHIS) of the USDA regulates the importation of animals and animal products into the United States. Furthermore, animals imported from outside North America are required to enter through a few selected ports where they are examined for evidence of contagious, communicable diseases and samples are collected to test for specific disease conditions. (For more information, go to www.aphis.usda.gov and click on Import and Export.)

Should a foreign animal disease (FAD) gain entry into the United States, private veterinary practitioners who are accredited by USDA to participate in federally regulated activities (for example, issuing certificates of veterinary inspection) would provide the foundation for surveillance and early detection. APHIS, in cooperation with state departments of agriculture, would provide the administrative structure and regulatory oversight for reporting and investigating these disease events. In support of this effort, APHIS provides specialized hands-on training in the diagnosis of foreign animal diseases to state and federal veterinarians. These foreign animal disease diagnosticians (FADD) are located throughout each state and are available 24 hours a day to investigate suspected cases.

Since 2003, a total of 2,704 FAD investigations have been conducted nationwide. Of these, 1,170 (43%) were for disease conditions of horses, the majority of which were conducted due to vesicular conditions of the skin and muzzle and for animals showing central nervous system signs.

Flow chart of officials FAD investigations are generated primarily via a system that relies on producers and practitioners to report suspect cases. Investigations have, however, been initiated at the request of extension agents following reports of dead or dying animals or on the basis of a suspicious laboratory test result. (Figure 2). Depending on the type and quality of information received, the decision to conduct an FAD investigation is generally at the discretion of the state veterinarian and/or the federal area veterinarian in charge (AVIC), who then assigns an FAD diagnostician to the case.

Once a decision has been made to investigate, the diagnostician is required to initiate the farm visit within 24 hours of notification by the state or USDA area veterinarian in charge. In reality, most investigations are conducted within a few hours of receiving the report of a suspicious illness. The diagnostician will routinely visit the premises to make an assessment of the disease situation and to collect and submit samples. Depending on the species being investigated, the specimens will be shipped to either the National Veterinary Services Laboratory in Ames, Iowa, or to the Foreign Animal Disease Diagnostic Laboratory, Plum Island, New York.

There is never a fee for an FAD investigation, but laboratory testing is restricted to ruling out diseases of foreign origin. Preliminary results can be expected within 24 to 48 hours, depending on the priority of the investigation and the infectious agent under consideration.

Based on the presenting signs, relevant clinical history, or other pertinent epidemiology information, the FAD diagnostician, in consultation with the state veterinarian, will have some discretion as to further regulatory actions imposed on the suspect premises. At a minimum, a quarantine is issued and the owner/operator instructed that no animals or animal products such as semen are allowed to move off the premises until the receipt of laboratory findings and notification from the Office of the State Veterinarian.

Reportable diseases On occasion, regulatory officials are asked to provide assistance with the investigations of diseases of unknown origin but which are not considered to be FADs. The investigation of Mare Reproductive Loss Syndrome is just such an example. Once an FAD had been ruled out, APHIS provided personnel and technical assistance with the collection and analysis of epidemiological data. (See www.ca.uky.edu/gluck/MRLSindex.aspx for further information.)

A list of federally reportable equine diseases is found in Figure 3. Veterinarians, diagnostic laboratories, extension agents, animal owners, and farm managers are all part of the early detection system for foreign animal diseases. Contact information, such as that for Kentucky in Figure 4, should be readily available, especially for veterinarians.

1. USDA (2000). Potential impact of the Contagious Equine Metritis-like organism on the equid industry in the U.S. USDA-APHIS-VS, CEAH, Center for Animal Disease Information and Analysis, Fort Collins, CO.

Contact: Dr. Barry J. Meade, 502/227-9651, barry.meade@aphis.usda.gov, USDA-APHIS-VS, Frankfort, Kentucky.

This is an excerpt from Equine Disease Quarterly, funded by underwriters at Lloyd's, London, brokers, and their Kentucky agents. More articles from Equine Disease Quarterly...

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