04 June 2010 - Teschen disease is caused by the Porcine Teschovirus (PTV). The teschoviruses belong to the Picornaviridae family of viruses. Genetically, all these viruses are single stranded linear RNA with a protein capsule and without a lipid covering. This virus is responsible for the disease scientifically called porcine enteroviral encephalomyelitis in swine populations. The virus multiplies in the cells lining the intestines and is shed in large quantities in the faeces. It is highly infectious thus requiring only a small dose of infected faeces to be ingested to establish intestinal infection.
PTV was diagnosed in Haitian swine samples collected by the Animal Health Department of Haiti in February 2009. These samples were submitted for diagnostic confirmation to the Animal and Plant Health Inspection Service of the United States Department of Agriculture (USDA) and the Foreign Animal Disease Diagnostic Laboratory at Plum Island, New York. A year after pathogen confirmation, pig farmers are still reporting numerous clinical cases of PTV infection..
From 24 April to 1 May 2010, a team of experts from the Food and Agriculture Organization of the United Nations (FAO), USDA and Haitian counterparts (diagnostic laboratory, swine health, disease epidemiology, and disease management) visited various locations in and around the Artibonite Valley (e.g. Mirebalais, La Chapelle, Laincour, Port Saint Marc) in Haiti. The team met with pig farmers that had clinically affected pigs in 2009 to better understand disease impacts. A questionnaire-based survey collected information on animal health practices and husbandry systems. During farm visits, any swine exhibiting clinical signs consistent with PTV were sampled, and apparently healthy pigs were also sampled to determine and assess other disease agents circulating in local swine populations. One hypothesis is that there are other disease agents circulating in the Haitian swine population in addition to classical swine fever (CSF) virus and PTV, such as porcine respiratory and reproductive syndrome (PRRS) virus and porcine circovirus (PCV), and that the immunosuppressive effect of these agents facilitates expression of PTV.
In the field, the most prominent clinical signs observed in sick pigs were central nervous system disorders, encephalitis and encephalomyelitis. Few lesions were observed at post-mortem examinations. Diagnostic samples (109 serum, 109 blood and 63 individual tissue samples) were collected from 111 sick and normal pigs. This targeted sampling was performed to collect information on the prevalence and distribution of diseases, with analysis of the clinical picture of cases and possible changes in their epidemiology. A preliminary assessment of the epidemiological situation of PTV in Haiti suggests that the disease has spread from the Artibonite Valley to other departments, as well as posing a threat to its next-door neighbour, the Dominican Republic. All tests will be completed in June 2010 and a final report with recommendations for disease control and elimination will be provided soon.
Haitian pig production systems in rural and urban areas not only support household nutrition as a source of protein-rich food, but also serve as income and easily cashable savings. The advent of Teschen disease to Haiti is causing considerable socioeconomic impacts, especially in terms of threatening food security and disrupting the livelihoods of small rural communities and diasporas moving to rural areas from urban areas of the capital city, Port-au-Prince, after the earthquake in January 2010. In addition to FAO’s work to help strengthen and rebuild agricultural structures, it will also continue its efforts to secure funding to provide Haiti with an effective vaccine for Porcine Teschovirus. There are serious concerns that PTV could be introduced to other Caribbean countries, as well as in Central and North America by movement of pigs or contaminated products. The development and production of a commercially available vaccine against this disease is a high priority and it should be seen as an insurance policy for countries at risk in the Caribbean.