Situation of classical swine fever and the epidemiologic and ecologic aspects affecting its distribution in the American continent

Abstract

Classical swine fever (CSF) is a viral transboundary animal disease that is highly contagious among domestic and wild pigs, such as boars and peccaries. Today, far from being what was classically described historically, the disease is characterized as having a varied clinical picture, and its diagnosis depends on resorting to proper sample collection and prompt dispatch to a laboratory that can employ several techniques to obtain a definitive diagnosis. Laboratory findings should be complemented with a field analysis of the occurrence of disease to have a better understanding of its epidemiology. The disease is still present in various regions and countries of Latin America and the Caribbean, thus hindering production, trade, and the livestock economy in the region. Consequently, it is among the diseases included in List A of the Office International des Epizooties (OIE). Currently, there are epidemiologic and ecologic aspects that characterize its geographical distribution in the region such as: continued trends in the demand for pork and pork products; an increase in swine investment with low production costs which are able to compete advantageously in international markets; the convention of associating CSF in the syndrome of "swine hemorrhagic diseases" owing to the historical description of its acute presentation and not to the new and more frequent subacute presentations or the diseases with which it may be confused (notably, porcine reproductive and respiratory syndrome and porcine dermopathic nephropathy syndrome, among others); dissemination of the virus through asymptomatic hosts such as piglets infected in utero; frequent lack of quality control and registration of vaccines and vaccinations; feeding of swine with contaminated food waste (swill); the common practice of smuggling animals and by-products across borders; the backyard family production system or extensive open field methods of swine rearing with minimal input in care and feeding; poor understanding of the epidemiologic role that boars and peccaries could have in the transmission and maintenance of the disease in the Americas; and new procedures in animal welfare that some countries are adopting for the production, transport, and slaughter of domestic animals. Consequently, many countries (i.e., Canada, USA, Chile, Belize, Costa Rica, Panama, and Mexico, where 13 of 32 States are disease free) have given priority to the control and progressive eradication of CSF. In other parts of the Americas, the disease appears under control, as is the case of the five countries of the Andean Region and the 12 northern States of Brazil. In South America, Chile, Uruguay and 13 States in Brazil are disease free. Argentina has mounted a national campaign and is in the process of eradicating the disease. No recent information on its presence or distribution in Paraguay is available. With no master strategy to harmoniously progress in the control and eradication of the disease, 17 countries of the region, jointly led by the Food and Agriculture Organization of the United Nations, developed the Continental Plan for the Eradication of CSF whose objective is expected to be reached by 2020.