APPROACHES & GOALS OF FMD DIAGNOSIS UNDER A CONTROL / ERADICATION PROGRAM

BERGMANN, I.E.

Encuentro; SENASA-ARGENTINE SOCIALIST REPUBLIC OF VIETNAM PROYECT-FMD SOUTH-SOUTH AND TRIANGULAR ARGENTINE FUND FOR HORIZONTAL COOPERATION (FO.AR); 2014

In this work we describe the approaches for diagnosis and sero-surveillance of FMD virus (FMDV) to be considered according to the stage of the Eradication Plan of the different regions of South America: endemic areas, free with vaccination and free without vaccination. The definition of the approaches to be followed for diagnosis should consider not only the requirements demanded by the epidemiological situation of each region but also some characteristics of FMDV such as: a) The clinical diagnosis is inconclusive because clinical signs may be mild in some species and for certain viral strains. Besides the clinical symptoms can be indistinguishable from other vesicular diseases. Therefore, a definitive diagnosis requires laboratory confirmation; b) There are seven serotypes of FMDV which do not provide cross-protection. Within a serotype a wide range of strains may occur, some of which may be sufficiently divergent to reduce the effectiveness of vaccines in use. Consequently, diagnostic procedures need to assess the antigenic / genetic / immunogenic relationship between field strains and vaccine strains and the protection conferred by the vaccines used; c) After the acute stage of infection, FMDV can cause persistent infection in some species, even in vaccinated animals. Consequently, the diagnosis should address the identification of such unapparent infection. The methodologies of both conventional diagnosis and newly developed methods are evaluated according to the advantages and disadvantages of different situations for each region, particularly in relation to the demands required according to the epidemiological situation. The work addressed not only detection methods but also genetic, antigenic and immunogenic characterization. Seroepidemiological studies required in areas with low prevalence of disease, including studies of viral activity and population immunity and its importance for supporting the application for international recognition of free area with or without vaccination and maintenance of such condition are also described. New international requirements regarding the use of validated and internationally harmonized methods, as well as the requirements for their quality control are discussed.