Evolving perception on the benefits of vaccination as a foot and mouth disease control policy: contributions of South America

Abstract

Within the past decade, changes in perceptions on the benefits of vaccination as an appropriate tool to achieve complete foot and mouth disease eradication have become evident. The former negative view was derived from misconceptions, resulting mainly from the belief that vaccines are not entirely effective and that vaccination masks asymptomatic viral circulation. The advent in the 1990s of vaccination policies implemented within a strategic eradication plan in South America, and during recurrence of the disease in disease-free regions contributed towards generating more reliable and visible outcomes of vaccination programs, paving the way towards a new perception. Particularly relevant was the development and application of novel serodiagnostic approaches to assess silent viral circulation, irrespective of vaccination. The use in South America of vaccination allied to serosurveys to accompany viral clarification during eradication campaigns and after emergencies clearly established the importance of this control tool to stop the spread of viral infection. This alliance gave input to break many myths associated with the use of vaccines, including the belief that immunized carrier animals pose an epidemiologic risk. This experience launched new concepts that supported the internationally recognized status of foot and mouth disease-free regions with vaccination and the 'vaccination to live' policy as an alternative to 'stamping out'.

Redefining the “carrier” state for foot-and-mouth disease from the dynamics of virus persistence in endemically affected cattle populations

“… 10 ), although there is a report of transmission from a “carrier” cow to a pig at the Plumb Island Animal Disease Centre 10 . From the evidence to date, if “carrier” cattle do transmit virus, it seems to be a rare event and the likelihood of transmission declines with time since infection 10 11 . However, the small number of experimental studies on which this is based involved only small numbers of animals.…”

Eradication Program of Foot and Mouth Disease in the State of São Paulo: Evaluation of Official Data Obtained Between 1997-2012

“…When animals that have received several doses of the vaccine present these antibodies, the confirmatory test is done by the isolation of the agent from the EPF. This procedure does not take into account the fact that some vaccine manufacturers laboratories already have purified ("clean") vaccines that do not stimulate the production of antibodies against non-capsidal proteins (21) .…”

Foot-and-mouth disease: overview of motives of disease spread and efficacy of available vaccines

“…Many countries have maintained their disease-free status by strict monitoring and culling of infected animals [ 11 , 12 ]. The southern part of South America achieved FMD-free status from the OIE in the late 1990s with the help of a strict eradication program, and other countries such as Uruguay, Argentina, Paraguay, and Brazil achieved FMD-free status via vaccination in 1994, 1997, 1997, and 1998, respectively [ 13 ].…”