Data from: The history of foot-and-mouth disease virus serotype C: the first known extinct serotype?

Foot-and-mouth disease (FMD) is a highly contagious animal disease caused
by an RNA virus subdivided into seven serotypes that are unevenly
distributed in Asia, Africa and South America. Despite the challenges of
controlling FMD, since 1996 there have been only two outbreaks attributed
to serotype C, in Brazil and in Kenya, in 2004. This review describes the
historical distribution and origins of serotype C and its disappearance.
The serotype was first described in Europe in the 1920s, where it mainly
affected pigs and cattle but as a less common cause of outbreaks than
serotypes O and A. No serotype C outbreaks have been reported in Europe
since vaccination stopped in 1990. FMD virus is presumed to have been
introduced into South America from Europe in the 19th century, although
whether serotype C evolved there or in Europe is not known. As in Europe,
this serotype was less widely distributed and caused fewer outbreaks than
serotypes O and A. Since 1994, serotype C had not been reported from South
America until four small outbreaks were detected in the Amazon region in
2004. Elsewhere, serotype C was introduced to Asia, in the 1950s to the
1970s, persisting and evolving for several decades in the Indian
subcontinent and for eighteen years in the Philippines. Serotype C virus
also circulated in East Africa between 1957 and 2004. Many serotype C
viruses from European and Kenyan outbreaks were closely related to vaccine
strains, including the most recently recovered Kenyan isolate from 2004.
International surveillance has not confirmed any serotype C cases,
worldwide, for over 15 years, despite more than 2000 clinical submissions
per year to reference laboratories. Serology provides limited evidence for
absence of this serotype, as unequivocal interpretation is hampered by
incomplete intra-serotype specificity of immunoassays and the continued
use of this serotype in vaccines. It is recommended to continue
strengthening surveillance in regions of FMD endemicity, to stop
vaccination against serotype C and to reduce working with the virus in
laboratories, since inadvertent escape of virus during such activities is
now the biggest risk for its reappearance in the field.