Abstract:
Sylvatic circulation of African swine fever virus (ASFV) in warthogs and Ornithodoros ticks
that live in warthog burrows historically occurred in northern South Africa. Outbreaks of
the disease in domestic pigs originated in this region. A controlled area was declared
in the north in 1935 and regulations were implemented to prevent transfer of potentially
infected suids or products to the rest of the country. However, over the past six decades,
warthogs have been widely translocated to the south where the extralimital animals have
flourished to become an invasive species. Since 2016, there have been outbreaks of ASF
in pigs outside the controlled area that cannot be linked to transfer of infected animals
or products from the north. An investigation in 2008–2012 revealed that the presence
of Ornithodoros ticks and ASFV in warthog burrows extended marginally across the
boundary of the controlled area. We found serological evidence of ASFV circulation in
extralimital warthogs further south in the central part of the country.
