Epidemiology of African swine fever in Africa today: Sylvatic cycle versus socio‐economic imperatives

Abstract

African swine fever (ASF) is believed to have evolved in eastern and southern Africa in a sylvatic cycle between common warthogs (Phacochoerus africanus) and argasid ticks of the Ornithodoros moubata complex that live in their burrows. The involvement of warthogs and possibly other wild suids in the maintenance of ASF virus means that the infection cannot be eradicated from Africa, but only prevented and controlled in domestic pig populations. Historically, outbreaks of ASF in domestic pigs in Africa were almost invariably linked to the presence of warthogs, but subsequent investigations of the disease in pigs revealed the presence of another cycle involving domestic pigs and ticks, with a third cycle becoming apparent when the disease expanded into West Africa where the sylvatic cycle is not present. The increase in ASF outbreaks that has accompanied the exponential growth of the African pig population over the last three decades has heralded a shift in the epidemiology of ASF in Africa, and the growing importance of the pig husbandry and trade in the maintenance and spread of ASF. This review, which focuses on the ASF situation between 1989 and 2017, suggests a minor role for wild suids compared with the domestic cycle, driven by socio‐economic factors that determine the ability of producers to implement the control measures needed for better management of ASF in Africa.

African Swine Fever in a Bulgarian Backyard Farm—A Case Report

“…In 1921, the disease was first described in Africa, where the disease is endemic. Nowadays it occurs in most countries with notable pig sectors [2,3]. The current Eurasian epidemic started in Georgia in 2007 [4] from where it spread through the Caucasus, Russian Federation, Ukraine and Belarus.…”

No Experimental Evidence of Co-Feeding Transmission of African Swine Fever Virus between Ornithodoros Soft Ticks

“…Three main transmission cycles are commonly described in these endemic areas: (i) the sylvatic cycle, corresponding to ASFV transmission between warthogs and ticks, (ii) the domestic/tick cycle, corresponding to ASFV transmission between domestic pigs and ticks, and (iii) the domestic cycle, corresponding to ASFV circulation between domestic pigs only [5,6]. It is assumed that soft ticks play an important role in maintaining ASFV within the sylvatic cycle, as well as in transmitting ASFV between wild and domestic Suidae [4,7,8].…”

African swine fever: Update on Eastern, Central and Southern Africa

“…All the known p72 genotypes have been reported from the ECSA region. The highest numbers described to date have emanated from the area extending northwards between South Africa and Tanzania and eastwards to Zambia (Figure ; Boshoff et al, ; Lubisi et al, ; Penrith, Bastos, Etter, & Beltrán‐Alcrudo, ). While a relationship between the intensity of research and the diversity of the viruses is likely, tapering off of the numbers to the north and west is probably real.…”