To date, three cycles involved in the transmission of ASF have been identified: the sylvatic cycle involving circulation of the virus between warthogs (Phacochoerus africanus) and soft ticks of the genus Ornithodoros, the tick-to-domestic pig cycle and lastly the domestic pig-to-pig cycle [ 7].
It is transmitted either by direct or in-direct contact between domestic pigs or wild suids with or without an arthropod vector and is maintained by three distinct cycles: 1) a sylvatic cycle between the Argasid tick and warthogs, and possibly bush pigs or giant forest hogs [ 23]; 2) a cycle between domestic pigs and the Argasid tick; and 3) a domestic pig cycle not requiring ticks [ 24].
We also predict that all of these countries, except Botswana, have a widespread distribution of areas of apparent high suitability for sustained transmission as part of domestic pig cycles.
Factors contributing to the transmission of ASF in these 'domestic' pig cycles may include the use of free-ranging husbandry methods, the movement of infected pigs between farms and to markets, and the feeding of contaminated domestic waste to pigs [ 1].
The predicted distribution of areas with high suitability for repeated introduction of ASF from wildlife reservoirs and for sustained transmission within pig populations also supports the anecdotal distribution of sylvatic and domestic pig cycles identified by a number of authors [ 1, 2, 5, 44].
In general, different transmission cycles are observed with ASFV: a sylvatic cycle, a soft tick-pig cycle, and a domestic cycle [ 3].
The tick-pig cycle was up to now observed in Africa [ 5] and on the Iberian Peninsula [ 6], where it involved domestic pigs and O. erraticus ticks infesting the pig pens.
An ongoing (and literal) hog cycle, embellished by some localized pig disease, caused pork prices to skyrocket.
Nevertheless, a pig-to-pig domestic cycle appears to be the main cycle of infection in the country, due to the large free-ranging pig population, along with regular reintroduction from disease-endemic countries.
Furthermore, the case study also shows that from the perspective of the pig life cycle, the improvement of feed composition and labor productivity in the grow-finisher step and the rearing level of breeding pigs are the most important points for the optimization of the large-scale pig farming system.
Because the pig production cycle is shorter than that for cattle, pig production is a major economic activity in Cameroon.
