African swine fever: how can global spread be prevented?

Abstract

African swine fever (ASF) is a devastating haemorrhagic fever of pigs with mortality rates approaching 100 per cent. It causes major economic losses, threatens food security and limits pig production in affected countries. ASF is caused by a large DNA virus, African swine fever virus (ASFV). There is no vaccine against ASFV and this limits the options for disease control. ASF has been confined mainly to sub-Saharan Africa, where it is maintained in a sylvatic cycle and/or among domestic pigs. Wildlife hosts include wild suids and arthropod vectors. The relatively small numbers of incursions to other continents have proven to be very difficult to eradicate. Thus, ASF remained endemic in the Iberian peninsula until the mid-1990s following its introductions in 1957 and 1960 and the disease has remained endemic in Sardinia since its introduction in 1982. ASF has continued to spread within Africa to previously uninfected countries, including recently the Indian Ocean islands of Madagascar and Mauritius. Given the continued occurrence of ASF in sub-Saharan Africa and increasing global movements of people and products, it is not surprising that further transcontinental transmission has occurred. The introduction of ASF to Georgia in the Caucasus in 2007 and dissemination to neighbouring countries emphasizes the global threat posed by ASF and further increases the risks to other countries. We review the mechanisms by which ASFV is maintained within wildlife and domestic pig populations and how it can be transmitted. We then consider the risks for global spread of ASFV and discuss possibilities of how disease can be prevented.

Role of Wild Suids in the Epidemiology of African Swine Fever

“…Recent molecular epidemiological studies have also uncovered substantial field heterogeneity with at least 22 genotypes being identified to date on the basis of C-terminus p72 gene sequencing (Bastos et al, 2003;Lubisi et al, 2005;Boshoff et al, 2007). The recent incursion of ASF into Georgia (Beltran Alcrudo et al, 2008;Rowlands et al, 2008) has highlighted the potential of the virus to expand its range towards Asia through the Caucasus and the Indian Ocean (Costard et al, 2009) as it encounters new populations of wild and domestic pigs, yet important gaps in our knowledge remain regarding the role of many wild Suidae in the maintenance of ASFV. The present paper summarizes current knowledge on the role of different species in the epidemiology of the disease and identifies priorities for research aimed at elucidating the role played by wild suid hosts and at directing future disease control strategies.…”

Risk factors for farm-level African swine fever infection in major pig-producing areas in Nigeria, 1997–2011

“…Husbandry practices and management styles used on farms should be evaluated to determine good hygiene practices that will suit Nigeriantype piggeries (Costard et al, 2009b).…”

Molecular detection of African swine fever virus in apparently healthy domestic pigs in Nasarawa state, Nigeria

“…As a cheap source of proteins for human consumption, with low economic input in production, it became an increasing activity undertaken by women and youths in and around cities and towns where the ASFV has remained a threat to the development of the pig industry in Nigeria and globally. The disease was first described in 1921 in Kenya and remained restricted to Africa until 1957, when it entered Portugal and other parts of Europe but was eventually eradicated through test and slaughter policy (Costard et al, 2009). Its destructive potential was well appreciated in 1957 when it occurred outside Africa (FAO, 2000).…”

“…ASF is a viral disease with severe consequences, and its expanding and continuous spread has been considered as a global threat to the pig industry worldwide (Costard et al, 2009). When introduced into a new territory, the high potential to spread, absence of vaccines or treatment makes it difficult to control.…”