Renewed research effort to tackle African Swine Fever
Causing up to 100 per cent mortality in previously unaffected animals, African Swine Fever (ASF) is a devastating disease of pigs. Endemic across much of Africa, the disease poses a wider threat to global food security, particularly in East Asia, where at least 50 per cent of the protein consumed is pork, much of it produced through small to medium-scale 'backyard' enterprises.
Current control methods are by diagnosis and slaughter but this approach is difficult, expensive and often not practical for smallholder farmers. To better understand the complexities of the disease, a consortium of research and development organisations* from around the world is implementing a range of approaches across Africa.
New strains add risk
Whilst there are currently no formal economic estimates of the overall losses to ASF in Africa, an outbreak in Madagascar in 1998 killed half the country's pig population (250,000 animals). During the last year, ASF outbreaks have also been reported in North Cameroon where over 100,000 animals may have been lost to the disease. In October 2010, the World Organisation for Animal Health (OIE) received notification of the first ASF outbreak in Chad.
In addition, there is evidence that different strains of virus causing the disease are spreading within the continent. In 2010, a highly lethal genetic type of the virus, previously known only from East Africa, was detected in the Republic of Congo. Beyond Africa, the disease is endemic in Sardinia as well as in the Caucasus and Southern Russia, posing a risk to the EU and parts of Eastern Europe.
The epidemiology of ASF is complex, involving wild pigs, particularly warthogs, and soft ticks, in eastern and southern Africa. In west and central Africa transmission is believed to be mostly by direct transfer of the virus between domestic pigs, or via infected offal contaminating feed.
African swine fever virus (ASFV), the causative agent, is a highly stable DNA virus that can survive under a wide range of temperatures and pH levels. DNA viruses tend to be much more stable than RNA viruses - the main cause of many important human diseases - and can be more easily disseminated over broad geographic areas through the movement of infected swine or contaminated pork products.
New funding for research
A new injection of research funding will enable African scientists to obtain in-depth data to provide improved insight into the transmission and spread of ASF between African countries. AusAID is supporting Australia's national science agency (CSIRO), in developing an institutional partnership with the Biosciences eastern and central Africa (BecA) hub.
The research team is working to better understand modes of viral transmission, between different geographical regions. These include transport of live pigs, pork products, or accidental transmission via clothing or vehicles contaminated with pig waste products. The role of resistance and immunity in different pig breeds is also being investigated. The work is also being supported by key research partners in Africa, Europe (with a major contribution from Spain), and USA.
"This international collaboration provides an opportunity to validate new diagnostic technologies that will enable rapid confirmation of ASF and improved surveillance of the disease at the regional laboratory level," explains Dr Brian Keating, director of CSIRO's sustainable agriculture flagship. Newly developed 'penside' serological and nucleic acid-based tests (LAMP) with simple readouts will be initially targeted on Kenya and Uganda in pilot projects, but linked to subsequent Africa-wide distribution, supported by major development agencies, particularly FAO.
Simple measures to prevent spread
Enhanced rapid response and control of ASF is also to be developed, through implementing improved biosecurity to supplement slaughter where possible. Simple measures such as restricting access to all but essential workers to pig farms, changing footwear on entry and exit and processing of feed, by cheap measures such as boiling of swill to inactivate viral contamination, can effectively reduce disease incidence. Awareness of these measures for disease mitigation will initially be communicated through farmer field days at selected sites with high densities of smallholder pigs.
"Collaboration and awareness of biosecurity measures between agencies and across borders is essential since ASF is a transboundary disease," explains Dr Richard Bishop, project leader. "Through BecA and other mechanisms, we now have national veterinary laboratories increasingly working together across Kenya, Uganda, Tanzania, Rwanda and Burundi, to formulate joint control policies, an initiative that is critical to secure East Africa's smallerholder pig industry," he adds.
In the longer term, development of vaccines as a more sustainable solution for control of ASF is underway. Recent research indicates that immunity to the disease exists and that experimental vaccines are possible.
* The work is being funded by development partners including AusAID, CISA-INIA Spain, the FAO-Emergency Centre for Transboundary Animal Diseases (FAO-ECTAD), AU-IBAR and OIE. The BecA hub is hosted and managed by the International Livestock Research Institute (ILRI).
Date published: November 2011
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Focus on: Livestock disease
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- Beyond eradication - maintaining a rinderpest-free world
- Strengthening animal health in Ethiopian pastoral areas
- Renewed research effort to tackle African Swine Fever
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- An environmental view of animal health and disease
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- Safe food, fair food: improving livestock health and livelihoods
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