Monthly Archives: May 2019

The spread of African swine fever is a serious threat to Asian pig farmers

By: Gunilla Ström Hallenberg, SLU Researcher at the Department of Clinical Sciences;
Division of Reproduction 

The current outbreak of African swine fever in several Asian countries is causing severe impacts on the pig industry. Since the disease has a very high mortality rate of up to 100%, it is associated with substantial losses for pig farmers and may lead to trade restrictions and ban on exports of pigs and pork from affected countries.

Destruction of dead pigs during an outbreak of African swine fever in a Cambodian village. Photo: Kristina Osbjer, FAO.

It was in August 2018 that the first outbreak was reported in China. Previously, African swine fever had only occurred in Africa, although with recent spread to Russia and parts of Europe. The emergence of the disease in China is highly worrisome, given that the country harbours around 50% of the world pig population (around 430 million pigs). Since the first reported outbreak, the disease has spread throughout eastern China, with a recent outbreak in the western province of Xinjiang. To date, it has been estimated that around one million pigs have died or been culled as a results of African swine fever in the country. 

As a consequence of the ongoing outbreaks in China, neighbouring countries have put in a lot of efforts in order to stop the disease from spreading into their countries. Despite these efforts, African swine fever was reported in Mongolia in January 2019. In Mongolia, the disease has so far led to that more than 10% of the country’s (although quite small) pig population have died or been culled.

On 19 February 2019, the first outbreak was reported in Vietnam, a country with more than 10 million pigs, of which the majority are still raised by smallholders. Initially, outbreaks were concentrated to the northern regions around Hanoi but the disease was recently reported in central Vietnam as well.

The most recent report on African swine fever is from Cambodia, where disease symptoms were first noticed on 22 March 2019 on a small-scale farm in Ratanakiri province, bordering Vietnam. The disease is believed to have been spread through contaminated food products imported from Vietnam. Since then, more outbreaks have been reported in neighbouring districts in Cambodia.

Map illustrating the outbreaks of African swine fever in Asian countries, from August 2018 to May 9, 2019. Source: FAO, “ASF situation in Asia update”.

The disease

African swine fever is caused by a virus of the Asfarviridae family. It affects both domestic pigs and the wild boar population. The disease is usually deadly, especially among domestic pigs. Wild boars appear to be less severely affected by the disease but may still carry the virus and infect other pigs. Infected pigs typically show symptoms like fever, loss of appetite, lack of energy and internal bleeding. Reddening of the ears and flanks is also a common symptom. Pigs infected with the virus usually die within ten days, sometimes before even showing any symptoms. The African swine fever virus does not cause disease in humans.

Sampling for African swine fever detection in a Cambodian village. Photo: Kristina Osbjer, FAO.

To date there are no vaccine available against African swine fever, which makes controlling the disease challenging. Early detection and good biosecurity are the main tools used to control the spread of the virus. As biosecurity measures are often poorer in backyard or non-commercial farms, those farms are often the ones first affected by the disease. With the exception of China, all outbreaks in Asia have so far occurred in backyard pig farms.

Transmission and spread

The African swine fever virus affects both domestic pigs and wild boars. Healthy pigs usually become infected through direct contact with infected animals, both domestic and wild boar, or if they are fed meat products from infected animals, for example from kitchen waste or through swill feeding. The virus is very heat resistant which means that infected products must be properly heated to eliminate the virus. According to FAO, the majority of the first 21 outbreaks of the disease in China were related to swill feeding, leading to updated feed restrictions and the banning of swill feeding to pigs.

Besides being heat resistant, the virus may also survive in cold or frozen meat products for several months. Importing meat products from affected countries may therefore involve a risk of introducing the virus to other countries. The virus may also be spread between farms and animals through contaminated material, such as clothing, vehicles and other equipment. This appears to be an important route in the transmission and spread of the virus in China. Thorough cleaning of any material or clothing in contact with infected animals or meat products is therefore of great importance. However, such practices might not be properly implemented in lower-income countries and on backyard farms, which facilitates the spread of the disease.

Contaminated meat products may be a source of transmission of the African swine fever virus. Photo: Gunilla Ström Hallenberg, SLU.

Impacts on the Asian pig production

The spread of African swine fever in Asia will seriously affect the pig production in the region. Besides the obvious effects the disease will have on animal health and welfare, the high mortality and the culling of pigs on positive farms will lead to substantial economic losses for the farmers. Since it is to a large extent small-scale backyard farms that have been affected, this will likely have extensive impact on the income and livelihoods of the farmers and their families. Consequently, these farmers will likely run out of business and there are projections that there will be a shift towards more large-scale pig farms that can afford better biosecurity measures.

The pig industry in affected countries will also suffer the consequences, not only through direct economic losses from deceased pigs, but also through stricter legislation on trade and export of pigs and pork. For example, the pig industry in Vietnam is of great economic importance for the country’s economy and depends to a large extent on the export of products to China and other countries in the region. However, not all changes will be bad. For example, the prospective ban on long-distance transport of live pigs, replaced by refrigerated transportation of pork, will be a step towards better animal welfare. Also, the necessary improvements in biosecurity will likely lead to reduced incidence of diseases and better animal health and productivity.

It is not only the pig industry that is affected by the spread of African swine fever. The decreased supply and availability of pork may lead to increased prices on those products, thereby affecting consumers and retailers. There have been some reports on increased prices on both the European and U.S. markets as well, resulting from the increased demand for pork in China.

Containment of African swine fever might be difficult, especially on small-scale backyard farms with low biosecurity. Photo: Gunilla Ström Hallenberg, SLU.

Containing African swine fever in Asia might be an impossible task, given the high density of pig farms in many parts of the region and the high proportion of small-scale backyard farms with low biosecurity. Despite this, governmental authorities and different organisations are working hard to control and prevent the disease from spreading further. If they will be successful remains to be seen. However, one can definitely state that it has been a tough start for the Year of the Pig in Asia.

Read more about African swine fever and a SLU research project in Uganda

Restoring degraded tropical landscapes with trees

By: Aida Bargues Tobella, Postdoctor at the Department of Forest Ecology and Management; Tropical Forestry and Land Use Management Unit 

Land degradation is a major problem in the tropics. Such degradation entails a decline in the capacity of the land to produce and provide ecosystem goods and services, with negative impacts for human livelihoods, food security and the environment at large. 

Land degradation is a widespread phenomenon across the tropics. The Nyando River Basin (Western Kenya) is a regional erosion hotspot and one of the main sources of sediment and phosphorous into Lake Victoria. Photo: Aida Bargues Tobella

The establishment of trees on degraded lands is considered a fundamental tool in landscape restoration. Establishing trees is about more than just planting trees, and can include assisted natural regeneration (ANR) of forests, farmer-managed natural regeneration or direct seeding among other techniques. Similarly, the concept of landscape restoration is not limited to re-establishing lost forests and should be seen on a broader perspective, taking into consideration, for instance, the incorporation of trees into farming systems (agroforestry).

Faidherbia albida is a popular agroforestry tree which generates numerous provisioning and regulating ecosystem services. Photo: Aida Bargues Tobella

The potential benefits from tree-based restoration include enhanced water quality, biodiversity, carbon sequestration, soil fertility, and food and nutrition security. But, how much do we know about tree-based restoration? What are the trade-offs and synergies among ecosystem services from trees? What management practices and tree traits contribute most to promote specific ecosystem services? As we enter the UN Decade on Ecosystem Restoration, answering such questions is pressing. 

Sesbania sesban improved fallows have a great potential to restore soil fertility and increase crop yields. Photo: Aida Bargues Tobella

In the research group on Tropical Forestry and Land Use Management at the Department of Forest Ecology and Management in SLU, we work towards advancing our understanding of tree-based restoration of degraded landscapes in the tropics. Currently, we have projects in six countries across the global tropics: Malaysia, Thailand, Kenya, Burkina Faso, Tanzania and Mozambique.

We currently have on-going research projects in six different countries across the global tropics

Rainforest degradation and restoration

The group has been doing research on rainforest degradation and restoration in Borneo for over 35 years. The INIKEA Sow-a-Seed rainforest restoration project in the Malaysian state of Sabah is a collaboration between the Sabah Foundation, SLU and the Swedish furniture company IKEA andit is unique in that it is one of the largest and most successful tropical rainforest restoration projects in the world. Since the startof the project in 1998, we have planted more than three millionseedlings, consisting of ca. 80 different indigenous tree species, and roughly14,000 ha of forest have been restored with assisted natural regeneration and enrichment plantings. 

In connection with the project, we have established a number of scientific experiments: 

  • In the SUAS experiment, established already in 1992, we aim to develop silvicultural methods that make management of natural forests environmentally and economically sustainable.
  •  In our three different species/genetic common gardens we seek to advance the present lack of knowledge on the economic and environmental values of indigenous species. Here we also study the importance of genetic variation in traits within and among species.
  •  In the Rainforest Restoration Experiment,we have established 84 plots in various forest types to evaluate where each of our four different approaches of restoration is most appropriate; 1) Passive protection; 2) ANR; 3) ANR with line planting and 4) ANR with gap-cluster planting.
  • In our permanent sampling plots inside the restoration area and surrounding landscape of large-scale oil palm and industrial tree plantations as well as undisturbed protected forests, we are evaluating ecosystem values, such as economic value, carbon sequestration, water quality and biodiversity among these land-use systems. 

These long-term forest management experiments in northern Borneo provide many opportunities for research. In the project Balancing production and ecosystem services from degraded tropical rainforests to aid the transition to a more sustainable bio-based economy, we are using data from these experiments to quantifybiomass production and a range of ecosystem services across multiple spatial and temporal scales. Using a multi-disciplinary approach, including aspects of economics, social science, silviculture, plant ecophysiology, ecology, human health,and biogeochemistry, we aim to identify sustainable management practices that can maximize the production of raw materials while at the same time minimizing adverseenvironmental impacts. Using this holistic approach, the overall objective is to obtain and communicate novel information to scientists, private, and government stakeholders about trade-offs between biomass production and ecosystem services to aid the transition to a sustainable bio-based economy.

Rainforest vulnerability to climatic water stress

The frequency and intensity of drought events are predicted to increase in tropical monsoon forests of Southeast Asia, ecosystems that are known to be biodiversity hotspots and a persistent carbon sink in the global carbon cycle. Such increases could drive rapid and large-scale shifts in forest structure and species composition as well as cause dramatic decreases in the amount of carbon stored by these tropical forests. We have recently started a research project thatbrings together scientists from Thailand, France,and Sweden, to assess the vulnerability of mature and secondary forests to climatic water stress. Such information is crucial to more accurately predicted how future climate change wouldaffect the cycling of carbon and water in tropical forested ecosystems. 

Trees and water in African tropical drylands

Another leading research topic of the group is how we can use trees to improve soil and water resources in African tropical drylands. Our previous research in the seasonally dry tropics indicates that an intermediate tree cover can maximize groundwater recharge, which is contrary to the predominant scientific view that more trees always lead to less water. But, under what specific conditions can more trees improve groundwater recharge? Together with scientists from the World Agroforestry Centre (ICRAF), the Norwegian University of Life Sciences and Wageningen University, we are evaluating the extent of the optimum tree cover theoryacross African tropical drylands. To do this, we are primarily using data from the network of Land Degradation Surveillance Framework (LDSF) sites, which is hosted at ICRAF. To date, the LDSF has been employed in over 200 sites across the global tropics and therefore constitutes a unique dataset to test this theory. The overall aim of the project is to provide evidence to inform better land-use policies in African tropical drylands and identify management options that can increase groundwater resources. 

LDSF field campaing in Embu county, Kenya. Photo: Aida Bargues Tobella
LDSF field campaing in Makueni county, Kenya. Photo: Aida Bargues Tobella

Courses

Are you interested in these questios and want to learn more about tropical forestry and land-use management? At the moment we offer two courses within this field:

This year’s MSc course on Sustainable Forestry and Land-se Management in the tropics included a one- week field trip to Mozambique. Photo: Rosa Goodman
Participants of the course “Forest Management Forest Management, Land Use Change and Ecosystem Services in Degraded Tropical Landscapes” had the opportunity to visit the INIKEA Sow-a-Seed restoration project in northern Borneo. Photo: Niles Hasselquist

Who we are

Ulrik Ilstedt, associate professor; ulrik.ilstedt@slu.se
Gert Nyberg, associate professor; gert.nyberg@slu.se
Niles Hasselquist, associate professor; niles.hasselquist@slu.se
Rosa Goodman,associate senior lecturer; rosa.goodman@slu.se
Aida Bargues Tobella, postdoc;  aida.bargues.tobella@slu.se
Daniel Lussetti, postdoc; daniel.lusetti@slu.se