Zoonotic Diseases


Live chicken vendor

Live chicken on sale in Hung Yen province, Vietnam (photo credit: ILRI/Nguyen Ngoc Huyen).

Can we predict the next global pandemic? How can we ensure that we are prepared to tackle the next global disease epidemic?

Ten years after the SARS pandemic, Alok Jha, a science correspondent at The Guardian, examines a new human-animal virus surveillance project in Vietnam as part of his investigation into the possibility of predicting the next global pandemic.

Read his article in The Guardian: A deadly disease could travel at jet speed around the world. How do we stop it in time?

Listen to his science documentary on BBC Radio 4: The Next Global Killer

Orma Boran cattle crossing a river in Kenya

Orma Boran cattle crossing a river in Kenya. A new research update by the Drivers of Disease in Africa Consortium offers insights into the drivers of Rift Valley fever in Kenya (photo credit: ILRI/R. Dolan)

The Dynamic Drivers of Disease in Africa Consortium has published five situation analysis research updates, one for each of its case study countries. Each update outlines the background to the case study disease being investigated, the key questions the research team is exploring, some of the knowns and unknowns, and the research methodologies being followed.

Bernard Bett, a veterinary epidemiologist at the International Livestock Research Institute (ILRI) is the leader of the Kenya team that is exploring the drivers of Rift Valley fever in Kenya.

The updates are available for download from the links below (PDF):

A new 3-minute video presents an overview of the work that the International Livestock Research Institute (ILRI) is doing towards the prevention and control of agriculture-associated diseases.

This is one of the key themes of the CGIAR Research Program on Agriculture for Nutrition and Health, which is led by the International Food Policy Research Institute (IFPRI).

This CGIAR Research Program was started in 2012 to investigate the links between agriculture, nutrition and health in poor nations.

The program aims at improving the nutritional and health benefits of the farming sector while mitigating the risks posed by diseases that are spread through food and water, as well as those that can be passed from animals to people (zoonotic diseases).

In addition to a focus on agriculture-associated diseases, it also carries out research on food value chains, biofortification, and integrated development policies and programs on agriculture, nutrition and health.

View the video, The prevention and control of agriculture-associated diseases

The prevention and control of agriculture-associated diseases from FILM for SCIENCE in AGRICULTURE on Vimeo.

You are welcome to share this video with research colleagues and partners or embed it in your PowerPoint/Prezi presentations on agriculture, nutrition, health and food safety.

Smallholder pig production in northern Viet Nam

Farmer Ma Thi Puong feeds her pigs on her farm near the northern town of Meo Vac, Vietnam. Intensification of livestock farming has been found to increase the risk of zoonotic disease transmission (photo credit: ILRI/Stevie Mann).

Modern farming practices, such as intensified livestock production, as well as environmental and biodiversity changes can be linked to the new wave of zoonotic diseases, according to a new study published in the 21 May 2013 edition of the Proceedings of the National Academy of Sciences (PNAS).

Human population growth and the expansion of agriculture to meet the ever-rising demand for food have been identified as the key drivers of recent outbreaks of emerging and re-emerging zoonotic diseases.

These human behavioural changes have led to encroachment of wildlife habitats, resulting in greater interactions between people, livestock and wildlife and increased chances of spillover of potential pathogens from wildlife to livestock and, consequently, people.

“Intensive livestock farming, especially of pigs and poultry, increases the risk of disease transmission due to increased population size and density,” the study reveals.

Environmental changes arising from settlement and agriculture, including land fragmentation, deforestation and replacement of natural vegetation with crops, alter the structure of wildlife population, giving rise to new environmental conditions that favour specific hosts, vectors and pathogens.

The study was carried out in form of a systematic review by a multidisciplinary team of researchers from the International Livestock Research Institute (ILRI) and the Royal Veterinary College, University of London.

The research team sought to analyze qualitatively scientific evidence on the effect of agricultural intensification and environmental change on the risk of zoonoses transmission at the interface of humans, livestock and wildlife.

While the study has identified a clear link between the threat of zoonotic disease and the wildlife-livestock interface, it does not adequately address the complex interactions between the environmental, social and biological drivers of pathogen emergence.

For this reason, there is need to carry out local interdisciplinary studies that can come up with locally relevant solutions to tackle the threat of emerging and re-emerging zoonoses, the authors conclude.

Delia Grace, veterinary epidemiologist and food safety expert at ILRI, is among the co-authors of the study. Grace also leads the agriculture-associated diseases theme of the CGIAR Research Program on Agriculture for Nutrition and Health.

Read the full-text article

Citation: Jones BA, Grace D, Kock R, Alonso S, Rushton J, Said MY, McKeever D, Mutua F, Young J, McDermott J and Pfeiffer DU. 2013. Zoonosis emergence linked to agricultural intensification and environmental change. Proceedings of the National Academy of Sciences of the United States of America (PNAS) 110(21): 8399-8404.

Delia Grace, food safety specialist at the International Livestock Research Institute (ILRI), is cited in this feature article on urban livestock farming and zoonoses in Dagoretti, Nairobi.

Research by Grace and colleagues found that peer pressure and targeted messages on hygienic livestock keeping work better to control the spread of cryptosporidiosis than banning the keeping of animals.

ILRI Clippings

Meat Store in Kawangware Slum

Butcher shop in a slum in Kawangare, Nairobi, Kenya (picture on Flickr by Brad Ruggles).

It’s not only people who are rapidly urbanizing in Africa: people migrating from rural areas are bringing their livelihoods with them, which in Africa largely means their cattle, goats, sheep, chickens and pigs. A scientific report from researchers based in Nairobi, Kenya, investigating the benefits and harms of livestock keeping in two of Africa’s most crowded and sprawling cities —Nairobi and Ibadan — recommends that people ‘keep on keeping cows’ but keep them more carefully so as to reduce the risk of diseases being transmitted from livestock to people.

Importantly, the study also finds that  peer pressure — not health codes — is the answer to more careful management of the growing livestock enterprises in Africa’s slums and urban centres.

The Atlantic, one of North America’s most popular and distinguished cultural and political magazines, explores this…

View original post 652 more words

Typical mixed crop-livestock farming of western Kenya

Typical mixed crop-livestock farming of western Kenya. Many smallholder farmers in western Kenya are taking advantage of the growing demand for pork to keep free-ranging pigs as a commercial enterprise (photo credit: ILRI/Pye-Smith).

Many people are familiar with the use of global positioning system (GPS) technology as a security measure to track the movement of vehicles, mobile phones and sophisticated high-tech gadgets and assets.

But researchers at the University of Edinburgh and the International Livestock Research Institute are using GPS technology to track the movement of a different kind of asset that, though not motorized or electronic, is nonetheless of great value to resource-poor farmers in rural western Kenya: free-ranging domestic pigs.

In western Kenya, as in many parts of the developing world, rural households keep pigs under extensive, low-input systems where the animals are left free to roam and scavenge food outside the homestead.

Such low capital investment production systems enable smallholder farmers to benefit from pig production by taking advantage of the growing demand for pork, especially in urban areas.

It is well known that irrespective of the production system under which they are kept, pigs can be the host of a variety of disease-causing microorganisms.

However, pigs that are left to roam freely and scavenge food have a much higher risk of picking up diseases and infections like the pork tapeworm and African swine fever and passing them on to other domestic and wild animals as well as to people.

Understanding the movement patterns of free-ranging pigs in a rural setting can help animal health researchers develop effective disease control policies for smallholder pig production systems, based on a better understanding of the patterns of disease transmission within populations of free range pigs.

The results of a year-long pig tracking study carried out in Busia, western Kenya between March 2011 and February 2012 are now available in the March 2013 issue of the open access journal BMC Veterinary Research.

The pigs were fitted with GPS collars that tracked their movements and recorded their location coordinates every 3 minutes for one week. The location data were then transmitted to a central GPS server for analysis. Blood samples were also collected from the pigs to check for infection with gastrointestinal parasites.

“This is the first study to use GPS technology to collect data on the home range of domestic pigs kept under a free range system and the data will give us new insights into the behaviour of free-ranging pigs in a resource-poor setting,” the authors say.

The study found that the free-ranging pigs spent almost half their time outside their homestead of origin, travelling an average of 4,340 metres in a 12 hour period.

This result shows that with respect to pathogen transmission, the village environment beyond the farm matters just as much as the environment on the farm itself.

In addition, the researchers found that free range domestic pigs spend a lot of energy while foraging and this reduced their potential for weight gain and economic benefit to their owners.

This is because the sale price is normally pegged on the live weight of the pigs: a heavier pig translates into more cash for the farmer.

“The movement data can also be combined with information on ration formulation and daily weight gain to provide farmers with advice on how to change their animal husbandry practices to improve the profitability of pig production,” the authors conclude.

Read the abstract here

Citation: Thomas LF, de Glanville WA, Cook EA and Fèvre EM. 2013. The spatial ecology of free-ranging domestic pigs (Sus scrofa) in western Kenya. BMC Veterinary Research 9: 46. doi:10.1186/1746-6148-9-46

Find out more about the Zoonotic and Emerging Diseases Research Group which is led by co-author Eric Fèvre.

Live chicken vendor in Vietnam

A live chicken vendor weighs a chicken in Hung Yen province, Vietnam (photo credit: ILRI/Nguyen Ngoc Huyen).

The experiences of the International Livestock Research Institute (ILRI) in using One Health and EcoHealth approaches to better manage emerging zoonoses were featured during a poster session at the 2013 Prince Mahidol Award Conference that was held in Bangkok, Thailand from 29 January to 2 February 2013. The theme of the conference was: “A world united against infectious diseases: Cross-sectoral solutions”.

ILRI scientists Jeffrey Gilbert and Rainer Assé presented two research posters from the project, Ecosystem approaches to the better management of zoonotic emerging infectious diseases in the Southeast Asia Region.

The project works with trans-disciplinary teams from governments, non-governmental organizations and universities in Cambodia, China, Indonesia, Laos, Thailand and Vietnam to increase the capacity of researchers and animal disease control personnel to understand the risks and impacts of zoonotic emerging infectious diseases and best practice options to better manage the diseases.

View the posters below.

The added value of an ecohealth approach for the prevention and control of emerging zoonotic diseases by Jeffrey Gilbert

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Examining the socioecology of zoonotic diseases: Ecohealth experiences in Southeast Asia by Rainer Assé, Korapin Tohtubtiang, Jeffrey Gilbert and Delia Grace

Poultry seller in a 'wet market' in Indonesia

A woman sells live ducklings in a ‘wet market’ in Indonesia (photo credit: ILRI/Christine Jost).

On 10–11 January 2013, over 50 international experts from science, policy, the media and academia met at Sussex University for a workshop to discuss what recent controversies can teach us about possible future responses to pandemic influenza outbreaks.

The workshop, convened by the Economic & Social Research Council STEPS Centre and the Centre for Global Health Policy, examined in depth why controversies have emerged around pandemic flu, in order to inform future approaches.

Veterinary epidemiologist Jeff Mariner represented the International Livestock Research Institute (ILRI) at the workshop as an invited panellist speaking on experiences with participatory surveillance in control of highly pathogenic avian influenza (HPAI).

Mariner said that HPAI has largely settled down to become endemic in those countries with dense and complex poultry populations and faded out from countries that were not very well suited to sustained transmission.

“The HPAI control programs had little impact in changing the epidemiological course of evolution of the epidemic, and the response to HPAI to large extent ignored key lessons from previous successful disease control activities,” he observed.

“The emergency response approach led investments to have limited sustained impact as they did not address the fundamental institutional issues and the limited capacity of host-country services to absorb the large amounts of money allocated,” he added.

In conclusion, Mariner proposed that in the future, pandemic preparedness should focus on long-term capacity building rather than short-term emergency responses.

Access the workshop report here

Cattle herded home in the evening in Mozambique

Cattle coming in from the fields in the evening in Lhate Village, Chokwe, Mozambique (photo credit: ILRI/Stevie Mann).

A group of research experts associated with the Dynamic Drivers of Disease in Africa Consortium have called for a system-based ‘One Health’ approach to help catalyze better preparedness and surveillance that are informed by cross-disciplinary approaches.

One Health is a globally recognised approach established to promote the collaborative effort of multiple disciplines, working locally, nationally and globally, to attain optimal health for people, animals and the environment.

Writing in an Institute of Development Studies (IDS) Rapid Response Briefing titled Zoonoses – From Panic to Planning (January 2013), the researchers also note that One Health could help “accelerate research discoveries, enhance the efficacy of response and prevention efforts, and improve education and care”.

However, realigning policy to embrace One Health requires a shift in focus from the current disease-centred approach to one that considers the whole system and takes into account human health, animal health and ecosystems.

Over two-thirds of all human infectious diseases have their origins in animals. The rate at which these zoonotic diseases have appeared in people has increased over the past 40 years, with at least 43 newly identified outbreaks since 2004. In 2012, outbreaks included Ebola in Uganda, yellow fever in the Democratic Republic of Congo and Rift Valley fever in Mauritania.

Zoonotic diseases have a huge impact – and a disproportionate one on the poorest people in the poorest countries. In low-income countries, 20% of human sickness and death is due to zoonoses. Poor people suffer further when development implications are not factored into disease planning and response strategies.

A new, integrated ‘One Health’ approach to zoonoses that moves away from top-down disease-focused intervention is urgently needed. With this, we can put people first by factoring development implications into disease preparation and response strategies – and so move from panic to planning.

The briefing is lead authored by Delia Grace, veterinary epidemiologist and food safety expert at the International Livestock Research Institute (ILRI). She leads ILRI’s research team on animal health, food safety and zoonoses as well as a research component on prevention and control of agriculture-associated diseases under the CGIAR Research Program on Agriculture for Nutrition and Health.

Citation: Grace D, Holley C, Jones K, Leach M, Marks N, Scoones I, Welburn S and Wood J. 2013. Zoonoses – From panic to planning. IDS Rapid Response Briefing 2. IDS (Institute of Development Studies), Brighton, UK.

Maasai father and son tend to their cattle in Kenya

Maasai father and son tend to their cattle in their paddock in Kitengela, Kenya (photo credit: ILRI/Stevie Mann).

Brucellosis, also referred to as undulant fever, is a highly contagious zoonotic disease caused by the microorganism Brucella which infects multiple animal species including cattle, sheep, pigs, small ruminants, camels, water buffaloes and yaks.

Brucellosis affects both humans and animals, causing chronic fever and joint and muscle pain in humans and abortion in animals.

Cases of brucellosis in humans are often linked to consumption of unpasteurized milk and soft cheese made from the milk of infected cows.

Brucella infection in some developing countries can reach 30% of the human population, making it a serious public health disease.

In response to the problem of this disease in Africa, some 60 animal health experts from across Africa, the United States and other countries gather in Addis Ababa, Ethiopia from 29 to 31 January 2013 for a workshop to discuss an integrated approach to controlling brucellosis.

The workshop aims to identify gaps in brucellosis epidemiology, diagnosis, surveillance and control programs.

This will assist in designing research programs and intervention strategies to aid in the control of brucellosis at national and regional levels.

Specific topics that will be addressed include:

  • Transmission of infection from animals to humans
  • Laboratory biosafety practices
  • Diagnostics assays, serology and organism identification
  • Vaccination strategies
  • Potential research collaborations

The workshop is co-organized by the Agricultural Research Service of the United States Department of Agriculture (USDA-ARS), the International Livestock Research Institute (ILRI) and the United States Agency for International Development (USAID).

It is sponsored by the US Department of State Biosecurity Engagement Program.

ILRI scientists Delia Grace, Eric Fèvre and Roger Pellé will attend the workshop.

Additional information is available on the USDA-ARS website

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