Zoonotic Diseases


Vaccinating chicks in Vietnam

Vaccinating chicks in Thuy Phuong province, Vietnam (photo credit: ILRI/Nguyen Ngoc Huyen).

Livestock production is beset by many challenges. Animal diseases, in particular, can lead to reduced production of milk, meat and eggs. In some cases, animal disease infections may result in death, leading to loss of livelihoods for livestock keepers.

Livestock in developing countries suffer a high burden of preventable disease, and this burden is likely to increase as livestock systems become more intensive. Antibiotics and other antimicrobial drugs are often used to treat animal disease infections.

However, authors of a study published in March 2015 in the Proceedings of the National Academy of Sciences of the United States of America (PNAS) warn that the use of antimicrobial drugs in livestock production could contribute to the spread of drug-resistant pathogens in both livestock and humans, posing a significant public health threat.

The study also projects that by the year 2030, global antimicrobial consumption will rise by 67% and nearly double in Brazil, China, India, Russia and South Africa.

In light of the global nature of the problem of antimicrobial resistance, the World Veterinary Association and the World Medical Association prioritized the topic during one of the sessions at their global conference on One Health held in Madrid, Spain on 21-22 May 2015. The conference was organized in collaboration with the Spanish medical and veterinary associations.

Over 300 delegates from 40 countries attended the conference which was aimed at achieving stronger collaboration between physicians, veterinarians and all relevant stakeholders to improve various aspects of the health and welfare of people, animals and the environment.

Delia Grace, veterinary epidemiologist and leader of the Food Safety and Zoonoses program of the International Livestock Research Institute (ILRI), attended the conference and presented on antimicrobial use in developing countries, highlighting some results from research by ILRI.

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The other conference sessions were on zoonotic diseases, natural disaster management, One Health in food production, and veterinary education of the One Health concept. More information is available in the conference report (PDF).

Orma Boran cattle crossing a river in Kenya

Orma Boran cattle crossing a river in Kenya (photo credit: ILRI/Rosemary Dolan).

The Dynamic Drivers of Disease in Africa Consortium is a research program that works to understand the relationships between ecosystems, zoonotic diseases, health and wellbeing in order to inform effective public health interventions.

Under this program, multidisciplinary country teams are studying four zoonotic diseases: henipavirus infection in Ghana, Lassa fever in Sierra Leone, Rift Valley fever in Kenya and trypanosomiasis in Zambia and Zimbabwe. The focus is on how changes in biodiversity, land use and climate affect disease transmission.

The development of irrigation schemes is thought to influence pathogen transmission in people and animals in several ways. For example, masses of stagnant water and high humidity support the development of disease vectors like mosquitoes. In addition, irrigated areas are likely to have a higher density of animal hosts like chicken and small ruminants.

In order to investigate the influence of irrigation and changes in biodiversity on the distribution of zoonoses, a cross-sectional study was carried out in Tana River County, Kenya, home to the Hola Irrigation Scheme. The zoonoses of interest were Rift Valley fever, Q fever, brucellosis, West Nile virus, dengue fever and leptospirosis.

Irrigation causes a decline in biodiversity as wildlife habitats are cleared to make way for crop agriculture. However, the linkages between biodiversity and disease risk remain unclear. It was also found that areas with a rich diversity of hosts have higher prevalence of multiple zoonotic pathogens as compared to areas with lower host diversity.

The study also found that while irrigated areas are infested with multiple species of mosquitoes (including primary vectors of Rift Valley fever), their high population densities alone are not enough to sustain the transmission of pathogens; reservoir hosts (for example, birds for West Nile virus) or other persistence mechanisms are required.

These and other findings from the study were presented at the 49th annual scientific conference of the Kenya Veterinary Association which was held in April 2015.

View the presentation, Land use, biodiversity changes and the risk of zoonotic diseases: Findings from a cross-sectional study in Tana River County, Kenya

Orma Boran cattle crossing a river in Kenya

Orma Boran cattle crossing a river in Kenya. Rift Valley fever can infect both cattle and people (photo credit: ILRI /Rosemary Dolan).

The International Livestock Research Institute (ILRI) has published a discussion paper on a study carried out to identify the successes and challenges associated with the use of a Rift Valley fever decision support tool in Kenya.

The decision support tool was developed by various stakeholders from government and non-government sectors following the 2006-07 outbreak of Rift Valley fever in East Africa. It identifies events leading to the disease outbreak and matches them with interventions that could be implemented at each point.

The study involved three activities:

  • a review of literature to describe systems that could be used with the decision support tool and to identify how other frameworks have been used to support disease control policies
  • focus group discussions and key informant interviews with farmer groups, local and international organizations and decision-makers in the Department of Veterinary Services
  • a stakeholder workshop to validate the findings obtained and develop recommendations on ways to improve awareness and utilization of the framework

Download the discussion paper

Citation
Mbotha, D. and Bett, B. 2015. Utilization of the Rift Valley fever decision support tool in Kenya: Successes and challenges. ILRI Discussion Paper 28. Nairobi, Kenya: ILRI.

Pork at the wet market

A local pork vendor at the wet market sells her meat to two local women, Hung Yen province, Vietnam (photo credit: ILRI/Nguyen Ngoc Huyen).

 

The 2014–2015 Global Food Policy Report launched last week (18 March 2015) by the International Food Policy Research Institute (IFPRI) examines the major food policy issues, developments and decisions around the world in 2014 and highlights challenges and opportunities for 2015.

An entire chapter has been dedicated to the subject of food safety which is a major global concern. The chapter titled Food safety: Reducing and managing food scares is authored by Delia Grace, leader of the Food Safety and Zoonoses program at the International Livestock Research Institute (ILRI), and John McDermott, director of the CGIAR Research Program on Agriculture and Health (A4NH) led by IFPRI.

The chapter begins with a review of the high-profile foodborne disease events that took place in 2014 as well as progress that has been made around the world to improve the management of infectious disease through better information, technology and institutions.

The complexity and diversity of food safety concerns in three ‘worlds’ – developed economies, least developed economies and emerging economies – are examined next.

The authors define developed economies as those where foodborne diseases are of high concern but impose relatively small health burdens. Least developed economies are those where foodborne diseases, although prevalent, are not among the highest priorities of public health officials. Emerging economies are those where foodborne diseases are both highly prevalent and highly prioritized.

The chapter also discusses other health impacts of agriculture such as antimicrobial resistance, which is emerging as a serious threat to human health. This is especially so in emerging economies, where large amounts of antibiotics are manufactured and used with minimal regulation or reporting.

“There is increasing consensus that resistance to antimicrobials of human importance has been generated in animals and has since spread to humans,” the authors note.

The chapter concludes with suggestions for better management of food safety, noting that food safety is a global public good and, as such, requires international cooperation and investment in safer agricultural and food systems.

Farming in the highlands of Ethiopia

Farming scene in the highlands of Ethiopia (photo credit: ILRI/Apollo Habtamu).

 

Zoonotic diseases, or zoonoses, are diseases that can be passed from animals to people. Nearly two-thirds of emerging infectious diseases affecting people are zoonotic and about 60% of all human pathogens are zoonotic.

Zoonoses such as brucellosis, anthrax and rabies are endemic in eastern Africa and yet formally published research studies on zoonoses in the region are hard to come by; useful research findings remain tucked away in the libraries of universities and other research institutions in form of working papers and students’ theses: the so-called ‘grey literature’.

In order to bring to the fore the wealth of unpublished research on zoonoses from studies carried out in Burundi, the Democratic Republic of the Congo, Ethiopia, Kenya, Rwanda, South Sudan, Tanzania and Uganda, the first-ever regional conference on zoonotic diseases in eastern Africa was held in Naivasha, Kenya on 9-12 March 2015.

The conference brought together academicians, researchers and graduate students from across Africa who presented on topics such as the One Health approach to disease prevention and control, the global health security agenda, the recent Ebola outbreak and its control, and control of rabies in East Africa.

Some 80 oral and poster presentations covered a wide range of aspects of research on zoonotic diseases including epidemiology, antimicrobial resistance, diagnosis, surveillance, outbreak investigations, disease modelling and foodborne zoonoses.

Bernard Bett, a veterinary epidemiologist at the International Livestock Research Institute (ILRI), gave a keynote presentation on behalf of the institute’s director general Jimmy Smith detailing how research by ILRI is contributing towards healthy people, animals and ecosystems.

Food insecurity remains a challenge for millions of people in the region. Animal-source foods can play a role in improving food and nutritional security, particularly in developing countries where demand for meat, milk and eggs is on the rise. Thus, food security is linked to the health of the livestock that produce these food products.

However, because of the threat of endemic and emerging zoonotic diseases, human health is influenced by animal health. Furthermore, changing patterns of land use, such as irrigation and intensified farming, can have an impact on the life cycles of vectors that spread diseases that affect both animals and people. Therefore, the impact of agriculture on ecosystem health also needs to be considered when tackling animal and human health challenges.

View the presentation “Healthy people, animals and ecosystems: The role of CGIAR research
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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).

Zoonoses account for 60% of human diseases, but traditional divisions between human, livestock and environmental health sectors undermine their control. This has led to calls for greater intersectoral cooperation through an approach known as One Health.

The cover story of the December 2014 – January 2015 issue of CTA’s Spore magazine focuses on the One Health approach to tackling zoonoses and highlights some examples of One Health research by the Food Safety and Zoonoses program at the International Livestock Research Institute (ILRI).

Read the Spore article, Together in sickness and health

The contribution of livestock to human and animal health was among the several topics discussed at a high-profile conference organized by the International Livestock Research Institute (ILRI) in Addis Ababa, Ethiopia on 6-7 November 2014. The theme of the conference was Livestock-based options for sustainable food and nutritional security, economic well-being and healthy lives.

The conference was the culmination of a series of events organized this year to mark 40 years of livestock research by ILRI and its predecessors, the International Laboratory for Research on Animal Diseases (ILRAD) and the International Livestock Centre for Africa (ILCA).

Discussions under the sub-theme of ‘livestock and healthy lives’ began on the morning of the first day of the conference with a featured talk by Lorne Babiuk, vice president for research at the University of Alberta on how healthy animals can improve the health, welfare and economy of people.

Lorne Babiuk, vice-president for research at the University of Alberta

Lorne Babiuk presents a featured talk titled Healthy animals equals healthy, productive people at the ILRI@40 conference held on 6-7 November 2014 in Addis Ababa, Ethiopia (photo credit: ILRI/Apollo Habtamu).

In his presentation, Babiuk noted that smallholder farmers dominate livestock production in many developing countries and globally, one billion poor people depend on livestock for their livelihoods.

However, despite the potential of smallholder livestock production to contribute to meeting the growing demand for animal protein in the developing world, the livestock sector is beset by several challenges such as emerging diseases and limited natural resources for raising livestock.

Zoonotic diseases, in particular, have impacts on international trade, food prices and human health.

Babiuk then discussed three biotechnology options that can be used to improve livestock production: vaccines, breeding and selection of disease-resistant animals, and marker-assisted management to produce better quality carcasses.

“Vaccination, in my opinion, has been one of the most cost-effective approaches for the management of infectious diseases,” he said.

“In fact, it’s been stated that vaccination has saved more lives than all other therapeutic interventions in the world.”

He also gave examples of how genetics can be used to improve productivity through classical breeding and selection and use of genomic tools.

Babiuk summed up his presentation by stating that increasing food security will become more critical as the world population increases and that “healthy animals equals healthy people equals healthy environment equals stable economic environments”.

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Continuing with the underlying theme of Babiuk’s talk, a roundtable discussion was held in the afternoon to examine the relationship between livestock, nutrition and health.

John McDermott, director of the CGIAR Research Program on Agriculture for Nutrition and Health, moderated the discussion. The panellists were Walter Masiga, the World Organisation for Animal Health sub-regional representative for eastern Africa; Juliana Rwelamira, managing director of Sasakawa Africa Association and Vish Nene, director of ILRI’s livestock vaccines initiative.

Vish Nene, Juliana Rwelamira and Walter Masiga, panelists at ILRI@40 roundtable discussion on livestock and healthy lives

Left to Right: Vish Nene (ILRI), Juliana Rwelamira (Sasakawa Africa Association) and Walter Masiga (World Organisation for Animal Health) take part in a roundtable discussion on livestock and healthy lives at the ILRI@40 Addis Ababa conference (photo credit: ILRI/Apollo Habtamu).

McDermott began with an overview of the controversial and somewhat counterintuitive role of livestock in nutrition.

He noted that while animal-source foods are important sources of nutrition for poor people in low-income countries, there is underconsumption of livestock products by the poor on account of the high price of meat, milk and eggs relative to that of cereals.

On the other hand, overconsumption of livestock products in high-and middle-income countries has led to an increase in cases of obesity and related non-communicable diseases, a trend that is starting to emerge in low-income countries as well.

McDermott also noted that while meat, milk and eggs are good sources of vital nutrients, there are considerable health risks associated with livestock and livestock products.

“The most nutritious foods are also the most risky. You’re not going to get very sick eating rice as compared to eating spoiled milk or meat,” he said.

Intensification of agriculture to increase the supply of livestock is also associated with environmental contamination and increase of microbial populations, he added, noting that three-quarters of emerging diseases are zoonotic.

The roundtable discussion sought to link the economic development agenda of the livestock sector with issues related to health and nutrition.

Among the topics discussed were the One Health approach for more effective control of emerging diseases; vaccines and diagnostics; value chain development to reduce postharvest food losses and improve food safety and nutritional quality; risk-based approaches to food safety in informal markets and strengthening of national control systems to prevent misuse of antibiotics in treatment of animals.

The outcomes of the discussions on livestock and health on the first day of the conference fed into a parallel session on the second day. The aim of the session was to look into the future to identify the key priority areas for research on livestock and health in the next 40 years.

About 20 participants, mostly veterinary practitioners, took part in the parallel session on livestock and healthy lives which began with three scene-setting PowerPoint presentations and one poster presentation by scientists from ILRI’s Food Safety and Zoonoses program:

Following the presentations, the participants split into three groups for an in-depth discussion of the identified priority areas for research on livestock and health in the next 40 years. The discussions were based on their individual experiences, the content of the three presentations and current global trends in animal and human health.

They identified the following three priority areas for research on livestock and health:

  • emerging infectious diseases;
  • vaccines and diagnostics; and
  • antimicrobial residues and resistance.

Research on emerging infectious diseases needs to focus on increased understanding of the drivers of disease, for example, agricultural intensification, climate change, new farming systems, irrigation and increased mobility of animals and people. Research activities could include mapping, modelling and analysis of vectors; vector control through the use of ‘green’ insecticides; biological control of vectors and adoption of the Ecohealth approach to disease prevention and control.

Research on vaccines should be aimed at developing safe, single-dose, affordable ‘combination’ vaccines that are easy to deliver and target multiple pathogens. Rapid diagnostics that can be used along the food chain and are linked into large databases for surveillance can provide early warning systems for quick detection and reporting of potential health hazards and timely intervention.

Research on antibiotic residues and resistance needs to ensure prudent use of antimicrobials for treatment of farm animals to avoid residues in animal-source food products. The transfer of antibiotic resistance from animals to milk, meat and eggs was also identified as an important research area.

Dieter Schillinger

Dieter Schillinger leads a group discussion on antimicrobial residues and resistance as a priority area for research on livestock and healthy lives (photo credit: ILRI/Apollo Habtamu).

The group summed up the vision of ILRI’s livestock-for-health research in the next 40 years as follows:

ILRI research has contributed to appropriate health management systems leading to healthy animals, people and ecosystems and increase animal-source food and income for all’.

Rift Valley fever, a viral disease that is endemic in sub-Saharan Africa, Saudi Arabia and Yemen, causes abortion and stillbirth in livestock and can cause serious conditions such as haemorrhagic fever and encephalitis in humans.

Download a brief that illustrates how scientists at the International Livestock Research Institute (ILRI) are working to identify key drivers for Rift Valley fever occurrence and transmission, and develop decision support tools to guide responses at various stages of the epidemic cycle of the disease.

Developed after the last devastating Rift Valley fever outbreak in Kenya in 2006-07, these research outputs are designed to enable decision-makers to take timely, evidence-based decisions to prevent and control future epidemics and reduce their impacts.

In particular, the Government of Kenya has incorporated the decision support tool in its Rift Valley fever contingency plan and local governments in the country regularly use outputs from ILRI’s work to assess their level of preparedness.

 

Annie Cook is a graduate fellow at the International Livestock Research Institute in Kenya. In this blog post she describes a day in the life of her PhD project.

“I am a veterinary epidemiologist which means I investigate the behaviour of diseases in animal populations. I am particularly interested in zoonoses: diseases that pass from animals to people.”

“The research project I am conducting was requested by the community. During a previous study that looked at zoonotic diseases in pigs at slaughter, our research group was asked to develop a project examining disease in the workers themselves. The workers wanted to know the occupational risks they faced at work.”

Read the full post on the CGIAR Development Dialogues blog

Agriculture imposes large burdens on human health. Three million deaths a year and one-quarter of all deaths from infection are agriculture-associated, and almost all of these occur in developing countries.

Zoonotic and food-borne diseases kill 2.2 million people and sicken 2.4 billion people annually; poor people are most affected by these diseases. For 70% of agriculture-associated diseases, proven and cost-effective agricultural solutions exist.

The presentation below, made at the Tropentag 2014 conference, gives an overview of the global burden of zoonotic and food-borne diseases and some research-based interventions that can be used to prevent and control these diseases.

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Healthy lives: Tackling food-borne diseases and zoonoses

This week, ILRI staff are participating in the Tropentag 2014 International Conference in Prague, Czech Republic (17-19 September 2014). There is also a dedicated ILRI@40 side event on livestock-based options for sustainable food and nutritional security and healthy lives.  See all the posters.

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