Zoonotic Diseases


Cows walk along an irrigation canal in Niolo, Mali (photo credit: ILRI/Stevie Mann).

As part of a special COVID-19 series by the International Food Policy Research Institute (IFPRI), Bernard Bett and Delia Randolph of the International Livestock Research Institute (ILRI) and John McDermott of IFPRI write on the growing risk in Africa of pathogens that spread from animals to people and how we can learn from past epidemics to improve preparedness and response.

In their article, the scientists discuss the evolving patterns of emergence and spread of zoonotic pathogens, factors that might influence the spread of emerging zoonotic pathogens and the opportunities for controlling emerging infectious diseases in Africa. 

They write: “The record thus far on COVID-19 and on past disease outbreaks shows that early, effective and sustained response is essential to winning the battle over these diseases. Innovative use of information and communication tools and platforms and engagement of local communities are crucial to improved disease surveillance and effective response. Building these systems requires demand from the public and commitment from policymakers and investors.” 

Read the full article, Africa’s growing risk of diseases that spread from animals to people, originally posted on the IFPRI website.

Bernard Bett is a senior scientist with ILRI’s Animal and Human Health program, Delia Randolph is the co-leader of ILRI’s Animal and Human Health program and John McDermott is the director of the CGIAR Research Program on Agriculture for Nutrition and Health. The analysis and opinions expressed in the article are of the authors alone.

Borana women with sheep and goats at a traditional deep well water source, Garba Tulla, Isiolo, Kenya (photo credit: ILRI/Fiona Flintan).

Brucellosis is an important zoonotic disease that affects wildlife and livestock. People may get exposed to the disease through direct contact with an infected animal or consumption of raw or undercooked animal products. In humans, the disease is characterized by prolonged fever, body aches, joint pains and weakness, while in livestock, it mainly causes abortions and infertility. 

A study carried out in Garissa and Tana River counties of Kenya set out to identify the factors that affect the spread of brucellosis in people and livestock. Livestock and people from randomly selected households were recruited and serum samples were obtained and screened for Brucella antibodies to determine the level of exposure to Brucella spp. 

The study found that the chances of exposure to brucellosis in humans were at least three times higher in households that had at least one Brucella-seropositive animal compared to those that had none. 

This finding can be used to design risk-based surveillance systems for brucellosis, based on the locations of the primary cases of the disease, where each case of Brucella infection identified in livestock could signal potential locations of additional brucellosis cases in humans, and vice versa.

Citation

Kairu-Wanyoike, S., Nyamwaya, D., Wainaina, M., Lindahl, J., Ontiri, E., Bukachi, S., Njeru, I., Karanja, J., Sang, R., Grace, D. and Bett, B. 2019. Positive association between Brucella spp. seroprevalences in livestock and humans from a cross-sectional study in Garissa and Tana River Counties, Kenya. PLOS Neglected Tropical Diseases 13(10): e0007506.

Women waiting to fetch water as cattle drink from a water pan in Taita Taveta, Kenya (photo credit: ILRI/ Juliet Kariuki)

One Health Day is a global campaign marked annually on 3 November to bring attention to the need for a One Health approach to address the shared health threats at the human–animal–environment interface.

The International Livestock Research Institute (ILRI) carries out One Health research through its Animal and Human Health program which seeks to effectively manage or eliminate livestock, zoonotic and food-borne diseases through the generation and use of knowledge, technologies and products. 

We commemorate this year’s One Health Day by featuring a selection of the program’s recent research outputs on this important topic.

For more information, contact Delia Randolph (d.randolph@cgiar.org) or Vish Nene (v.nene@cgiar.org), co-leaders of ILRI’s Animal and Human Health program. 

Open Access logo

Open Access Week is celebrated globally every year during the last complete week of October. To mark Open Access Week 2019, we highlight some recent open access research articles authored and co-authored by scientists from the Animal and Human Health program of the International Livestock Research Institute (ILRI). 

The program seeks to effectively manage or eliminate livestock, zoonotic and foodborne diseases that matter to the poor through the generation and use of knowledge, technologies and products, leading to higher farmer incomes and better health and nutrition for consumers and livestock.

Read about our research on antimicrobial resistance, food safety, One Health and zoonotic diseases from this selection of peer-reviewed, open access journal articles published this year:

For more information, contact Delia Randolph (d.randolph@cgiar.org) or Vish Nene (v.nene@cgiar.org), co-leaders of ILRI’s Animal and Human Health program.

Taking sheep for disease testing in Bako, Ethiopia
Taking sheep for disease testing in Bako, Ethiopia (photo credit: ILRI/Barbara Wieland).

World Zoonoses Day is marked annually on 6 July to commemorate the day in 1885 when Louis Pasteur successfully administered the first vaccine against a zoonotic disease when he treated a young boy who had been mauled by a rabid dog. The day is also an opportunity to raise awareness of the risk of zoonoses, infectious diseases that are spread between animals and people. 

Scientists estimate that 60% of known infectious diseases in people and 75% of new or emerging infectious diseases in people are transmitted from animals. Neglected zoonoses associated with livestock, such as brucellosis and cysticercosis, impose a huge health burden on poor people and reduce the value of their livestock assets.

Through its Animal and Human Health program, the International Livestock Research Institute (ILRI) carries out research with national and international partners towards improving the control of zoonotic diseases through a range of tools and approaches such as risk mapping and risk targeting, modelling of zoonotic pandemics, decision-support tools and advice on vaccination strategies. The program also generates evidence for policymakers on the cost and impact of zoonoses and the benefits of their prevention.

Some of our collaborative research on zoonoses includes work on developing optimal vaccination strategies for Rift Valley fever in East Africa, studying the epidemiology, ecology and socio-economics of disease emergence in Nairobi and developing an effective surveillance program for zoonoses in livestock in Kenya.

For an in-depth look, listed below are some of our research publications on zoonoses:

For more information on ILRI’s research on zoonoses, contact Bernard Bett, senior scientist at ILRI (b.bett@cgiar.org) or Eric Fèvre, professor of veterinary infectious diseases, Institute of Infection and Global Health, University of Liverpool on joint appointment at ILRI (eric.fevre@liverpool.ac.uk).

Researchers entering sampling data (photo credit: Zoonoses and Emerging Diseases).

In the cities of developing nations, where unregulated antibiotic use is common and livestock jostle with people amid often unsanitary conditions, scientists have found a potentially troubling vector for the dissemination of antimicrobial resistant bacteria: wildlife.

The epidemiological study published in the June 2019 issue of the journal Lancet Planetary Health shows that urban wildlife in Nairobi carry a high burden of clinically relevant antimicrobial resistant bacteria. The research team included scientists from the International Livestock Research Institute (ILRI), the University of Liverpool and the Kenya Medical Research Institute, among other research institutions.

Antimicrobial resistance is an increasingly serious threat to public health. Through misuse and overuse of antibacterial medication, more and more of the bacterial diseases that were once easily treated with antibiotics have become drug-resistant; these new strains of old germs require expensive and prolonged treatment at best and at worst can be lethal.

The study deployed teams of veterinary, medical, environmental and wildlife personnel to sample 99 households randomly chosen from Nairobi’s socio-economically diverse neighbourhoods.

The study found higher diversity of antimicrobial resistance in livestock and the environment than humans and wildlife. Rodents and birds were significantly more likely to carry resistance to multiple drugs when exposed to human and livestock waste through poor management practices, a common feature of lower-income neighbourhoods.

“This paper shows that contamination of urban environments with antimicrobial resistance is a serious issue. This is not just specific to Nairobi but findings can be extrapolated to other cities in Africa,” said Eric Fèvre, a joint appointed scientist at ILRI and professor of veterinary infectious diseases at the University of Liverpool.

“We tend to think of antimicrobial resistance in primarily medical terms, of developing new drugs and better using old ones. But we need to take an ecological approach to addressing this threat. Urban cities can address this by better urban planning, better waste disposal, better livestock husbandry practices. This can go far toward disrupting antimicrobial resistance exchange between wildlife, livestock and humans,” said Fèvre.

The lead author of the study, James Hassell, said, “Although we found no evidence to suggest that antimicrobial resistance carried by urban wildlife poses a direct threat to human health, that these animals harbour high levels of resistance to drugs used in human and animal medicine is particularly worrisome. Since wildlife are not treated with antibiotics, this is indicative of how pervasive antimicrobial resistance is in urban environments. Species that move freely across cities and further afield could disseminate resistance acquired in urban areas more widely.”

“We cannot address the rise of antimicrobial resistance without focusing on the environmental, ecological and social settings in which humans exist,” said Hassell.

Citation

Hassell, J.M., Ward, M.J., Muloi, D., Bettridge, J.M., Robinson, T.P., Kariuki, S., Ogendo, A., Kiiru, J., Imboma, T., Kang’ethe, E.K., Öghren, E.M., Williams, N.J., Begon, M., Woolhouse, M.E.J. and Fèvre, E.M. 2019. Clinically relevant antimicrobial resistance at the wildlife–livestock–human interface in Nairobi: An epidemiological study. Lancet Planetary Health 3(6): e259–e269.

Cross-bred Pigs in Kiboga District, Uganda

Cross-bred Pigs in Kiboga District, Uganda (photo credit: ILRI/Kristina Roesel).

Today is International One Health Day, an occasion celebrated around the world every year on 3 November to bring global attention to the need for One Health interactions and for the world to ‘see them in action’.

To mark this day, we highlight a new discussion paper published by the International Livestock Research Institute (ILRI) that contributes towards a greater understanding of One Health from a largely overlooked social science perspective.

The report provides a summary of research conducted in 2016 in the peri-urban to urban pig value chain between Mukono District and Kampala in Uganda’s central region. Its focus is the zoonotic parasite Taenia solium, also referred to as the pork tapeworm, and cysticercosis, an infection with the larvae of T. solium. It highlights perceptions of T. solium and other pathogens associated with pigs as articulated by farmers, butchers, slaughterhouse workers, pork consumers and medical professionals.

Download the report, Pigs, people, pathogens: A qualitative analysis of the pig value chain in the central region of Uganda by Rebekah Thompson.

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