Zoonotic Diseases


A pastor and his dog, Yabello, Ethiopia (photo credit: ILRI/Camille Hanotte).

World Zoonoses Day is commemorated on 6 July every year to mark the day in 1885 when Louis Pasteur successfully administered the first vaccine against rabies, a deadly zoonotic disease. The day is also an occasion to raise awareness of the risk of zoonoses, infectious diseases that can be spread between animals and people.

On this year’s World Zoonoses Day, we highlight a new research study published in PLOS Neglected Tropical Diseases (July 2020) that reports on the development, implementation and effectiveness of grassroots mass dog vaccination campaigns against rabies conducted in 2015, 2016 and 2017 in Laikipia County, Kenya.

According to the World Health Organization, rabies kills tens of thousands of people every year, mainly in Asia and Africa. Globally, rabies causes an estimated cost of US$ 8.6 billion per year. Dog bites are responsible for 99% of all cases of human rabies. Therefore, vaccinating dogs is the most cost-effective way to prevent rabies in people.

The research study found that while grassroots volunteer-based dog vaccination campaigns against rabies can be useful, these efforts need to be supported at a larger scale by county and national governments for a more sustainable approach towards eradicating the disease. Below is the author summary.

“Given the importance of mass vaccinations of domestic dogs towards eliminating human rabies in Africa and the site-specific challenges facing such campaigns, additional studies on the development and implementation of such efforts are needed.

One mechanism of mass vaccination lies in grassroots efforts that often begin at a very local scale and either develop into larger campaigns, remain local, or cease to persist past several years once interest and funding is exhausted.

Here, we discuss the development of a grassroots campaign in Laikipia County, Kenya from its local inception to its development into a county-wide rabies elimination effort.

Our results highlight challenges associated with achieving the targeted 70% coverage rate, including a need for consistent and systematic demographic monitoring of dog populations, limitations of the central point method, and logistical and financial challenges facing a volunteer-based effort.

Serious political commitment from both the local and national governments are necessary to take the budget beyond what a crowdfunded campaign can raise, including availability and access to quality dog rabies vaccines.

Without such outside support and substantial time to grow, grassroots campaigns might be better relegated to raising awareness and vaccinating dogs in small communities to protect those communities directly, without contributing to the broader ecosystem-wide transmission-stopping aim often sought by government human health and veterinary organizations.”

Citation

Ferguson, A.W., Muloi, D., Ngatia, D.K., Kiongo, W., Kimuyu, D.M., Webala, P.W., Olum, M.O., Muturi, M., Thumbi, S.M., Woodroffe, R., Murugi, L., Fèvre, E.M., Murray, S. and Martins, D.J. 2020. Volunteer based approach to dog vaccination campaigns to eliminate human rabies: Lessons from Laikipia County, Kenya. PLOS Neglected Tropical Diseases 14(7): e0008260.

Pastoralism

A gender-inclusive approach to community livestock vaccination can help address the different barriers faced by men and women farmers and may increase the uptake of livestock vaccines

Scientists at the International Livestock Research Institute (ILRI) recently published a study on the uptake of the Rift Valley fever vaccine in Kenya and Uganda, incorporating gender in their analysis to better understand the different barriers that men and women farmers face in adopting and using livestock vaccines.

The barriers include the cost of vaccines, long distances to vaccination points, lack of information on vaccination campaigns and decision-making processes at the household level. Understanding these barriers can help veterinary workers design more effective community livestock vaccination programs of benefit to both men and women farmers.

‘Conducting gender analysis on livestock vaccine interventions can enable implementers to identify generic and gender-specific needs of their target beneficiaries’, says Edna Mutua, the lead author of the study and gender consultant at ILRI.

‘This will allow the use of the findings to inform the design and delivery of vaccination interventions to increase efficiency and uptake’, she adds.

Rift Valley fever is a viral, mosquito-borne zoonotic disease that affects cattle, sheep, goats and camels. It causes abortions in livestock and flu-like illness in humans. People can get infected through contact with secretions or tissue of infected animals.

Rift Valley fever is endemic in East Africa and its impacts are significant. An outbreak of the disease in Kenya in 2006–07 caused 150 human deaths and led to losses of USD 32 million from livestock deaths, reduced animal productivity and trade bans on livestock and livestock products.

Vaccination of livestock is currently the most effective measure to control the disease. Previous research on Rift Valley fever vaccines have tended to focus on the production, safety and efficacy of the vaccines. Very few studies have been carried out on the uptake and adoption of livestock vaccines and most of these did not include gender in the study design and analysis but treated male and female livestock farmers as a homogeneous group.

This new ILRI-led study, published in the journal Vaccines (August 2019), provides useful insights into how prevailing gender dynamics in communities such as the division of roles and responsibilities in farmers’ households can influence the uptake and adoption of livestock vaccines.

Uptake was defined as the process the farmers take from when they receive livestock vaccination information to consenting to have their animals vaccinated and presenting the animals for vaccination. Adoption was defined as the continuous use of the vaccine when needed, even without the intervention of veterinary departments.

The study was carried out in Kwale and Murang’a counties in Kenya and Arua and Ibanda districts in Uganda. Data were collected through 58 focus group discussions (30 in Kenya and 28 in Uganda), with 8–12 discussants per group, selected based on whether or not livestock were vaccinated during recent outbreaks of Rift Valley fever.

To incorporate gender into the study design, in each country, half of the focus groups comprised men only and the other half women only. This gender disaggregation enabled the research team to collect data from the different gender groups across all four study locations.

The researchers found that men and women farmers faced different barriers in accessing and using livestock vaccines and that these constraints were influenced by socio-cultural and economic contexts and location.

For all focus groups across the four locations, the farmers ranked the top three barriers to the uptake of livestock vaccines as the cost of vaccines, limited access to information on vaccination and the side effects of the vaccines. However, including the gender and locational differences in the analysis brought forth a clearer picture of which group was most affected by which constraint.

Women in one region, for example, cited the cost of vaccines as the key challenge while women in another cited the limited information available on vaccination campaigns. In one region, the cultural dynamics around livestock ownership were paramount; in another, the long distances the women had to walk their animals to access the vaccination points was key.

The general lesson, however, was the same: ‘Provision of livestock vaccines by veterinary departments does not always guarantee uptake by men and women farmers’, lead author Edna Mutua notes.

Mutua is optimistic that veterinary authorities in Kenya and Uganda will use the research findings to design more effective community vaccination campaigns to prevent and control Rift Valley fever.

‘My hope is that this study serves as an eye-opener to veterinary departments in Kenya and Uganda on the need to integrate gender analysis into their livestock vaccine programs’, she says. ‘Optimizing vaccine uptake requires us to have a better understanding of the local contexts and constraints within which male and female farmers operate’.

This article by Tezira Lore was first published in the ILRI 2019 Annual Report.

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

Amid the COVID-19 pandemic that has focused global attention on the interconnectedness of people, animals and the environment and how this links to the spread of zoonotic diseases, two postdoctoral scientists affiliated with the International Livestock Research Institute (ILRI) are among five recipients of this year’s Soulsby Fellowships, awarded to support early career researchers in human or veterinary medicine working on One Health projects. 

One Health can be defined as the collaborative efforts of multiple disciplines working locally, nationally and globally to attain optimal health for people, animals and the environment.

The two postdoctoral scientists, Lisa Cavalerie from the University of Liverpool and Mark Nanyingi from the University of Liverpool and the University of Nairobi, are collaborators in the One Health Regional Network for the Horn of Africa project, a multidisciplinary international partnership that is working to improve the health and wealth of people in the Horn of Africa through One Health research.

Lisa Cavalerie, a veterinary epidemiologist, will study the benefits and risks of livestock ownership to maternal health in women in Ethiopia. She says: ‘The aim of the study will be to develop sustainable livestock health management to improve both maternal and child health.’

Mark Nanyingi, an infectious disease epidemiologist, will investigate the presence of Rift Valley fever virus in people, livestock and mosquitoes in Kenya. He aims to develop a human-animal integrated surveillance system which will inform national policy- and decision-making in the event of outbreaks. ‘This study will enhance our understanding of the geographical risk, distribution and genetic diversity of the virus,’ says Nanyingi.

We congratulate them on their awards and wish them all the best as they undertake their research projects.

Read more about the Soulsby Foundation and the other 2020 Soulsby Fellows.

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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