The COVID-19 pandemic has underscored the need to strengthen national surveillance systems to protect a globally connected world.
In low-income and middle-income countries, zoonotic disease surveillance has advanced considerably in the past two decades. However, surveillance efforts often prioritize urban and adjacent rural communities.
Communities in remote rural areas have had far less support despite having routine exposure to zoonotic diseases due to frequent contact with domestic and wild animals, and restricted access to health care. Limited disease surveillance in remote rural areas is a crucial gap in global health security.
Although this point has been made in the past, practical solutions on how to implement surveillance efficiently in these resource-limited and logistically challenging settings have yet to be discussed.
A new paper in Lancet Global Health (Apr 2022) highlights why investing in disease surveillance in remote rural areas of low-income and middle-income countries will benefit the global community and review current approaches.
Using semi-arid regions in Kenya as a case study, the authors’ viewpoint provides a practical approach by which surveillance in remote rural areas can be strengthened and integrated into existing systems.
The viewpoint represents a transition from simply highlighting the need for a more holistic approach to disease surveillance to a solid plan for how this outcome might be achieved.
There’s been widespread concern in Kenya over the shrinking of green spaces in Nairobi, the capital city. Most recently, there was uproar over the construction of a raised highway. This resulted in the felling of hundreds of trees, though protests managed to save the life of one 100-year-old fig tree.
It was also proposed that part of the highway run through Uhuru park – one of the city’s few recreational parks. Protests successfully diverted the highway to the park’s outskirts, but development still threatens the city’s few undeveloped spaces.
To give an idea of how much green space has already been lost, between 1976 and 2000, Nairobi’s forest cover went from 14% to 3%. Bushland cover, over the same period, was also reduced from 22% to 13%.
This will have an impact on the city’s wildlife and livestock. Nairobi, like other urban environments in the tropics, has an ecosystem that includes wildlife – such as birds, rodents, primates – and livestock such as cattle, goats, sheep and pigs. As green spaces are lost, native wildlife and bird species can dwindle and non-native species proliferate.
But very few studies explore how development affects wildlife and livestock in tropical cities. Recognising this gap, we explored the impact of a growing and changing urban environment on the wildlife and livestock that live with people in Nairobi from 2013 to 2018.
We found that, as land use in Nairobi transformed, there have been significant changes.
Competition between invasive and endemic species has grown, to the detriment of native biodiversity. Species – many of which play important roles in ecosystems such as fruit bats, primates and pollinators – are lost. And as the ecological landscape becomes less diverse, wildlife species that co-exist with humans – such as rats, scavenging and seed-eating birds (collectively known as synanthropes) – thrive, particularly in the poorer, most densely populated areas of Nairobi.
This is troubling because evidence suggests that synanthropes host more germs and could pass diseases on to people and make them sick. These are called “zoonotic diseases” and range from minor short-term illness to major life-changing illness and even death.
We could not assess the risk posed by zoonoses in Nairobi in our study. What we do know is that the city (and likely most other biodiverse, tropical cities) harbours all the ingredients for zoonotic spillover to occur between animals and people, particularly in the most densely populated areas.
Urban development policymakers must recognise that by shrinking green spaces, they increase the likelihood that people will catch zoonotic diseases. This is because species such as rodents proliferate.
Which species dominate, and where
We studied 99 household compounds – people’s houses and private land – across the city. These were selected to represent the different ways in which people interact with livestock and wildlife across the city. Households were stratified by people’s wealth, the types of livestock they kept and the ecological habitats in which they live.
Our data show that synanthropic species – like rats and insectivorous bats – dominate lower income, densely populated areas of the city. Here the synanthropes live in close quarters with poultry, pigs and small ruminants, such as goats and sheep.
We found that the decline in biodiversity – and subsequent colonisation by synanthropes – was driven by urban development. Trees and other forms of vegetation were replaced by man-made structures, removing the natural resources that most wildlife require to survive. Meanwhile, the resources (such as waste) on which synanthropes thrive increased.
As we argue in our paper, this kind of restructuring has important implications for the emergence of novel diseases at urban interfaces, which is why we used our research results to generate a set of testable hypotheses that explore the influence of urban change on microbial communities.
By testing the hypotheses we provide insights into how rapid urbanisation can generate interfaces for pathogen emergence, which should be targeted for surveillance.
Research done elsewhere shows that synanthropes – which thrive in disturbed environments with lower biodiversity – host more pathogens. And synanthropes seek resources provided by humans and their livestock, such as waste, which brings them into closer contact and increases opportunities for pathogens to cross between them.
For instance, our work in Nairobi shows that, as densities of humans and livestock increase, there is more sharing of antimicrobial resistance with wild birds.
Policy recommendations
Our findings have important implications for the public health and the sustainable planning and management of cities, particularly rapidly developing, biodiverse cities.
The high levels of competent disease carriers near humans is a huge risk to public health. The current response to COVID-19 has shown that the ability to limit the spread of a disease depends upon good public health infrastructure. Developing this infrastructure, while more studies are conducted to assess the risk of zoonotic disease transmission, is crucial.
Mitigating steps can be taken. One would be to maintain areas of forests, grasslands and clean waterways throughout the city. This would preserve and increase the wildlife biodiversity that competes with synanthropes, while also improving biosecurity within households, which could help moderate the presence of synanthropic species in urban centres.
It is, however, worth noting that some synanthropes, like insectivorous bats, help to control mosquito populations and agricultural pests in heavily urbanised environments. Eradicating them would not be advisable. Managing people’s interactions with synanthropes through smart urban planning – for example by removing resources on which synanthropes rely such as manure and rubbish from households – is best.
Our findings also raise important concerns about the social equality of urban development. The benefits of urban biodiversity and risks posed by human exposure to animal-borne diseases are not equally distributed. Currently equitable access to green spaces is restricted in many cities due to socioeconomic barriers, such as land ownership, proximity or lack of transportation. Reconfiguring the distribution of green space from the peri-urban fringe of the city to densely populated areas would build a more equitable society, allowing more city dwellers to have access to recreational space.
David Aronson, Senior Communications Advisor with ILRI, and Timothy Offei-Addo, a Princeton-in-Africa fellow with ILRI, contributed to the writing of this article.
Eric Fèvre, Professor of Veterinary Infectious Diseases, University of Liverpool and International Livestock Research Institute, Kenya, University of Liverpool and James Hassell, Wildlife Veterinarian with Smithsonian’s Global Health Program, and adjunct Assistant Professor, Yale University
Developing risk maps for endemic livestock diseases is important for effective disease prevention and control, particularly in resource-limited countries.
For endemic and easily diagnosed diseases such as anthrax, a useful approach involves analysis and mapping of historical data to identify disease hotspots and define risk factors of its occurrence.
A new paper published in BMC Infectious Diseases (Feb 2021) presents the results of risk mapping of the 666 livestock anthrax events that occurred in Kenya between 1957 and 2017.
The mapping exercise found that there were about 10 anthrax events in Kenya annually, with the number increasing to as many as 50 events annually by 2005.
Mapping also revealed spatial clustering of the disease events in certain sub-counties; 12% of sub-counties were responsible for over 30% of anthrax events while 36% of sub-counties did not report any incidents of anthrax over the 60-year period under study.
Additionally, there was significantly greater risk of anthrax occurring in agro-alpine high- and medium-potential agro-ecological zones than in the arid and semi-arid regions of the country.
Cattle were over 10 times more likely to be infected by Bacillus anthracis (the bacterium that causes anthrax) than sheep, goats or camels.
There was lower risk of anthrax in August and December, months that follow the long and short rain periods, respectively.
By enabling analysis of the trends and patterns of occurrence of livestock anthrax across different regions over the years, the risk maps will be a useful tool for livestock health officials to identify and characterize Kenya’s anthrax hotspots, leading to better targeting of disease management interventions.
The intensification of livestock production calls for the development of contextually relevant policy frameworks that mitigate potential human health risks such as antimicrobial resistance and zoonotic diseases, a new expert review paper says.
The review by scientists from the University of Liverpool and the International Livestock Research Institute also calls for better data on the burden of antimicrobial resistance and zoonoses arising from intensive livestock production. This would improve evidence-based approaches and resource allocation towards managing these global health challenges.
The paper, published in the journal Animal (Feb 2021), reviews the drivers of livestock intensification and the negative externalities that may arise from it in terms of antimicrobial resistance and zoonoses.
The authors highlight the need for livestock development plans to incorporate risk mitigation measures, including supportive national policies and development of professional capacity in the veterinary and public health sectors.
Quantifying the burden of animal diseases stemming from livestock intensification, establishing surveillance for antimicrobial resistance and recording the use of antimicrobial products are required to enable governments to appropriately allocate resources to mitigate the twin health risks of antimicrobial resistance and zoonoses, the authors say.
Animal health leaders and researchers from the Global Burden of Animal Diseases (GBADs) program have secured US$ 7 million from the Bill & Melinda Gates Foundation and the UK’s Foreign, Commonwealth and Development Office to roll out a framework on measuring animal health burdens and their impacts on human lives and economies.
The information provided by the GBADs program will guide public policy and private sector strategy, contributing to improve animal health and welfare more effectively. It will also be a basis for further academic research.
Across the world, livestock production and aquaculture are critical to human nutrition and health. These animals play critical roles in society, providing income and food, but also clothing, building materials, fertilizer and draught power. However, the presence of endemic and emerging diseases, as well as other factors, negatively impact them, jeopardizing their contributions.
Every year, hundreds of millions of dollars are invested globally on disease mitigation in order to improve livestock health and productivity. Yet, a systematic way to determine the burden of animal disease on the health and wellbeing of people is not available.
It is still unknown how the burden is apportioned between smallholders and the commercial sector, or across regions and gender. Consequently, decision-makers lack the information to accurately assess whether their investments target the animal health issues that have the most significant impact on human wellbeing.
The GBADs program, led by the University of Liverpool, the World Organisation for Animal Health (OIE) and a partnership of international institutions, will enable the examination of animal health and the disease burden from a different perspective.
By assessing the global burden in economic terms, the program will help identify the individuals and communities which are the most impacted, demonstrating how animal health is intrinsically linked to agricultural productivity, smallholder household income, the empowerment of women and the equitable provision of a safe, affordable, nutritious diet.
Professor Dame Janet Beer, Vice Chancellor, University of Liverpool, said: ‘The GBADs program is a key part of our commitment to deploying our research capacity towards the welfare of humankind. The GBADs program is crucial in building a world with zero hunger, good health and equality for all, an urgent mission in which we are proud to play our part. We are grateful for the support of the Bill & Melinda Gates Foundation and the UK’s Foreign, Commonwealth and Development Office, who are supporting this work in partnership with the OIE. Together, we will realise a brighter future for animal and human well-being.’
Dr Monique Eloit, OIE Director General, said: ‘It is more evident now for everyone that animal health and public health are interconnected and play an essential role in building a sustainable and healthy planet, especially if we succeed in incorporating the environmental and socioeconomic components.’
The international institutions partnering with the University of Liverpool and OIE in the GBADs program are the Commonwealth Scientific and Industrial Research Organisation; the University of Guelph; the Institute for Health Metrics and Evaluation at the University of Washington; the International Livestock Research Institute; Murdoch University; Sciensano; Washington State University; the University of Zurich; and the Food and Agriculture Organization of the United Nations. The program has also received funding from the Brooke Foundation and the Australian Centre for International Agricultural Research.
The International Livestock Research Institute will play a key role in investigating and applying approaches to improve our understanding of the burden of animal disease in farming systems in Ethiopia. This work will act as a case study, providing insights relevant to other settings and methods that can be used elsewhere. Understanding the scale and nature of how animal disease impacts livelihoods and economies is key, but this information then needs to be used to better advise governments and other investors in livestock and disease control. Therefore, tools and approaches will be developed to ensure that animal health policies are rational and informed by evidence.
The new partnership will support the implementation of the GBADs program. In a world where 1.25 billion people work in agriculture, the program will have a positive impact on the Sustainable Development Goals contributing to Zero Hunger; Good Health and Well-being; Gender Equality; Decent Work and Economic Growth; and Responsible Consumption and Production.
The current coronavirus disease (COVID-19) pandemic has brought into sharp focus the interconnectedness of people, animals and the environment and how this can contribute to the spread of disease.
One Health is a concept that recognizes that the health and well-being of people is intricately linked to the health of animals and the environment. For this reason, disease outbreaks are best tackled through a One Health approach that harnesses the collaborative efforts of multiple disciplines and sectors. This is especially so for zoonotic diseases that are spread between animals and people. One Health is also useful for addressing other public health issues such as antimicrobial resistance and food safety.
One Health is not a new concept, but it has become more important in recent years. This is because many factors have changed interactions between people, animals and the environment. These changes have led to the emergence and re-emergence of zoonotic diseases.
The International Livestock Research Institute (ILRI) has an established record of collaborative One Health research in Africa and Southeast Asia. To mark One Health Day coming up next week on 3 November, we bring you highlights of some One Health research initiatives by ILRI and partners.
This project worked directly with over 100 actors involved in managing zoonotic emerging infectious diseases across eight multi-disciplinary teams in Cambodia, China, Indonesia, Laos, Thailand and Vietnam. The project increased the capacity of researchers and policy implementers to use One Health approaches for better control of zoonotic diseases. The project also produced various research outputs and increased understanding of the teams’ knowledge, attitudes and practice in relation to One Health and how this approach could lead to better health outcomes for people, animals and the environment.
This project aims to improve the health and wealth of the people of the Horn of Africa by developing a regional network of individuals and organizations that can undertake high quality research into the link between people’s health and that of livestock and the environment. The project builds capacity to undertake basic and applied research in One Health through training programs and research placements for both research and non-research staff from participating institutions.
The One Health Research, Education and Outreach Centre in Africa was launched barely a week ago (on 22 October 2020) and is hosted at ILRI’s Nairobi campus. Its goal is to improve the health of humans, animals and ecosystems through capacity building, strengthening of local, regional and global networks and provision of evidence-based policy advice on One Health in sub-Saharan Africa. It has four research themes: control of neglected tropical zoonotic diseases; emerging infectious diseases; food safety and informal markets; and prevention and control of antimicrobial resistance. The centre is currently supporting the Government of Kenya’s national response to the COVID-19 pandemic through COVID-19 testing in ILRI’s bioscience laboratories.
This project applies a One Health approach to enhance the well-being and resilience of vulnerable communities in pastoralist and agro-pastoralist areas of Ethiopia, Kenya and Somalia. The project brings together professionals in human and animal health and the environment to achieve better access to human and veterinary health services and sustainable natural resource management.
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.”
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’.
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.
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.”
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.
In addition to organizations recognized for specific projects and outputs, we thank all donors which globally supported the work of ILRI and its partners through their contributions to the CGIAR system
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