Livestock


Hundreds of trees have been felled along Nairobi’s Uhuru and Waiyaki highways to make space for a new expressway. CELINE CLERY/AFP via Getty Images

Eric Fèvre, University of Liverpool and James Hassell, Yale University

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

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Cattle and wildlife at the ILRI Kapiti Research Station (photo credit: ILRI/Paul Karaimu)

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.

Citation
Nderitu, L.M., Gachohi, J., Otieno, F., Mogoa, E.G., Muturi, M., Mwatondo, A., Osoro, E.M., Ngere, I., Munyua, P.M., Oyas, H., Njagi, O., Lofgren, E., Marsh, T., Widdowson, M.-A., Bett, B. and Njenga, M.K. 2021. Spatial clustering of livestock anthrax events associated with agro-ecological zones in Kenya, 1957-2017. BMC Infectious Diseases 21(1): 191.

Photo credit: Cattle and wildlife at the ILRI Kapiti Research Station (ILRI/Paul Karaimu)

Sheep market in Doyogena, Ethiopia

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.

Citation
Gilbert, W., Thomas, L., Coyne, L. and Rushton, J. 2021. Review: Mitigating the risks posed by intensification in livestock production: The examples of antimicrobial resistance and zoonoses. Animal 15(2): 100123.

Photo credit: Sheep market in Doyogena, Ethiopia (ILRI/Zerihun Sewunet)

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

The effects of COVID-19 have gone undocumented in nomadic pastoralist communities across Africa, which are largely invisible to health surveillance systems despite their significance in the setting of emerging infectious disease.

A new research paper in the American Journal of Tropical Medicine and Hygiene (online first 10 Sept 2020) exposes these landscapes as a ‘blind spot’ in global health surveillance, elaborates on the ways in which current health surveillance infrastructure is ill-equipped to capture pastoralist populations and the animals with which they coexist, and highlights the consequential risks of inadequate surveillance among pastoralists and their livestock to global health.

As a platform for further dialogue, the authors of the paper also present solutions to address this gap. These include the development of an integrated One Health surveillance system that links pastoralists, their livestock and overlapping wildlife populations with centralized disease reporting. Community-based syndromic surveillance and participatory epidemiology would also improve early detection and reporting of disease outbreaks for more timely control interventions.

Citation
Hassell, J.M., Zimmerman, D., Fèvre, E.M., Zinsstag, J., Bukachi, S., Barry, M., Muturi, M., Bett, B., Jensen, N., Ali, S., Maples, S., Rushton, J., Tschopp, R., Madaine, Y.O., Abtidon, R.A. and Wild, H. 2020. Africa’s nomadic pastoralists and their animals are an invisible frontier in pandemic surveillance. American Journal of Tropical Medicine and Hygiene. https://doi.org/10.4269/ajtmh.20-1004

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

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.

Photo credit: A herder with his livestock in Isiolo County, Kenya (ILRI/Dorine Odongo)

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.

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

Maize. Mozambique, Tete province, Pacassa village (photo credit: ILRI/Mann).

In sub-Saharan Africa, contamination of dairy feed with mycotoxins has been frequently reported. Mycotoxins pose a threat to animal health and productivity and are a hazard to human health as some mycotoxins and their metabolites are excreted in milk, such as aflatoxin M1.

A new review paper published in the journal Toxins (April 2020) describes the major mycotoxins, their occurrence and their impact in dairy cattle diets in sub-Saharan Africa, highlighting the problems related to animal health, productivity and food safety and the latest post-harvest mitigation strategies to prevent and reduce contamination of dairy feed with mycotoxins.

Citation
Kemboi, D.C., Antonissen, G., Ochieng, P.E., Croubels, S., Okoth, S., Kang’ethe, E.K., Faas, J., Lindahl, J.F. and Gathumbi, J.K. 2020. A review of the impact of mycotoxins on dairy cattle health: Challenges for food safety and dairy production in sub-Saharan Africa. Toxins 12(4): 222.

Photo credit: Maize crop, Pacassa village, Tete province, Mozambique (ILRI/Mann)

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.

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

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).

To the grazing field, Afar, Ethiopia

Cattle going to the grazing field in Afar region, Ethiopia (photo credit: ILRI/Apollo Habtamu).

Climate change influences the occurrence and transmission of a wide range of livestock diseases through multiple pathways. Diseases caused by pathogens that spent part of their life cycle outside the host (for instance, in vectors or the environment) are more sensitive in this regard, compared to those caused by obligate pathogens.

A newly published book, The Climate-Smart Agriculture Papers, brings together some of the latest research by agricultural scientists on climate-smart agriculture in eastern and southern Africa. The 25 chapters of the book highlight ongoing efforts to better characterize climate risks, develop and disseminate climate-smart varieties and farm management practices, and integrate these technologies into well-functioning value chains.

In a chapter on climate change and livestock diseases, scientists from the International Livestock Research Institute (ILRI) use two well-studied vector-borne diseases—Rift Valley fever and tick-borne diseases—as case studies to describe direct pathways through which climate change influences infectious disease-risk in East and southern Africa.

Access the chapter, Climate change and infectious livestock diseases: The case of Rift Valley fever and tick-borne diseases by Bernard Bett, Johanna Lindahl and Delia Grace.

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