Emerging 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.

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.

ILRI Asia

Nobody likes getting sick. However, climate change, like higher temperatures, heavier rainfall and higher humidity, is already a given, and diseases highly sensitive to such changes would likely increase over time.

Climate change might also make the environment more suitable for diseases to spread, not only among individuals of the same species, but also across species (known as zoonotic diseases). In fact, 70% of the emerging diseases today, like ebola, A(H1N1) (‘swine flu’) and avian influenza (‘bird flu’), have been transferred from animals to humans. Such diseases threaten not only agricultural and food production, but also human lives as well.

A better understanding of how diseases are linked to climate change is needed. “We need more information on climate-sensitive zoonotic diseases to improve healthcare,” said Dr Hu Suk Lee of the International Livestock Research Institute (ILRI).

A team of researchers from ILRI and national climate, agricultural and…

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ILRI Clippings

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A woman sorts through a heap of garbage at the Dandora dumping site among other people, cattle, pigs and storks, in Nairobi (photo credit: Simon Maina / AFP / Getty Images).

Written by Eric Fèvre

‘There are fears that Africa’s next major modern disease crisis will emerge from its cities. Like Ebola, it may well originate from animals. Understanding where it would come from and how this could happen is critical to monitoring and control.

‘Growth and migration are driving huge increases in the number of people living in Africa’s urban zones. More than half of Africa’s people are expected to live in cities by 2030, up from about a third in 2007.

‘The impact of this high rate of urbanisation on issues like planning, economics, food production and human welfare has received considerable attention. But there hasn’t been a substantive effort to address the effects on the transmission of the organisms—pathogens—that…

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An Ethiopian woman breeds sheep for a living (photo credit: ILRI/Zerihun Sewunet).

On the matter of global health and tackling the looming threat of emerging infectious disease pandemics, Delia Grace, a veterinary epidemiologist at the International Livestock Research Institute (ILRI) shares her views in a recent blog post, Pandemic proofing the world, published by How We Get To Next.

The post argues the case for greater attention to diseases that can be transmitted to people through livestock, better incentive structures for reporting of livestock disease outbreaks so that timely disease reporting is rewarded rather than punished, and the need to tackle the root causes and not just the symptoms of emerging zoonotic diseases.

Read the post, Pandemic proofing the world by Delia Grace, How We Get To Next, 29 June 2016

Delia Grace presents on zoonotic diseases, UNEP Nairobi, 20 May 2016
ILRI veterinary epidemiologist Delia Grace presenting at the United Nations Environment Programme (UNEP) Science-Policy Forum that preceded the second session of the United Nations Environment Assembly (UNEA-2), on 20 May 2016 (photo credit: ILRI).

The United Nations Environment Programme (UNEP) held its first global Science-Policy Forum in Nairobi, Kenya on 19-20 May 2016 as part of the overall programme of the second session of the United Nations Environment Assembly (UNEA-2) held on 23-27 May 2016.

The forum offered a platform to the science community to engage with policymakers and civil society stakeholders on the science and knowledge needed to support informed decision-making to deliver on the environmental dimension of the 2030 Agenda for Sustainable Development.

Delia Grace, a veterinary epidemiologist at the International Livestock Research Institute (ILRI), took part in the forum as a panellist for the launch of the UNEP Frontiers 2016 report on emerging issues of environmental concern.

Her presentation on zoonotic and emerging infectious diseases focused on the global burden of zoonotic diseases (diseases that can be transmitted between animals and people), the drivers of disease (among them, land use change, environmental degradation and climate change) and how the multidisciplinary One Health approach can be used to support timely response to the threat of zoonotic diseases.

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Zoonotic diseases are also featured in a chapter in the UNEP Frontiers 2016 report, Zoonoses: Blurred lines of emergent disease and ecosystem health by Delia Grace and ILRI colleagues Bernard Bett, Hu Suk Lee and Susan MacMillan.

ILRI news

MERS-Coronavirus_NIADTransmission electron micrograph of Middle East Respiratory Syndrome coronavirus, MERS-CoV (image credit: NIAID). MERS-CoV belongs to the coronavirus family. Human coronaviruses were first identified in the mid-1960s; MERS-CoV was first reported in 2012 in Saudi Arabia. Coronaviruses can also infect animals. Named for the crown-like spikes on their surface, coronaviruses are common in people, usually causing mild to moderate upper-respiratory tract illnesses. Two exceptions are the MERS-CoV and the SARS (Severe Acute Respiratory Syndrome)-CoV.

A new study published in the science journal Emerging Infectious Diseases reports that two individuals in Kenya have tested positive for the presence of antibodies to Middle East Respiratory Syndrome coronavirus (MERS-CoV). Neither person is ill or recalls having any symptoms associated with MERS.

There is no evidence of a public health threat and scientists concluded that the infections caused little or no clinical signs of illness. But they plan follow-up studies, as this is the…

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AITVM conference logo 2016

The holistic concept of ‘One World-One Health’ in disease prevention and control will be among the topics of discussion at the first joint international conference of the Association of Institutions for Tropical Veterinary Medicine (AITVM) and the Society of Tropical Veterinary Medicine (STVM) which is scheduled to place on 4-8 September 2016 in Berlin, Germany.

AITVM is a foundation of 24 veterinary faculties and livestock institutes based in Africa, Asia and Europe with the mandate to improve human health and quality of life by means of increased and safe food production in tropical regions through enhancement of research, training and education in veterinary medicine and livestock production within the framework of sustainable development.

STVM is made up of scientists, veterinarians and students from more than 40 countries with common interests in tropical veterinary medicine. It is a non-profit organization whose purpose is the advancement of tropical veterinary medicine, hygiene and related disciplines.

The joint conference will bring together animal health and production experts, senior and junior career researchers and students from all over the world to discuss research and development topics including animal and zoonotic disease control, food safety, genetic resources and biodiversity, rural development and animal production, training and capacity building and animal welfare.

The conference is organized by the Institute for Parasitology and Tropical Veterinary Medicine and the Food and Agriculture Organization of the United Nations Reference Centre for Veterinary Public Health of the Freie Universität Berlin.

The co-organizing institutions are:

  • the Friedrich-Loeffler Institute – Federal Research Institute for Animal Health
  • the Federal Institute for Risk Assessment
  • the German Veterinary Medical Society
  • Vétérinaires Sans Frontières Germany
  • the Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences of the Humboldt-Universität zu Berlin

The conference organizers are now accepting abstracts. The deadline for submission of abstracts is 15 March 2016.

Visit the conference website for more information.

Catch of the day, Khulna, Bangladesh. Photo by Yousuf Tushar.

Catch of the day, Khulna, Bangladesh. Fish are among the aquatic hosts of microsporidia, a group of emerging foodborne parasites. (photo credit: WorldFish/Yousuf Tushar).

In December 2015, the World Health Organization published a report of the first ever global and regional estimates of the burden of foodborne diseases.

The report estimates the burden of foodborne diseases caused by 31 agents – bacteria, viruses, parasites, toxins and chemicals – and shows that almost 1 in 10 people fall ill every year from eating contaminated food and 420,000 die as a result.

Children under five years of age are at particularly high risk, with 125,000 children dying from foodborne diseases every year. Africa and Southeast Asia have the highest burden of foodborne diseases.

Microsporidia are among the many contributors to the global burden of foodborne disease, although they are not currently considered to be priority foodborne parasites.

Microsporidia are a group of spore-forming parasites that infect a wide range of host organisms, including humans. People can get infected with microsporidia through ingesting contaminated food and water. People with weakened immune systems are at particularly high risk of infection.

To address the growing threat of this emerging group of pathogens, a group of experts met at a symposium entitled “Microsporidia in the animal to human food chain: An international symposium to address chronic epizootic disease”. The meeting was sponsored by the Organisation for Economic Cooperation and Development and held in Vancouver, Canada in August 2015.

Kristina Roesel, a scientist at the International Livestock Research Institute (ILRI), presented a paper entitled “Parasites in food chains”. Her presentation contributed to a collaborative review article, “Microsporidia – Emergent pathogens in the global food chain”, published in the journal Trends in Parasitology (18 Jan 2016).

The article examines the threat of microsporidia in food, water and major food production chains. The authors note that climate change may result in a greater disease burden in hosts from all environments and thus increase the contact rate between infected animals and humans. A One Health approach will, therefore, be useful to manage the risks of microsporidian infections in wildlife, food animals and humans.

Orma Boran cattle crossing a river in Kenya

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

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

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

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

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

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

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

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

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

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