Global food systems and zoonoses
Delia Grace
Professor Food Safety Systems, Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB. UK
Joint appointed scientist, Animal and Human Health Program, International Livestock Research Institute, Box 30709, Nairobi, Kenya
22nd Annual Harvard Nutrition and Obesity Symposium
Global Food Systems and Sustainable Nutrition in the 21st Century
15 June 2021

Animal source food (ASF) demand driven
revolutions: livestock products > fish
FAOSTAT

HLPE 2017 Food Systems and Nutrition Report
Food systems for health and nutrition
CGIAR

Where do we get our diseases?
• Few are Legacies
• Paleolithic baseline: yaws, staph, pinworms, lice, typhoid,
human TB
• Most are “Earned”/ associated human behaviour
• Degenerative diseases: heart failure, stroke, diabetes,
cancer
• Allergies, asthma, autoimmune diseases
• Sexually transmitted infections such as HSV-2, gonorrhea
• Many are Souvenirs
• Around 60% of human diseases shared with animals
• 75% of emerging infectious disease zoonotic

Zoonoses
•Neglected zoonoses: brucellosis,
bovine tuberculosis, leptospirosis,
Rift Valley fever
•Emerging zoonoses: mad cow,
bird flu, SARS, MERS, COVID-19

Secondary
Host (livestock)
Secondary
Host
(human)
Vec
tor
Sylvatic cycle
Sustained transmission:
- peri-domestic or urban cycle
- sub-clinical, epidemic, pandemic
Type of pathogen: mutation,
heterogeneity, host specificity
Habitat change
Biodiversity
Host density
Vector density
Spillover! •Increasing human population
and density
•Human behaviour
•Expansion of agriculture
•Intensification of livestock
production
Pathogen flow
Spill-over
Spill-over
Spill-over
Reservoir
Host (wildlife)

7
Warning! Increasing frequency of pandemics
Graphics: Annabel Slater, ILRI; adapted fromUnited Nations Environment Programme and International Livestock Research
Institute (2020). Preventing the Next Pandemic: Zoonotic diseases and how to break the chain of transmission. Nairobi, Kenya.

8
Costs of emerging zoonoses and pandemics
Graphics: Annabel Slater, ILRI

Economic costs
Young girl presenting her pet chicken to culling team during a mass cull,
Indramayu District January 2006. Photo by Peter Roeder.

Timely responses to reduce impacts
• Surveillance and response in animal hosts can reduce
costs by 90%
Adapted from IOM 2009

11
Pandemics and endemics: One Health
approach needed
Prepare – detect – prevent – respond

Food Safety

Growing concern about food safety
In low and middle income countries:
• Many/most reported concern over food
safety (40-97%)
• Willing to pay 5-10% premium for food
safety
• Buy 20-40% less during animal health
scares
• Younger, wealthier, town-residing,
supermarket-shoppers willing to pay most
for safety
Grace (2015), IJERPH

Years of life lost annually for FBD
FERG: Havelaar et al., 2015; Gibb et al., 2019
Health impact of FBD comparable to that
of malaria, HIV/AIDs or TB
USA – 1 in 6
Greece 1 in 3
Africa 1 in 10??
zoonoses
non zoonoses

Food safety & nutrition
• Diarrhoea a risk factor for stunting – perhaps 10-20%?
• Ingestion of faecal material on food or in the environment may contribute
to environmental enteric dysfunction
• Regulations aimed to improve food safety may decrease the availability
and accessibility of foods
• Associations between aflatoxins and stunting
• Food-scares decrease consumption
Grace et al., 2018

Problem: fresh foods in wet markets
Painter et al., 2013, Sudershan et al., 2014, Mangan et al.,
2014; Tam et al., 2014; Sang et al., 2014 ; ILRI, 2016
0% 20% 40% 60% 80% 100%
UK
Netherlands
India
Vietnam
USA
China
Animal source food
Produce
Other

Most ASF sold in wet markets: risky for FBD
but important for livelihoods & nutrition
Benefits of wet markets
Cheap,
Fresh,
Local breeds,
Accessible,
Small amounts
Sellers are trusted,
Credit may be provided
(results from PRAs with
consumers in Safe Food, Fair Food
project)
Wet market
milk
Supermarket
milk
Most common
price /litre
56 cents One dollar
Infants
consume daily
67% 65%
Boil milk 99% 79%
Survey in supermarkets and wet markets in Nairobi in 2014

18

19

20

21

22

23

24
0
10
20
30
40
50
60
70
80
90
100
Poor total bacteria Unacceptable total
bacteria
Unacceptable
faecal bacteria
Unaccpetable
Staph
Unacceptable
listeria
Any unacceptable
Supermarket
Wet market
Village
Formal worse than informal
Fahrion et al., 2016

25
Risk
Assessment
Risk
Management
Risk
Communication
Solution: Risk analysis
a tool for decision-making under uncertainty

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Hazard identification
Hazard characterization Exposure assessment
Risk characterization
Risk communication
What harm does it cause?
How does harm depend on
dose?
Can it be present in food?
Can it cause harm?
How and to what extent does it
get from source to victim?
What is the harm?
What is its likelihood?
Participatory methods
fit well
Risk assessment and risk communication

• Branding & certification of milk
vendors in Kenya & Guwahti,
Assam led to improved milk safety.
• It benefited the national economy
by $33 million per year in Kenya
and $6 million in Assam
• 70% of traders in Assam and 24%
in Kenya are currently registered
• 6 million consumers in Kenya and
1.5 million in Assam are benefiting
from safer milk
Kaitibie et al., 2010; Lapar et al., 2014

Take home messages
• Food systems to achieve nutrition, food safety and health
outcomes are complex, changing and challenging
• Informal / wet markers play an important role in food
security and safety in low and middle income countries
• Zoonoses are ever-present and emerging zoonoses and
foodborne zoonoses increasing
• What you worry about and what makes you sick and kills
you are not the same
• Control & command approaches don’t work but solutions
based on working with the informal sector more
promising: One Health and Participatory Risk Analysis.

Acknowledgement
Photos not attributed taken by ILRI staff

This presentation is licensed for use under the Creative Commons Attribution 4.0 International Licence.
better lives through livestock
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