The document discusses aflatoxin contamination in Africa and strategies to manage it. Aflatoxins are toxic metabolites produced by the fungus Aspergillus flavus that infect crops like maize and groundnuts. Studies show high levels of aflatoxins in staple crops across Africa, which poses risks to health and trade. Researchers are developing approaches like breeding resistant crop varieties, using atoxigenic biocontrol agents, and integrating management across the value chain to reduce contamination. Regional partnerships are needed to implement solutions and improve food safety.

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Advances in
Integrated
Management of
Aflatoxins in Africa
Ranajit Bandyopadhyay
IITA, Ibadan, Nigeria
Peter Cotty
USDA-ARS, University of Arizona,
Tucson, USA
2011 Annual Meeting of APS/IAPPS
6 -10 Aug, Honolulu, Hawaii

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• Highly toxic metabolite produced
by the ubiquitous Aspergillus
flavus fungus
• The fungus infects crops and
produces the toxin in the field and
in stores
• Fungus carried from field to store
• Contamination possible without
visible signs of the fungus
• Some predisposing factors:
– pre-harvest high temp and
drought stress
– wet conditions at harvest
and
post-harvest periods
– insect damage
Aflatoxin Facts

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Aflatoxin, Health & Trade
 Synergistic with Hepatitis B Virus (HBV) to
cause liver cancer
• 30 times more potent in HBV+ people
• 5-60 times higher cancer risk
 Impairs growth and development of
children
 Suppress immune system – increased
susceptibility to diseases, e.g., HIV, malaria?
 Impedes uptake and utilization of
micronutrients in human systems
 Animal productivity reduced – growth rate,
embryo toxicity, feed efficiency, cancer,
death……
 ~2.3 million bags contaminated maize not
tradable in 2010 in Kenya

4. Prevalence of Aflatoxins
in Food & Feed
• 2.5 billion exposed worldwide
• Several African staple commodities affected
• High human exposure in Africa – mother to baby
• Levels and frequency of occurrence high
– >30% maize in stores with >20 ppb aflatoxin
– ~90% stores are contaminated with Afla fungi
– Up to 40% grain in households with aflatoxin
• Concern for food and feed processors, government
and emergency food reserve agencies
• Highly toxic strains, conducive environmental
conditions, traditional farming methods and improper
grain drying and storage practices, unregulated
markets

5. PROBLEM DEFINITION

6. Some Ground Truths
Primary data:
qualitative and
quantitative surveys
(Kenya: 1344 hh, 80
communities, 300
traders; Mali: 1093
hh, 80 communities,
169 Traders).
Secondary data:
(WHO Gems data
base, KIHBS, UN
Comtrade, WDI, FAO
stat, EPII France data
base)
Lead institutions:
IFPRI, CIMMYT,
ICRISAT, KARI, IER
• Maize and groundnuts grown largely for home
consumption
• Testing is rare and slow
• Preliminary results indicate many consumers are
aware of aflatoxins, but few are knowledgeable
of their health risks.
• Lack of knowledge and testing -- few incentives
to reduce aflatoxins
• Consumers show a high discount for
contaminated maize, and a high premium for
labeled and tested maize.
• Producers find alternative markets (e.g. feed,
countries with less strict regulation)
Courtesy: Pippa Chenevix Trench, IFPRI

7. Samples from farmers’ fields (pre-harvest), at harvest, and post harvest from
farmers’ stores; from traders, small-scale retailers, wholesalers, at local,
national. regional levels.
Kenya -- MAIZE (Mahuku et al, 2011):
• Approx 6,000 maize samples between
Sept 2009 and June 2011.
• 2010: max aflatoxin in farmer stores
(1,776 ppb) and markets (1,632 ppb)
• Approx 40% of samples from farmers’
fields in eastern and western Kenya had
aflatoxin levels > 10 ppb in Feb 2011.
• Lower levels in second harvest in Aug
2010.
Mali -- GROUNDNUT (Waliyar et al., 2011) :
• Nearly 12,000 samples (seed and paste)
between Sept 2009 and June 2011.
• 2009/2010, 35 to 61% samples from farmers’
fields > 10 ppb, increasing to 39 to 91%
samples from farmers stores.
• Similar levels in traders stores: groundnut
“paste” showed an extremely high level
(>300 ppb) of aflatoxin in a majority of the
samples
• Significant contamination above recommended safe limits in pre-harvest as
well as post-harvest and along value chain.
• Contamination varies in time and from region to region.
• Current storage practices a significant factor in increasing aflatoxin risk.
Aflatoxin in Food
Courtesy: Pippa Chenevix Trench, IFPRI

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Aflatoxin
levels in
feeds in
Nigeria
Aflatoxin level (ppb) Samples (%)
<20 (safe) 38
>20 to 100 (up to 5x) 14
>100 to 500 (up to 25x) 41
>500 to 1,000 (up to 100x) 7
AF-free diet 500 ppb AF diet
AF-free
diet
500 ppb AF diet
~40% reduction in
live weight (8 weeks)
Aflatoxin in Feed

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SUMMARY OF KEY MESSAGES
27. The meeting noted the importance of advancing sanitary and
phyto-sanitary (SPS) matters within CAADP to enhance food
security and market access. In this context, the meeting
underscored the need to address aflatoxin control and other SPS
challenges in a holistic and integrated manner across the entire
value chain and across the various partners involved.
Mainstreaming SPS
62. The meeting urged the AUC and the NEPAD Agency to oversee
the establishment of a Continental SPS Working Group to
mainstream SPS matters in the CAADP framework and
establishment of an Africa-led Partnership for Aflatoxin control.

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Aflatoxin Mitigation by Native
Beneficials: Principles
 Fungal communities differ in aflatoxin-
producing ability & this influences crop
vulnerability to contamination.
 Some strains produce a lot (toxigenic),
and others no aflatoxin (atoxigenic)
 Competitive exclusion (one strain
competing to exclude another) is the
biocontrol principle practiced
 Shift strain profile from toxigenic to
atoxigenic
 Thus, aflatoxin contamination reduced
 Strains move from field to stores
 Multiple year carry-over effect
 We identify and promote only native
beneficial strains
0
25
50
75
100
Natural Biocontrol
Incidence(%)
T
O
X
I
G
E
N
I
C
A
T
O
X
I
G
E
N
I
C
S Strain A. flavus L Strain or “typical” A. flavus
On average, S strain isolates produce much
more aflatoxin than L strain isolates.

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How does Biocontrol Work?
Broadcast
@ 10 kg/ha 2-3 weeks
before flowering
Sporulation on moist soil
Spores
Insects
Inoculum on
sorghum grain carrier
3-20
days
Wind
Soil
colonization
30-33 grains m-2
Hyphal network
in seed pericarp

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B-aflatoxin in stored maize grains from
untreated and atoxigenic treated plots
Location Treatment
At harvest Poorly stored
Aflatoxin
(ppb)
Reduction
(%)
Aflatoxin
(ppb)
Reduction
(%)
Ibadan
Control 42
73
2408
96
Treated 11* 105**
Ikene
Control 54
91
956
93
Treated 5* 62**
Zaria
Control 73
85
7561
95
Treated 11* 343**
Mokwa
Control 50
86
2481
94
Treated 7* 149**
* P < 0.05, ** P < 0.01

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Farmers treating maize and groundnut fields with AflaSafe
Aflatoxin reduction at corn harvest:
2009: 80% 2010: 89%
Aflatoxin reduction at peanut harvest:
Nigeria -- 2009: 96% 2010: 98%
Senegal -- 2010: 87%
71% and 52% carry-over of
inoculum 1 & 2 years after
application

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Impact on Health and Trade
75
94
100
0
3
39
73
27
100
80
60
40
20
0
<4 <10 <20 >20
EU WFP US unsafe
maximum allowable aflatoxin level (ppb)
farmers'fields(%)
untreated
cost-effectiveness ratio:
GDP x DALYs saved (liver cancer)
bio-control cost
DALYs saved: 103,000 - 184,000
cost-effectiveness ratio: 5.1 - 24.8
treated

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Ownership and
Advocacy by the
Nigerian Government
• Ministry of Agriculture
• Ministry of Commerce
• Ministry of Health
• Commercial Agriculture
Development Program
• State Agriculture
Development Program
• NGOs

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How to Generate Demand in the
Medium-Term
• Enable development of native
beneficials in key countries
• Develop manufacturing capacity
• Create awareness about aflatoxin
• Demonstrate efficacy of Aflasafe
• Incentivize use of Aflasafe by the poor
• Train farmers in aflatoxin management
• Enable aflatoxin testing of products
• Link Aflasafe users to food and feed
market including institutional buyers

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Aflatoxin Mitigation in a
Value Chain Approach
A combined package, and not a single tactic, can produce the best results
for improving safety and value of maize. Following multi-pronged
approach in a value chain mode proposed:
 Aflatoxin awareness among farmers and their community to enable them to
value the need for aflatoxin management
 Native beneficial adoption by farmers will be the main pillar
 Training of extension staff and key farmers on good pre-harvest, harvest and
post-harvest practices for aflatoxin management.
 Aflatoxin testing of maize for assessing safety and utilization channels of the
grains
 Warehouse development for aggregation of grains to enable purchasers to
procure grains from a ‘single window’
 Market linkages with appropriate value chain participants for grains with
various levels of aflatoxins to maximize profits.

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Farmer Training

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Some Target Groups for
Awareness & Advocacy
• Policy makers - Ministries of
Agriculture, Health, and Commerce
• National agriculture development
programs
• Non-Government Organizations
• Producers and producer groups
• Private sector
• National and international food
reserve programs
• Medical professionals
• Religious and local “traditional”
leaders.
• Consumers, particularly women

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14
14 tons inoculum produced in 2011 for deployment

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Farmers harvesting and
threshing groundnut
40 farmers in 2 zones
treated groundnut
fields with AflaSafe
Senegal

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Zone
Number of
farmers
Mean B-aflatoxin
(ng/g) Reduction
(%)Aflasafe™ Control
Diourbel 19 1.9 29.7 93
Nioro 19 4.4 17.6 75
Mean 3.2 23.6 87
Aflatoxin Reduction in Groundnut
After Aflasafe Application in Senegal

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Cotty, Mutegi and
Sila in KARI-
Kiboko treated plot Atoxigenic
Aspergillus spores
on sorghum grain
carrier in KARI-
Kiboko treated plot
KENYA
• 13 strains repatriated
and released in three
research farms
• 4 being selected for
efficacy testing and
product registration

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Focus Countries and Stages of
Native Beneficial Development
Country Strain
identification Partnerships Commercialization
Capacity
development
Nigeria
Kenya
Senegal
Burkina Faso
Mozambique
Yet to startPartially startedCompleted
Expression of Interest: Ghana, Mali, Ethiopia, Malawi,
Tanzania and Uganda
New projects: Zambia and Mozambique

25. International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Breeding for Resistance
Research focus
• Continual evaluation of germplasm under naturally
occurring severe disease pressure
• Breed maize for reduced aflatoxin contamination
with selection using a laboratory kernel screening
assay (KSA)
• Screen maize germplasm for resistance to A. flavus
and F. verticillioides using artificial field inoculation

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334 396 400 488
800 809 816 956
5474 5671
6438
6087
5685
7115
6040 5891
5743
5662
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
Hybrids
Aflatoxin (ppb)
Grain yield (kg/ha)
Aflatoxin(ppb)
Grainyield(kg/ha) Less Aflatoxin Susceptible, High-
Yielding Yellow Maize Hybrids
Less toxin – high yield

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Aflatoxin (ppb) in Low-Aflatoxin
Maize Lines With and Without
Aflasafe Treatment
Experimental
variety
At harvest
Control Treated
RSYN2-Y 19.6 1.7
RSYN3-W 6.9 1.8
SYN3-Y 18.4 1.7
TZB-SR (susc.) 57.5 4.7
After poor storage
Control Treated
462 44
627 38
387 19
1152 163

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Experimental
varieties
Aflatoxin reduction (%)
Resistance
alone
Biocontrol
alone
Resistance +
Biocontrol
RSYN2-Y 66 91 97
RSYN3-W 88 74 97
SYN3-Y 68 91 97
TZB-SR (Susc.) 58 ppb 92
% Reduction in experimental varieties compared to susceptible variety (TZB-SR) under natural conditions
% Reduction in varieties with biocontrol compared to susceptible variety (TZB-SR) under natural conditions
% Reduction in biocontrol treated plots compared to control plots of the same experimental variety
% Reduction in varieties with biocontrol compared to susceptible variety (TZB-SR) under natural conditions
% Reduction in biocontrol treated plots compared to untreated plots of the same variety
Synergistic Effect of Resistance
and Biocontrol in Reducing
Aflatoxins at Harvest

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Experimental
varieties
Aflatoxin reduction (%)
Resistance
alone
Biocontrol
alone
Resistance +
Biocontrol
RSYN2-Y 60 90 96
RSYN3-W 46 94 97
SYN3-Y 66 95 98
TZB-SR (Susc.) 1152 ppb 86
% Reduction in experimental varieties compared to susceptible variety (TZB-SR) under natural conditions
% Reduction in varieties with biocontrol compared to susceptible variety (TZB-SR) under natural conditions
% Reduction in biocontrol treated plots compared to control plots of the same experimental variety
% Reduction in varieties with biocontrol compared to susceptible variety (TZB-SR) under natural conditions
% Reduction in biocontrol treated plots compared to untreated plots of the same variety
Synergistic Effect of Resistance
and Biocontrol in Reducing
Aflatoxins after Poor Storage

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Summary
• Aflatoxins in food and feed pervasive in Africa
• Aflatoxin mitigation plan developed
• Support needed from regional and continental
institutions to galvanize partnerships among
national governments, donors, private food
sector, farmer groups, and regulators to
improve health and income of people
• Technologies available but policies and
institutions must be strengthened for their
effective implementation to reduce aflatoxin
burden in African economies and food system
Partnership for
Aflatoxin Control
in Africa

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Donors