Advances in integrated management of aflatoxins in africa

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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

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

PROBLEM DEFINITION

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

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

Incid

en

ce (

%)

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)

farm

ers

' fie

lds (

%)

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

www.iita.org 23

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 start Partially started Completed

Expression of Interest: Ghana, Mali, Ethiopia, Malawi, Tanzania and Uganda

New projects: Zambia and Mozambique

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)

Afl

ato

xin

(p

pb

)

Gra

in y

ield

(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 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 biocontrol treated plots compared to control plots of the same experimental variety


% 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

Advances in integrated management of aflatoxins in africa

Science

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