Aflatoxin impacts and management

P

Aflatoxins Impacts & Management

Ranajit Bandyopadhyay IITA, Ibadan, Nigeria

EAC WORKING GROUP OF AFLATOXIN EXPERTS

11-15 MARCH 2013, ARUSHA, TANZANIA

Food Systems

• Large Scale and Regulated – Developed countries

– Trade based

– Advanced infrastructure

– Capital intensive

Tim Williams, Peanut CRSP

Small Scale and Unregulated

– Developing countries

– Informal markets

– Subsistence

– High food insecurity

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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 Contamination Occurs in

Two Phases

Phase I: Before Crop Maturity

Developing crops become infected.

Associated with crop damage (insect, bird, stress).

Favored by high temperature (night) and dry conditions.

Phase II: After Crop Maturity

Aflatoxin increases in mature crop.

Seed is vulnerable until consumed.

Rain on the mature crop increases contamination.

Associated with high humidity in the field & store, insect

damage, and improper crop storage or transportation.

Contamination is most severe at low elevations and during dry periods. During drought the zone with contamination expands.

35°N

35°S Zone with Perennial Contamination Risk

Aflatoxin Contamination: A Perennial Concern in Warm Climates

Prevalence of Aflatoxins in Food & Feed

• 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, school-feeding

• Aflatoxins disproportionately impact the poor

• Highly toxic strains, conducive environmental

conditions, traditional farming methods and improper

grain drying and storage practices, unregulated markets

International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org

www.iita.org

Aflatoxins in Food

District Samples Aflatoxin levels (ppb)

< 20 21 - 99 100 - 1,000 > 1,000

Makueni 91 35 13 40 12

Kitui 73 38 21 32 10

Machakos 102 49 25 23 3

Thika 76 66 17 13 4

TOTAL 342 47% 19% 27% 7%

Kenya – 2004 by CDC and Ministry of Health


Aflatoxin-albumin adducts (pg AFB1-lysine eq./mg albumin)

<5 5-25 26-100 >100

Nu

mb

er

of

ind

ivid

ua

ls (

%)

0

20

40

60

80

100 Gambia (n = 950)

Benin (n = 479)

USA (n = 48)

Europe (n = 74)

Aflatoxin Exposure in Africa,

Europe & USA


Aflatoxin Exposure in Africa

• Exposure to aflatoxin in sub-Saharan Africa is common and at high levels – important exposure occurs at the small subsistence farm level

• Exposure begins in utero and continues throughout life, with a reduced exposure during breastfeeding

• Exposure in young children is associated with impaired growth and development

• Under-nutrition and growth faltering is an underlying cause of 50% of deaths in children <5 years age (Black et al., Lancet, 2003)


Aflatoxin and Human Health

Death

Binds with DNA -- mutagenic

Type I carcinogen

Causes liver cancer – increasing incidence

Aflatoxin interacts with HBV

• 30 times more potent in HBV+ people

• 5-60 times higher cancer risk

• 40% of liver cancer cases linked to aflatoxin

Impede uptake and utilization of micronutrients in human systems

Associated with Kwashiorkor in children

Contributes to 40% of DALYs


Organs/Systems Effects

Gene and Gene

Expression

Teratogenic effect (birth defect)

Gene and Gene

Suppression

Carcinogenic effect—higher

incidence of cancer

Pathological changes Liver, kidney, and spleen

enlargement, fatty liver

syndrome

Immunosuppression Decreased resistance to

enteropathy, HIV, TB, and other

opportunistic infections

Aflatoxin Effect on Human Health


Aflatoxin & Stunting in Children

• Stunting - 40% more frequent in the high exposure zone

• 28% reduction in height gain

Aflatoxin exposure

group

AF-alb adduct

(pg mg-1)

Ht. increase*

(cm)

Lower quartile <23.3 5.88

Upper quartile >101.5 4.21

Aflatoxin and HIV

• HIV increases the toxic effect of Aflatoxin (AF) by decreasing the levels of anti-oxidant nutrients that helps detoxify AF in the body

• For HIV virus to penetrate a cell it has to overcome the barrier of cell membrane & secretory IgA. AF reduces the level of secretory IgA thereby easing one of the barriers.

• In a large number of HIV cases there is a co-infection of HBV causing liver damages thereby potentiating the effects of AF


Animal Health Impact of Aflatoxin

Livestock and poultry losses

liver damage including cancer

recurrent infection due to immune system suppression

reduced growth rate

losses in feed efficiency

decreased milk and egg yield

embryo toxicity (reduced reproductivity)

death (cattle, turkey, poultry, swine..)

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Aflatoxin and Poultry (Broilers)

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)

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Trade Losses due to Aflatoxins

• Nigeria and Senegal major groundnut exporters

in 1960s. Compliance has economic incentives

• Senegal: US$ 4.1 million added capital

investment and 15% recurring cost would attract

30% price differential to oil cake.

• Export would increase from 25K tons to 210K

tons.

• Increased export volume and price differential

would annually add $281 million value to

groundnut export for the capital investment.

• For confectionary groundnut, adherence to Good

Management Practices would increase export

value by US$ 45 million annually.

• Best quality exported; poorer quality consumed

domestically. Peanut

Maize

Coffee

Cocoa

Groundnut Pyramids in

Nigeria during 1960s Pyramids in Egypt?

World Bank; Mbaye (2004)


EU Rejections of Imports

According to Risks

SOURCE: EU Rapid Alert System For Food and

Feed (RASFF, 2005)

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Trade Losses due to Aflatoxins

• Export compliance with food safety

and quality standards.

• Total losses: $1.2 billion

• World Bank estimate of unrealized

trade

– 2005 study: ~ Tens of millions of $

• Reasonable estimate: US$ 450 million

• Some countries active to meet

standards by putting in place relevant

institutions

• Best quality exported; poorer quality

consumed domestically. Peanut

Maize

Coffee

Cocoa

Aflatoxin

Intervention

Medical

Agriculture

Surveillance

Enterosorption

Pre-harvest

Post-harvest

Crop resistance to fungal infection or

aflatoxin biosynthesis

Biocontrol e.g. nonaflatoxigenic strains

Reduce crop stress- irrigation,

Insecticides, fungicides

Improved drying, sorting, insect control

and storage

Detoxification, e.g., ammoniation

Alternative uses

e.g. Novasil clay

Agriculture & Medical Prevention of Aflatoxin-

related Food Security and Health Effects

(Adapted from Wild and Hall, Mutation Res., 2000)

Awareness

Regulation

Provision of safe food

Early diagnosis

Agriculture Based Prevention of Aflatoxin-

related Food Security and Health Effects

• Pre-harvest

– Resistant cultivars, if available

– Biological control, e.g., aflasafe

– Irrigation and water conservation practices

– Lime and FYM application

• Post-harvest

– Sorting

– Insect control

– Improved drying and storage

– Detoxification, e.g., ammoniation

– Alternative uses including blending

www.iita.org

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 (60) 91 (90) 97 (96)

RSYN3-W 88 (46) 74 (94) 97 (97)

SYN3-Y 68 (66) 91 (95) 97 (98)

TZB-SR (Susc.) 58 (1152) ppb 92 (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 at Harvest and after poor storage

Contaminated Crops have Uses and Can be Valuable

Markets are needed to provide value to crops unsafe for human consumption

US FDA

Action Level

Permitted Use

(Examples)

500 ppb Middleman (Blender)

300 ppb Finishing Beef

200 ppb Finishing Swine

100 ppb Breeding beef and

swine; mature poultry

20 ppb Human Food, Feed

0.5 ppb (M1) Milk

Ammoniation is Highly

Effective in

Eliminating Aflatoxin

Trade Based Prevention of Aflatoxin-related

Food Security and Health Effects

• Awareness campaigns to increase demand for aflatoxin safe products

and incentivize adoption of aflatoxin control strategies along the value

chain

• Upgrade food control system

• Enhanced laboratory capacity and availability of rapid test kits, trained

users, documentation of results and withdrawal of contaminated

products

• Improved trader compliance with national regulatory codes

• Create a commodity exchange system such as warehouse receipts

• Improve enforcement mechanisms for domestic, import and export

trades

www.iita.org 28

Awareness and Training

Branding for Aflatoxin Testing as a Case for Self-Regulation

Breeding Tens of Millions of dollars spent for over 40 years… No results

Exceptionally difficult problem due to complex trait

Leading international seed companies given up

Storage Pre-harvest problem, that can be made worse post-harvest

Toxic levels exist at harvest… Garbage in garbage out

Studies

• Health

• Economics

• Trade

Already regulated to the most stringent standards globally; 0.05 ppb in milk

26 animal studies have proven health effects; Why test on African children

Prevalence and severity can shift 100 fold in one year

Fungus likes warm, humid places… A.K.A, African Tropics

Aflatoxin reduces the revenue potential of poor farmers

Alternative

uses

A critical piece of the puzzle, but is NOT a solution

Alternative uses would by default create a lower price market

Must first control, or volumes would be too large to be sustainable

Biocontrol Proven, Cost Effective Solution

Solves the problem at it’s root cause

Dedicated team of African and International partners

Builds on over a decade of work to fin real solution for Africa

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Aflatoxin Problem Starts in the Field

0

20

40

60

80

100

120

140

160

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Farmers

Afl

ato

xin

(p

pb

)

792 309

2010: Maize

64% fields above 20 ppb at harvest in northern Nigeria

Increases in stores; interventions required in field and stores

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Texas 2010: At harvest this field’s grain contained 400 to 1200 ppb aflatoxins

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AF36

Aflaguard

Biocontrol WORKS

In 100’S of thousands of acres in

the US!

IT WORKS In Africa

TOO!

Aflasafe

www.iita.org

From an article in Southwest Farm Press by Ron

Smith published October 24th, 2011 in which Ron

interviews Dr. Jim Swart, Integrated Pest

Management Specialist, Texas A&M based in

Commerce, Texas

• In spite of 40 years of research, no

aflatoxin resistant cultivars are

available commercially

• Biocontrol is the only viable solution

used by farmers

Strong Partnership

www.iita.org

• IITA

• USDA

• AATF

• BMGF

• Doreo Partners

• KARI

• Several African institutions Training is an important

component

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Aflatoxin Mitigation by Native

Beneficials: Principles In nature, some strains produce a lot

(toxigenic), and others no aflatoxin

(atoxigenic)

Atoxigenic strains identified from

nature, introduced in a carrier, and

applied in fields to exclude toxigenic

strains

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.

www.iita.org

Atoxigenic Strain Identification

Collection/characterization Toxin assay

Lab

competition

assay

VCG/DNA characterization

cnx nia-D

Unknown 2

+

Pre-field selection criteria

does not produce aflatoxin

can genetically not produce aflatoxin

can genetically not produce CPA

outcompetes toxigenic strains

belongs to different clonal lineages (SSR)

VCG with wide geographic distribution in country

VCG does not contain a single toxigenic member

~12 native strains are tested in the field

Selection of 4 strains

selection criteria:

superior capacity

to colonize,

multiply and

survive

superior field

efficacy in

reducing aflatoxin

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4 native strains formulated

into a registered product

NAFDAC officials inspecting maize fields treated with AflaSafe

Product: Aflasafe

Mixture of 4 native atoxigenic strains

Nigeria

How Does aflasafe Work?

Broadcast @ 10 kg/ha 2-3 weeks before flowering

Sporulation on moist soil

Spores

Insects

Aflasafe in 5 kg boxes

3-20 days

Wind

Soil colonization

30-33 grains m-2

Fungal network in killed grain

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Farmers treating maize and groundnut fields with Aflasafe in Nigeria

MAIZE: Aflatoxin reduction (%)

Stage 2009 2010 2011

Harvest 82 94 83

Storage 92 93 x

PEANUT: Aflatoxin reduction (%)

Stage 2009 2010 2011

Harvest - 95 82

Storage 100 80 x

Results from 382

on-farm trials

71% and 52% carry-over of

inoculum 1 & 2 years after

application

www.iita.org

0

10

20

30

40

50

60

70

80

90

untreated fields treated fields

reco

ve

ry o

f re

lea

se

d

ato

xig

en

ic s

train

s (

%) soil before inoculation

soil at harvest grain at harvest

Recovery of Atoxigenic Strains from

Treated and Untreated Fields

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Aflatoxin Reduction in 4 zones 4

Months after Poor Storage in Nigeria

0

200

400

600

800

Birnin Gwari Lere Maigana Pampaida

Afl

ato

xin

(p

pb

) Control

Treated

96

14

271

49

646

17

171

9

85% 82% 99% 95%

% reduction in aflatoxin reduction in treated fields over control

Mean

reduction

90%

Moist conditions may lead to moulding of feed

Aflasafe-treated maize: non-toxic strains grow

Non-aflasafe maize: mostly toxic strains grow

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

(%)

Aflasafe

untreated

Productivity increased of communities in

aflasafe-treated areas

DALYs saved: 103,000 - 184,000 cost-effectiveness ratio: 5.1 - 24.8

Source: Felicia Wu, Pittsburgh Univ.

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Impact of Aflasafe on Trade and Health

Aflasafe Development in Kenya

• More than 3,400 isolates recovered from 263 maize samples obtained between 2004 and 2006 from the Eastern, Coast and Rift Valley

• 11 atoxigenic VCGs (13 strains) repatriated to Kenya and tested in three experimental stations.

• Reduced aflatoxin contamination in on-station trials by 88%

• Four selected and formulated as aflasafe KE01

• 4.5 tons inoculum shipped from Nigeria to Kenya

• 240 efficacy trials completed in farmers’ field in 2012; 200 more in 2012/2013

Plots

Observed

aflatoxin

Apparent

reduction

Applied

VCGs

in Control

Aflatoxin if

Applied VCGs

not Present

Actual

Reduction

Treated 17 ppb

64% 88%

Control 49 ppb 66% 143 ppb

Data Measured Calculated Measured Calculated Calculated

Apparent Versus Actual Reductions in Maize Aflatoxin

Content, Bura Irrigation Scheme, 2011

Observed Aflatoxin = Quantity of total aflatoxin measured in the harvested crop.

Apparent Reduction = Calculated from the Observed Aflatoxin = [1 – (Treated Observed Aflatoxin ÷ Control

Observed Aflatoxin)] x 100.

Percent Applied VCGs in Control = the percent of the overall A. flavus community on the harvested crop composed

of the applied atoxigenic VCGs. Measured by performing Vegetative Compatibility Analyses on isolates from the

harvested crops.

Toxin if Applied VCGs not Present = Control Observed Aflatoxin ÷ [1 – (% Applied VCGs in Control ÷ 100)].

Actual Reduction = [100 – (Treated Observed Aflatoxin ÷ Aflatoxin if Applied VCGs not Present)] x 100.

www.iita.org Farmers treating groundnut fields with

AflaSafe

Aflatoxin Reduction:

2010 : 87% at harvest; 89% after Storage

2011: 82% at harvest; 93% after Storage

Senegal

38 Farms Treated in 2010



Area-wide application: 196 Farms Treated in 2012

La

Capacity Development

Laboratory infrastructure

• Burkina Faso

• Kenya

• Zambia

Human Technical capacity

• Senegal

• Ghana

• Cameroon

• Tanzania

• Nigeria

53

Awareness and Training

B

Ownership and Advocacy by the Nigerian Government

Billboard Interactive Forum

A commercialization strategy for distribution and adoption being piloted Consider Aflasafe as public health intervention for aflatoxin

Policy Statement by the Honorable Minister of Agriculture, Nigeria

Various Nigerian stakeholders have developed a 5 year, 4 step commercialization plan. All parties involved, IITA, Doreo, and the government, have critical roles to play over the next five years to ensure that Aflasafe treated food crops are successfully introduced into the market.

When we consider the potential benefits of Aflasafe, it is ultimately the smallholder farmer who stands to gain the most benefits. Farmers consume 65% of the maize they produce thus they stand to benefit the most from the improved health benefits of Aflasafe maize. Trading in Aflasafe products also increases smallholders’ opportunity to access premium and foreign markets where the product is in demand.

How do we Generate Demand in the Medium-Term

• 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

• Being piloted by Doreo Partners

Babban Gona Franchise Pilot

• Farmers’ cooperative with professional management

• Credit, inputs and technical services

• Yield enhancing practices

• Aflasafe use

• Aflatoxin testing – 100% met standard

• Incentive for meeting aflatoxin standard

• Warehousing

• Output marketing – linking to market

• Return profit after sale

• Farmers keep part of the harvest for family use

Poultry feeding study

• Stakeholders’ meeting on 15 Jan

• Poultry producers with farmers’ groups on one platform

• Build relationships and create sustainable market

Farmers’ Willingness to Pay

100% 99%

83%

60%

25%

19%

34% 31%

18%

12%

5% 4% 0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

$0 $3 - $6 $6 -$9 $9 - $12 $12 - $15 $15 - $19 $20

Farmers who have used Aflasafe (n=246) Farmers who have not used Aflasafe (n=119)

Target Farm Gate Price

Range

Source: Godwin Okpachu & Tahirou Abdoulaye

• 365 farmers in Kano and Kaduna interviewed in Nigeria

• All prior-users willing to pay; almost 50% non-users willing to pay

• Prior-users willing to pay more than non-users

AF36 manufacturing facility Arizona Cotton Research & Protection Council, USA

Innovative Product, Excellent Efficacy……. SCALING!

Manufacturing facility in

Africa is the missing piece for SCALING

Aflasafe plant in Nigeria (under construction)

Capacity:

5 tons/hour OR

4,000 ha per shift

• G20: Aflasafe incentivization selected for implementation in Nigeria

• Aflasafe will be used by smallholder farmers in 200,000 ha

Strategic Plan to Drive Sustainability Leverage Strong Regulatory Enforcement to Sustain Premium Market for Aflasafe maize

64

1

Year

2 3 4 5

PACA and Pull Mechanism Generate Supply of

Cost Effective Low

Aflatoxin Maize

Enforce Regulatory

Policy

Enable Market

Forces to Drive

Sustainability

Promote Health

Awareness to Value

Chain Actors

Policy:

Build

Regulators

Capacity

Policy:

Develop

regulatory

framework

Policy: Phased in regulatory enforcement mechanism

Market Forces

Health Awareness: Farmer Focus

Health Awareness: Industry

Focus Health Awareness: End Consumer

1

2

3

4

Partnerships are Key: Nigeria

• USDA-ARS, IITA, Universities of Ibadan and Bonn: Technology development

• GTZ/AATF/EU/BMGF: Funds

• Doreo Partners: Commercialization

• AATF: Intellectual propriety

• USDA-FAS: Registration

• NAFDAC: Regulation, monitoring

• Ag Dev Program (extension): Testing/promotion/awareness

• Maize Association of Nigeria: Promotion/awareness

• Ministry of Health: Promotion/awareness

• Ministry of Agric: Promotion/awareness

• Nigerian Mycotoxin Society: Awareness

• Commercial Ag Development Program: Testing/awareness

• Millennium Village Program:

Testing/awareness

• Nestle: Market

• Babban Gona: Commercialization

• Obasanjo Farms: Poultry Study

• Poultry Association of Nigeria: Market

• UNIDO: Promotion/investor forum

• Nigerian Export Promotion Council:

Promotion/investor forum

• NEPAD Business Group: Promotion/investor

forum

• Nigerian Economic Summit Group:

Promotion/investor forum

• Bill and Melinda Gates Foundation:

Promotion/commercialization

National Products

www.iita.org

Products ready for registration

Products under testing in farmers’ fields

Strain development to start or in progress

Aflasafe-NigeriaTM

Aflasafe-SenegalTM

Aflasafe-KenyaTM etc…

Aflasafe-WestTM

Aflasafe-EastTM

Aflasafe-SouthTM

Regional Products

Senegal Mali

Burkina

Ghana

Nigeria

Kenya

Tanzania

Mozambique

Zambia

Aflatoxin Biocontrol Facts

Crops are infected by complex

communities of diverse fungi Fungal communities differ in aflatoxin-

producing ability & this influences crop

vulnerability to contamination. Atoxigenic

strains can be used to reduce aflatoxin-

producing ability.

There are many atoxigenics Select safe strains best adapted to cropping

systems, ecosystems, & climates

Atoxigenics are Already

Present on the Crop Just increase the frequency of endemic

strains & natural interference with

contamination

Treatments May have

Long-Term Influence

& Cumulative

Benefits

More than One Crop

May Benefit From

the Applied Strain

Atoxigenic Strains can

be Applied Without

Increasing Infection and without increasing the overall

quantity of A. flavus on the crop &

throughout the environment

Summary • Aflatoxins in food and feed pervasive in Africa

• Biological control in conjunction with other management practices can dramatically reduce aflatoxin contamination

• Efforts underway to pilot commercialization of aflatoxin biocontrol and develop regional strains

• Technologies available but must be implemented to reduce aflatoxin burden in African economies and food system

• Support and partnership needed from national governments, regulators, donors/investors, private food/feed sector and farmer groups

IITA Aflasafe Team

Science

Aflatoxin impacts and management