Aflatoxins, major contributions to harvest loss – what do we know and what don’t we know?

Lindahl, J

Grace, D

Agriculture for development conference

Uppsala

September 2013

The topics of today

• What are aflatoxins?

• Why are aflatoxins so important?

• Health and economic impact?

• Losses?

• What can be done?

• Where is the research now?

White maize cobs with different severities of Aspergillus colonization. Photo by IITA..

Why a veterinary public health question?

The concept of one health

Ecosystem health

Animal health

Human health

Why a veterinary public health question?

What is necessary for health?

Food security

Food safety

Health

Measuring and mitigating the risk of mycotoxins in maize and dairy products for poor consumers in

Kenya

The MyDairy project

What are aflatoxins?

• Aflatoxin “discovered” as the cause of Turkey X disease, 1960s

• Toxin produced by Aspergillus spp, mainly Aspergillus flavus and Aspergillus parasiticus

• Aspergillus flavus toxin

http://www.fda.gov/Food/FoodborneIllnessContaminants/CausesOfIllnessBadBugBook/ucm070664.htm

Characteristics

• Invisible toxin

• Odourless

• Heat-stable Clean maize or fungus-free maize cobs. Photo by IITA.

Consequence: not always a loss of harvest noted, but a loss of safe products

Why is the toxin there?

• Fungi infect stressed crops pre-harvest, during harvest or during storage

• Especially susceptible crops: maize, groundnuts

• Maize ear rot

• Optimum temperature 37C (range 12-48)

• Mainly tropical disease

• Metabolic by-product from certain strains

Photo by CIMMYT.

Photo by IITA. Aspergillus naturally infected groundnuts in Mozambique.

What promotes the fungal growth?

• Pre-harvest: damage by insects, draughts

• Insects cause damage and are mechanical vectors

• Post-harvest: Poor storage conditions

Improper drying of grains - Different grains being dried on roadside with rains looming in the horizon. Photo by IITA

What is the problem?

• Aflatoxin one of the most potent carcinogens known

• Acute aflatoxicosis

• Hepatotoxic

• Chronic exposures

• Carcinogenic- hepatocellular carcinoma

• Immunomodulation?

• Stunting?

How gigantic is the problem?

• Maize and groundnuts staple foods

• Acute outbreaks can claim 100s of lives (Kenya outbreak 2004-2005 150 known fatal cases)

• 4.5 billion people chronically exposed (estimate by US CDC)

Food crops such as maize, tomatoes, yam tubers, bunches of plantain on sale at ijaye market, Oyo State, Nigeria. Photo by IITA.

More problems?

• International standards

Ref: Wu. VOL. 38, NO. 15, 2004 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

FDA limits

National limits

The effect on trade

• Estimated that total mycotoxin losses in the states are 1.4 billion USD annually

• Some years farmers are forced to dispose of half their crops of corn and peanuts

• Thailand, Indonesia, Phillipines total market loss: 200 million USD (and 700 million USD costs for livestock losses and health costs)

The effect on trade

When EU harmonized the limits:

• Decrease to 4 ppb: saves 2 lives per billion

• Europe receives 57% of African and Middle eastern exports

• Estimated to decrease African exports by 64% (670 million USD)

• Peanuts one of Africa’s few export commodities (Gambia, Senegal, South Africa)

The consequences of export barriers

• The best products are exported

• The bad products are left to the national markets

Photo by IITA.

Why the sudden alert?

• Been known for a while

• International standards reinforced

• Little problem in most countries

• New rules that food aid should be purchased partly locally

Problems moping up: What to do with contaminated crops?

What is done with mouldy food?

• Feed to chicken

• Feed to other animals

• Discard in pit, manure

• Mix with good crop and mill

• Wash, dry, re-cook

T. Kiama, unpublished

What is done to mouldy feed?

• Discard for manure

• Keep feeding, or dry before feeding

• Dry and mix with new feed

• Burn (4 out of 54 groups)

T. Kiama, unpublished

What can be done?

• Genetically modified maize (Bt corn)

• Saves 23 millions in the US

• Aflasafe

• Dr Charity Mutegi awarded World food prize 2013

• Aflatoxin binders?

Improved maize plants with mature cobs in a field in northern Nigeria. Photo by IITA.

Where is the research? Knowledge, attitudes and practices

• What is the KAP among the dairy value chain?

Participatory epidemiology among farmers (T. Kiama, unpublished results)

• 53/54 says mouldy food is dangerous

• 20/54 says it is poisonous or can kill

• 5/54 know about aflatoxin or know that mould can cause cancer

Where is the research? Knowledge, attitudes and practices

• What is the KAP among consumers?

Consumers in low income and middle-high income areas (M. Walke, unpublished results)

• Low income areas:

• 55% know of aflatoxin (45% of these believe it can be transferred to milk)

• 53% think aflatoxin is a serious threat, 19% medium, 10% minor.

• Middle-high income:

• 80% know of aflatoxin(51% of these believe it can be transferred to milk)

• 32% think aflatoxin is a serious threat, 7% medium, 1% minor.

Where is the research? Gender influence

• What is the differences of KAP between men and women?

Where is the research? Children and stunting

• What is the association between aflatoxin exposure and childhood stunting?

• Exposure? RCT?

• What importance is aflatoxin exposure in milk to the childhood stunting?

• Consumption? Aflatoxin levels in milk?

Where is the research? Risk mapping exercises

• Global mapping of the presence of aflatoxin

• Risk mapping in Kenya

• Predictive mapping?

P. Ochungo

Maize consumption

P. Ochungo

Milk consumption

P. Ochungo

Where is the research? The dairy value chain

• Risk assessment of the value chain

• Consumption

• Levels

• Costs of aflatoxin within the dairy value chain

• Health

• Production

Farmer Consumer

Economic flow

Aflatoxin flow

Human exposure

Feed producer

AB1

AB1

AB1-> AM1

AM1

Corn/feed produced at farm

Corn/feed purchased

Milk produced at farm

AB1 AM1

Treatments

Feed seller Farmer

Veterinary services

Milk retailer

Agricultural services

Consumer

Where is the research? Willingness to pay

• Are people willing to pay for certified maize?

• Are people willing to pay for certified free milk?

Where is the research? Mitigations

• Can we find bacteria that stops the fungal growth?

• Can we find bacteria that bind the aflatoxin?

• Can we identify practices that decrease fungal growth and promote these?

Maize storage structure in Cameroon. Photo by IITA.

Conclusions

Maize storage barns. Photo by IITA.

Aflatoxins are serious threats to human and animal health

Aflatoxins cause crop losses for millions

The main burden is in low-income countries

Why a veterinary public health question?

What is necessary for health?

Food

security Food safety

Health

Food security

Food safety

A big team

• Delia Grace, PI • Johanna Lindahl, coordinator • Anima Sirma, PhD student • Daniel Mugangai, PhD student • Sara Ahlberg, PhD student • Maria Walke, master student • Teresa Kiama, post doc • Nadhem Mtimet • Elizabeth Waithanji • Pamela Ochungo • Nouhoum Traore • Partners at MTT, BecA, IFPRI • and all participants

This work is financed by Ministry of foreign affairs, Finland It is implemented in a partnership with International food policy research institute (IFPRI) MTT Finland Biosciences in eastern and central Africa (BecA) It contributes to the CGIAR Research Program on Agriculture for nutrition and health (CRP 4)

Acknowledgements

The presentation has a Creative Commons licence. You are free to re-use or distribute this work, provided credit is given to ILRI.

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