Poster by Vincent Were, Samuel Mutiga, Jagger Harvey, Vivian Hoffman, Rebecca Nelson, Michael Milgroom. For the BecA Opening, Nairobi, 5 November 2010.

1. Detection and Management of Aflatoxin Contamination in Kenyan Smallholder Maize
Vincent Were1, Samuel Mutiga2, Jagger Harvey1, Vivian Hoffman3, Rebecca Nelson2, Michael Milgroom2.
1Biosciences eastern and central Africa Hub, International Livestock Research Institute, Nairobi, Kenya;
2Dept. of Plant Pathology and Plant-Microbe Biology, Cornell University, USA; 3Maryland Population Research Center, University of Maryland, USA
Introduction Expected Outputs
Aflatoxins are potent toxins and carcinogens found in the human and
livestock food supply. They are produced primarily by the fungal -Build aflatoxin diagnostics capacity at the Hub, for use by African and
genus Aspergillus, a pre‐ and postharvest pest. These toxins other partners.
continue to be a major health problem in the developing world, where -Develop novel, higher throughput diagnostics (adapt Near Infrared
cases of acute exposure can be fatal. Aflatoxins are particularly Spectroscopy to detect Aspergillus in maize flour).
damaging to children’s health, stunting child growth and increasing
vulnerability to disease. The scope and dynamics of aflatoxin -Characterize the aflatoxin problem in the smallholder farmer food
contamination of food in many parts of sub‐Saharan Africa have yet supply.
to be clearly characterized. The BecA Hub is involved in a -Limit aflatoxin accumulation and exposure through identification of proper
collaborative effort to characterize the scope of the aflatoxin problem crop management and storage conditions.
in Kenya, develop new techniques for higher throughput diagnostics
and identify existing farmer practices that may help reduce aflatoxin
accumulation in smallholder maize.
Aflatoxin levels in smallholder maize
Maize in Kenya: a staple crop for people and a livestock feed
moldy maize grains posho mill (smallholder Ugali 90
Number of samples in each Aflatoxin (ppb) bracket
maize flour production) 80 Aflatoxin levels by area
50
45 70
40
60
Aflatoxin
35
Frequency (%)
(ppb)
30 50
25
40
20
15 30
10
5 20
0
10
Negatives Below 10 10 to 20 Above 20
Aflatoxin (ppb)
0
Bungoma Eldoret Kisii Kitale Machakos Makueni Nairobi
livestock feed milk
Conclusion: Maize samples from many areas were positive for aflatoxins, even
in a year in which aflatoxicosis was not a recognized problem (May-June 2009).
Mycelium sclerotia
kernels Cobs Debris http://www.aspergillusflavus.org/aflavus
Grain scoring
Posho mill users visually sort out moldy and damaged grains. We are
investigating whether sorting reduces aflatoxin levels in maize meals,
BecA Hub: and if so, identifying which kernel characteristics can be used for
Sample collection and analysis sample analysis effective sorting. The kernel integrity; moldiness, discolor, rot (MDR); and
kernel texture was measured and correlated with aflatoxin levels. Data
analysis is in progress.
High MDR score Low MDR score dent flint
Aflatoxin extraction
Potential Management Strategies
•Biological control – using atoxigenic Aspergillus which grows faster than
Helica MycoMonitor
Total Aflatoxin Assay, a
toxigenic Aspergillus.
solid phase direct
competitive enzyme •Some maize have genes that help in resistance (e.g, genes that
immunoassay with a
detection limit of 1 part enhance hardness of grain cover). Breeders can develop more
per billion (ppb).
already analyzed resistant maize varieties.
Vicam aflatest
(fluorometer/monoclonal
•Get a cheaper, easier and faster way of aflatoxin detection for
Analysis in progress antibodybased
consumers (e.g., at the posho mills).
affinity chromatography;
0.1‐300 ppb aflatoxin
measurement) •Reduce pre-harvest crop stress and insect damage, which favor fungal
infection.
Data analysis •Improve storage conditions.
Results Future directions
Of the smallholder maize samples tested to date (by Helica), 35% have •Completing analysis of 2009 and 2010 smallholder maize surveys.
tested positive for aflatoxin, 11% above the 10ppb level used by some •Incorporating VICAM and Near Infrared Spectroscopy (NIRS) in aflatoxin
countries as a threshold above which grains should not be consumed by analysis.
humans, and 3% were above the 20ppb used as the threshold by •Potential development of extension guide for training smallholder farmers
Kenya. Note that the samples were collected in 2009, a time when to properly dry, store and sort grain.
aflatoxicosis was not reported. Analysis of samples from an aflatoxicosis •Engagement of strategic national partners to better ensure impact for
year (2010) are in progress. smallholder farmers in Kenya and beyond.