Image: Said Karogo, a farmer in Kenya’s Tana River coastal region.
Kenyan scientists are advancing an innovative bio-control remedy that is helping smallholder farmers fight the scourge of aflatoxin.
The remedy comes in the form of a product known as Aflasafe KE01TM, which scientists say can dramatically reduce crop contamination by aflatoxins, a naturally occurring toxin produced by fungi found on various crops.
Scientists say almost 70 percent of Kenyans are at risk of chronic exposure to the toxins, which killed 150 people from lower Eastern Kenya who consumed highly contaminated maize during the 2004 and 2005 cropping seasons, according to Dr. Eliud Kireger, director general of the Kenya Agricultural and Livestock Research Institute (KALRO).
Additionally, the government declared at least 2.3 million bags of maize unfit for human and livestock consumption and trade as a result of aflatoxin contamination in 2010, Kireger said. Another 155,000 bags were declared similarly unfit in 2014.
The events underscored the need to focus on taming aflatoxin, which remains a major challenge to maize production and significantly decreases the quality of the crop, in addition to posing a health hazard, he said. Aflatoxins have been categorized as carcinogens and could be a contributor to the increase in reported cancer cases in Kenya.
Aflasafe seems to be the best hope for controlling the production of the toxins in the field. The biopesticide is applied two-to-three weeks before the maize crop flowers to displace aflatoxin-producing fungal strains known as Aspergillus flavus.
“The adoption of this bio-control technology with other management practices by farmers will reduce aflatoxin contamination by over 70 percent in maize and groundnut, increase crop value by at least 5 percent and improve the health of consumers,’’ Kireger said.
Farmers also need to follow good agriculture practices for harvesting, drying and storage to minimize aflatoxin contamination as well as to curb general food loss, he said. Climate change and the accompanying extreme weather conditions, from drought to excessive rain, create favorable conditions for the fungus that produces aflatoxin. Any increase in aflatoxin contamination threatens food security.
An Aflasafe manufacturing plant — funded by the Bill & Melinda Gates Foundation and USAID, among other partners — was established in 2015 in Kenya. It has the capacity to produce 10 tonnes per day in the current first phrase and could ramp up further if demand increases. The funders established a similar manufacturing plant in Nigeria.
The product was tested in the Galana Kulalu irrigation scheme, an aflatoxin-prone maize- producing area. Initial tests confirmed the presence of pathogenic Aspergillus flavus S- strain in large proportions in the soil, indicating a potential high level of exposure to aflatoxin contamination. But after application of the product, 100 percent of the harvest was determined safe for human consumption.
”If applied properly and combined with good agricultural practices, Aflasafe effectively controls aflatoxin during crop development and post-harvesting,’’ said Dr. Charity Mutegi, East Africa Aflasafe coordinator and the 2013 Borlaug Prize winner for field research and application.
The continuous consumption of aflatoxin-contaminated foods and feed decreases productivity in people and animals, and can sometimes cause death, Mutegi said. Aflatoxin can cause liver cancer, suppress the immune system, and retard growth and development in children, among other health problems.
“One cannot see, smell or taste aflatoxin, even when the level of contamination is lethal. It takes a laboratory levels test to determine aflatoxin levels in food,’’ she said.
In Kenya, foods should have no more than 10 parts per billion of aflatoxin, Mutegi explained. The United States Department of Agriculture (USDA) allowable level of aflatoxin in corn for human and dairy cattle is 20 ppb.
Research by Gong et al., posits that human exposure occurs in utero, via breast milk, during weaning and consistently throughout an individual’s lifetime. Other direct exposure to aflatoxin, such as skin contact, inhalation and consumption of contaminated animal products, can also be harmful, experts said. Aflatoxin also poses a significant economic burden, causing an estimated 25 percent or more of the world’s food crops to be destroyed.
According to Raphael Wanjogu, chief research officer of the National Irrigation Board, Alfasafe keeps the soil free from aflatoxin. Prior to the development of Aflasafe, Kenya’s first maize crop was rejected by World Food Program due to high levels of aflatoxin. Of the 60,000 bags of maize produced, about 80 percent had more than 10 ppb, leading to rejection, Wanjogu recalled. These losses lowered the morale of smallholder farmers and diminished their zeal for cultivating the crop.
In response, farmers tried to control aflatoxin by observing cleanliness in handling crops and harvesting it in tumplines, a sort of sling carried on the back. But Aflasafe brought better results.
“With the introduction of Aflasafe, we have seen increased production,” Wanjogu said. “The average production now is 20 bags per hectare.’’ Seed farmers have also increased their income because seed crop is more valuable than a commercial product.
“With the introduction of Aflasafe in collaboration with KALRO and IITA, we have seen maize being accepted into the market and we can now open up to more partners like World Food Program to purchase maize from our farmers,” he added.
“We are also introducing a correlation between pastoral farmers and crop farmers, an interrelationship which is reducing conflict among communities,’’ said James Kirimi, manager of the Galana Kulalu Scheme. “We cannot mob out everything, but the Aflasafe can mitigate the levels of aflatoxin in the food chain,” he said.
John Asumbi, Hola Irrigation Scheme farmer’s leader, recalled his farming journey since 2009. “We have been farming food crops, mainly commercial maize. We also grow maize seed. In 2012-2013 aflatoxin infestation escalate. We were affected because we had maize with hope to get market. When we harvested, and scientists tested for aflatoxin, we discovered that our maize was contaminated with aflatoxin.
“Even though farmers continued farming in subsequent seasons, despite low morale, most of the farmer’s maize was not suitable for consumption,” he continued. “I personally at that time had harvested 38 bags of maize in my three-hectare farm — almost 60 percent was not suitable for consumption as it contained high levels of aflatoxin.
“So you can imagine the level of wastage that farmers acquired during that time. We did not give up and we continued farming,” Asumbi said. “The following season we applied Aflasafe as per the instructions from agronomists. Farmers planted maize in more than 2500 hectares. The maize was free from aflatoxin and millers bought maize from farmers.”
The good results are continuing, Asumbi said, with farmers harvesting more than 2,000 bags of aflatoxin-free maize that they sold to the county government.
Dr. Joel Ochieng, the agricultural biotechnology program leader at the University of Nairobi, told the Cornell Alliance for Science that although fungal infections are common in hot and humid conditions, mycotoxin infection can also occur in cool-dry and hot-dry environments.
Previous aflatoxin prevention mechanisms involved breeding fungal-resistant crops (selective breeding), biocontrol with atoxigenic fungal strains (similar principle to biopesticide), improved post-harvest storage methods and use of trapping agents to block uptake of aflatoxins.
However, millions of tons of crops continued to be lost due to aflatoxin each year, suggesting the need to complement these efforts with other technologies, Ochieng said.
To date, Aflasafe products have been registered for use in Nigeria and Kenya, according to Ochieng. Research is currently underway to secure registration of tailor-made Aflasafe products in Burkina Faso, Burundi, Ghana, Malawi, Mozambique, Rwanda, Tanzania, Uganda, and Zambia.