SPECIAL REPORT: Can Africa sort out the Aflatoxin problem?
Africa faces many challenges on the food front. The continent is grappling with efforts to feed its increasing population, projected to reach 2 billion by 2050, by the African Union. The presence of aflatoxin in foods has adversely affected not only the grain milling sector of the economy but also the health of the population and the ability of the Continent to trade with the rest of the World.
Perhaps no issue straddles the cereals sector in Africa like the issue of aflatoxin. The problem of aflatoxin in many African diets has had a huge but, many a time, silent effect on the population of Africa.
The presence of aflatoxin in maize, peanuts and other cereals is extremely critical in a continent where there are many challenges; including low productivity of cereals due to poor agronomic practices, high levels of post-harvest losses, low levels of sophistication in processing and handling of grains, frequent shortages that often lead to famines, and high consumer prices of grain
The issue of aflatoxins in cereals is a huge impediment to the nutritional and economic well-being of Africa’s population. For the cereal handling and milling sector of the food industry, the economic and nutrition effects of aflatoxin in grains are huge.
This is an issue that worries Stephen Muchiri, the CEO of the Eastern African Farmers Federation (EAFF), Nairobi, Kenya, to no small extent.
Mr Muchiri, who heads this regional farmers association, contends that “national governments don’t seem to be doing enough to create awareness on this issue to farmers, traders, processors and consumers; establish and invest in data collection and enforce the regulations especially on standards of various products”.
He also adds that farmers are “not at all equipped with the know-how or alternatives or tools for control of aflatoxin”.
Aflatoxins tend to affect Africa quite drastically as the entire continent falls within the 40 N and 40 S of the equator, where aflatoxin prevalence is most common.
In Africa, the problem is caused by various factors such as drought, poor agricultural practices, as well as improper storage and postharvest handling systems. It is further exacerbated due to heavy dietary reliance on staple foods such as maize and groundnuts which are highly susceptible to aflatoxin, according to Amare Ayalew, PhD., the Program Manager for Partnership for Aflatoxin Control in Africa (PACA), an Africa wide forum based at the African Union, based in Addis Ababa, Ethiopia.
What are aflatoxins?
Aflatoxins are toxic metabolites produced by certain fungi in/on foods and feeds. They are mainly caused by some strains of Aspergillus flavus, but also most if not all strains of A. parasiticus, A. niger and A. nomius.
The occurrence of aflatoxins iscommon inpeanuts, tree nuts, maize, and animal feeds while they are occasionally found in milk, cheese, cottonseed, nuts, almonds, figs, spices, and a variety of other foods and feeds. Milk, eggs, and meat products are sometimes contaminated because of the animal consumption of aflatoxin-contaminated feed
There are 4 main types of aflatoxins that are important as contaminants of food and feed: B1, B2, G1 and G2; and those that are metabolic products: M1 and M2
Aflatoxin B1 and B2 are so named because they exhibit blue fluorescence under UV light; G1 and G2 exhibit yellow-green fluorescence under the same conditions. M1 and M2 were first isolated from lactating cows fed aflatoxin feed, according to Cornell University College of Agriculture and Life Sciences
Aflatoxins have been associated with various diseases, such as aflatoxicosis, in livestock, domestic animals and humans.
Occurrence
It is critical to note that aflatoxin contamination starts at the farm, and that measures to control the menace should start when the produce from planting, harvesting, post-harvest handling, storage and distribution. While on the farm contamination is the least appreciated by many, further contamination can occur during drying, especially on the soil, and at storage or transport.
On the farm, aflatoxins contaminate the crop if harvesting is delayed and if the moisture content of the crop exceeds the required for crops stored at the farm after harvest. Bird and rodent attack of the crop at the farm is a great contributor to aflatoxin contamination.
Certain environmental factors influence the occurring of aflatoxin. The extent of contamination will vary with geographic location, agricultural and agronomic practices, and the susceptibility of commodities to fungal invasion during pre-harvest, storage, and/or processing periods
The fact that the toxin is invisible to the naked eye creates a problem for farmers (and traders and processors) who work on the principle of ‘seeing is believing’, according to Mr Muchiri of EAFF. There is also the common wisdom that visibly damaged and rotten grains find easy use in feeding of livestock at the farm, which transfers the problem to the animals
Mr Muchiri contends that predisposing factors, including high temperature related stresses and droughts, wet harvest, insect damage and high moisture post-harvest conditions, are common in most African farms, thereby making the aflatoxin problem have a huge burden on the continent.
Aflatoxins affect the population
The Food and Agriculture Organisation of the UN approximates that 25% of the world’s crop is affected by mycotoxins, the majority of which is aflatoxins, or about 4.5 billion of the current 7 billion population of the world. In sub-Saharan African alone, an estimated 26,000 people die annually of liver cancer associated with aflatoxin exposure, according to IFPRI
Aflatoxins and other mycotoxins affect trade, consumer safety and the economic health of the population and countries. Aflatoxins exhibit potent carcinogenic effect in susceptible laboratory animals and have acute toxicological effects in humans.
Kenya has faced some well-known challenges with aflatoxin, with the 2004 case of aflatoxicosis that led to the death of 125 in its Eastern Province, being the most publicized. According to the International Food Policy Research Institute, (IFPRI), Washington USA, investigations by the US Centres for Disease Control & Prevention (CDC) and the World Health Organisation (WHO) after the 2004 case showed that aflatoxicosis was the cause of these deaths.
The effect on trade is also enormous. Dr Ayalew of PACA confirms that it is estimated that Africa loses US$ 450 million a year from lost export trade due to aflatoxins.
With the CDC recently showing through a study that over 60% of the Kenyan population is chronically exposed to aflatoxin, Charity Mutegi, PhD., a researcher at the Kenya Agricultural Research Institute (KARI) and who is Kenya Country Coordinator for the Aflatoxin Biocontrol Project at International Institute of Tropical Agriculture (IITA), is concerned about the adverse effect of aflatoxin on the economy and health.
The award winning Dr Mutegi, was the 2013 recipient of the Norman Borlaug award for Field Research and Application for her work on aflatoxins.
Dr Mutegi, who spearheaded efforts to identify the cause of, and solution to, a deadly outbreak of aflatoxicosis in Kenya in 2004-05, says that aflatoxin leads to loss of livelihoods caused by poisoning; economic burden of treating aflatoxin related illnesses; loss of trade when food is condemned in markets with stringent regulatory and testing mechanisms; and nutritional effects that cause stunting in children and immune suppression that affect the lives of the children throughout their lifetime
“The devastating effects of maize grain contaminated with aflatoxins on many Kenyan households cannot be understated. Several lives have been lost, tons of staple food destroyed, millions of shillings worth from the livestock sector have been lost; and by extension, several livelihoods have been destroyed through death and/or economic disempowerment,” Dr Mutegi says
Research has shown that aflatoxins cause liver damage, decreased milk and egg production in birds and animals, recurrent infection as a result of immunity suppression, in addition to embryo toxicity in animals consuming low dietary concentrations.
Young children and the young of animals are most susceptible, although all ages are affected but in different degrees for different species. Aflatoxin causes stunting in children which results to delayed development
Clinical signs of aflatoxicosis in animals include gastrointestinal dysfunction, reduced reproductivity, reduced feed utilization and efficiency, anaemia, and jaundice. Nursing animals may be affected as a result of the conversion of aflatoxin B1 to the metabolite aflatoxin M1 excreted in milk of dairy cattle,
Aflatoxins are also known to cause cancer in animals, with aflatoxin B1, M1 and G1 having been shown to cause various types of cancer in different animal species. However, only aflatoxin B1 is considered by the International Agency for Research on Cancer (IARC)as having produced sufficient evidence of carcinogenicity in experimental animals to be identified as a carcinogen.
Recent research that aflatoxin may hasten the spread of infectious diseases by suppressing the immune system.Pauline Jolly, PhD professor in the Department of Epidemiology at the University of Alabama, US, has produced work that suggests aflatoxin exposure is having particularly detrimental effects in areas with high HIV rates, according to theinformationdaily.com
In the study, 314 HIV-positive Ghanaians, who had not yet started taking antiretroviral medication, were tested both for their exposure to aflatoxin and their HIV ‘viral load’, which translates to likelihood of transmission from person to person. It was found that those with the highest exposure to aflatoxin were also 2.6 times more likely to have a higher than average viral load.
Control measures exist
The control of management of aflatoxins is a complex problem and requires an integrated approach, according to Dr Ayalew of PACA. A combination of technology solutions, effective regulations and standards, and enabling environment could bring about mitigation and control of aflatoxin on the continent, he adds
“It is important for producers to realize that good agricultural practices (GAP) represent the primary line of defense against contamination of cereals with mycotoxins, followed by the implementation of good manufacturing practices (GMP) during the handling, storage, processing, and distribution of cereals for human food and animal feed”. This statement, from the Codex Alimentarius, is perhaps the most critical in the possibility of the African continent on reducing the impact of aflatoxin in its food systems
Well tried and tested methods exist, including drying grains to the right moisture content (water activity); separation of grain using colour sorters, and fairly traditional ways, including the application of ash or decorticating of the grains, which have been found to be effective ways to reduce aflatoxin.
Bio-control at the farm
It is worth noting that Codex Alimentarius advices that good agricultural practices on the farm are the first line of defense in dealing with aflatoxin.
According to Dr Mutegi, the biocontrol product for aflatoxin management currently under testing in Kenya is Aflasafe KE01. Aflasafe KE01 is a mixture of spores of the bio-control atoxigenic strains (non-toxigenic indigenous Aspergillus flavus fungi) that are coated onto sterile grain (sorghum), which serves as carrier and food for the fungi. The atoxigenic strains grow and multiply on, and disperse from, the carrier to initiate displacement of aflatoxin-producers in the field. The product is applied 2–4 weeks prior to crop flowering.
The product is broadcast onto the crop and soil at an application rate of 10 kg/ha. In Kenya, field testing for an even lower rate of 5kg/ha is underway, translating to a direct cost benefit to the farmer through reduced pricing as a farm input.
Dr Mutegi contends that this method has several advantages including: Modifications to fungal communities caused by application of bio-control strains carry over through the value chain, discouraging contamination in storage and transport, even when conditions are very favorable to fungal growth; Positive influences of atoxigenic strain applications carry over between crops and provide multi-year benefits, with a single application of atoxigenic strains benefiting not only the treated crop but also rotation crops and second season crops that miss a treatment; and that because fungi can spread, as the safety of fungal communities within treated fields improves, so does the safety of fungal communities in areas neighboring treated fields.
The effect of this treatment is therefore carried over year into year and the net effect is that the crop is protected throughout the supply chain. If this can be applied to African farms, and these benefits realised, the effect of aflatoxin in Africa will surely reduce drastically
Manage the whole supply chain
Grain millers and other food handlers and processors are advised to “embrace Total Quality Management systems that ensure the quality and safety of material as well as processes”, advices Mr Mutegi. Through such systems, sources of raw material will be known, production lines will be checked for sources of contamination, storage will be monitored, including packaging and even transportation of finished products. All these steps are possible entry/contamination points for aflatoxin.
African efforts getting organized
For a problem that engulfs the whole continent and which as Dr Ayalew, the program manager of the pan-African Partnership for Aflatoxin Control in Africa (PACA), reckons requires a ‘comprehensive, systematic and multi-sectoral approach’, it is good to note that continent wide and regional approaches are beginning to be formed to combat aflatoxin
This is where the (PACA) comes into the fore. PACA has a vision of an “Africa free from the harmful effects of aflatoxins”.
PACA was formed as a “consortium that aims to coordinate aflatoxin mitigation and management across the most affected sectors of health, trade and agriculture in Africa. As a continental, inter-governmental body, PACA’s role is to provide leadership and coordination for Africa’s aflatoxin control efforts, acting primarily as catalyst, facilitator, partnership and knowledge broker, project developer and information clearing house as well as knowledge management hub related to aflatoxins”.
“PACA also advocates for the establishment of enabling policies and institutions by working with regional economic communities and countries, for increased investment and the mobilization of resources, and acts as a grant maker to support catalytic projects on aflatoxin control priority areas while simultaneously promoting capacity building through the grants”, according to Dr Ayalew, the program manager.
Quite a mouthful mandate, but Dr Ayalew believes that with PACA strategically located within the African Union Commission (AUC), this provides the forum with “the opportunity to utilize the convening power of the AUC and the array of organs, institutions, and mechanisms to facilitate integration, harmonization, and joint action”, and hence should find it easier to deliver on this mandate.
PACA also works with Regional Economic Communities as well as other stakeholders such as technical organization, farmers’ organizations and the private sector. This is where the goals of farmers (as represented by Mr Muchiri’s EAFF, the Governments, researchers, food companies and other stakeholders meet
To add to these efforts, several regional bdies have been formed in the recent years including the Capacity and Action for Aflatoxin Reduction in Eastern Africa (CAAREA), which aims to reduce aflatoxin in Kenyan and Tanzanian maize.
The CAAREA project “will contribute to aspects of the PACA overall aims for Africa, bringing together a multi-disciplinary, multi-national team of scientists to help address the spectre of aflatoxins in eastern Africa” according to its website.
The project includes several partners including KARI, BecA-ILRI Hub, Tanzanian Agricultural Research Institute (ARI), The Commonwealth Scientific and Industrial Research Organisation (CSIRO) of Australia, the Tanzania Ministry of Agriculture and Food Security, Cornell University, among others
The project team is working to establish a regional mycotoxin analytical shared platform at the Biosciences eastern and central Africa – International Livestock Research Institute Hub (BecA-ILRI Hub). The platform will include a range of technologies including novel diagnostics well suited to the African context.
These include state-of-the-art, commonly accepted aflatoxin diagnostics and sample preparation and diagnostics technologies (Romer Mills, ultra high performance liquid chromatography mass spectrometry (UHPLC), enzyme-linked immunosorbent assay (ELISA) and immunocapture-fluorometry); as well as new technologies suited to the African research and crop improvement context (near infrared spectroscopy (NIR)), it adds
Other efforts include the Aflatoxin Policy and Program for the East Africa Region (APPEAR) which aims to ‘provide a comprehensive package of training, technical assistance and pilot operational research activities relevant’ to aflatoxin.
To add to these efforts, the East African Community (EAC) recently formulated the Regional Working Experts Group on Aflatoxins (REWGA) in March 2014 in Burundi. REWGA’s mandate is to provide technical and advisory guidance to EAC Sectoral Council on Agriculture and Food Security and key stakeholders in the region on prevention and control of aflatoxin in the region.
Aflatoxins are not alone
Aflatoxins are not the only mycotoxin groups to worry about, for there are many types of mycotoxins present in our food chain.
Mycotoxins are toxic metabolises produced by fungi, specifically moulds growing on foodstuffs or animal feeds. Mycotoxins, though part of the food chain for centuries, were just discovered in the 1960s and 1970s, with the conclusion that they in fact had been responsible for several cases of animal disease and death. In the decade following 1970 it became clear that mycotoxins have been the cause of human illness and death as well, according to the FAO
It has been established that mycotoxins had been responsible for ergotism, which killed thousands of people in Europe in the last thousand years, alimentary toxic aleukia (ATA) which was responsible for the death of many thousands of people in the USSR in the 1940s; stachybotryotoxicosis, which killed tens of thousands of horses and cattle in the USSR in the 1930s; and aflatoxicosis, which killed 100,000 young turkeys in England in 1960 and has caused death and disease in many other animals, and perhaps man as well, according to Wikipedia
The fact that studies report that 75-100% of the samples contain more than one mycotoxin is an important consideration in the management of mycotoxins.
Multiple occurrences of mycotoxins occur due to the fact that (i) mostfungiare able to simultaneously produce a number ofmycotoxins, (ii) commodities can be contaminated by several fungi, and (iii) completed feed is made from various commodities, according to a paper, Current situation of mycotoxin contamination and co-occurrence in animal feed–focus on Europe by Streit et al.
There are five major groups of mycotoxins that occur in food products: aflatoxins, Zearalenone, ochratoxin, fumonisins, and Deoxynivalenol
