Biomonitoring and determinants of mycotoxin exposures from pregnancy until post-lactation in HIV-infected and HIV-uninfected women from Harare, Zimbabwe

The human immunodeficiency virus (HIV) heavily affects women from resource-limited settings who are vulnerable to potentially harmful mycotoxins including aflatoxin B1 (AFB1), fumonisin B1 (FB1) and ochratoxin A (OTA). We aimed to conduct biomonitoring and ascertain the determinants of maternal mycotoxin exposure in pregnancy, lactation and post-lactation periods. We conducted a retrospective longitudinal study in HIV-infected and HIV-uninfected women from Harare, Zimbabwe. 175 and 125 random urine samples in pregnancy and 24 months after delivery (post-lactation) respectively were analysed for aflatoxin M1 (AFM1) and FB1 by ELISA. 6 weeks after delivery (lactation), 226 and 262 breast milk (BM) samples were analysed for AFM1 and OTA respectively by ELISA. The association of demographics and food consumption with mycotoxins was evaluated using multivariable logistic regression. In HIV-infected, urinary AFM1 was detected in 46/94 (Median: 0.05; Range: 0.04-0.46 ng mL-1) in pregnancy and 47/66 (Median: 0.05; Range: 0.04-1.01 ng mL-1) post-lactation. Urinary FB1 was detected in 86/94 (Median: 1.39; Range: 0.17-6.02 ng mL-1) in pregnancy and 56/66 (Median: 0.72; Range: 0.20-3.81 ng mL-1) post-lactation. BM AFM1 was detected in 28/110 (Median: 7.24; Range: 5.96-29.80 pg mL-1) and OTA in 11/129 (Median: 0.20; Range: 0.14-0.65 ng mL-1). In HIV-uninfected, urinary AFM1 was detected in 48/81 (Median: 0.05; Range: 0.04-1.06 ng mL-1) in pregnancy and 41/59 (Median: 0.05; Range: 0.04-0.52 ng mL-1) post-lactation. Urinary FB1 was detected in 74/81 (Median: 1.15; Range: 0.17-6.16 ng mL-1) in pregnancy and 55/59 (Median: 0.96; Range: 0.20-2.82 ng mL-1) post-lactation. BM AFM1 was detected in 38/116 (Median: 7.70; Range: 6.07-31.75 pg mL-1) and OTA in 4/133 (Median: 0.24; Range: 0.18-0.83 ng mL-1). Location, wealth, and peanut butter consumption were determinants of AFB1 exposure. HIV infection, BMI, location, rainy season, unemployment, and age were determinants of FB1 exposure. Women especially those pregnant and/or HIV-infected are at risk of adverse effects of mycotoxins.

Dietary exposure of school children to aflatoxin and fumonisin through githeri and effectiveness of nixtamalization in reduction of these toxins in githeri from Turkana County

Exposure of school children to aflatoxin and fumonisin is mainly through diet. In Kenyan public schools, children are given porridge made from maize flour for breakfast, a mixture of maize and beans, also known as githeri for lunch and ugali for dinner. Nixtamalization has proved to reduce mycotoxins in most cereals and not a mixture of maize and beans. This study, therefore, aimed to assess the exposure of primary school children in Turkana County to aflatoxin and fumonisin through maize-based food under the school meals program and the effectiveness of nixtamalization in the reduction of these mycotoxins. Samples of githeri were randomly collected from all public primary schools (n = 128) under the homegrown school meals program in Turkana County and analyzed for aflatoxin and fumonisin. The data was analyzed using SAS software, version 9.4. The deterministic model was used to calculate the estimated daily intake (EDI) and the margin of exposure (MOE) used to characterize the exposure risk. The contaminated samples were then treated with various concentrations of Ca(OH)2, 0.5-2.5%. The treated samples were cooked for 60 and 75 min and soaked for 6 and 8 h. Forty percent of the schools contained githeri samples with aflatoxin B1 levels above 5 µg/Kg, the maximum limit for Kenya. Exposure to aflatoxin B1 and total aflatoxin was up to 2 µg/kg/bw/day. The range for fumonisin exposure was 60-80 µg/kg/bw/day. Ca(OH)2 concentration levels of up to 2.5% reduced aflatoxin by 75% and fumonisin by 72%. The findings indicate that githeri is contaminated with aflatoxin and fumonisin which exposes school children to these mycotoxins and nixtamalization can be used to reduce mycotoxin contamination in githeri.

The role of maize sap beetles (Coleoptera: Nitidulidae) and maize weevils (Coleoptera: Curculionidae) in the spread of Aspergillus flavus in pre-harvest maize in Kenya

The spread of toxigenic Aspergillus into maize by insects and the subsequent aflatoxin contamination poses a risk to humans and animals and has been investigated in North and South America. To evaluate this effect in an African context, Greenhouse studies were conducted in 2022 to determine the role of sap beetles, Carpophilus dimidiatus Fabricius, 1792 (Coleoptera: Nitidulidae) and maize weevils, Sitophilus zeamais Motschulsky, 1855 (Coleoptera: Curculionidae) on infection of maize kernels by Aspergillus flavus Link and the resultant aflatoxin accumulation. To test the beetles' efficacy, treatments were applied on partially opened primary ears at 3 different stages of kernel development (BBCH 75, 83, and 87). The treatments were: (i) distilled water, (ii) water with A. flavus spores, (iii) maize grits, (iv) maize grits with A. flavus spores, (v) C. dimidiatus, (vi) C. dimidiatus with A. flavus spores, (vii) S. zeamais, and (viii) S. zeamais with A. flavus spores. Data on kernel infection, maize rotting, yield, and aflatoxin content in kernels were collected. The highest kernel spoilage and yield loss were recorded for the co-inoculation of S. zeamais and A. flavus spores, followed by S. zeamais without A. flavus spores, and then C. dimidiatus with the fungal spores. Inoculation of maize at the BBCH 83 growth stage resulted in the highest kernel damage and aflatoxin contamination. S. zeamais and, to a lesser extent, C. dimidiatus effectively spread the A. flavus inoculum into non-wounded ears, resulting in fungal and aflatoxin contamination. The yield loss from S. zeamais-Aspergillus co-inoculation occurred due to the grain rotting and actual feeding of the maize weevils. Thus, insect management is important in reducing pre-harvest contamination of maize with mycotoxigenic fungi and their resultant toxins.

Aflatoxins Levels in Concentrate Feeds Collected from Specialized Dairy Farms and Local Markets in Selected Urban Centers of Eastern Ethiopia

Aflatoxin constitutes a significant concern for food and feed safety, posing detrimental health risks to both animals and humans. This study aimed to examine the prevalence and concentration of aflatoxins in maize feed, total mixed ration, and wheat bran collected from specialized dairy farms and local markets in three major urban centers in eastern Ethiopia. A total of 180 feed samples were collected from September 2021 to January 2022 in Chiro town, Dire Dawa city, and Harar city. These samples underwent thorough extraction and immunoaffinity clean-up before aflatoxin analysis using HPLC/FLD. The results revealed that AFB1, AFB2, AFG1, AFG2, and TAF contamination was detected in 72.2%, 66.1%, 71.1%, 68.7%, and 82.8% of the feed samples, respectively. The corresponding mean levels of each aflatoxin were 28.15 ± 3.50, 3.3 ± 0.40, 19.87 ± 1.87, 2.7 ± 0.32, and 54.01 ± 4.72 µg/kg, respectively. The occurrence and levels of aflatoxin varied across different study sites and feed types. Notably, feeds from Dire Dawa city exhibited significantly higher mean levels of AFB1 (43.98 ± 5.3 µg/kg), AFB2 (5.69 ± 0.6 µg/kg), AFG1 (32.25 ± 2.7 µg/kg), and AFG2 (5.01 ± 0.5 µg/kg) than feeds from other urban centers did. Additionally, a significantly higher occurrence of AFB1 (29.4%) and AFG1 (28.3%) was detected in feed from Dire Dawa city. Similarly, the total mixed ration (TMR) displayed significantly higher levels of AFB1 (50.67 ± 5.2 µg/kg), AFB2 (4.74 ± 0.6 µg/kg), AFG1 (32.87 ± 2.6 µg/kg), and AFG2 (3.86 ± 0.5 µg/kg) compared to the other feed types. Moreover, a significantly higher occurrence of AFB1 (30.7%) and AFG1 (28.7%) was detected in the TMR. Furthermore, a moderate correlation was observed between the count of aflatoxigenic Aspergillus species and the levels of TAF in the feed samples. Overall, this study underscores the widespread presence of aflatoxin contamination in dairy feeds in eastern Ethiopia, highlighting the urgent need for stringent monitoring and mitigation measures to ensure food and feed safety, as well as public health.

Prevalence and concentration of aflatoxin M1 in breast milk in Africa: a meta-analysis and implication for the interface of agriculture and health

Breast milk is one of the many distinct forms of food that can be contaminated with aflatoxin M1 (AFM1). They may be consumed by eating contaminated foods, such as contaminated meat and crops, which would then be present in breast milk and cause health problems, including nervous system disorders and cancers of the lungs, liver, kidneys, and urinary tract. However, the prevalently inconsistent explanation of prevalence and concentration remains a big challenge. Thus, this meta-analysis was conducted to determine the prevalence and concentration of harmful chemicals in breast milk in an African context. The databases MEDLINE, PubMed, Embase, SCOPUS, Web of Science, and Google Scholar were searched for both published and unpublished research. To conduct the analysis, the collected data were exported to Stata version 18. The results were shown using a forest plot and a prevalence with a 95% confidence interval (CI) using the random-effects model. The Cochrane chi-square (I2) statistics were used to measure the studies' heterogeneity, and Egger's intercept was used to measure publication bias. This review included twenty-eight studies with 4016 breast milk samples and newborns. The analysis showed the overall prevalence and concentration of aflatoxin M1 in breast milk were 53% (95% CI 40, 65; i2 = 98.26%; P = 0.001). The pooled mean aflatoxin M1 concentration in breast milk was 93.02 ng/l. According to this study, the eastern region of Africa was 62% (95% CI 39-82) profoundly affected as compared to other regions of the continent. In subgroup analysis by publication year, the highest level of exposure to aflatoxins (68%; 95% CI 47-85) was observed among studies published from 2010 to 2019. This finding confirmed that more than half of lactating women's breast milk was contaminated with aflatoxin M1 in Africa. The pooled mean aflatoxin M1 concentration in breast milk was 93.02 ng/l. According to this study, the eastern region of Africa was profoundly affected compared with other regions. Thus, the government and all stakeholders must instigate policies that mitigate the toxicity of aflatoxins in lactating women, fetuses, and newborns.

Aflatoxins in food products consumed in the Kingdom of Saudi Arabia: A preliminary dietary risk assessment

Aflatoxins (AFs) are hepatotoxic, mutagenic, genotoxic, and immunosuppressive toxins. Several food commodities consumed in the Kingdom of Saudi Arabia (KSA) are susceptible to AF contamination because of improper storage practices and the warm and humid climate of the country. Therefore, the occurrence of AFs in 2388 food samples was measured and the estimated daily intake (EDI) of AFs in Saudi adults was assessed. The risks of AFB1 exposure were characterized using the margin of exposure (MoE) approach and by estimating the number of possible hepatocellular carcinoma (HCC) cases in the KSA. The results revealed that 12.1% of the analyzed samples were contaminated with AFs and the highest concentration of total AFs was observed in the nut and seed group. The mean EDI of AFB1 was estimated to be 0.21 and 0.55 ng/kg body weight (bw)/day for the lower bound (LB) and upper bound (UB) scenarios, respectively. The MoEs were estimated to be 1902.4 and 722.1, while the estimated liver cancer risk ranged from 0.002 to 0.008 cancer cases/year/100,000 persons. Based on the study's findings, contamination with AFs in the KSA is low; however, AFs are considered potent genotoxic contaminants, and therefore, exposure through food should be kept as low as possible.

Human Breast Milk Contamination with Aflatoxins, Impact on Children's Health, and Possible Control Means: A Review

Aflatoxins are natural toxicants produced mainly by species of the Aspergillus genus, which contaminate virtually all feeds and foods. Apart from their deleterious health effects on humans and animals, they can be secreted unmodified or carried over into the milk of lactating females, thereby posing health risks to suckling babies. Aflatoxin M1 (AFM1) is the major and most toxic aflatoxin type after aflatoxin B1 (AFB1). It contaminates human breast milk upon direct ingestion from dairy products or by carry-over from the parent molecule (AFB1), which is hydroxylated in the liver and possibly in the mammary glands by cytochrome oxidase enzymes and then excreted into breast milk as AFM1 during lactation via the mammary alveolar epithelial cells. This puts suckling infants and children fed on this milk at a high risk, especially that their detoxifying activities are still weak at this age essentially due to immature liver as the main organ responsible for the detoxification of xenobiotics. The occurrence of AFM1 at toxic levels in human breast milk and associated health conditions in nursing children is well documented, with developing countries being the most affected. Different studies have demonstrated that contamination of human breast milk with AFM1 represents a real public health issue, which should be promptly and properly addressed to reduce its incidence. To this end, different actions have been suggested, including a wider and proper implementation of regulatory measures, not only for breast milk but also for foods and feeds as the upstream sources for breast milk contamination with AFM1. The promotion of awareness of lactating mothers through the organization of training sessions and mass media disclosures before and after parturition is of a paramount importance for the success of any action. This is especially relevant that there are no possible control measures to ensure compliance of lactating mothers to specific regulatory measures, which can yet be appropriate for the expansion of breast milk banks in industrialized countries and emergence of breast milk sellers. This review attempted to revisit the public health issues raised by mother milk contamination with AFM1, which remains undermined despite the numerous relevant publications highlighting the needs to tackle its incidence as a protective measure for the children physical and mental health.

Drivers of Post-Harvest Aflatoxin Contamination: Evidence Gathered from Knowledge Disparities and Field Surveys of Maize Farmers in the Rift Valley Region of Kenya

Maize-dependent populations in sub-Saharan Africa are continually exposed to aflatoxin poisoning owing to their regular consumption of this dietetic cereal. Being a staple in Kenyan households, consumption of maize-based meals is done almost daily, thereby exposing consumers to aflatoxicoses. This study assessed awareness levels, knowledge disparities, and perceptions regarding aflatoxin contamination at the post-harvest phase among farmers in the Rift Valley Region of Kenya. Households were randomly selected using a geographical positioning system (GPS) overlay of the agro-ecological zones within Uasin Gishu and Elgeyo Marakwet counties. Face-to-face interviews were conducted in 212 smallholder and large-scale farms. The study documented the demographic profiles of farmers and knowledge, awareness, and perceptions of aflatoxin contamination using a pre-designed structured questionnaire. Most farmers were familiar with aflatoxins and the adverse effects they present to health (61.32%). Almost all the farmers (94.37%) were aware of storage molds and food-spoilage fungi. However, few farmers adopted good post-harvest practices (PHPs), such as avoiding premature harvests (49.8%), using well-ventilated storage spaces (44.6%), grain sorting (30.5%), proper drying of maize (17.8%), and using hermetic bags for storage (30.5%). Conclusively, intensified farmer education is required to train farmers on good PHPs to protect their maize from aflatoxigenic fungi and aflatoxin accumulation.

Climate Change and Effects on Molds and Mycotoxins

Earth’s climate is undergoing adverse global changes as an unequivocal result of anthropogenic activity. The occurring environmental changes are slowly shaping the balance between plant growth and related fungal diseases. Climate (temperature, available water, and light quality/quantity; as well as extreme drought, desertification, and fluctuations of humid/dry cycles) represents the most important agroecosystem factor influencing the life cycle stages of fungi and their ability to colonize crops, survive, and produce toxins. The ability of mycotoxigenic fungi to respond to Climate Change (CC) may induce a shift in their geographical distribution and in the pattern of mycotoxin occurrence. The present review examines the available evidence on the impact of CC factors on growth and mycotoxin production by the key mycotoxigenic fungi belonging to the genera Aspergillus, Penicillium, and Fusarium, which include several species producing mycotoxins of the greatest concern worldwide: aflatoxins (AFs), ochratoxins, and fumonisins (FUMs).

Ex Vivo and In Vitro Studies Revealed Underlying Mechanisms of Immature Intestinal Inflammatory Responses Caused by Aflatoxin M1 Together with Ochratoxin A

Aflatoxin M1 (AFM1) and ochratoxin A (OTA), which are occasionally detected in milk and commercial baby foods, could easily enter and reach the gastrointestinal tract, posing impairment to the first line of defense and causing dysfunction of the tissue. The objective of this study was to investigate the immunostimulatory roles of individual and combined AFM1 and OTA on the immature intestine. Thus, we used ELISA assays to evaluate the generation of cytokines from ex vivo CD-1 fetal mouse jejunum induced by AFM1 and OTA and explored the related regulatory pathways and pivot genes using RNA-seq analysis. It was found that OTA exhibited much stronger ability in stimulating pro-inflammatory cytokine IL-6 from jejunum tissues than AFM1 (OTA of 4 μM versus AFM1 of 50 μM), whereas the combination of the two toxins seemed to exert antagonistic actions. In addition, transcriptomics also showed that most gene members in the enriched pathway ‘cytokine–cytokine receptor interaction’ were more highly expressed in OTA than the AFM1 group. By means of PPI network analysis, NFKB1 and RelB were regarded as hub genes in response to OTA but not AFM1. In the human FHs 74 Int cell line, both AFM1 and OTA enhanced the content of reactive oxygen species, and the oxidative response was more apparent in OTA-treated cells in comparison with AFM1. Furthermore, OTA and AFM1 + OTA raised the protein abundance of p50/RelB, and triggered the translocation of the dimer from cytosol to nucleus. Therefore, the experimental data ex vivo and in vitro showed that OTA-induced inflammation was thought to be bound up with the up-regulation and translocation of NF-κB, though AFM1 seemed to have no obvious impact. Since it was the first attempt to uncover the appearances and inner mechanisms regarding inflammation provoked by AFM1 and OTA on immature intestinal models, further efforts are needed to understand the detailed metabolic steps of the toxin in cells and to clarify their causal relationship with the signals proposed from current research.

Lactic Acid Bacteria from African Fermented Cereal-Based Products: Potential Biological Control Agents for Mycotoxins in Kenya

Cereals play an important role in global food security. Data from the UN Food and Agriculture Organization projects increased consumption of cereals from 2.6 billion tonnes in 2017 to approximately 2.9 billion tonnes by 2027. However, cereals are prone to contamination by toxigenic fungi, which lead to mycotoxicosis. The current methods for mycotoxin control involve the use of chemical preservatives. However, there are concerns about the use of chemicals in food preservation due to their effects on the health, nutritional quality, and organoleptic properties of food. Therefore, alternative methods are needed that are affordable and simple to use. The fermentation technique is based on the use of microorganisms mainly to impart desirable sensory properties and shelf-life extension. The lactic acid bacteria (LAB) are generally regarded as safe (GRAS) due to their long history of application in food fermentation systems and ability to produce antimicrobial compounds (hydroxyl fatty acids, organic acids, phenyllactic acid, hydrogen peroxide, bacteriocins, and carbon dioxide) with a broad range of antifungal activity. Hence, LAB can inhibit the growth of mycotoxin-producing fungi, thereby preventing the production of mycotoxins. Fermentation is also an efficient technique for improving nutrient bioavailability and other functional properties of cereal-based products. This review seeks to provide evidence of the potential of LAB from African fermented cereal-based products as potential biological agents against mycotoxin-producing fungi.

Mycotoxin-mixture assessment in mother-infant pairs in Nigeria: From mothers' meal to infants' urine

Exposure to food and environmental contaminants is a global environmental health issue. In this study, innovative LC-MS/MS approaches were applied to investigate mycotoxin co-exposure in mother-infant pairs (n = 23) by analyzing matched plate-ready food, breast milk and urine samples of mothers and their exclusively breastfed infants. The study revealed frequent co-occurrence of two to five mycotoxins. Regulated (e.g. aflatoxins, deoxynivalenol and ochratoxin A) and emerging mycotoxins (e.g. alternariol monomethyl ether and beauvericin) were frequently detected (3 %-89 % and 45 %-100 %), in at least one specimen. In addition, a moderate association of ochratoxin A in milk to urine of mothers (r = 0.47; p = 0.003) and infants (r = 0.52; p = 0.019) but no other significant correlations were found. Average concentration levels in food mostly did not exceed European maximum residue limits, and intake estimates demonstrated exposure below tolerable daily intake values. Infants were exposed to significantly lower toxin levels compared to their mothers, indicating the protective effect of breastfeeding. However, the transfer into milk and urine and the resulting chronic low-dose exposure warrant further monitoring. In the future, occurrence of mycotoxin-mixtures, and their combined toxicological effects need to be comprehensively considered and implemented in risk management strategies. These should aim to minimize early-life exposure in critical developmental stages.

Management strategies for aflatoxin risk mitigation in maize, dairy feeds and milk value chains—case study Kenya

Widespread aflatoxin contamination of a great number of food and feed crops has important implications on global trade and health. Frequent occurrence of aflatoxin in maize and milk poses serious health risks to consumers because these commodities are staple foods in many African countries. This situation calls for development and implementation of rigorous aflatoxin control measures that encompass all value chains, focusing on farms where food and feed-based commodities prone to aflatoxin contamination are cultivated. Good agricultural practices (GAP) have proven to be an effective technology in mitigation and management of the aflatoxin risk under farm conditions. The prevailing global climate change is shown to increase aflatoxin risk in tropical and subtropical regions. Thus, there is an urgent need to devise and apply novel methods to complement GAP and mitigate aflatoxin contamination in the feed, maize and milk value chains. Also, creation of awareness on aflatoxin management through training of farmers and other stakeholders and enforcement of regular surveillance of aflatoxin in food and feed chains are recommended strategies. This literature review addresses the current situation of aflatoxin occurrence in maize, dairy feeds and milk produced and traded in Kenya and current technologies applied to aflatoxin management at the farm level. Finally, a case study in Kenya on successful application of GAP for mitigation of aflatoxin risk at small-scale farms will be reviewed.

The impact of management practices to prevent and control mycotoxins in the European food supply chain: MyToolBox project results

The presence of mycotoxins in cereals has led to large economic losses in Europe. In the course of the European project MyToolBox, prevention and control measures to reduce mycotoxin contamination in cereals were developed. This study aimed to estimate the impact of these prevention and control measures on both the reduction in crop losses and the increased volume of crops suitable for food and/or feed. It focused on the following measures: the use of fungicides during wheat cultivation, the use of resistant maize cultivars and/or biocontrol during maize cultivation, the use of real time sensors in storage silos, the use of innovative milling strategies during the pasta making process, and the employment of degrading enzymes during the process of bioethanol and Dried Distillers Grains with Solubles (DDGS) production. The impact assessment was based on the annual volume of cereals produced, the annual levels of mycotoxin contamination, and experimental data on the prevention and control measures collected in the course of the MyToolBox project. Results are expressed in terms of reduced volumes of cereals lost, or as additional volumes of cereals available for food meeting the current European legal limits. Results showed that a reduction in crop losses as well as an increase in the volume of crops suitable as food and/or feed is feasible with each proposed prevention or control measure along the supply chain. The impact was the largest in areas and in years with the highest mycotoxin contamination levels but would have less impact in years with low mycotoxin levels. In further research, the impact assessment may be validated using future data from more years and European sites. Decision makers in the food and feed supply chain can use this impact assessment to decide on the relevant prevention and control strategies to apply.

Improved Sample Selection and Preparation Methods for Sampling Plans Used to Facilitate Rapid and Reliable Estimation of Aflatoxin in Chicken Feed

Aflatoxin B1 (AFB1), a toxic fungal metabolite associated with human and animal diseases, is a natural contaminant encountered in agricultural commodities, food and feed. Heterogeneity of AFB1 makes risk estimation a challenge. To overcome this, novel sample selection, preparation and extraction steps were designed for representative sampling of chicken feed. Accuracy, precision, limits of detection and quantification, linearity, robustness and ruggedness were used as performance criteria to validate this modification and Horwitz function for evaluating precision. A modified sampling protocol that ensured representativeness is documented, including sample selection, sampling tools, random procedures, minimum size of field-collected aggregate samples (primary sampling), procedures for mass reduction to 2 kg laboratory (secondary sampling), 25 g test portion (tertiary sampling) and 1.3 g analytical samples (quaternary sampling). The improved coning and quartering procedure described herein (for secondary and tertiary sampling) has acceptable precision, with a Horwitz ratio (HorRat = 0.3) suitable for splitting of 25 g feed aliquots from laboratory samples (tertiary sampling). The water slurring innovation (quaternary sampling) increased aflatoxin extraction efficiency to 95.1% through reduction of both bias (-4.95) and variability of recovery (1.2-1.4) and improved both intra-laboratory precision (HorRat = 1.2-1.5) and within-laboratory reproducibility (HorRat = 0.9-1.3). Optimal extraction conditions are documented. The improved procedure showed satisfactory performance, good field applicability and reduced sample analysis turnaround time.

The Scourge of Aflatoxins in Kenya: A 60-Year Review (1960 to 2020)

Aflatoxins are endemic in Kenya. The 2004 outbreak of acute aflatoxicosis in the country was one of the unprecedented epidemics of human aflatoxin poisoning recorded in mycotoxin history. In this study, an elaborate review was performed to synthesize Kenya’s major findings in relation to aflatoxins, their prevalence, detection, quantification, exposure assessment, prevention, and management in various matrices. Data retrieved indicate that the toxins are primarily biosynthesized by Aspergillus flavus and A. parasiticus, with the eastern part of the country reportedly more aflatoxin-prone. Aflatoxins have been reported in maize and maize products (Busaa, chan’gaa, githeri, irio, muthokoi, uji, and ugali), peanuts and its products, rice, cassava, sorghum, millet, yams, beers, dried fish, animal feeds, dairy and herbal products, and sometimes in tandem with other mycotoxins. The highest total aflatoxin concentration of 58,000 μg/kg has been reported in maize. At least 500 acute human illnesses and 200 deaths due to aflatoxins have been reported. The causes and prevalence of aflatoxins have been grossly ascribed to poor agronomic practices, low education levels, and inadequate statutory regulation and sensitization. Low diet diversity has aggravated exposure to aflatoxins in Kenya because maize as a dietetic staple is aflatoxin-prone. Detection and surveillance are only barely adequate, though some exposure assessments have been conducted. There is a need to widen diet diversity as a measure of reducing exposure due to consumption of aflatoxin-contaminated foods.

Effects of the Use of Good Agricultural Practices on Aflatoxin Levels in Maize Grown in Nandi County, Kenya

Aflatoxin contaminated maize is of public health concern in Kenya. Training farmers on good agricultural practice (GAP) has been touted as a mitigative measure. Little is known of the effect of such training on aflatoxin levels in maize grown in Kenya. This study evaluated what effect training farmers on GAP has on aflatoxin levels in maize grown in Kaptumo, Kilibwoni, and Kipkaren divisions in Nandi County. Ninety farmers were recruited for the study and interviewed on GAP. Maize samples were additionally collected from the participating farmers and analyzed for aflatoxins using competitive enzyme-linked immunosorbent assay (c-ELISA). All farmers prepared the land before planting, applied correct spacing between the planted crops, carried out weeding, cleaned their stores before use, checked the condition of the maize after harvesting, sorted maize after shelling, and knew about aflatoxins. The majority of the farmers (90%) used fertilizers, dried maize after harvesting, knew that aflatoxins were harmful to humans, and used clean transport in transporting the harvested maize. About 98% of farmers did stooking after harvesting and 97% used wooden pallets in the maize stores. The percentage of farmers who practiced early planting, top dressing, crop rotation, raising stores above the ground, applying insecticide after shelling and feeding damaged/rotten seeds to their animals was 84–96%, 62–80%, 67–85%, 86–98%, 63–81%, and 7–21% respectively. About 18/90 (20%) of all farmers reported that they had a relative who had died from liver cancer, and the mean aflatoxin levels in season 1 were significantly different from those in season 2 (1.92 ± 1.07 ppb; 1.30 ± 1.50 ppb). Our findings suggest that although training farmers to adopt good agricultural practices was observed to be efficient in mitigating the problem of aflatoxins, the receptiveness of farmers to different aspects of the training may have differed. Therefore, in designing an optimized regional aflatoxin contamination strategy, local applicability should be considered.

Mycotoxin Occurrence, Exposure and Health Implications in Infants and Young Children in Sub-Saharan Africa: A Review

Infants and young children (IYC) remain the most vulnerable population group to environmental hazards worldwide, especially in economically developing regions such as sub-Saharan Africa (SSA). As a result, several governmental and non-governmental institutions including health, environmental and food safety networks and researchers have been proactive toward protecting this group. Mycotoxins, toxic secondary fungal metabolites, contribute largely to the health risks of this young population. In SSA, the scenario is worsened by socioeconomic status, poor agricultural and storage practices, and low level of awareness, as well as the non-establishment and lack of enforcement of regulatory limits in the region. Studies have revealed mycotoxin occurrence in breast milk and other weaning foods. Of concern is the early exposure of infants to mycotoxins through transplacental transfer and breast milk as a consequence of maternal exposure, which may result in adverse health effects. The current paper presents an overview of mycotoxin occurrence in foods intended for IYC in SSA. It discusses the imperative evidence of mycotoxin exposure of this population group in SSA, taking into account consumption data and the occurrence of mycotoxins in food, as well as biomonitoring approaches. Additionally, it discusses the health implications associated with IYC exposure to mycotoxins in SSA.

Morphological and Molecular Characterization of Toxigenic Aspergillus flavus from Groundnut Kernels in Kenya

Pathogenesis of Aspergillus flavus on important agricultural products is a key concern on human health due to the synthesis and secretion of the hazardous secondary metabolite, aflatoxin. This study identified and further characterized aflatoxigenic A. flavus from groundnuts sampled from sundry shops in Kenya using integrated morphological and molecular approaches. The groundnuts were plated on potato dextrose agar for isolation and morphological observation of A. flavus based on macroscopic and microscopic features. Molecular characterization was done through amplification and comparison of the partial sequence of the ITS1-5.8S-ITS2 region. The expression analysis of aflR, aflS, aflD, aflP, and aflQ genes in the aflatoxin biosynthesis pathways was conducted to confirm the positive identification of A. flavus. The gene expression also aided to delineate toxigenic isolates of A. flavus from atoxigenic ones. Morphologically, 18 isolates suspected to be A. flavus were identified. Out of these, 14 isolates successfully amplified the 500 bp ITS region of A. flavus or Aspergillus oryzae, while 4 isolates were not amplified. All the remaining 14 isolates expressed at least one of the aflatoxigenic genes but only 5 had all the genes expressed. Partial sequencing revealed that isolates 5, 11, 12, 13, and 15 had 99.2%, 97.6%, 98.4%, 97.5%, and 100% homology, respectively, to the A. flavus isolate LUOHE, ITS-5.8S-ITS2, obtained from the NCBI database. The five isolates were accurate identification of atoxigenic A. flavus. Precise identification of toxigenic strains of A. flavus will be useful in establishing control strategies of the fungus in food products.

Effects of the Use of Good Agricultural Practices on Aflatoxin Levels in Maize Grown in Nandi County, Kenya

Aflatoxin contaminated maize is of public health concern in Kenya. Training farmers on good agricultural practice (GAP) has been touted as a mitigative measure. Little is known of the effect of such training on aflatoxin levels in maize grown in Kenya. This study evaluated what effect training farmers on GAP has on aflatoxin levels in maize grown in in maize grown in Kaptumo, Kilibwoni, and Kipkaren divisions in Nandi County. Ninety farmers were recruited for the study and interviewed on GAP. Maize samples were additionally collected from the participating farmers and analyzed for aflatoxins using competitive enzyme-linked immunosorbent assay (c-ELISA). All farmers prepared the land before planting, did correct spacing between the planted crops, carried out weeding, cleaned their stores before use, checked the condition of the maize after harvesting, sorted maize after shelling, and knew aflatoxins. A majority of the farmers (90%) used fertilizers, dried maize after harvesting, knew that aflatoxins were harmful to humans, and used clean transport in transporting the harvested maize. About 98% of farmers did stooking after harvesting and 97% used wooden pallets in the maize stores. The percentage of farmers who practiced early planting, top dressing, crop rotation, raising stores above the ground, applying insecticide after shelling and feeding damaged/rotten seeds to their animals was 84–96%, 62–80%, 67–85%, 86–98%, 63–81%, and 7–21% respectively. About 18/90 (20%) of all farmers reported that they had a relative who had died from liver cancer and the mean aflatoxin levels in season 1 were significantly different from season 2 (1.92 ± 1.07 ppb; 1.30 ± 1.50 ppb). Our findings suggest that although training farmers to adopt good agricultural practices was observed to be efficient in mitigating the problem of aflatoxins, the receptiveness of farmers to different aspects of the training may have differed. Therefore, in designing an optimized regional aflatoxin contamination strategy, local applicability should be considered.

A Review of the Impact of Mycotoxins on Dairy Cattle Health: Challenges for Food Safety and Dairy Production in Sub-Saharan Africa

Mycotoxins are secondary metabolites of fungi that contaminate food and feed and have a significant negative impact on human and animal health and productivity. The tropical condition in Sub-Saharan Africa (SSA) together with poor storage of feed promotes fungal growth and subsequent mycotoxin production. Aflatoxins (AF) produced by Aspergillus species, fumonisins (FUM), zearalenone (ZEN), T-2 toxin (T-2), and deoxynivalenol (DON) produced by Fusarium species, and ochratoxin A (OTA) produced by Penicillium and Aspergillus species are well-known mycotoxins of agricultural importance. Consumption of feed contaminated with these toxins may cause mycotoxicoses in animals, characterized by a range of clinical signs depending on the toxin, and losses in the animal industry. In SSA, contamination of dairy feed with mycotoxins has been frequently reported, which poses a serious constraint to animal health and productivity, and is also a hazard to human health since some mycotoxins and their metabolites are excreted in milk, especially aflatoxin M1. This review describes the major mycotoxins, their occurrence, and impact in dairy cattle diets in SSA highlighting the problems related to animal health, productivity, and food safety and the up-to-date post-harvest mitigation strategies for the prevention and reduction of contamination of dairy feed.

Risk assessment of aflatoxins in food

EFSA was asked to deliver a scientific opinion on the risks to public health related to the presence of aflatoxins in food. The risk assessment was confined to aflatoxin B1 (AFB1), AFB2, AFG1, AFG2 and AFM1. More than 200,000 analytical results on the occurrence of aflatoxins were used in the evaluation. Grains and grain-based products made the largest contribution to the mean chronic dietary exposure to AFB1 in all age classes, while 'liquid milk' and 'fermented milk products' were the main contributors to the AFM1 mean exposure. Aflatoxins are genotoxic and AFB1 can cause hepatocellular carcinomas (HCCs) in humans. The CONTAM Panel selected a benchmark dose lower confidence limit (BMDL) for a benchmark response of 10% of 0.4 μg/kg body weight (bw) per day for the incidence of HCC in male rats following AFB1 exposure to be used in a margin of exposure (MOE) approach. The calculation of a BMDL from the human data was not appropriate; instead, the cancer potencies estimated by the Joint FAO/WHO Expert Committee on Food Additives in 2016 were used. For AFM1, a potency factor of 0.1 relative to AFB1 was used. For AFG1, AFB2 and AFG2, the in vivo data are not sufficient to derive potency factors and equal potency to AFB1 was assumed as in previous assessments. MOE values for AFB1 exposure ranged from 5,000 to 29 and for AFM1 from 100,000 to 508. The calculated MOEs are below 10,000 for AFB1 and also for AFM1 where some surveys, particularly for the younger age groups, have an MOE below 10,000. This raises a health concern. The estimated cancer risks in humans following exposure to AFB1 and AFM1 are in-line with the conclusion drawn from the MOEs. The conclusions also apply to the combined exposure to all five aflatoxins.

Aflatoxins: Producing-Molds, Structure, Health Issues and Incidence in Southeast Asian and Sub-Saharan African Countries

This review aims to update the main aspects of aflatoxin production, occurrence and incidence in selected countries, and associated aflatoxicosis outbreaks. Means to reduce aflatoxin incidence in crops were also presented, with an emphasis on the environmentally-friendly technology using atoxigenic strains of Aspergillus flavus. Aflatoxins are unavoidable widespread natural contaminants of foods and feeds with serious impacts on health, agricultural and livestock productivity, and food safety. They are secondary metabolites produced by Aspergillus species distributed on three main sections of the genus (section Flavi, section Ochraceorosei, and section Nidulantes). Poor economic status of a country exacerbates the risk and the extent of crop contamination due to faulty storage conditions that are usually suitable for mold growth and mycotoxin production: temperature of 22 to 29 °C and water activity of 0.90 to 0.99. This situation paralleled the prevalence of high liver cancer and the occasional acute aflatoxicosis episodes that have been associated with these regions. Risk assessment studies revealed that Southeast Asian (SEA) and Sub-Saharan African (SSA) countries remain at high risk and that, apart from the regulatory standards revision to be more restrictive, other actions to prevent or decontaminate crops are to be taken for adequate public health protection. Indeed, a review of publications on the incidence of aflatoxins in selected foods and feeds from countries whose crops are classically known for their highest contamination with aflatoxins, reveals that despite the intensive efforts made to reduce such an incidence, there has been no clear tendency, with the possible exception of South Africa, towards sustained improvements. Nonetheless, a global risk assessment of the new situation regarding crop contamination with aflatoxins by international organizations with the required expertise is suggested to appraise where we stand presently.

Variation in Occurrence and Aflatoxigenicity of Aspergillus flavus from Two Climatically Varied Regions in Kenya

Aflatoxins are carcinogenic chemical metabolites produced by Aspergillus spp. of the section Flavi. In Kenya, Aspergillus flavus is the most prevalent and has been associated with several acute and chronic aflatoxin outbreaks in the past. In this study, we evaluated the occurrence of A. flavus in soils from two agro-ecological regions with contrasting climatic conditions, aflatoxin contamination histories and cropping systems. Aspergillus spp. were first isolated from soils before the identification and determination of their aflatoxigenicity. Further, we determined the occurrence of Pseudomonas and Bacillus spp. in soils from the two regions. These bacterial species have long been associated with biological control of several plant pathogens including Aspergillus spp. Our results show that A. flavus occurred widely and produced comparatively higher total aflatoxin levels in all (100%) study sites from the eastern to the western regions of Kenya. For the western region, A. flavus was detected in 4 locations (66.7%) that were previously under maize cultivation with the isolates showing low aflatoxigenicity. A. flavus was not isolated from soils under sugarcane cultivation. Distribution of the two bacterial species varied across the regions but we detected a weak relationship between occurrence of bacterial species and A. flavus. We discuss these findings in the context of the influence of climate, microbial profiles, cropping systems and applicability in the deployment of biological control remedies against aflatoxin contamination.

Aflatoxin M1 binding by lactic acid bacteria in milk

This research focused on biocontrol solution to increase food safety through studying lactic acid bacteria (LAB) which can bind aflatoxins in milk. Aflatoxins are toxic contaminants found in feeds and foods. In milk aflatoxin is found in metabolised form, aflatoxin M1 (AFM1). Three indigenous LAB Lactobacillus strains and one Lactococcus strain isolated from Kenyan spontaneously fermented foods were tested for their AFM1 binding abilities in different conditions and after different treatments along with two reference Lactobacillus strains. Binding of AFM1 in different concentrations was examined with unconcentrated, concentrated, heat treated and concentrated heat-treated LAB cultures. Observed binding of AFM1 by LAB varied between 11 to 100%, being approximately at the level of 40% throughout the analysis sets. The results of this study suggest that the aflatoxin binding ability by LAB strain is not strongly strain specific and depends on many external and condition variables. Also, the methods used in determination of aflatoxin binding warrant critical evaluation.

Aflatoxin Binders in Foods for Human Consumption-Can This be Promoted Safely and Ethically?

Aflatoxins continue to be a food safety problem globally, especially in developing regions. A significant amount of effort and resources have been invested in an attempt to control aflatoxins. However, these efforts have not substantially decreased the prevalence nor the dietary exposure to aflatoxins in developing countries. One approach to aflatoxin control is the use of binding agents in foods, and lactic acid bacteria (LAB) have been studied extensively for this purpose. However, when assessing the results comprehensively and reviewing the practicality and ethics of use, risks are evident, and concerns arise. In conclusion, our review suggests that there are too many issues with using LAB for aflatoxin binding for it to be safely promoted. Arguably, using binders in human food might even worsen food safety in the longer term.

Effects of the Use of Good Agricultural Practices on Aflatoxin Levels in Maize Grown in Nandi County, Kenya

Aflatoxin contaminated maize is of public health concern in Kenya. Training farmers on good agricultural practice (GAP) has been touted as a mitigative measure. Little is known of the effect of such training on aflatoxin levels in maize grown in Kenya. This study evaluated what effect training farmers on GAP has on aflatoxin levels in maize grown in Kaptumo, Kilibwoni, and Kipkaren divisions in Nandi County, Kenya. Ninety farmers were recruited into farmer field schools and a questionnaire on GAP administered to each farmer. Maize samples were collected from the farmers and analyzed for aflatoxins using competitive enzyme-linked immunosorbent assay (c-ELISA). All farmers weeded their farms before planting, prepared the land, correctly spaced the seedlings, sorted the maize after shelling, cleaned stores before use and knew that aflatoxins were harmful to humans and animals. Eighty-one farmers did early planting, 88/90 did stooking after harvesting, 89/90 applied fertilizer, 89/90 cleared bushes around the stores, 87/90 used wooden pallets to store maize, 89/90 dried maize after harvesting, 83/90 did crop rotation, and 89/90 used clean transport. Moreover, 62/90 had a relative who had died from liver cancer, 13/90 had fed damaged/rotten seeds to animals, and 45/90 had stored harvested seeds on the ground. The mean aflatoxin levels in season 1 were significantly different from season 2 (1.918 ± 1.065; 1.301 ± 1.501). Our findings suggest that some aspects of the training on GAP were better received than others. Training farmers on GAP results in a decrease in aflatoxin levels in maize grown in Nandi County. Farmers in other maize growing areas of Kenya may benefit from similar training on GAP.

Pre-harvest management is a critical practice for minimizing aflatoxin contamination of maize

Maize, the main dietary staple in Kenya, is one of the crops most susceptible to contamination by aflatoxin. To understand sources of aflatoxin contamination for home grown maize, we collected 789 maize samples from smallholder farmers' fields in Eastern and South Western, two regions in Kenya representing high and low aflatoxin risk areas, respectively, and determined aflatoxin B1 (AFB1) using ELISA with specific polyclonal antibodies. AFB1 was detected in 274 of the 416 samples from Eastern Kenya at levels between 0.01 and 9091.8 μg kg-1 (mean 67.8 μg kg-1). In South Western, AFB1 was detected in 233 of the 373 samples at levels between 0.98 and 722.2 μg kg-1 (mean 22.3 μg kg-1). Of the samples containing AFB1, 153 (55.8%) from Eastern and 102 (43.8%) from South Western exceeded the maximum allowable limit of AFB1 (5 μg kg-1) in maize for human consumption in Kenya. The probable daily intake (PDI) of AFB1 in Eastern Kenya ranged from 0.07 to 60612 ng kg-1 bw day-1 (mean 451.8 ng kg-1 bw day-1), while for South Western, PDI ranged from 6.53 to 4814.7 ng kg-1 bw day-1 (mean 148.4 ng kg-1 bw day-1). The average PDI for both regions exceeded the estimated provisional maximum tolerable daily intake of AFB1, which is a health concern for the population in these regions. These results revealed significant levels of preharvest aflatoxin contamination of maize in both regions. Prevention of preharvest infection of maize by toxigenic A. flavus strains should be a critical focal point to prevent aflatoxin contamination and exposure.

Prevalence and mitigation of aflatoxins in Kenya (1960-to date)

Aflatoxins are highly toxic metabolites of several Aspergillus species widely distributed throughout the environment. These toxins have adverse effects on humans and livestock at a few micrograms per kilogram (μg/kg) concentrations. Strict regulations on the concentrations of aflatoxins allowed in food and feed exist in many nations in the developing world. Loopholes in implementing regulations result in the consumption of dangerous concentrations of aflatoxins. In Kenya, where 'farm-to-mouth' crops become severely contaminated, solutions to the aflatoxins problem are needed. Across the decades, aflatoxins have repeatedly caused loss of human and animal life. A prerequisite to developing viable solutions for managing aflatoxins is understanding the geographical distribution and severity of food and feed contamination, and the impact on lives. This review discusses the scope of the aflatoxins problem and management efforts by various players in Kenya. Economic drivers likely to influence the choice of aflatoxins management options include historical adverse health effects on humans and animals, cost of intervention for mitigation of aflatoxins, knowledge about aflatoxins and their impact, incentives for aflatoxins safe food and intended scope of use of interventions. It also highlights knowledge gaps that can direct future management efforts. These include: sparse documented information on human exposure; few robust tools to accurately measure economic impact in widely unstructured value chains; lack of long-term impact studies on benefits of aflatoxins mitigation; inadequate sampling mechanisms in smallholder farms and grain holding stores/containers; overlooking social learning networks in technology uptake and lack of in-depth studies on an array of aflatoxins control measures followed in households. The review proposes improved linkages between agriculture, nutrition and health sectors to address aflatoxins contamination better. Sustained public awareness at all levels, capacity building and aflatoxins related policies are necessary to support management initiatives.