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
Mycotoxins constitute a family of secondary metabolites biosynthesized by fungi from genera
Aflatoxins are a group of mycotoxins produced by at least 20 fungal strains of
Aflatoxins are mutagenic, genotoxic, immunosuppressive, carcinogenic, and teratogenic [
Structure of major AFs of toxicological concern: (a) AFB1; (b) AFM1; (c) AFG1; (d) AFB2; (e) AFG2.
Mutegi et al. [
Aflatoxins in Kenya are predominantly produced by
Kenya possesses an erratic tropical climate characterized by periodic droughts, high humidity, and high temperatures preceding harvests [
Poor grain conditioning before storage, use of propylene storage bags, drying of grain on bare grounds, insect infestation, poor storage structures (stores with leaking roofs), poor transportation, and handling of produce as well as chronic poverty have been incriminated for the aflatoxigenic contamination of Kenyan foods [
Aflatoxins in Kenya have been reported to contaminate staple foods such as maize (
Maize, millet, and sorghum are Kenyan staples for specific regions. Maize is the main dietary staple [
In Kenya, maize meal consumption is estimated at 400 g/person/day with an average total AF content of 0.132
Later, Muthomi et al. [
Similarly, a random study appraising market maize contamination as well as the relationship between market maize AFs and aflatoxicosis outbreak was conducted [
Distribution of AFs in maize products from some Kenyan districts following the 2004 aflatoxicosis.
District | Number of samplesa | Total aflatoxin concentrationb | |||
---|---|---|---|---|---|
≤20 | 21–99 | 100–1,000 | >1,000 | ||
Makueni | 91 | 32 (35) | 12 (13) | 36 (40) | 11 (12) |
Kitui | 73 | 28 (38) | 15 (21) | 23 (32) | 7 (10) |
Machakos | 102 | 50 (49) | 26 (25) | 23 (23) | 3 (3) |
Thika | 76 | 50 (66) | 13 (17) | 10 (13) | 3 (4) |
Total | 342 | 160 (47) | 66 (19) | 92 (27) | 24 (7) |
Excerpted from Lewis et al. [
Probst et al. [
Another study reaffirmed the foregoing. For 306 maize samples collected from markets in Upper Eastern Kenya (
In consonance with the aforementioned, Muthomi et al. [
AFs contamination of foods in Eastern Africa.
Food | Country | Per capita intake (g/person/day) | Average AF level ( |
---|---|---|---|
Maize | Kenya | 405 | |
Tanzania | 69 | ||
Uganda | 400 | 9.7 | |
Groundnuts (peanuts) | Uganda | ||
Tanzania | |||
Burundi | 65 | ||
Cassava chips | Uganda | 0.5 | |
Tanzania | 214 | 0.9 | |
Sorghum | Tanzania | 40 | 3.0 |
Milk | Kenya | 750 ml | |
Tanzania | 750 ml | ||
Rwanda | 750 ml | Not detected |
Values in bold indicate exceedance of East African thresholds.
A total of 54 processed and unprocessed (brands A and B) cattle feed from agricultural and veterinary stores and 96 human foods (unprocessed and processed maize, polished and unpolished rice, peanut seeds, and flour) samples collected from open market traders in Nairobi County were analyzed [
Aflatoxin exposure via intake of maize and its products was evaluated through analysis of 20 samples each of maize kernels,
To check for chronic inadvertent exposure to AFs, maize (
Recently, maize from smallholder farmers’ fields in Eastern and Southwestern Kenya (
The prevalence and levels of AFs in freshly harvested maize and freshly milled maize flour (
Peanuts (groundnuts) are the only affordable dietary protein source in Kenya [
In one of the earlier surveys [
In another survey by Mutegi et al. [
Accordingly, it was hypothesized that the processing of peanuts in the cottage industry could facilitate their contamination by AFs. As such, Ndung’u et al. [
AF content of peanuts and peanut butter from market outlets in Nairobi and Nyanza Provinces, Kenya.
Source | Sample | Sample type | AF level ( | Aflatoxin-positive samples (%) | |||
---|---|---|---|---|---|---|---|
Range | Mean | ≤4.0 | ≤10.0 | ≥10.0 | |||
Cottage industry | Raw peanuts | Pink regular ( | BDL-52.4 | 18.3 | 60 | 80 | 20 |
Red regular ( | NA | 5.0 | |||||
Red small ( | NA | BDL | |||||
Roasted peanuts | Red regular ( | 2.4–297.7 | 54.8 | 25 | 50 | 50 | |
Peanut butter | Paste ( | BDL-2,377.1 | 318.3 | 18 | 27 | 73 | |
Nairobi wholesale outlets | Unsorted peanuts | Pink regular ( | BDL-364.7 | 111.2 | 22 | 26 | 74 |
Red regular ( | BDL-276.1 | 89.1 | |||||
Sorted peanuts | Pink regular ( | BDL-82.4 | 24.0 | 36 | 82 | 18 | |
Red regular ( | 2.0–9.2 | 5.3 | |||||
Red small ( | 6.0–7.8 | 6.9 | |||||
Nyanza retail outlets | Unsorted nuts | Pink large ( | 3.7–128.8 | 71.6 | 71 | 75 | 25 |
Pink regular ( | BDL-229.8 | 44.9 | |||||
Red regular ( | BDL-14.0 | 1.9 | |||||
Red mixed ( | NA | BDL |
Adapted from [
The prevalence and diversity of fungal spp and aflatoxigenic contamination of 228 marketed peanut samples (from 140 formal and 88 from informal markets) in Kericho and Eldoret towns of Kenya were established [
Another investigation [
Oil content and total aflatoxins of peanuts from Busia and Kisii Central districts of Kenya.
District | Variety | Mean oil content (%) | Mean total AFs ( |
---|---|---|---|
Busia | Valencia red | 47.2 | 2.3 |
Uganda local red | 46.7 | 2.4 | |
Homa Bay local | 43.2 | 2.8 | |
Local red | 42.7 | ||
Kisii Central | Valencia red | 46.6 | |
Uganda local | 45.7 | ||
Homa Bay local | 40.6 |
Adapted from [
From the prevenient reports, it is notable that relatively higher AF concentrations have been detected and quantified in Kenyan peanuts. A plausible explanation advanced has been that aflatoxigenic fungi infect the shells, testa, and seeds as the pods in the soil grow. Further, mechanical damage while harvesting, drying, and storing aggravates the risk of invasion by the toxigenic fungi and aflatoxin biosynthesis. This is corroborated by a Tanzanian report which unveiled that grains and oilseeds borne on aerial generative structures had comparatively lower AF levels vis-à-vis those borne in geocarpic structures of Bambara and peanuts [
Cassava is a revered food crop with edible carbohydrate-rich tuberous roots and proteinaceous young leaves [
In a study, dried cassava chips (
There are no reports in the open literature on plant products such as sugarcane, spices, beans, wheat, and barley in Kenya.
Aflatoxin-contaminated animal products such as blood, eggs, ghee, meat, milk, and dairy products present food safety concerns [
A correlative study conducted in four urban centers by Kang’ethe and Lang’a [
Synopsis of aflatoxins in animal feeds and bovine milk in some Kenyan municipalities (from [
Source/municipality | % AF positive | >5.0 | Mean | Range | |
---|---|---|---|---|---|
Aflatoxin B1 (feed samples) | |||||
Nyeri ( | 68.6 | 49.2 | 136.0 ± 10.0 | 4.0–63.0 | |
Eldoret ( | 98.1 | 61.1 | 23.2 ± 23.2 | 4.2–178.2 | |
Machakos ( | 94.9 | 73.3 | 27.7 ± 74.9 | 3.6–595.0 | |
Nakuru ( | 80.5 | 58.6 | 17.4 ± 11.1 | 1.8–58.0 | |
Nyeri ( | 100.0 | 42.9 | 6.4 ± 4.9 | 1.9–15.8 | |
Eldoret ( | 88.9 | 66.7 | 13.9 ± 12.8 | 1.9–49.0 | |
Machakos ( | 100.0 | 100.0 | 43.8 ± 0.0 | 43.8 | |
Nakuru ( | 77.8 | 43.3 | 26.0 ± 44.5 | 0.9–280.0 | |
Nairobi ( | 84.6 | 56.4 | 13.0 ± 15.9 | 0.9–280.0 | |
Nyeri ( | 89.5 | 31.6 | 8.9 ± 8.5 | 1.9–28.7 | |
Eldoret ( | 93.1 | 72.4 | 17.0 ± 34.6 | 1.8–238.0 | |
Machakos ( | 79.3 | 43.3 | 17.6 ± 19.6 | 2.0–64.4 | |
Nakuru ( | 84.1 | 43.5 | 46.0 ± 8.4 | 2.0–46.2 | |
Aflatoxin M1 (milk samples) | |||||
Nyeri ( | 60.8 | 3.3 | 33.8 ± 68.7 | 5.0–46.0 | |
Eldoret ( | 68.2 | 10.3 | 39.9 ± 39.7 | 5.4–228.0 | |
Machakos ( | 82.8 | 24.2 | 99.7 ± 168.9 | 5.1–780.0 | |
Nakuru ( | 77.3 | 20.9 | 83.3 ± 129.3 | 5.2–550.0 | |
Nyeri ( | 76.0 | 0.0 | 20.2 ± 29.0 | 5.2–50.0 | |
Eldoret ( | 68.8 | 12.5 | 115.6 ± 202.7 | 5.5–560.0 | |
Machakos ( | 100.0 | 50.0 | 52.2 ± 34.7 | 10.9–102.5 | |
Nakuru ( | 89.9 | 55.6 | 65.1 ± 36.7 | 5.3–165.0 | |
Nairobi ( | 100.0 | 50.0 | 99.8 ± 97.3 | 10.0–245.0 | |
Nyeri ( | 100.0 | 30.0 | 129.3 ± 198.8 | 16.5–600.0 | |
Eldoret ( | 100.0 | 22.2 | 36.4 ± 24.5 | 5.8–74.0 | |
Machakos ( | 94.4 | 16.7 | 33.1 ± 17.0 | 11.0–67.0 | |
Nakuru ( | 100.0 | 36.8 | 36.1 ± 22.9 | 8.0–71.0 | |
Nairobi ( | 100.0 | 41.7 | 64.9 ± 76.4 | 7.9–300.0 |
AFM1 contamination of bovine milk in some selected agroecological zones of Kenya (from [
County | Agroecological zone | Number of samples | AFM1-positive samples (%) | ||
---|---|---|---|---|---|
<0.002 | ≤0.002–0.05 | ≥0.05 | |||
Tharaka-Nithi | Humid | 64 | 34 | 41 | 25 |
Kwale | Subhumid | 29 | 76 | 17 | 7 |
Bungoma | Temperate | 64 | 53 | 41 | 6 |
Kisii | Temperate | 63 | 65 | 30 | 5 |
Isiolo | Semiarid | 60 | 77 | 22 | 2 |
Aflatoxins were detected and quantified in fresh and sun-dried
In a bid to assess the AF status of marketed raw milk and associated risk factors in periurban Nairobi, raw milk retailers in Dagoretti division were interviewed and milk samples were drawn and tested for AFM1 [
In the same manner, AFM1 was detected in 291 samples of raw, pasteurized, and UHT milk, yoghurt, and
In a recent study [
Kang’ethe et al. [
In Kisumu, Anyango et al. [
According to Sirma et al. [
As pointed earlier, farming is one possible exposure route to AFs. For example, maize which is known to be highly susceptible to AF contamination in Kenya is also a major component of livestock and poultry feeds, and therefore, regular indirect human exposure through the consumption of animal products that contain AF residues cannot be underrated. Elevated levels of AFB1 have been recorded in Kenyan animal feeds [
Further, 81 fish feeds sourced from 70 farms and 8 feed manufacturing establishments located in Nyeri, Kenya, were subjected to AF analysis by Mwihia et al. [
It is now established that mycotoxins can coexist in foods [
Fumonisin B1 and AFB1 in symptomless and rotten maize harvested at different harvest time points after physiological maturity (HTPAPM) from Malava and Tongaren were evaluated [
In a study scrutinizing commodities, feeds, and feed ingredients from Middle East and Africa [
Similarly, maize samples were collected from 30 markets in diverse agroecological zones of Meru, Machakos, and Kitui counties during the 2013 harvest [
The prevalence of AFs and FUM was investigated in maize intended for immediate human consumption in Eastern Kenya. Samples were collected from people who brought their maize for processing at local commercial mills [
Besides, the presence of AFs, FUM, and DON in
Comparably, Mutiga et al. [
Samples of 74 animal feeds and 120 milk samples were simultaneously collected from individual cows and actors in the informal subvalue chains of rural and periurban dairy systems in Nakuru County, Kenya [
Herbal preparations were sampled from Eldoret (14 liquid, 2 oil, and 34 powder samples) and Mombasa (12 liquid, 1 capsule, 3 oil, 6 tablets, and 28 powder samples) towns and analyzed for total AFs and FUMs [
Into the bargain, a survey covering 116 push‐pull and 139 non‐push‐pull cropping systems was conducted to determine the socioeconomic and agronomic factors that influence farmers’ knowledge on incidence and contamination of maize by ear rots and associated mycotoxins in Siaya, Kakamega, Kisumu, Migori, and Vihiga counties of Western Kenya [
Kenya was one of the hotspots of AFs first recorded [
Detection and quantification of AFs are key to their mitigation because their distribution in samples is often skewed [
Another emerging challenge in analyses of food toxins in Africa, Asia, America, and Europe is “masked mycotoxins” as they are not often identified and detected by the usual analytical techniques [
The methods for the detection of AFs used by studies in Kenya are outlined in Table
Analytical methods used by aflatoxin investigations in Kenya.
Methods of analysis | Samples/matrices | Mycotoxins analyzed | Years | Authors |
---|---|---|---|---|
ELISA | Maize grain | Total AFs | 2020 | Marete et al. [ |
Fluorimetry, PCR | Soil | Total AFs | 2020 | Monda et al. [ |
UHPLC | Maize grain (fresh), maize flour | AFB1, AFG1, AFB2, AFG2 | 2020 | Nabwire et al. [ |
UPLC, PCR | Maize grain | AFB1, AFG1, AFB2, AFG2 | 2019 | Oloo et al. [ |
Quantitative PCR (qPCR), TLC, HPLC | Maize tissues/grain | 2019 | Mitema et al, [ | |
ELISA | Bovine milk | AFM1 | 2019 | Kagera et al. [ |
ELISA | Maize | AFB1 | 2019 | Mahuku et al. [ |
ELISA | Maize | Total AFs, FUM | 2019 | Njeru et al. [ |
ELISA | Bovine milk | AFM1 | 2019 | Kuboka et al. [ |
PCR | Soils | 2018 | Islam et al. [ | |
LC-MS/MS, UHPLC-TTQS, PCR | Maize samples | AFB1, AFG1, AFB2, AFG2, | 2018 | Okoth et al. [ |
PCR, HPLC | AFB1 | 2018 | Nduti [ | |
LFI | Maize grain, human sera (children) | Total AFs, AFB1 (lysine adducts) | 2018 | Hoffmann et al. [ |
ELISA | Raw, pasteurized and UHT milk, yoghurt, | AFM1 | 2018 | Lindahl et al. [ |
ELISA, TLC, HPLC | Maize grain | Total AFs, AFB1 | 2018 | Obonyo and Salano [ |
ELISA, PCR | Maize kernels | Total AFs | 2018 | Gachara et al. [ |
ELISA, LC-HRMS/MS | Fish feeds | Total AFs | 2018 | Mwihia et al. [ |
ELISA, HPLC | Urine, breast milk, maize flour, sorghum, millet | AFM1 | 2017 | Kang’ethe et al. [ |
LFI | Maize grain and maize flour | Total AFs | 2017 | Nduti et al. [ |
ELISA | Herbal products | Total AFs, FUMs | 2017 | Keter et al. [ |
HPLC, UPLC-MS/MS, LC-MS/MS | Human urine, human blood | AFM1, AFB1 (lysine adducts) | 2017 | Awuor et al. [ |
ELISA | Dairy cattle feeds, bovine milk | AFB1, AFM1 | 2016 | Ochungo et al. [ |
ELISA | Bovine milk | AFM1 | 2016 | Kirino et al. [ |
ELISA | Animal feeds and bovine milk | AFB1, DON, and AFM1 | 2016 | Makau et al. [ |
ELISA, HPLC, LC/MS | Maize grain, urine | AFB1, AFM1 | 2016 | Nduti et al. [ |
ELISA | Dairy cattle concentrates, bovine milk | AFB1, AFM1 | 2016 | Senerwa et al. [ |
ELISA | Bovine milk (raw and processed), dairy products | AFM1 | 2016 | Langat et al. [ |
ELISA | Maize, sorghum, and milk | Total AFs and AFM1 | 2016 | Kiarie et al. [ |
HPLC | Peanuts | Total AFs | 2016 | Menza et al. [ |
ELISA | Maize grain | Total AFs | 2016 | Kirui [ |
ELISA | Cassava (chips and flour) | Total AFs | 2015 | Gacheru et al. [ |
ELISA | AFB1, AFM1 | 2015 | Obade et al. [ | |
ELISA | Maize (grain and flour) | Total AFs, FUM | 2015 | Mutiga et al. [ |
ELISA | Maize, sorghum, millet | Total AFs | 2015 | Sirma et al. [ |
HPLC | Human sera (women) | AFB1 (lysine adducts) | 2015 | Leroy et al. [ |
ELISA, qPCR | Human sera (children) | AFB1 (albumin adducts) | 2015 | Castelino et al. [ |
TLC, HPLC | Fresh and sun-dried fish ( | Total AFs | 2015 | Orony et al. [ |
ELISA | Cattle feeds, rice, maize, peanuts | Total AFs | 2014 | Nyangaga [ |
ELISA | Maize grain | Total AFs, FUM | 2014 | Mutiga et al. [ |
TLC, HPLC | Maize grains, | Total AFs | 2014 | Kilonzo et al. [ |
ELISA | Bovine milk | AFM1 | 2014 | Sirma et al. [ |
ELISA, BGYF | Maize grain | Total AFs, FUM | 2014 | Murithi [ |
LFI | Total AFs, FUM, DON | 2014 | Kirui et al. [ | |
ELISA | Peanuts (raw and roasted) | Total AFs | 2013 | Nyirahakizimana et al. [ |
ELISA | Peanuts | Total AFs | 2013 | Mutegi et al. [ |
ELISA | Peanuts and peanut products | Total AFs | 2013 | Mutegi et al. [ |
ELISA | Peanuts (raw and roasted), peanut butter | Total AFs | 2013 | Ndung’u et al. [ |
TQMS | Human sera | AFB1 (lysine adducts) | 2013 | Yard et al. [ |
ELISA | Peanuts | Total AFs | 2012 | Mutegi et al. [ |
LC-MS/MS, PCR | Maize kernels | AFB1, AFG1, AFB2, AFG2 | 2012 | Okoth et al. [ |
TLC | Maize (grains, flour), milled maize-cereal products, dairy cattle feed, oil seed cake | Total AFs | 2012 | Okoth and Kola [ |
ELISA | Human plasma (children) | AFB1 (albumin adducts) | 2012 | Gong et al. [ |
ELISA | Maize (grains, flour, semiprocessed), soil, mill dust | Total AFs | 2012 | Muthomi et al. [ |
Fluorimetry | Maize grain | Total AFs | 2011 | Daniel et al. [ |
LC-MS, HPLC | Commodities, feeds, and feed ingredients | Total AFs, FUM, ZEA, trichothecenes (A&B), ochratoxin A | 2011 | Rodrigues et al. [ |
ELISA | Ground maize, soil | Total AFs | 2010 | Probst et al. [ |
ELISA | Milk, animal feeds | AFM1, AFB1 | 2009 | Kang’ethe and Lang’a [ |
ELISA | Maize, soils, mill dust | AFB1 | 2009 | Muthomi et al. [ |
ELISA | Peanuts | Total AFs | 2009 | Mutegi et al. [ |
ELISA | Maize grain | AFB1, FB1 | 2009 | Alakonya et al. [ |
HPLC/fluorimetry | Maize grain | AFB1 | 2007 | Probst et al. [ |
ELISA | Peanuts | Total AFs | 2007 | Mutegi et al. [ |
HPLC | Maize kernels, maize flour, | Total AFs | 2005 | Lewis et al. [ |
Fluorimetry | Maize grain | Total AFs | 2005 | Azziz-Baumgartner et al. [ |
Fluorimetry | Maize grain and maize products | Total AFs | 2005 | Muture and Ogana [ |
ELISA | Pilsner and Tusker beers | AFB1, FB1, DON, ZEA | 2004 | Mbugua and Gathumbi [ |
TLC | Peanuts | Total AFs | 2004 | Gachomo et al. [ |
TLC | Weaning foods | Total AFs | 2004 | Okoth and Ohingo [ |
TLC, HPLC | Malted millet, maize flour | AFB1, AFB2 | 2000 | Kenji et al. [ |
ELISA, HPLC-FS | Human sera | AFB1 (lysine adducts) | 1990 | Wild et al. [ |
HPLC | Breast milk, human sera, neonatal cord blood, blood (pregnant women) | AFB1, AFB2, AFG1, AFG2, AFM1, AFM2, aflatoxicol | 1989 | Maxwell et al. [ |
HPLC | Human urine | AFB1 (guanine adduct) | 1987 | Autrup et al. [ |
TLC | Local beer, food (maize, millet, sorghum, pigeon peas, and yam components) | Total AFs | 1973 | Peers and Linsell [ |
Years are those in which the data joined scientific literature with most data gathered and analyzed in more than 3 months before publication.
However, the drawbacks of the foregoing standard methods are that they are unsuitable for rapid and real-time applications in food and feed sample analyses as they are relatively tedious and require technical know-how to operate. Rapid and robust methods such as polymerase chain reaction (PCR) and nondestructive methods based on fluorescence/near-infrared spectroscopy (FS/NIRS) and hyperspectral imaging (HSI) have emerged for quick and easy detection of AFs [
Exposure to AFs occurs via periodic ingestion of contaminated plant or animal products such as meat, eggs, blood, and milk of livestock previously served AF-contaminated rations [
It is now established that detecting and quantifying food AF levels are not always adequately reflective of the extent of exposure because the quantities in foods are not directly the same as those ingested. For this reason, epidemiological biomarkers are often used to assess exposure. Biomarkers are quite exact in evaluating the magnitude of AF exposure because of their nonsubjectivity and faculty that allows the estimation of internal and biologically effective doses. Popular AF biomarkers are urinary AF-N7-guanine (for assessing previous day’s exposure) and breast milk AFM1 which indicate exposure levels in the past 24 hours and plasma/serum aflatoxin-albumin (AF-alb) adduct with a half-life of about 2 months enhancing the evaluation of chronic and routine exposure [
Biopsy material was first utilized in 1967 to illustrate that the Kamba ethnic community of Kenya had a frequency of liver cancer that was doubling that of the Kikuyus [
To validate the assertion, another team [
Further, Maxwell et al. [
AF content of breast milk and cord blood from Kenya, Sudan, Ghana, and Nigeria.
Sample | Country | Number of samples | Number of AF-positive samples | Positive samples (%) |
---|---|---|---|---|
Breast milk | Kenya | 191 | 53 | 28 |
Sudan | 99 | 37 | 37 | |
Ghana | 510 | 163 | 32 | |
Cord blood | Kenya | 101 | 37 | 37 |
Nigeria | 78 | 9 | 12 | |
Ghana | 282 | 86 | 30.5 |
Adapted from [
Differently, a survey which recruited adults from Kenya, Thailand, The Gambia, and France was used to validate the measurement of AF-albumin adducts by three methods [
In another study, random samples of weaning flours were obtained from 242 households with 3- to 36-month-old children (43.6% males and 53.4% females) in Kisumu district, Kenya, and analyzed for AFs [
Agreeably, Leroy et al. [
Further, samples of
Another cross-sectional study was undertaken involving 204 low-income households randomly selected in two low-income areas (Korogocho and Dagoretti), Nairobi, Kenya [
Kang’ethe et al. [
In a recent study [
Overall average estimation of exposure rates based on annual consumption, as is appropriate for cancer risk because of the cumulative nature of this response, indicates that AF exposure was 3.5 to 14.8 ng/kg/day in Kenya for about 67% of the population [
Aflatoxin poisoning could be compounded by the occurrence of AFs in combination with other mycotoxins such as FUM, trichothecenes, ochratoxins, ZEA, and DON [
The current review did not identify any reports evaluating coexposure to AFs in combination with other mycotoxins and the potential adverse health outcomes. There have been developments in both mycotoxin-specific and multimycotoxin methods developed for biological matrices [
In addition, coexposure to mycotoxins
The first 1,000 days of life (from conception to about 36 months) is a critical window for healthy growth and development. Dietary intake of AFs during pregnancy plays a fundamental role in the child’s future health status [
Aflatoxin levels in foods and stunting in some aflatoxin hotspots of Kenya.
County | Stunting (%) | Highest reported AF levels in foods ( | Authors |
---|---|---|---|
Urban Nairobi | 22.7 | 4,593.93 (maize and maize products), total AFs | Okoth and Kola [ |
Nairobi (Korogocho and Dagoretti) | 41.0 | 88.83 (maize), 194.41 (sorghum), total AFs | Kiarie et al. [ |
Kisumu | 33.1 | 82.0 (cereal-based weaning foods), total AFs | Okoth and Ohingo [ |
Homa Bay | 37.0 | 1,000 (peanuts), total AFs | Mutegi et al. [ |
Makueni | 33.5 | 5,400 (maize), total AFs | Lewis et al. [ |
Kitui | 47.4 | 25,000 (maize), total AFs | Lewis et al. [ |
Machakos | 31.3 | 3,800 (maize), total AFs | Lewis et al. [ |
Embu | 23.7 | 21.0, total AFs | Collins et al. [ |
Kakamega (Malava) | 34.2 | 17.0 (rotten maize), AFB1; FB1 >5,000 | Alakonya et al. [ |
Tongaren (Bungoma) | 52.1 | 17.0 (rotten maize), AFB1; FB1 was >5,000 | Alakonya et al. [ |
Kisii South | 35.3 | 3,442; total AFs | Collins et al. [ |
Adapted from Obade et al. [
It was advanced that AF exposure may disrupt the insulin-like growth factor (IGF) pathway through liver toxicity. In a study in Kenya [
Aflatoxin-child growth impairment may be explained by the immunosuppressive effect of AFs that aggravates neonatal infection susceptibility, thereby impairing nutritional status through inappetence and diminished nutrient absorption [
Since the discovery of AFs, Kenya has been one of the countries with devastatingly severe human exposure to AFs [
Aflatoxicosis outbreaks reported in Kenya since the discovery of aflatoxins in 1960.
Affected group | Case-patients/number affected | Area | Toxin source | Recorded effects | Years | Authors |
---|---|---|---|---|---|---|
Humans, dogs | None confirmed | Eastern Kenya (29 districts) | Suspected contaminated maize | Price spiral down, grain trade breakdown, unconfirmed dog deaths in Nairobi | 2010 | Muthomi et al. [ |
Humans | 5 | Kibwezi, Kajiado, Mutomo | Maize | 3 hospitalized, 2 deaths | 2008 | Muthomi et al. [ |
Humans | 4 | Kibwezi, Makueni | Maize | 2 deaths in Makindu town of Mukueni County | 2007 | Wagacha and Muthomi [ |
Humans | 20 | Makueni, Kitui, Machakos, Mutomo | Contaminated maize | Acute poisoning, 10 deaths in Mutomo and 9 in Makueni | 2006 | Daniel et al. [ |
Humans | 75 | Machakos, Makueni, Kitui | Maize | Acute poisoning, 75 cases, 32 deaths | 2005 | Azziz-Baumgartner et al. [ |
Humans | 331 | Eastern/Central Machakos, Kitui, and Makueni areas | Contaminated maize | Acute poisoning, 125 deaths | 2004 | Lewis et al. [ |
Humans | 6 | Thika | Mouldy maize | 6 deaths | 2003 | Onsongo [ |
Poultry/dogs | Large numbers | Coast | Contaminated feed | 150 deaths | 2002 | Njapau and Probst [ |
Humans | 3, 26 | Meru North, Maua | Mouldy maize, contaminated maize | Severe liver damage, 16 deaths | 2001 | Probst et al. [ |
Humans | 3 | Meru North | Maize | Acute effects, 3 deaths | 1998 | Mutegi et al. [ |
Poultry | Large numbers | Kenya | Imported maize | Deaths | 1984/1985 | [ |
Humans | 12 | Machakos | Poorly stored maize | Deaths | 1981 | Ngindu et al. [ |
Poultry/dogs | Large numbers | Nairobi, Mombasa, Eldoret | Poorly stored feed | Deaths | 1977/1978 | Muraguri et al. [ |
Ducklings | 16,000 | Rift Valley | Peanut ration | Deaths | 1960 | Peers and Linsell [ |
Years are those in which the aflatoxicoses occurred rather than the years the data were published. Data are from [
In Kenya, aflatoxicosis was first witnessed in 1960 which recorded the death of at least 16,000 ducklings [
Since 2004, outbreaks among subsistence farmers have recurred annually in Eastern Province and it is right to assert that the magnitude of exposure to AFs could be higher than reported due to the dearth of robust monitoring systems [
Appreciable efforts have been advanced towards AF control in Kenya through countrywide awareness creation [
After the fatal aflatoxicosis in which dogs fed on contaminated rations died between 1970 and 1980s, KEBS came up with a standard for dog feeds in 1985. Standards for maize grain, other grains, and their products that have been in existence were also revised. For example, total AFs were initially at 20
Following its launch way back in 2006, EAGC has been among the lead in the fight against AFs in East Africa as a whole. It has advanced several interventions to reduce the incidence of AFs, including (1) harmonization of AF control measures and improving the regulatory environment, (2) launch of AF control training programs, (3) furnishing moisture meters and waterproof sheets for drying, fumigation, and storing grains, (4) outsourcing portable kits for detecting and quantifying AFs, (5) farmer-based assessment of AFs prevalence, (6) collaborating with East African Community to expand AF testing and surveillance in maize, and (7) laying strategies of the Partnership for Aflatoxin Control in Africa (PACA) strategy 2013–2022 and revising EAC AFs communication strategy [
Kenya Agricultural and Livestock Research Organization in connection with the International Institute of Tropical Agriculture (IITA) in 2018 developed a farmer-centered manual for the management of AFs in maize and peanuts [
Further, there are some projects running in the country to handle the plague of mycotoxins and these include the Aflacontrol Project and Purchasing for Progress (P4P) Programme. The Aflacontrol Project strives to minimize the ravage of AFs in maize and peanut value chains and is spearheaded by International Food Policy Research Institute (IFPRI). In addition, it seeks to increase the understanding of the economic and health impacts of AF contamination and identify and promote cost-effective methods and technologies available to reduce contamination of foods and feeds. The project, funded by Bill and Melinda Gates Foundation, has a partnership with the International Maize and Wheat Improvement Center (CIYMMT), University of Pennsylvania (USA), United States Uniformed Health Services, Kenya Agricultural Research Institute (KARI), and Agricultural Cooperative Development Initiative (ACDI-VOCA). The project has been experimented in Mbere (Embu), Makueni, Homa Bay, Kisii, and Rongo at the household level [
Earlier reports on the fate of AFs during the processing of maize into
Intermediate processes such as sorting and dehusking were shown to reduce AF in peanuts [
In the same struggle, a probiotic yoghurt was formulated with AFB1 binding
In another intervention survey, the use of a calcium montmorillonite clay (calcium silicate 100, popularized as ACCS100) in food reduced the bioavailability of AFs [
Another study [
In a 2020 report [
Staple food crop varieties that are disease-, drought-, and pest-tolerant or less susceptible to fungal growth could be adopted. This approach is so far the best for the reduction of effects of AFs-producing fungi [
Prompt harvest of mature food crops as well as selective disposal of broken kernels or cobs is a recommended AF mitigation measure [
Pest control is another measure of AF management. This may be affected using ash for maize [
Proper drying of produce to moisture contents between 12 and 14%, preferably 12.5% or below, is recommended. Fresh harvests should be shelled and cleaned prior to storage to minimize pest infestation that may initiate mould growth [
Following good agricultural, good storage, and good manufacturing practices as well as the use of advanced agricultural technologies can reduce AF contamination [
Clays notably Novasil Plus can ably bind AFs [
The management strategies suggested each have their advantages and limitations. Thus, biocontrol measures in tandem with physicochemical approaches could be adopted to manage the plague of AFs in Kenya.
Aflatoxin exposure is ubiquitous in Kenya, and the different commodities have relatively high levels of AFs, usually above statutory compliance limits by several folds. Maize, peanuts, and their products are the most contaminated food crops in Kenya. Variations in AF exposure are evident between the different regions of the country and are fundamentally a function of diet and economic status. Large-scale, evidence-based interventions are required to reduce exposure. More exposure assessments including coexposure with other mycotoxins alongside routine monitoring of AFs should be adopted.
This article is a review article and no raw data were collected. Any data used and/or analyzed are within this article.
The authors declare that there are no conflicts of interest regarding the publication of this paper.
TO, PN, MPO, CKN, and SBO are grateful to the World Bank and the Inter-University Council of East Africa (IUCEA) for the scholarship awarded to them through the Africa Center of Excellence II in Phytochemicals, Textiles and Renewable Energy (ACE II PTRE) at Moi University which prompted this review. TO is grateful to the Directors of AgroWays Uganda Limited, Uganda, for the leave granted which made this study a success. The authors commend preceding authors for their efforts in mycotoxin studies done in Kenya, the results of which were recapitulated in this study.