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.

Hepatocellular carcinoma surveillance among people living with hepatitis B in Senegal (SEN-B): insights from a prospective cohort study

BACKGROUND

Chronic hepatitis B virus (HBV) infection is the predominant cause of hepatocellular carcinoma in west Africa, yet data on the incidence of HBV-related hepatocellular carcinoma remain scarce. We aimed to describe the uptake and early outcomes of systematic ultrasound-based hepatocellular carcinoma screening in SEN-B, which is a prospective HBV cohort in Senegal.

METHODS

In this prospective cohort study, we included treatment-naive, HBsAg-positive individuals who were referred to the two infectious diseases clinics (the Department of Tropical and Infectious Diseases and Ambulatory Treatment Center) at Fann University Hospital of Dakar, Senegal, between Oct 1, 2019, and Oct 31, 2022. All participants resided within the Dakar region. Participants underwent abdominal ultrasound, transient elastography, and clinical and virological assessments at inclusion and every 6 months. Liver lesions at least 1 cm in diameter on ultrasound were assessed using four-phase CT, MRI, or liver biopsy. Adherence to hepatocellular carcinoma surveillance was measured using the proportion of time covered, calculated by dividing the cumulative months covered by abdominal ultrasound examinations by the overall follow-up time, defined as the number of months from the date of cohort entry until the last recorded visit, hepatocellular carcinoma diagnosis, or death. Optimal adherence was defined as a proportion of time covered of 100%.

FINDINGS

Overall, 755 (99·6%) of 758 participants had at least one abdominal ultrasound performed. The median age of the enrolled participants was 31 years (IQR 25-39), 355 (47·0%) of 755 participants were women, and 82 (10·9%) had a family history of hepatocellular carcinoma. 15 (2·0%) of 755 individuals were HBeAg positive, 206 (27·3%) of 755 individuals had HBV DNA of more than 2000 IU/mL, and 27 (3·6%) of 755 had elastography-defined liver cirrhosis. Of ten (1·3%) participants with a focal lesion at least 1 cm at initial assessment, CT or MRI ruled out hepatocellular carcinoma in nine, whereas imaging and subsequent liver biopsy confirmed one patient with hepatocellular carcinoma. Two further patients with hepatocellular carcinoma were diagnosed at study presentation due to the presence of portal thrombosis on ultrasound. Excluding the three participants with hepatocellular carcinoma identified at baseline, 752 participants were eligible for screening every 6 months. Median follow-up time was 12 months (IQR 6-18) and the median number of ultrasounds per patient was 3 (2-4). During 809·5 person-years of follow-up, one incident hepatocellular carcinoma was reported, resulting in an incidence rate of 1·24 cases per 1000 person-years (95% CI 0·18-8·80). Overall, 702 (93·0%) of 755 participants showed optimal hepatocellular carcinoma surveillance, but this proportion decreased to 77·8% (42 of 54 participants) after 24 months.

INTERPRETATION

Hepatocellular carcinoma screening is feasible in HBV research cohorts in west Africa, but its longer-term acceptability needs to be evaluated. Long-term hepatocellular carcinoma incidence data are crucial for shaping tailored screening recommendations.

FUNDING

Swiss National Science Foundation, the Swiss Cancer Research Foundation, the National Cancer Institute, and Roche Diagnostics.

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

Soil and human health: Understanding agricultural and socio-environmental risk and resilience in the age of climate change

Prolonged monocropping of commodity crops, such as peanuts (Arachis hypogea L.) in West Africa, typically strips nutrients from soils and may exacerbate vulnerability to insects and diseases. In this paper, we focus on aflatoxins, toxic chemicals produced by certain molds growing on moist crops, as one risk of growing importance for its negative impacts on human health, crop yields, and agricultural livelihoods and ecosystems. We link the increased prevalence of this deadly fungus to the long history of peanut monoculture, exacerbated by market liberalization and China's increased investment and export demand for peanuts, climate change, food insecurity, as well as disregard for and displacement of traditional agricultural knowledge. We use a political ecology approach to place the public health threat from aflatoxin in the context of both historical pressures for cash-crop production of peanuts and contemporary soil degradation, food insecurity, climate change precarity and changes within social and economic systems of agriculture in Senegal.

Can it be all more simple? Manufacturing aflatoxin biocontrol products using dry spores of atoxigenic isolates of Aspergillus flavus as active ingredients

Aflatoxin contamination of staple crops, commonly occurring in warm areas, negatively impacts human and animal health, and hampers trade and economic development. The fungus Aspergillus flavus is the major aflatoxin producer. However, not all A. flavus genotypes produce aflatoxins. Effective aflatoxin control is achieved using biocontrol products containing spores of atoxigenic A. flavus. In Africa, various biocontrol products under the tradename Aflasafe are available. Private and public sector licensees manufacture Aflasafe using spores freshly produced in laboratories adjacent to their factories. BAMTAARE, the licensee in Senegal, had difficulties to obtain laboratory equipment during its first year of production. To overcome this, a process was developed in Ibadan, Nigeria, for producing high-quality dry spores. Viability and stability of the dry spores were tested and conformed to set standards. In 2019, BAMTAARE manufactured Aflasafe SN01 using dry spores produced in Ibadan and sent via courier and 19 000 ha of groundnut and maize in Senegal and The Gambia were treated. Biocontrol manufactured with dry spores was as effective as biocontrol manufactured with freshly produced spores. Treated crops contained safe and significantly (P < 0.05) less aflatoxin than untreated crops. The dry spore innovation will make biocontrol manufacturing cost-efficient in several African countries.

Estimating the risk of aflatoxin-induced liver cancer in Tanzania based on biomarker data

Evidence about the magnitude of the aflatoxin menace can help policy makers appreciate the importance of the problem and strengthen policies to support aflatoxin mitigation measures. In this study, we estimated aflatoxin-induced liver cancer risk in 2016 for Tanzania and used the information to estimate the health burden due to the aflatoxin exposure in the country. The burden of aflatoxin-induced liver cancer was assessed based on available aflatoxin biomarker data from a previous epidemiology study, hepatitis B virus infection prevalence and population size of Tanzania in 2016. The health burden due to aflatoxin-induced liver cancer was estimated using disability adjusted life years (DALYs). The aflatoxin exposures ranged from 15.0-10,926.0 ng/kg bw/day (median, 105.5 ng/kg bw/day). We estimated that in 2016 there were about 1,480 (2.95 per 100,000 persons) new cases of aflatoxin-induced liver cancer in Tanzania and assumed all of them would die within a year. These morbidity and mortality rates led to a total loss of about 56,247.63 DALYs. These results show, quantitatively, the cases of liver cancer and related deaths that could be avoided, and the healthy life years that could be saved, annually, by strengthening measures to control aflatoxin contamination in Tanzania.

The Atoxigenic Biocontrol Product Aflasafe SN01 Is a Valuable Tool to Mitigate Aflatoxin Contamination of Both Maize and Groundnut Cultivated in Senegal

Aflatoxin contamination of groundnut and maize infected by Aspergillus section Flavi fungi is common throughout Senegal. The use of biocontrol products containing atoxigenic Aspergillus flavus strains to reduce crop aflatoxin content has been successful in several regions, but no such products are available in Senegal. The biocontrol product Aflasafe SN01 was developed for use in Senegal. The four active ingredients of Aflasafe SN01 are atoxigenic A. flavus genotypes native to Senegal and distinct from active ingredients used in other biocontrol products. Efficacy tests on groundnut and maize in farmers' fields were carried out in Senegal during the course of 5 years. Active ingredients were monitored with vegetative compatibility analyses. Significant (P < 0.05) displacement of aflatoxin producers occurred in all years, districts, and crops. In addition, crops from Aflasafe SN01-treated fields contained significantly (P < 0.05) fewer aflatoxins both at harvest and after storage. Most crops from treated fields contained aflatoxin concentrations permissible in both local and international markets. Results suggest that Aflasafe SN01 is an effective tool for aflatoxin mitigation in groundnut and maize. Large-scale use of Aflasafe SN01 should provide health, trade, and economic benefits for Senegal.[Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Impaired growth in rural Gambian infants exposed to aflatoxin: a prospective cohort study

BACKGROUND

Exposure to aflatoxin, a mycotoxin produced by fungi that commonly contaminates cereal crops across sub-Saharan Africa, has been associated with impaired child growth. We investigated the impact of aflatoxin exposure on the growth of Gambian infants from birth to two years of age, and the impact on insulin-like growth factor (IGF)-axis proteins.

METHODS

A subsample (N = 374) of infants from the Early Nutrition and Immune Development (ENID) trial (ISRCTN49285450) were included in this study. Aflatoxin-albumin adducts (AF-alb) were measured in blood collected from infants at 6, 12 and 18 months of age. IGF-1 and IGFBP-3 were measured in blood collected at 12 and 18 months. Anthropometric measurements taken at 6, 12, 18 and 24 months of age were converted to z-scores against the WHO reference. The relationship between aflatoxin exposure and growth was analysed using multi-level modelling.

RESULTS

Inverse relationships were observed between lnAF-alb and length-for-age (LAZ), weight-for-age (WAZ), and weight-for-length (WLZ) z-scores from 6 to 18 months of age (β = - 0·04, P = 0·015; β = - 0·05, P = 0.003; β = - 0·06, P = 0·007; respectively). There was an inverse relationship between lnAF-alb at 6 months and change in WLZ between 6 and 12 months (β = - 0·01; P = 0·013). LnAF-alb at 12 months was associated with changes in LAZ and infant length between 12 and 18 months of age (β = - 0·01, P = 0·003; β = - 0·003, P = 0·02; respectively). LnAF-alb at 6 months was associated with IGFBP-3 at 12 months (r = - 0·12; P = 0·043).

CONCLUSIONS

This study found a small but significant effect of aflatoxin exposure on the growth of Gambian infants. This relationship is not apparently explained by aflatoxin induced changes in the IGF-axis.

Aflatoxin exposure assessed by aflatoxin albumin adduct biomarker in populations from six African countries: REVIEW ARTICLE

Aflatoxins are a group of carcinogenic mycotoxins that have been implicated to have other adverse health impacts, including child growth impairment and immune function suppression. Aflatoxin B₁ is the most toxic and most common of the aflatoxins. Contamination of various food crops is common in sub-Saharan Africa, particularly in staple crops such as maize and groundnuts, leading to chronic dietary exposure in many populations. For many years we have used the aflatoxin albumin adduct as a biomarker of aflatoxin exposure, assessed using a competitive inhibition enzyme linked immunosorbent assay (ELISA). Here, we review our recent studies of human exposure in six African countries; Gambia, Guinea, Kenya, Senegal, Tanzania and Uganda. This data shows the widespread exposure of vulnerable populations to aflatoxin. Geometric mean (95% confidence interval) levels of the biomarker ranged from 9.7 pg/mg (8.2, 11.5) in Ugandan children to 578.5 pg/mg (461.4, 717.6) in Kenyan adolescents during an acute aflatoxicosis outbreak year. We describe how various factors may have influenced the variation in aflatoxin exposure in our studies. Together, these studies highlight the urgent need for measures to reduce the burden of aflatoxin exposure in sub-Saharan Africa.

Urinary aflatoxin exposure monitoring in rural and semi-urban populations in Ogun state, Nigeria

Aflatoxins are a major class of fungal toxins that have food safety importance due to their economic and health impacts. This pilot aflatoxin exposure biomonitoring study on 84 individuals was conducted in a rural (Ilumafon) and a semi-urban community (Ilishan Remo) of Ogun state, Nigeria, to compare aflatoxin exposures among the two population cohorts. First morning urine samples were obtained from the participants, and the urinary aflatoxin M₁ (AFM₁) levels were measured by a quantitative Helica Biosystems Inc. ELISA kit assay. About 99% (83 out of 84) of the urine samples had detectable AFM₁ levels in the range of 0.06 to 0.51 ng mL^-1 (median: 0.27 ng mL^-1). The mean urinary AFM₁ levels were significantly (p = 0.001) higher in the semi-urban population (0.31 ± 0.09 ng mL^-1) compared to the rural population (0.24 ± 0.07 ng mL^-1). There were, however, no significant differences in mean urinary AFM₁ levels of males and females, and among children, adolescents and adults. This study indicates high aflatoxin exposure to the extent of public health concerns in the studied populations. Thus, more efforts are required for aflatoxin exposure monitoring and control in high-risk regions.