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

International agricultural research to reduce food risks: case studies on aflatoxins

Despite massive expansion of human and livestock populations, fuelled by agricultural innovations, nearly one billion people are hungry and 2 billion are sickened each year from the food they eat. Agricultural and food systems are intimately connected to health outcomes, but health policy and programs often stop at the clinic door. A consensus is growing that the disconnection between agriculture, health and nutrition is at least partly responsible for the disease burden associated with food and farming. Mycotoxins produced by fungi are one of the most serious food safety problems affecting staple crops (especially maize and groundnuts). Aflatoxins, the best studied of these mycotoxins, cause around 90,000 cases of liver cancer each year and are strongly associated with stunting and immune suppression in children. Mycotoxins also cause major economic disruptions through their impacts on trade and livestock production. In this paper we use the case of fungal toxins to explore how agricultural research can produce innovations, understand incentives and enable institutions to improve, simultaneously, food safety, food accessibility for poor consumers and access to markets for smallholder farmers, thus making the case for research investors to support research into agricultural approaches for enhancing food safety in value chains. We first discuss the evolution of food safety research within the CGIAR. Then we show how taking an epidemiological and economic perspective on aflatoxin research connects health and nutrition outcomes. Finally, we present three case studies illustrating the traditional strengths of CGIAR research: breeding better varieties and developing new technologies

An overview of the diversity of microorganisms involved in decomposition in soils

Decomposition is a complex and prolonged process initiated before death and with rate constants varying with the nature of the substrate, and the characteristics of the environment. The process of decomposition is generally slow but presents a pattern suggesting sequential colonisation of senescent and dead tissue, associating weak parasites with senescing tissues and a primary and secondary saprophytic flora with the utilisation of simple carbohydrates and eventually of cellulose and lignin. A corpus of dead tissue is gradually broken down by the activities of the saprophytic soil fauna and the heterotrophic soil fungi, actinomycetes and bacteria. Among these, fungi are typically the pioneer colonisers and decomposers of dead tissues. Fungi are fitted for this pioneering role by their physical organisation into a network of mycelium which penetrate cellulose walls in plant tissue, even those strengthened by lignification, by a combination of enzyme action and growth pressure exerted by the hyphal apices, supported by rigid mycelium. The final results of this breakdown are the liberation of the essential mineral nutrients locked up in the dead organic matter, and yet needed by higher plants. Studies in the temperate region have shown that many of the practices involved in agricultural management decreases soil biodiversity and alters the structure of soil biological communities. In Kenya, very little work related to soil microbial diversity and decomposition as a process has been done. Research in soil science has focussed on fertility in relation to addition of organic and chemical fertilisers to the soil and the eventual crop yield, ignoring the effects of these additions to the soil inhabitants. There is a need, in Kenya and in other tropical countries, to focus more research on the gradual changes in diversity at finer levels of taxonomic resolution, and relating these changes to effects on ecosystem function as agriculture intensifies. Journal of Tropical Microbiology Vol.3 2004: 3-1

Influence of soil lead (Pb) levels on fungal occurrence, growth and sporulation

The emission of exhaust fumes into the environment, which are eventually deposited in to soils, contributes to the increasing hazardous levels of lead in the soil ecosystem. Kenya has a high number of automotives that emit high levels of exhaust fumes that make lead a major environmental pollutant. At high levels, lead has adverse effect on the soil microbiota. This study was designed to investigate the effect of lead on mucoraceous fungi in a roadside habitat. Mucoraceous fungi are mostly saprophytes and play an important role in nutrient cycling, elemental storage and transport in the soil. Soil plate and dilution methods were used to isolate fungi from the topsoil collected from the Kiambu roadside habitat and forest stand. The soil lead content was determined by atomic absorption spectrometry. The effect of lead on the occurrence, growth and sporulation of the fungi was studied. Lead concentration of up to 160 μg g-1 was recorded from the roadside, habitat soils. This decreased with increase in distance away from the road. The mucoraceous fungi showed a decline in frequency of occurrence and species diversity with increasing lead pollution load in the soil. However, Cunninghamella spp. were predominantly present in the heavily contaminated soils and showed good in vitro growth in lead agar medium. Cunninghamella. elegans, which was the most common species showed tolerance for lead. Theses results showed that lead negatively affected the occurrence and diversity of mucoraceous fungi. The presumed tolerance of lead by species of Cunninghamella presents them as candidates for use in remediation of contaminated soils. Key Words: Mucorales, soil fungi, soil contamination, lead, pollution, exhaust fumes. J. Trop. Microbiol Vol.2 2003: 27-3

Evaluation of potency of native Bacillus thuringiensis against maize insect pests and aflatoxin producing fungi in Kenya

Bacillus  thuringiensis  is  the most  used  biological  control  agent  to  date. Among major  constraints  to maize  production,  safety  and hence  food  sufficiency  in Kenya  is  infestation, damage  and  contamination by  insect pests. Maize grains  are  adversely damaged by Prostephanus  truncatus which occasionally paves way  for  the growth of  aflatoxin producing  fungi. The  focus of  this  study was to establish the toxicity of native Bt against adult P. truncatus, second instar larvae of Chilo partellus, Aspergillus flavus and Aspergillus parasiticus. Seven Bt isolates (i.e. KG 411, KG 12-0, KG 20, KG 420, KM 31, KM 12 and KM 24) caused over 50% mean mortality of P. truncatus at the first preliminary dose of 10mg/ml. With subsequent analysis of  the efficacy of Bt against P. truncatus, isolate KG 411 was significantly more  toxic  to  it at 95% confidence  limit  (p <0.001)  than all  the other Bt  isolates. Bt  isolate KG 411 had LD50 of 0.30mg/ml which caused 77.1% mean mortality of adult P. truncatus. Potency tests of the Bt isolates against the second instar larvae of C. partellus showed significant differences at 95% confidence limit (p<0.001), with isolate KM 12 causing the highest mean mortality of 76%. Evaluation of effects of spores and crystals produced by the Bt isolates on A. flavus and A. parasiticus showed that isolate KM 31 caused  the highest inhibition of fungal growth. Only  isolate KM 31 was potent against both P. truncatus and the two fungal  species. However  isolate KG  411 which was  highly  toxic  against  P.  truncatus  had  no  significant  growth  inhibition  effect against  the  two  fungal  strains. This  result  demonstrates  that  native Bt  could  constitute  an  alternative  biological  control  option  for management of adult P. truncatus, A. parasiticus and A. flavus in maize protection.Key Words: Bacillus  thuringiensis;  Prostephanus  truncatus;  Chilo  partellus;  Aspergillus  spp.,  aflatoxin