Influence of aflatoxin on nutrition and malaria in mice

Aggravation of pathogenesis mediated by ochratoxin A in mice infected with Trypanosoma brucei rhodesiense

Mice fed 1.5 mg ochratoxin A (OTA) per kg body weight and infected with Trypanosoma brucei rhodesiense were compared with trypanosome-infected placebo-fed and uninfected OTA-fed controls. Uninfected OTA-fed mice showed fever, lethargy, facial and eyelid oedemas, mild hepatitis and nephritis, and high survival. Infected placebo-fed controls had mean pre-patent period (PPP) of 3.26 days, lethargy, dyspnoea, fever, facial and scrotal oedema, survival of 33-65 days, reduced red cell counts (RCC: 10.96-6.87x106 cells/microl of blood), packed cell volume (PCV: 43.19-26.36%), haemoglobin levels (Hb: 13.37-7.92 g/dL) and mean corpuscular volume (MCV) of 37.96-41.31 fL, hepatosplenomegaly, generalized oedemas, heart congestion, hepatitis and nephritis. Compared to infected placebo-fed controls, infected OTA-fed mice had significantly (P<0.05) shorter mean PPP (2.58 days), reduced survival (6-47 days), more pronounced fever and dyspnoea. The latter had significantly (P<0.05) reduced RCC (10.74-4.56x106 cells/microl of blood), PCV (43.90-20.78%), Hb (13.06-5.74 g/dL), increased MCV (39.10-43.97 fL), severe generalized oedemas, haemorrhages, congestion, hepatic haemosiderosis, hepatitis, nephritis, endocarditis, pericarditis and exclusively, splenic macrophage and giant cell hyperplasia, expanded red pulp and splenic erythrophagocytosis. It was concluded that OTA aggravated the pathogenesis of T. b. rhodesiense infection in mice, and should therefore be taken into consideration during trypanosomosis control programmes.

The effects of aflatoxin B1 on the development of kwashiorkor in mice

Seventy Swiss albino mice (6-week-old male) were selected for the investigation into aflatoxin B1's role in the cause of kwashiorkor. The mice were divided randomly into four groups. They were grouped within each group by being fed either low or normal protein level diets supplemented with very small amounts of aflatoxin B1 (0.5 microg/day). The control groups were fed aflatoxin B1-free diets containing either normal or low protein levels. All groups were monitored for 7 weeks. The increase in body weight was found to be low in groups I and II, given diets contaminated with aflatoxin B1. Although groups II and IV, which were given low dietary protein, showed remarkable decreases in serum total protein and albumin levels (group II: total protein 4.1 +/- 0.1 g/dL, albumin 2.6 +/- 0.8 g/dL and group IV: total protein 4.6 +/- 1.3 g/dL, albumin 2.8 +/- 0.82 g/dL) when compared with the groups fed a normal dietary protein level (group I: total protein 5.9 +/- 1.3g/dL, albumin 3.4 +/- 0.7g/dL and group III: total protein 5.4 +/- 1.6g/dL, albumin 3.5 +/- 1.2g/dL; P < 0.05). The statistical difference between these two groups was found not to be significant (P > 0.05). However, decreases in total protein and albumin levels were a little more prominent in group II. In addition, histopatological changes of the liver was remarkable in the group fed a low protein diet and aflatoxin B1 when compared with the group fed only a low protein diet and no aflatoxin B1. More significantly, however, was the increase in liver weight in both groups fed a low protein diet (groups II and IV). Our conclusion is that aflatoxin B1 could not have contributed to the development of kwashiorkor.

Nutritional modulation of malaria morbidity and mortality

This review critically examines the relationship between nutritional status and malaria. The data indicate that protein-energy malnutrition is associated with greater malaria morbidity and mortality in humans. In addition, controlled trials of either vitamin A or zinc supplementation show that these nutrients can substantially reduce clinical malaria attacks. Data for iron indicate that supplementation may minimally aggravate certain malariometric indices in some settings and also strongly improve hematologic status. Withholding of iron supplements from deficient population is, therefore, not currently indicated. Available evidence for other nutrients describe varied effects, with some deficiencies being exacerbative (e.g., thiamine), protective (e.g., vitamin E), or both exacerbative and protective in different settings (e.g., riboflavin, vitamin C). The roles of folate, other B vitamins, unsaturated fatty acids, amino acids, and selenium are also examined. Study of the interactions between nutrition and malaria may provide insight to protective mechanisms and result in nutrient-based interventions as low-cost and effective adjuncts to current methods of malaria prevention and treatment.

Of sick turkeys, kwashiorkor, malaria, perinatal mortality, heroin addicts and food poisoning: research on the influence of aflatoxins on child health in the tropics

Similarities between the geographical and climatic prevalences of kwashiorkor and of exposure to dietary aflatoxins, and between the biochemical, metabolic and immunological derangements in kwashiorkor and those in animals exposed to aflatoxins, prompted investigation of the associations between kwashiorkor and aflatoxins. Studies in Africa in the 1980s indicated a role for these toxins in the pathogenesis of the disease. Paediatric cases of kwashiorkor are less prone to severe Plasmodium falciparum malaria than normal children. In mice infected with P. berghei, aflatoxin exposure inhibits parasite growth and ameliorates morbidity. Aflatoxins occur in < or = 40% of samples of breast milk from tropical Africa, usually as low concentrations of the relatively non-toxic derivatives of aflatoxin B1 (AFB1) but sometimes as high concentrations of the very toxic AFB1. This could explain kwashiorkor in breast-fed babies. Aflatoxin exposure occurs in > or = 30% of pregnancies in tropical Africa and the toxins are often in cord blood, sometimes at extremely high concentrations. Aflatoxins are now incriminated in neonatal jaundice and there is circumstantial evidence that they cause perinatal death and reduced birthweight. Aflatoxin-induced immunosuppresion may explain the aggressive behaviour of HIV infection in Africa. There are similarities between observations on HIV cases in Africa and those on heroin addicts in Europe, where 'street' heroin is frequently contaminated with aflatoxin. Aflatoxins were found in 20% of random urine samples from heroin addicts in the U.K. and the Netherlands. Aflatoxins have also been incriminated in episodes of food poisoning which have been associated with serious morbidity and mortality, particularly among young children.

Enhanced depletion of glutathione and increased liver oxidative damage in aflatoxin-fed mice infected with Plasmodium berghei

The effect of dietary aflatoxins B1 and G1 and Plasmodium berghei infection on glutathione (GSH) levels and liver status in mice was investigated. Three days after intraperitoneal injection of 0.1 x 10(6) parasitized red blood cells into the mice, there was a significant fall in blood glutathione levels accompanied by a significant increase in serum cholinesterase and liver malonic dialdehyde levels in the mice fed aflatoxin compared with those in the control group. The results suggested that malaria parasites can enhance depletion of host glutathione and oxidative damage of the liver in mice fed low levels of aflatoxins.

Aflatoxin exposure, malaria and hepatitis B infection in rural Gambian children

Aflatoxin-albumin adduct levels were measured in serum samples obtained from a group of Gambian children. The relationships between exposure to aflatoxin and the prevalence of malaria, between exposure and humoral and cellular responses in vitro to defined malaria antigens and, amongst children with evidence of exposure to hepatitis B infection, between aflatoxin and carriage of the hepatitis B surface antigen (HBsAg), were assessed. Aflatoxin-albumin adduct was found in nearly all serum samples collected during a survey performed at the end of the dry season and levels of adduct were generally high (up to 720 pg aflatoxin-lysine equivalent/mg albumin). Higher levels of aflatoxin-albumin adduct were detected in Wollof children than in children of other ethnic groups and marked variation in mean adduct levels between villages was observed. Aflatoxin-albumin adduct levels were higher in children who were HbsAg positive and in children with Plasmodium falciparum parasitaemia than in controls. However, levels of adduct had no consistent effect on either malaria-specific antibody responses, lymphoproliferative responses in vitro, or morbidity from malaria during the subsequent rainy season. Much lower levels of aflatoxin-albumin adduct were detected in repeat samples obtained at the end of the rainy season. There was poor correlation between dry and rainy season levels of adduct in individual children. We have shown that Gambian children are exposed to high levels of aflatoxin. The seasonal variation of aflatoxin-albumin adduct and marked fluctuation of adduct with time in individual children need to be considered in the future planning of epidemiological studies using this marker of exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Climatic conditions and kwashiorkor in Mumias: a retrospective analysis over a 5-year period

Hospital records from a rural hospital in Kenya were retrospectively analysed for the total monthly admissions for kwashiorkor and all other forms of malnutrition over a 5-year period. These figures were related to the climatic conditions that prevailed during the year as derived from the records of a meteorological station in the area. The peak prevalence for kwashiorkor coincided each year with the season during which relative humidity was highest. The prevalence of kwashiorkor is discussed in relation to variable aflatoxin formation, which is influenced by seasonal changes in weather conditions.