The gut microbiome in konzo

Konzo, a distinct upper motor neuron disease associated with a cyanogenic diet and chronic malnutrition, predominately affects children and women of childbearing age in sub-Saharan Africa. While the exact biological mechanisms that cause this disease have largely remained elusive, host-genetics and environmental components such as the gut microbiome have been implicated. Using a large study population of 180 individuals from the Democratic Republic of the Congo, where konzo is most frequent, we investigate how the structure of the gut microbiome varied across geographical contexts, as well as provide the first insight into the gut flora of children affected with this debilitating disease using shotgun metagenomic sequencing. Our findings indicate that the gut microbiome structure is highly variable depending on region of sampling, but most interestingly, we identify unique enrichments of bacterial species and functional pathways that potentially modulate the susceptibility of konzo in prone regions of the Congo.

Reduced foodborne toxin exposure is a benefit of improving dietary diversity

Naturally occurring foodborne toxins are common in subsistence diets of low-income human populations worldwide. Often, these populations rely on one or two staple foods for the bulk of their calories, making them more susceptible to chronic intake of certain toxins. Exposure to common foodborne toxins is associated with diverse conditions such as cancer, immunotoxicity, growth impairment, and neurological deficits. Interventions focused solely on reducing toxin levels have proven difficult to sustain. Using case studies of two foodborne toxins, aflatoxin and cassava cyanide, this article addresses the heightened risk of particular diseases from eating monotonous diets based in maize, groundnuts, and cassava: common in sub-Saharan Africa and parts of Asia. We also discuss the potential role of increased dietary diversity in counteracting these diseases. Increased dietary diversity can reduce consumption of toxins and increase intake of nutrients that could counteract the toxicity of such chemicals. In Qidong, China, a population that previously consumed a monotonous maize-based diet and increased dietary diversity since the 1980s has experienced a dramatic reduction in liver cancer mortalities. That liver cancer decreased as dietary diversity increased is the catalyst for the hypothesis that dietary diversity could have a direct impact on reducing health effects of foodborne toxins. Future research, agricultural development, and food policy reforms should take into consideration the multifaceted benefits associated with improved dietary diversity. Collaborations between toxicologists, nutritionists, and policymakers are important to development of sustainable interventions to reduce foodborne toxin exposure and promote health through increased dietary diversity.

Determinants of cognitive performance in children relying on cyanogenic cassava as staple food

While risk factors for konzo are known, determinants of cognitive impairment in konzo-affected children remain unknown. We anchored cognitive performance (KABC-II scores) to serum levels of free-thyroxine (free-T4), thyroid-stimulating hormone (TSH), albumin, and motor proficiency (BOT-2 scores) in 40 children including 21 with konzo (median age: 9 years) and 19 without konzo (median age: 8 years). A multiple regression model was used to determine variables associated with changes in KABC-II scores. Age (β: -0.818, 95% CI: -1.48, -0.152) (p = 0.018), gender (β: -5.72; 95% CI: -9.87, -1.57 for females) (p = 0.009), BOT-2 score (β: 0.390; 95% CI: 0.113, 0.667) (p = 0.008), and free-T4 (β: 1.88; 95% CI: 0.009, 3.74) (p = 0.049) explained 61.1 % of variation in KABC-II scores. Subclinical hypothyroidism was not associated with poor cognition. A crude association was found between serum albumin and KABC-II scores (β: 1.26; 95 % CI: 0.136, 2.39) (p = 0.029). On spot urinary thiocyanate reached 688 μmol/l in children without konzo and 1,032 μmol/L in those with konzo. Female gender and low serum albumin are risk factors common to cognitive and proportionally associated motor deficits in children exposed to cassava cyanogens. The two types of deficits may share common mechanisms.

Memory deficits associated with sublethal cyanide poisoning relative to cyanate toxicity in rodents

Food (cassava) linamarin is metabolized into neurotoxicants cyanide and cyanate, metabolites of which we sought to elucidate the differential toxicity effects on memory. Young 6-8 weeks old male rats were treated intraperitoneally with either 2.5 mg/kg body weight (bw) cyanide (NaCN), or 50 mg/kg bw cyanate (NaOCN), or 1 μl/g bw saline, daily for 6 weeks. Short-term and long-term memories were assessed using a radial arm maze (RAM) testing paradigm. Toxic exposures had an influence on short-term working memory with fewer correct arm entries (F(2, 19) = 4.57 p < 0.05), higher working memory errors (WME) (F(2, 19) = 5.09, p < 0.05) and longer RAM navigation time (F(2, 19) = 3.91, p < 0.05) for NaOCN relative to NaCN and saline treatments. The long-term working memory was significantly impaired by cyanide with fewer correct arm entries (F(2, 19) = 7.45, p < 0.01) and increased working memory errors (F(2, 19) = 9.35 p < 0.05) in NaCN relative to NaOCN or vehicle treated animals. Reference memory was not affected by either cyanide or cyanate. Our study findings provide an experimental evidence for the biological plausibility that cassava cyanogens may induce cognition deficits. Differential patterns of memory deficits may reflect the differences in toxicity mechanisms of NaOCN relative to NaCN. Cognition deficits associated with cassava cyanogenesis may reflect a dual toxicity effect of cyanide and cyanate.

Manioc flour consumption as a risk factor for lead poisoning in the Brazilian Amazon

Recent studies reported elevated blood lead (Pb) levels in riparian populations of the Amazon. For this reason, the aim of the present study was to assess the risk to riparians in the Brazilian Amazon to Pb exposure due to the intake of contaminated manioc flour. Lead levels were determined in whole blood (n = 74) and in manioc flour samples (n = 30) in three different communities. Mean blood Pb levels were 16.8 μg/dl, with individuals living in Açaituba presenting the highest mean blood Pb level (22.4 μg/dl), followed by Nova Canaã (17.3 μg/dl) and Santa Cruz (9.8 μg/dl). The minimum blood Pb level found was 0.83 μg/dl and the maximum was 44.3 μg/dl. The estimated daily intake (EDI) was calculated and compared to the benchmark dose lower confidence limit (BMDL) for neurotoxicity. Mean Pb in manioc flour was 0.34 μg/g while EDI was 79 μg/d, corresponding to 260% of the BMDL (varying from 168 to 308%). This finding is of great importance since this high EDI may exert adverse effects on the nervous system of this population. Manioc flour intake may thus present considerable risk of Pb exposure in this region. Risk management strategies and further studies on adverse effects in this population are needed.

Combination of cassava flour cyanide and urinary thiocyanate measurements of school children in Mozambique

The maximum daily cassava flour intake of children may be calculated from determination of the total cyanide content of cassava flour and urinary thiocyanate levels of school children in samples collected at the same time and place. Four sites, two with and two without recent konzo cases, were chosen for study. In two sites with recent konzo cases, 84% and 93% of school children consumed cassava the previous day, and the calculated maximum daily consumption of cassava was over 700 g. In two sites without recent konzo cases, about 50% of school children consumed cassava the previous day and the calculated daily consumption of cassava flour was less than 150 g. By measurements of cyanide in flour and urinary thiocyanate we are therefore able to distinguish between communities whose diet is almost totally reliant on cassava, and who are therefore susceptible to konzo, and those who have a broader diet and are free from konzo. In another calculation it is shown that 4-23% of the essential S-containing amino acids in the cassava flour consumed by children is used up to detoxify and flour cyanide to thiocyanate. This depletion of methionine and cystine may leads to protein deficiency and may contribute to onset of konzo.

Cassava-enriched diet is not diabetogenic rather it aggravates diabetes in rats

Chronic intake of cassava has been thought to play a role in the pathogenesis of diabetes. We investigated the effects of dietary cassava (Manihot esculenta), which naturally contains cyanogenic glycosides, in the progression of diabetes mellitus in rats. Diabetes was induced by five mild doses of streptozotocin, in male Wistar rats which were fed a standard or cyanide-free cassava (CFC) diet containing or not containing exogenous cyanide with or without methionine. Methionine was employed to counterbalance the toxic effects of cyanide. During diabetes progression, we determined glycaemia and antioxidant status, by measuring vitamin C levels and activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione reductase (GSSG-Red). Feeding CFC diet did not induce diabetes in control rats; rather this diet, in diabetic animals, aggravated hyperglycaemia the severity of which was increased in these animals fed CFC diet, supplemented with cyanide. Addition of methionine curtailed the toxic effects of cyanide supplementation in CFC diet-fed diabetic animals. In standard diet-fed animals, the activities of SOD, GSH-Px and GSSG-Red were lower in diabetic rats than control rats. Interestingly, all of the CFC diets with or without cyanide or methionine, increased vitamin C levels and antioxidant enzyme activities in both control and diabetic animals. However, supplementing cyanide to CFC diet (without methionine) curtailed SOD and GSH-Px activities in diabetic rats. Our study shows that cassava diet containing cyanide is 'diabetes-aggravating'.

High mortality of subjects with endemic ataxic polyneuropathy in Nigeria

BACKGROUND

Endemic ataxic polyneuropathy, a neurological syndrome that was thought to be benign, has been shown to persist in some communities in south-western Nigeria, where it was first described in the 1950s.

OBJECTIVES

This study was conducted to compare mortality of cases and controls, and to determine if mortality is related to exposure to cyanide from cassava foods.

MATERIAL AND METHODS

Cases of endemic ataxic polyneuropathy and two groups of controls, one group living in an endemic community and the other group living in a non-endemic community, were followed for 25 months. The outcome was death from medical causes.

RESULTS

A total of 5970 subjects, 204 cases and 5766 controls - 4000 controls in the endemic community and 1766 controls in the non-endemic community, were followed. A total of 153 subjects died, 24 cases, 115 controls in the endemic community, and 14 controls in the non-endemic community. Relative risks of death (95% CI), adjusted for age and gender, were 4.5 (2.3-8.9) for cases (P < 0.0001), but 2.6 (1.5-4.6) for controls living in the endemic community (P = 0.001).

CONCLUSION

This study shows that endemic ataxic polyneuropathy decreases survival. The finding of lower risk of death in the community with higher exposure to cyanide from cassava foods indicates that mortality of endemic ataxic polyneuropathy is not associated with exposure to cyanide from cassava foods.

Fish are central in the diet of Amazonian riparians: should we worry about their mercury concentrations?

The Amazon rain forest extends over an area of 7.8x10(6)km(2) in nine countries. It harbors a diverse human population distributed in dense cities and isolated communities with extreme levels of infrastructure. Amazonian forest people, either autochthons or frontier riparians (ribeirinhos) living in isolated areas, share the same environment for survival and nutritional status. The peculiarities of the hydrological cycle determine disease patterns, agricultural conditions, and food availability. Feeding strategies depend heavily on cassava products and fish. These two foods carry toxic substances such as linamarin (naturally present in cassava) and monomethyl mercury (MMHg) (bioconcentrated in fish flesh) that cause neurotoxic diseases in other parts of the world but not in Amazonia, where neurotoxic cases of food origin are rare and not related to these staples. While cassava detoxification processes may partly explain its safe consumption, the Hg concentrations in Amazonian fish are within traditionally safe limits for this population and contribute to an important metabolic interaction with cassava. The gold rush of the 1970s and 1980s brought large-scale environmental disruption and physical destruction of ecosystems at impact points, along with a heavy discharge of metallic Hg. The discharged Hg has not yet impacted on MMHg concentrations in fish or in hair of fish consumers. Hair Hg concentration, used as a biomarker of fish consumption, indicates that the Amazonian riparians are acquiring an excellent source of protein carrying important nutrients, the lack of which could aggravate their existing health problems. Therefore, in a scenario of insufficient health services and an unhealthy environment, food habits based on fish consumption are part of a successful survival strategy and recommendations for changes are not yet justifiable.

Thiocyanate overload and thyroid disease

Thiocyanate [SCN-] is a complex anion which is a potent inhibitor of iodide transport. It is the detoxification product of cyanide and can easily be measured in body fluids. Consumption of naturally occurring goitrogens, certain environmental toxins and cigarette smoke can significantly increase SCN- concentrations to levels potentially capable of affecting the thyroid gland. Goiter endemics were reported to develop when the critical urinary iodine/ SCN- ratio decreases below 3 microg iodine per mg SCN-. Iodine supplementation completely reverses the goitrogenic influence of SCN-. SCN- is also generated from cigarette smoking as a detoxifying product of cyanide. During the past two decades many reports dealt with the possible effects of cigarette smoking on thyroid hormone synthesis, thyroid gland size and thyroid autoimmunity including infiltrative ophtalmopathy of Graves' disease. In this mini-review, issues regarding thiocyanate overload and thyroid disease will be summarized.

Evaluation of the cariogenic potential of cassava flours from the Amazonian region

Cassava flour is the main dietary carbohydrate source in the Amazonian region. The cariogenic potentials of the two main kinds of cassava flour - 'seca' and 'd'água' - were evaluated in vivo and in vitro. A sweet made from a regional fruit (cupuaçú) and a species of local fish (tambaqui) were used as positive and negative controls, respectively. For in vivo evaluation of dental plaque acidogenicity, the study had a crossover design, in four legs, with 19 volunteers in four treatment groups. Dental plaque pH was determined by the microtouch method before and for 60 min after food consumption. For in vitro evaluation, stimulated saliva of each volunteer was incubated with the food and pH variation was determined over 4 h. Carbohydrates were chemically determined in the flours and the majority was found to be water-insoluble. In vivo, plaque pH decreased significantly after the consumption of the sweet (p < 0.05), increased after the fish (p < 0.05), but did not change after intake of the flours (p > 0.05). In vitro, the flours were slowly fermented by bacteria present in saliva. The in vivo and in vitro findings suggest that, in the form that the main cassava flours from the Amazonian region of Brazil are customarily eaten, they may be considered to have no or very low cariogenicity.

[Endemic spastic paraperesis (konzo)]

Konzo is characterized by the abrupt onset of isolated and symmetric spastic paraparesis of the lower extremities which is permanent but nonprogressive. Epidemic outbreaks in subtropical and tropical regions are associated with drought-provoked agricultural and social crises rendering populations dependent on a diet of insufficiently processed bitter cassava. The shortcuts in processing allow large amounts of cyanogens to remain in the cassava consumed and hence there is a high dietary cyanide exposure. Mainly children and ill people, often malnourished (and with kwashiorkor), are not able to detoxify the cyanide sufficiently, consequently developing symptoms of upper motoneuron damage. Konzo generally seems not to be caused by ignorance concerning the correct processing of cassava, but predominantly directly and indirectly by poverty.

Konzo outbreak, in the south-west of the Democratic Republic of Congo, 1996

In August 1996, cases of poliomyelitis were reported in Kahemba zone, in the south-west of the Democratic Republic (DR) of Congo. The diagnosis was reviewed and charged to Konzo, a spastic paraparesis attributed to food cyanide intoxication. In order to describe the phenomena, a community-based survey took place and found 237 people affected. The highest prevalence was found in the most isolated part of the zone. The patients suffered from an isolated non-progressive spastic paraparesis of abrupt onset. Children and women were the most affected groups, especially women after childbirth. Most of the patients developed the disease after 1990 with 101 cases in 1996. Cassava processing was the same over time and in all the villages. The study did not fully explain the increased number of cases in 1996 but suggested that complementary investigations regarding micronutrient intakes, especially vitamin A, would be necessary.

Persistent konzo and cyanogen toxicity from cassava in northern Mozambique

We aimed to detect new cases of konzo and monitor cyanogen exposure from cassava flour in communities previously affected by konzo epidemics in Nampula Province, northern Mozambique. Other objectives were to detect subclinical upper motor neuron damage in schoolchildren and test a new kit to measure urinary thiocyanate concentration. In 1999 and 2000, we carried out active and passive case detection for konzo in Memba and Mogincual Districts. In July and October, 1999, we collected cassava flour from 30 houses in three communities and measured cyanogen concentrations with a picrate kit. In October 1999, we examined all schoolchildren in three communities for ankle clonus and measured urinary thiocyanate concentration in thirty schoolchildren in each of five communities with a picrate kit. We found 27 new cases of konzo in Mogincual District. Mean total cyanogen concentrations in cassava flour varied between both seasons and years, but were always high, ranging from 26 to 186 ppm. Very high mean levels at three sites in November 1998 and July 1999 were probably due to low rainfall in the 1997-1998 season. The proportion of schoolchildren with ankle clonus varied from 8 to 17%. The new picrate kit for urinary thiocyanate worked well; mean concentrations in schoolchildren ranged from 225 to 384 micromol x l(-1). Konzo and sub-clinical upper motor neuron damage persist in poor rural communities in northern Mozambique, associated with high cyanogen concentrations in cassava flour and high urinary thiocyanate concentrations in schoolchildren.

Cassava diet--a cause for mucopolysaccharidosis?

Studies were carried out to determine the changes in glycosaminnoglycan (GAG) metabolism in rats fed cassava with varying cyanoglucoside levels and two levels of protein. Results indicated that there was an enhancement in the level of total and individual GAG with a corresponding reduction in the activity of enzymes involved in the degradation of glycosaminoglycan. These changes were significant for rats given a cassava diet (raw and boiled cassava) and low protein. The changes in total and individual GAG and the decrease in the activity of degrading enzymes was more for high cyanide (raw cassava) groups compared with other groups showing that consumption of untreated cassava is an additive factor for the promotion of mucopolysaccharidosis.

[An epidemiological study on the risk factors of irritable bowel syndrome in Zhanjiang, Guangdong province]

OBJECTIVE

To assess the risk factors in the pathogenicity of irritable bouel syndrome(IBS) in Zhanjiang city.

METHODS

Two hundred and seven IBS patients were randomly selected and compared with "healthy" people diagnosed in the same hospital during the same period. Roles of major risk factors to IBS were studied through using a case-control study.

RESULTS

Family history of hysteria or mental disease and vegetorsis was closely related to IBS, with ORs 3 and 4 respectively. There was alse close relationship between IBS and psychic trauma, often taking antibiotics, tension at work and eating sweet potato or cassava, with ORs between 1 and 2.

CONCLUSION

Our investigation suggested that the six major risk factors mentioned above played important roles in the progression of IBS in Zhanjiang city.

Impairments, disabilities and handicap pattern in konzo--a non-progressive spastic para/tetraparesis of acute onset

PURPOSE

To assess impairments, disabilities and handicap pattern in konzo.

METHOD

The study included 17 konzo subjects, of which three were males and 14 females (mean age 21, median 18 years). A detailed neurological examination was performed on all subjects. Subsequently, an assessment of impairments, disabilities and handicap was done with a constructed rating scale partially based on the ICIDH-2 framework.

RESULTS

The overall disablement picture in all subjects consisted of motor dysfunction in lower limbs leading to limitations in walking and movement activities, and restrictions in mobility. Hip mobility was severely impaired in most cases (15/17). Although konzo subjects showed normal muscle power in upper limbs (13/17), they had impaired fine motor function (10/17).

CONCLUSION

Further studies are needed to assess the effectiveness of the WHO criteria for konzo in defining its forms. The applicability of the ICIDH-2 framework in this study demonstrates the possibility of its use as a common language among researchers in the field of motor disorders. However, a revision is suggested of its taxonomy, and a definition of operational criteria to clarify the content of different qualifiers provided to assess the level of functioning or disability.

Ecological variation of intake of cassava food and dietary cyanide load in Nigerian communities

AIM

To study the ecological variation of intake of cassava foods and dietary cyanide load.

DESIGN

Ecological study design.

SETTING

Five communities in south-western Nigeria where tropical ataxic neuropathy (TAN) was described as endemic (area A), 11 communities in south-western Nigeria where TAN was described as absent (area B), and five communities in northern Nigeria (area C).

SUBJECTS

Subjects were randomly sampled from selected communities. Intake of cassava foods was estimated from dietary history and dietary cyanide load was estimated from urine thiocyanate concentrations. Residual cyanogens in cassava food samples from the community markets were determined.

RESULTS

In total, 1272 subjects from 21 communities - 238 from area A, 659 from area B and 375 from area C - were selected. Intake of cassava food per person per week was 17 meals in area A, 10 meals in area B, and one meal in area C. Geometrical mean urine thiocyanate concentrations were 73 micromol l(-1), 51 micromol l(-1) and 17 micromol l(-1) in areas A, B and C, respectively. Mean residual cyanogen content in cassava food samples was 16 mg HCN eq kg(-1) (confidence interval (CI) 13-18) in area A, and 13 mg HCN eq kg(-1) in area B (CI 11-14).

CONCLUSION

This study shows that the intake of cassava foods and dietary cyanide load is high in several communities in south-western Nigeria, predominantly in communities where TAN has been reported. Dietary cyanide load in these communities appears to be determined by the combination of frequency of intake and cyanogen content of cassava foods. Measures to improve the effectiveness of removal of cyanogen from cassava roots during processing are needed in the affected communities.

Effect of Wainan Rogo on body weight and plasma glucose in Wistar rats

Wainan Rogo (WR) is a deep-fat fried dough made from grated fresh cassava. It was found in a cross sectional case-control study to have a risk factor 3.2 times higher in diabetic than non diabetic indigenes of Borno State of Nigeria. This study examines the chemical composition, and effects of WR on body weight and blood glucose in Wistar rats. The study found a higher fat and lower protein composition of the WR diet, and found a higher plasma glucose in the WR fed rats and a more significant weight loss in this group than in the control (CF) fed rats. The findings of this study seem to support the high risk for diabetes associated with WR in the cross sectional study. The chemical composition of WR and its effect on body weight and blood glucose are further discussed, with a call for further studies of the food as a marker in the search for the pathophysiology of Malnutrition-Related Diabetes Mellitus (MRDM).

Effect of cassava consumption on open-field behavior and brain neurotransmitters in albino rats

Diet exerts a critical influence on human biology and thus studies on the interrelationship of nutrition and behavior continues to be a major and important focus of research in the natural experimental sciences. Cassava is known to cause metabolic and neurological derangement on long-term consumption as a staple diet in the tropics. In this article we present the effects of cassava consumption on open-field behavior and catecholamine levels in the hypothalamus of albino rats. Cassava consumption for 30 days alters the emotional status of the rats, with changes in the basal neurotransmitter levels in the hypothalamus. The role of the cyanide (liberated from cassava) and protein deficiency (associated with cassava consumption) has been discussed.

[Coexistence of mass hysteria, konzo and HTLV-1 virus in the Democratic Republic of the Congo]

A cross-sectional study was carried out in Pindi located 115 kilometers from Kikwit, Democratic Republic of the Congo to characterize a local school epidemic involving paralysis of the lower extremities, identify risk factors, and establish differential diagnosis with konzo and spastic paralysis related to human T-lymphotropic virus type 1 (HTLV-1). Data was obtained using a qualitative approach based on records, interviews, focus group technique, and neurological examination. Blood tests using the ELISA and western blot tests were performed to detect HTLV-1 and HIV 1 and 2. A total of 41 cases of paralysis were observed between 1994 and 1998. All patients were female and most (n = 28) were between the ages of 16 and 20 at the time of the study. The majority of cases were recorded in 1998 (31 prevalent cases and 16 incidents). Epidemiological data, clinical findings, and laboratory tests suggested that the etiology was mass hysteria with somatic conversion rather than toxic or viral causes in most cases. The psychosocial environment played an important role in the spread of the epidemic. These findings demonstrate the crucial role of the psychosocial environment in the occurrence of mass hysteria and support use of integrated health programs in developing countries.

Low dietary cyanogen exposure from frequent consumption of potentially toxic cassava in Malawi

In a cassava-growing area in Malawi, where roots are processed by soaking and water is available throughout the year, we interviewed 176 women farmers regarding their preferences for cassava cultivars and frequency of cassava consumption. Dietary cyanogen exposure was estimated from urinary levels of linamarin, the cyanogenic glycoside in cassava, and urinary thiocyanate, the main cyanide metabolite. Protection against unplanned harvest by family members, theft and animal spoilage were stated to be very important reasons for growing bitter cassava cultivars by 91%, 90% and 74% of the women, respectively. The mean (+/- SD) number of cultivars grown by each woman was 4.6 (+/- 2.4). The correlation between mean taste and mean danger scores for the 25 most grown cultivars was strong (r > 0.98). The scoring indicated that cultivars belonged to two distinct groups, eight to a group referred to as 'cool' and 17 to a group termed 'bitter'. The dumpling-like porridge (kondowole) made from cassava flour from bitter roots was eaten twice daily by 51% and at least weekly by 81%. The mean (+/- SEM) urinary linamarin was 14 (+/- 1) mumol/L and thiocyanate was 50 (+/- 4) mumol/L, less than a tenth of levels reported from populations eating insufficiently processed bitter cassava roots, and in the same range as in a non-smoking Swedish reference population. We conclude that cyanogenesis is a preferred characteristic of cassava by the studied farmers because it enhances food security. The availability of water and their knowledge about toxicity and processing enables these women farmers to provide a safe staple food from bitter cassava roots.

Cyanide poisoning, 2 cases report and treatment review

Two patients, a 4-year-old girl and her brother 1 1/2 year-old, with cyanide poisoning are reported. They vomited and became comatose 9 hours after ingestion of boiled cassava. At a community hospital, they were intubated and given ventilatory support. The girl was transferred to Ramathibodi Intensive Care Unit. At 19 hours after ingestion, sodium nitrite and sodium thiosulfate were given as well as other supportive treatment. She recovered with normal breathing on the next day. The boy was referred to Ramathibodi 4 hours later. On arrival, he appeared normal except for the bitter almond breathe. Only supportive treatment was given. Their blood cyanide levels on arrival were 0.56 and 0.32 microgram/ml (normal value < 0.3 microgram/ml) respectively confirming the diagnosis of cyanide poisoning. Other abnormal laboratory findings included metabolic acidosis and lactic acidemia. The pathogenesis and management of cyanide poisoning are reviewed.

[The consumption of cassava is not responsible for the etiology of endemic goiter in rural areas in Senegal]

An epidemiological study of iodine deficiency disorders (IDD) was carried out in West Senegal and Casamance. Five hundred and eighty five households were selected in 3 areas with a high prevalence of goiter. We assessed the relative impact of iodine deficiency (estimated by mean iodine excretion in the urine of family members) and cassava consumption (mean frequency of consumption by the household). Cassava consumption, even if on a regular basis, neither caused nor increased goiter formation in this area of West Africa. This was probably due to the local method of cassava root preparation, which reduces the amount of cyanogenic compounds consumed. Iodine deficiency was principally responsible for goiter formation. Therefore, the commercial availability of iodine-supplemented salt should lead to the eradication of IDD from Senegal in the near future.

Comparative effects of scopoletin and cyanide on rat brain, 1: histopathology

Four week old male Wistar rats were used to study the effects of scopoletin and cyanide on the histopathology of rat brain. The rats were divided into a control and three experimental groups (2-4) and fed rations containing 0.07 microg scopoletin/100 g, 0.07 microg scopoletin + 1.8 mg cyanide/100 g and 1.8 mg cyanide/100 g, respectively. These levels of scopoletin and cyanide corresponded to levels found in a processed cassava diet. The first group was fed the same ration as the others but without scopoletin and cyanide. The rats were fed these rations for twelve months. Rats from each group were sacrificed at the third, sixth, ninth and twelfth months; the relative brain weight of the rats (% of body weight) and histology of their brains were studied. The lipid peroxide levels of the rat brains were also studied at the twelfth month. The results showed that the relative brain weights of the rats fed scopoletin + cyanide were significantly (p<0.05) less than that of the control from the third month. There were no significant changes in the lipid peroxide levels of the rat brains in the various groups. Histological examination of the brains of the rats suggested that scopoletin is involved in the pathogenesis of the neuropathy seen in cassava consuming populations.

Parameters of thyroid function in the endemic goitre of Akungba and Oke-Agbe villages of Akoko area of southwestern Nigeria

The parameters of thyroid function were determined in Akungba and Oke-Agbe communities of Akoko area, where goiter is endemic and compared to a control population of Erinmo and Ifewara in Ijesha area, both areas being in southwestern Nigeria. The two study areas have similar physical and geological settings. However, while the main carbohydrate source of the control population are yam and/or bread-fruit, the Akoko population derives her carbohydrates mainly from cassava which could lead to increased serum thiocyanate, a goitrogen. The serum level of tetraiodothyronine (T4) was significantly (P < 0.05) higher in Ifewara (11.0) and Erinmo (11.8) compared to Akungba (7.1) and Oke-Agbe (8.8[symbol: see text]micrograms/dL). The triiodothyronine (T3) was significantly (P < 0.05) higher in Ifewara (193) than Erinmo (133) and also significantly (P < 0.05) higher in Oke-Agbe (127) compared to Akungba (107 mg/dL). Conversely, thyroid stimulating hormone (TSH) (microU/mL) level was significantly (P < 0.05) higher than values obtained from Ifewara (4.5) and Erinmo (3.3). T3/T4 ratio above 25, indicative of hypothyroidism and endemic goiter, was 14, 7, 4 and 0% from Akungba, Oke-Agbe, Ifewara and Erinmo, respectively. The results of the present study clearly explain the Akoko goiter endemia in the light of modification (s) of thyroid metablism.

Fibrocalculous pancreatic diabetes

Fibrocalculous pancreatic diabetes (FCPD) is a unique form of diabetes secondary to chronic pancreatitis seen in developing countries of the world associated with either overt protein-calorie malnutrition or, more likely, with deficiency of certain micronutrients. FCPD affects young individuals and runs an aggressive course to reach the endpoints of diabetes, pancreatic calculi and exocrine pancreatic dysfunction (steatorrhoea) in the majority of cases. There are characteristic features of FCPD radiologically, ultrasonographically, on endoscopic retrograde cholangiopancreatography and on histopathology which distinguish it from chronic pancreatitis of other aetiologies seen in temperate zones, e.g. alcoholic chronic pancreatitis. Although a secondary form of diabetes, specific diabetes-related complications like retinopathy and nephropathy do occur in FCPD. There appears to be a high risk of developing pancreatic carcinoma. Although the aetiology of FCPD is still unclear, the role of micronutrient (antioxidant) deficiency is emerging as a possible aetiological or predisposing factor. The contribution of genetic factors and environmental toxins, e.g. cyanogenic glycosides or other nutritional/toxic factors, merit further study. Studies on FCPD, a good model of a secondary form of diabetes, could lead to improved understanding of other primary forms of diabetes as well. If the underlying aetiological factors are identified, it may also be possible to prevent this type of diabetes.

Health effects of cassava consumption in south Ethiopia

Health problems associated with cassava consumption was studied in three villages (Kodowono, Lotte and Woidewashe) of Gamo-Gofa, South Ethiopia. Total goitre rate (% TGR) increased with increasing rate of cassava consumption while, urinary iodine excretion (UIE) was found to be in the normal value range for the three villages. In both males and females incidence of goitre after the introduction of cassava to Kodowono village was significantly higher than before introduction of cassava (p < 0.001). This may indicate that the high rate of goitre is attributed to the frequency of cassava consumption. Of 450 individuals interviewed for health problems associated with cassava meal consumption, 50% reported that they were suffering from epigastric burning pain and dizziness while 38.7% reported abdominal distention and vomiting. Vomiting was relatively higher in the age group 20 years and below than it was in those above 20 years of age. These problems may be attributed to cassava consumption because, cassava contains cyanide which results in intoxication when poorly processed cassava meal is taken. Goitre prevalence and health problems attributed to cassava consumption therefore, necessitate an intervention programme to control iodine deficiency disorders (IDD), develop appropriate processing techniques to eliminate cassava toxicity and educate villagers on how to prepare safer meals from cassava.

Geographical and seasonal association between linamarin and cyanide exposure from cassava and the upper motor neurone disease konzo in former Zaire

High cyanide intake from consumption of insufficiently processed cassava has been advanced as a possible aetiology of the upper motor neurone disease konzo. However, similar neurodamage has not been associated with cyanide exposure from any other source. With an ecological study design, we compared 22 cases of konzo, 57 unaffected household members and 116 members from unaffected households, a total of 195 subjects, in konzo-affected savanna villages with 103 subjects in adjacent non-affected forest villages in the Paykongila area in the Bandundu Region, Zaire. In the dry season, the mean value (+/- SEM) of urinary thiocyanate, the main cyanide metabolite, was higher in the three groups in konzo-affected villages (563 +/- 105, 587 +/- 44 and 629 +/- 47 micromol/l) than in unaffected villages (241 +/- 17 micromol/l). In affected villages in the dry season when konzo incidence was high, mean urinary thiocyanate was also higher than the levels found in the wet season when incidence was low. The wet season values (mean +/- SEM) were 344 +/- 60, 381 +/- 35 and 351 +/- 27 micromol/l. Urinary levels of inorganic sulphate were low in all groups, indicating low intake of the sulphur amino-acids which provide a substrate for cyanide detoxification. These findings support an aetiological role for cyanide in konzo. However, urinary linamarin, the cyanogenic glucoside and source of cyanide in cassava, was more closely associated with the occurrence of konzo. The mean value (+/- SEM) of urinary linamarin in the konzo cases was 632 +/- 105 micromol/l and in their household members 657 +/- 52 micromol/l, which was significantly higher than in members of control households in the same village (351 +/- 28 micromol/l) and in unaffected villages (147 +/- 18 micromol/l). This suggests that a specific neurotoxic effect of linamarin, rather than the associated general cyanide exposure resulting from glucoside breakdown in the gut, may be the cause of konzo.

Konzo associated with war in Mozambique

We report an epidemic of konzo, symmetric spastic paraparesis associated with cassava consumption and cyanide exposure: 384 patients were treated in rehabilitation centres; the prevalence rate in a badly affected area was 30/1000. Most patients were children over 3 and women. Owing to war, communities turned to bitter cassava as their staple and took shortcuts in its processing. When the war ended, they continued to depend on inadequately processed bitter cassava. The epidemic lasted 2 years (the last year of war and the first of peace) with peaks each year during the cassava harvest. Although most cases were reported from rural inland areas, patients also came from small towns and the coast. School children had raised urinary thiocyanate and linamarin and low inorganic sulphate concentrations. Urinary thiocyanate values were lower than those previously reported in konzo epidemics, probably because we collected specimens before the cassava harvest and epidemic peak. The necessary conditions for konzo were present: intensive cultivation of bitter casava, insufficient processing, a probable high cyanide intake, and a low intake of protein-rich foods.

Cariogenic [correction of Carcinogenic] potential of a typical cassava flour from the Amazonian region of Brazil

The purpose of this study was to compare the cariogenic potential of a typical cassava flour (CF) with sucrose and starch, using a severe cariogenic challenge model in rats. Thirty Wistar female pups with their dams (mutans streptococci free) were infected by Streptococcus sobrinus 6715, desalivated when aged 25 days, and placed in a Konig-Hofer programmed feeder at age 26 days. They received 17 meals daily at hourly intervals for 21 days as follows: group (1) powdered plain sucrose and sterile distilled water ad libitum (sdwal); (2) Lf and Sdwal (3) powdered starch and sdwal. Essential nutrition was administered by gavage. Data were analyzed by ANOVA. The percentage of S. Sobrinus related to the total flora and the number of this microorganism were higher in the sucrose and CF groups than starch group. Smooth-surface and [sulcal] caries scores for the groups were: (1) 105.5 [48.0]; (2) 34.1 [39.2]; (3) 10.2 [18.1]. All the groups were statistically significantly different from each other (p < 0.01), although the result for sulcal score for CF was very close to the sucrose group. It is concluded that cassava flour, the main source of carbohydrate for the Amazonian population of Brazil, has moderate cariogenic potential.

Long-term follow-up of konzo patients

Nine patients with konzo, a symmetric spastic paraparesis of acute onset that occurs during agricultural crises in cassava-growing areas, were re-examined after 14 years. Konzo outbreaks are associated with eating insufficiently processed bitter cassava and a low intake of essential amino acids. Bitter cassava contains cyanogenic glycosides; processing breaks them down to acetone cyanohydrin and hydrogen cyanide. This long-term follow-up showed that the neurological signs in konzo patients remained constant. Four severely affected patients, however, showed functional improvement. This non-progression clearly distinguishes konzo from myelopathy associated with human T lymphotropic virus type I infection. One child, originally classified as a konzo case, showed signs of cretinism at follow-up.

Milling reduces the goitrogenic potential of cassava

Cyanide exposure from consumption of insufficiently processed cassava has been implicated in aggravating iodine deficiency disorders (IDD). The cyanide metabolite, thiocyanate (SCN) may interfere with iodine (I) uptake of the thyroid gland. A study on 217 women in an IDD endemic area in western Tanzania showed that 98% consumed cassava daily. Total and visible goitre rates were 72.8% and 13.3%, respectively. Median urinary iodine was 3.6 micrograms/dl indicating moderate iodine deficiency. Processing methods which remove cyanogens from cassava roots have changed with time. Urinary thiocyanate (mean; 128 mumol/l) was moderately increased, but women who frequently milled cassava had significantly lower urinary thiocyanate levels. This indicates that mechanical milling could reduce the goitrogenic potential of cassava and we conclude that IDD in the studied area is mainly due to iodine deficiency and sustainable iodine supplementation should be given highest priority.

Effects of cassava diet on Cercopithecus aethiops livers: a case for cassava as the cause of both tropical splenomegaly syndrome (TSS) and endomyocardial fibrosis (EMF)

The aetiology of endomyocardial fibrosis (EMF) and tropical splenomegaly syndrome (TSS) though speculative, was considered by the author to be the same or related since the two diseases may occur in the same individual and locality. Accordingly, when attempting to prove a hypothesis for the causation of EMF that prolonged ingestion of tuber (cassava/tapioca) associated with extreme deprivation of protein causes EMF; one group of three Cercopithecus aethiops was fed on uncooked cassava while a second group was fed with uncooked bananas and in addition to harvesting the hearts whenever the animal health deteriorated, livers were also harvested for histological changes. While hearts from the animals on cassava revealed changes seen in human EMF the livers from the same animals exhibited Kupffer cell hyperplasia and hypertrophy as well as sinusoidal lymphocytosis, features seen in human TSS thereby confirming that the aetiology of these two diseases is the same. However, the banana diet did not produce such changes.

Carbohydrate tolerance in patients with tropical ataxic neuropathy--A human model of chronic cyanide intoxication

Patients with tropical ataxic neuropathy (TAN) have been shown to have chronic cyanide intoxication. Glucose tolerance test data in a group of 88 patients with TAN and 88 matched controls who were studied several years ago were analysed. A standard glucose tolerance test (SGTT) with 50 gm dextrose preceded by 50 mgs cortisone acetate orally 8 1/2 and 2 hours before the tests were performed. The SGTT was considered abnormal if the capillary blood glucose at 0.60 and 120 were greater than 120, 200 and 140 mg/100 ml (6.6, 11.1, 7.8 mmol/l) respectively. Capillary blood glucose considered abnormal for CGTT were 205 and 155 mg/100 ml at 60 and 120 (113 and 8.6 mmol/I) respectively. The SGTT was abnormal in 1 of the TAN patients and 2 controls while CGTT was abnormal in 9 TAN patients and 7 controls. However, all controls with abnormal CGTT were older than 50 years while only 1 TAN patient was older than 50 and 6 were 30 years or younger (p = 0.0105), Fischer's probability test. The results suggest a greater statistical risk for subjects with TAN 30 years or younger to have an abnormal CGTT. While this does not predict the future development of diabetes, our observation indicates the need for better designed prospective studies among such patients in developing countries.

Prolonged brainstem auditory evoked potential latencies in tropical pancreatic diabetics with normal hearing

Twenty patients with Tropical Pancreatic Diabetes (TPD) were evaluated by Brainstem Auditory Evoked Potentials (BAEP) in order to detect any possible subclinical involvement of auditory pathways. The latencies of BAEP Wave III (p < 0.009) and V (p < 0.47) as well as the Interpeak Latencies I-III (p < 0.002), and I-V (p < 0.019) were significantly prolonged in patients with TPD when compared to age and sex matched healthy volunteers. There was correlation between the abnormalities of BAEP and duration of diabetes (p < 0.006), male sex of patients (p < 0.05), and the presence of retinopathy (p < 0.003) and nephropathy (p < 0.38). There was no significant correlation with the age of the patients, type of treatment, blood sugar levels and presence of peripheral neuropathy. These changes suggest a subclinical involvement of the auditory pathways in TDP patients.

The adverse effects of long-term cassava (Manihot esculenta Crantz) consumption

Cassava (Manihot esculenta Crantz) is an important dietary staple for more than 500 million people in developing countries. People eat 60% of the cassava produced and one third of the harvest feeds animals. All cultivars of cassava contain the cyanogenic glucoside, linamarin, but in different concentrations. The roots of those cultivars with high cyanogenic content are processed to reduce the level of linamarin, because linamarin is hydrolysed in the intestinal tract of both men and animals by microbial flora and HCN is released. Researchers have implicated the sublethal levels of HCN produced on ingestion in the development of a number of metabolic diseases in both man and animals when cassava-based diets are consumed over a long period of time but the release of HCN cannot fully explain the metabolic effects of ingested linamarin. A significant amount of linamarin remains intact and is excreted in the urine. It appears that the intact linamarin inhibits Na+K+ATPase causing electrolyte imbalance within the cell. This phenomenon is exacerbated by free radicals generated by the hypoxia/normoxia cycles created by cyanide released from linamarin, which cause lipid peroxidation and cell membrane damage. When the supply of endogenous thiosulphate is adequate, cyanide plays a very minor role in the development of lesions. The amount of damage is related to the quantity of linamarin routinely ingested at sublethal levels. There appears to be species differences in the rate of the development of diseases and the intensity.

Cassava processing, consumption, and cyanide toxicity

The frequency of cassava consumption was investigated among three groups of people representing students from traditional and nontraditional cassava-consuming environments and cassava processors. Of these, 64% of the students at Obafemi Awolowo University, Ile-Ife, 38% of those at the Federal University of Technology, Akure, and 44% of the cassava processors consumed cassava products at least once a day, while 4, 35, and 28% of the groups, respectively, were moderate consumers (4-6 times a week). The serum thiocyanate level of the processors was significantly higher (0.57 mg/dl) than those of the students (0.38 mg/dl), but there was no significant difference in the urinary thiocyanate level of the three groups. Analysis of cassava and its intermediate and final products for free cyanide, acetone cyanohydrin, and intact glucosides during the production of such cassava products as gari, fufu, and lafun revealed that while the finished products might be safe for human consumption, the workers were probably exposed at different stages of processing to nondietary sources of cyanide.

Lack of association between cassava consumption and tropical pancreatitis syndrome

Previous studies suggesting an association between use of tubers of cassava and tropical pancreatitis have been weak and conflicting. To test a possible association the cassava consumption of 40 consecutive cases of tropical pancreatitis syndrome were compared with age-matched and sex-matched healthy hospital visitors. The sociodemographic characteristics of the two groups were comparable. There was no association between cassava consumption and tropical pancreatitis syndrome (odds ratio = 0.56; 95% confidence interval = 0.21-1.45). Controlling for the possible confounding effects of low socio-economic status and vegetarian diet did not alter the odds ratio. Testing for interaction also failed to show any effect modification of the association of cassava by economic status, chilli consumption or vegetarian diet. A significantly higher number of cases gave a positive family history of diabetes compared to the controls (odds ratio = 4.11; 95% confidence interval = 1.04-16.30; P = 0.04). In this case-control study which had sufficient power to detect an odds ratio > or = 3.5, there was no association between cassava consumption and tropical pancreatitis syndrome.

Konzo in the Central African Republic

We identified a new focus of konzo, an upper motor neuron disease, in a part of western Central African Republic. Interviews and high serum levels of thiocyanate indicate that cyanide exposure from insufficiently processed cassava may cause konzo. Abrupt onset, nonprogressive course, and seronegativity to HTLV-I clearly differentiate konzo from HTLV-I-associated myelopathy in tropical countries.