Intervention for the control of soil-transmitted helminthiasis in the community

The global strategy for the control of soil-transmitted helminthiasis, based on regular anthelminthic treatment, health education and improved sanitation standards, is reviewed. The reasons for the development of a control strategy based on population intervention rather than on individual treatment are explained. The evidence and experience from control programmes that created the basis for (i) the definition of the intervention package, (ii) the identification of the groups at risk, (iii) the standardization of the community diagnosis and (iv) the selection of the appropriate intervention for each category in the community are discussed. How to best deliver the appropriate intervention, the impact of the control measures on morbidity and on indicators such as school attendance, cognitive development and productivity are presented. The factors influencing the cost-benefits of helminth control are also considered. The recent progress on the control of soil-transmitted helminth infections is illustrated. Research needs are analysed in relation to the most recent perceptions from private-public partnerships involved in helminth control. The way forward for the control of soil-transmitted helminth infections is described as a multi-disease approach that goes beyond deworming and fosters a pro-poor strategy that supports the aims of the Millennium Development Goals.

Prevalence and intensity of intestinal parasitic infections in relation to nutritional status in Mexican schoolchildren

Undernutrition and intestinal parasitic infections affect childhood development and morbidity in many developing countries. Undernutrition may increase susceptibility to parasitic infections which in turn impair the nutritional status of the host. The relationship between intestinal parasitic infections and nutritional status in 400 Mexican schoolchildren was investigated. More than half of the children in the study showed intestinal parasites and polyparasitism. The prevalence of helminth infections was significantly higher in Oaxaca than in Sinaloa (P < 0.05). Z scores for weight-for-age (WA) and height-for-age (HA) were much lower in children of Oaxaca than in Sinaloa (P < 0.001). A significantly higher Z score for weight-for-height (WH), WA, and HA were found in non-infected versus infected children (P < 0.05). Higher prevalences of intestinal infections were found in children with lower HA and WA than in normally nourished children (P < 0.05). Higher intensities of Ascaris lumbricoides and Trichuris trichiura were found in the schoolchildren of Sinaloa than in Oaxaca (P < 0.01). Negative and significant associations were found between Hymenolepis nana and T. trichiura infection (eggs per gram) and nutritional status. Intestinal parasitic infections may be regarded as main risk factors associated with poor nutritional status in Mexican schoolchildren.

Intermittent iron supplementation regimens are able to maintain safe maternal hemoglobin concentrations during pregnancy in Venezuela

Daily iron supplementation programs for pregnant women recommend amounts of iron that are considered by some to be excessive, and either lower-dose or less frequent iron supplementation regimens have been proposed. A randomized, placebo-controlled study was performed to assess and compare the relative effectiveness of a weekly (WS) or twice weekly (TW) iron supplementation schedule in maintaining or achieving hemoglobin (Hb) levels at term considered to carry minimal maternal and fetal risk (90-130 g/L). Pregnant women (n = 116) at wk 10-30 of gestation (63 WS and 53 TW) were enrolled in the study (52 in WS and 44 TW completed the study). Women were randomly allocated to receive a 120-mg oral dose of iron as ferrous sulfate and 0.5 mg of folic acid weekly (n = 52) or 60 mg iron and 0.25 mg folic acid and a placebo twice weekly (n = 44). Hb, hematocrit, serum ferritin, and transferrin saturation were estimated at baseline and at 36-39 wk of gestation. Baseline dietary data and the presence and intensity of intestinal helminthic infections were assessed. The duration of supplementation was 14 +/- 4 wk and the median level of adherence was 60.5%. Hb concentrations improved in women following the TW regimen and in women following WS who had low baseline Hb levels. About 89% of WS women and 95% of TW women maintained Hb levels at term (between 90 g/L and 130 g/L), a range associated with optimal pregnancy outcomes. One woman in the TW group exhibited higher Hb levels that potentially carried perinatal risk (>130 g/L). Intermittent iron and folic acid supplementation may be a valid strategy when used as a preventive intervention in prenatal care settings.

Use of benzimidazoles in children younger than 24 months for the treatment of soil-transmitted helminthiasis

Considerable experience and limited quantitative evidence indicate that infections with the soil-transmitted helminths Ascaris lumbricoides and Trichuris trichiura usually start to become established in children aged 12 months and older. Since children living in countries where the infections are endemic are at risk of morbidity, even those as young as 12 months may need to be considered for inclusion in public health programmes designed to reduce morbidity by means of regular anthelminthic chemotherapy. This situation raises the question as to whether such young children should be given anthelminthic drugs. Systems for the absorption, distribution, metabolism and elimination of drugs do not fully develop until children are in their second year of life. Current knowledge, however, reveals that the incidence of side effects linked to benzimidazole drugs in young children is likely to be the same as in older children. Accordingly, we conclude that albendazole and mebendazole may be used to treat children as young as 12 months if local circumstances show that relief from ascariasis and trichuriasis is justified.

Nutritional impact of intestinal helminthiasis during the human life cycle

Poor people in developing countries endure the burden of disease caused by four common species of soil-transmitted nematode that inhabit the gastrointestinal tract. Disease accompanying these infections is manifested mainly as nutritional disturbance, with the differing infections having their deleterious effects at different phases during the human life cycle. Reduced food intake, impaired digestion, malabsorption, and poor growth rate are frequently observed in children suffering from ascariasis and trichuriasis. Poor iron status and iron deficiency anemia are the hallmarks of hookworm disease. The course and outcome of pregnancy, growth, and development during childhood and the extent of worker productivity are diminished during hookworm disease. Less is known about the impact of these infections in children under 2 years of age. The severity of disease caused by soil-transmitted nematodes has consistently been found to depend on the number of worms present per person. Cost-effective measures based on highly efficacious anthelminthic drugs are now available to reduce and control disease caused by these infections.