Impact of helminth infection during pregnancy on cognitive and motor functions of one-year-old children

OBJECTIVE

To determine the effect of helminth infection during pregnancy on the cognitive and motor functions of one-year-old children.

METHODS

Six hundred and thirty five singletons born to pregnant women enrolled before 29 weeks of gestation in a trial comparing two intermittent preventive treatments for malaria were assessed for cognitive and motor functions using the Mullen Scales of Early Learning, in the TOVI study, at twelve months of age in the district of Allada in Benin. Stool samples of pregnant women were collected at recruitment, second antenatal care (ANC) visit (at least one month after recruitment) and just before delivery, and were tested for helminths using the Kato-Katz technique. All pregnant women were administered a total of 600 mg of mebendazole (100 mg two times daily for 3 days) to be taken after the first ANC visit. The intake was not directly observed.

RESULTS

Prevalence of helminth infection was 11.5%, 7.5% and 3.0% at first ANC visit, second ANC visit and at delivery, respectively. Children of mothers who were infected with hookworms at the first ANC visit had 4.9 (95% CI: 1.3-8.6) lower mean gross motor scores compared to those whose mothers were not infected with hookworms at the first ANC visit, in the adjusted model. Helminth infection at least once during pregnancy was associated with infant cognitive and gross motor functions after adjusting for maternal education, gravidity, child sex, family possessions, and quality of the home stimulation.

CONCLUSION

Helminth infection during pregnancy is associated with poor cognitive and gross motor outcomes in infants. Measures to prevent helminth infection during pregnancy should be reinforced.

Multiparasitism and intensity of helminth infections in relation to symptoms and nutritional status among children: a cross-sectional study in southern Lao People's Democratic Republic

The occurrence and spatial distribution of intestinal helminth infection in children is fairly well understood. However, knowledge on how helminth infections govern intestinal morbidity is scarce. We conducted a cross-sectional study to assess and quantify the relationship between single and multiple species helminth infection with clinical and self-reported morbidity indicators and nutritional status in Champasack province, southern Lao People's Democratic Republic (Lao PDR). A random sample of 1313 children, aged 6 months to 12 years, from villages in nine rural districts were enrolled and examined for helminth infection using duplicate Kato-Katz thick smears. Morbidity was assessed by self-reported symptoms, coupled with clinical examination and appraisal of nutritional status and anaemia. Bivariate and multivariate logistic regression was employed to study associations between helminth infection and morbidity indicators and anaemia. We found considerable morbidity among the surveyed children, including hepatomegaly (13.7%), pale conjunctiva (13.2%) and abdominal pain (10.4%). Anaemia was recorded in 60.4% of the children, whilst signs of stunting and low body mass index (BMI) were observed in 49.8% and 33.3% of the surveyed children, respectively. Hookworm and Opisthorchis viverrini were the predominant helminth species with prevalences of 51.0% and 43.3%, respectively. The prevalence of Schistosoma mekongi in the surveyed children was 5.6%. Multiple species helminth infections were recorded in 40.4% of the study cohort. Morbidity was associated with specific helminth species infection (e.g. S. mekongi with hepatomegaly; adjusted odds ratio (aOR): 9.49, 95% confidence interval (CI): 2.07-43.51) and multiparasitism (e.g. two or more helminth species with abdominal pain; aOR: 2.40, 95% CI: 1.46-3.93). Anaemia was associated with hookworm infection (aOR: 1.64, 95% CI: 1.16-2.34) and multiparasitism (aOR: 1.64, 95% CI: 1.18-2.29). Low BMI was associated with O. viverrini infection (aOR: 1.68, 95% CI: 1.14-2.49) and multiparasitism (aOR: 1.42, 95% CI: 1.01-2.00). The multiple strong associations reported here between helminth infections (single or multiple species) and intestinal morbidity among children in rural parts of southern Lao PDR call for concerted efforts to control helminth infections, which in turn might improve children's health and development.

Therapeutic approaches to patients with hypereosinophilic syndromes

Hypereosinophilic syndromes (HES) are a heterogeneous group of disorders that range from asymptomatic eosinophilia > 1,500/mL to aggressive disease complicated by life-threatening end organ involvement, including endomyocardial fibrosis and thromboembolism. To complicate matters further, similar clinical manifestations can occur in the setting of marked eosinophilia due to helminth infection, drug hypersensitivity, and other causes. In the past, therapy was guided only by the exclusion of these secondary causes of eosinophilia and the severity of the clinical manifestations. More recently, the availability of novel targeted therapies and a better understanding of the etiologies of some subtypes of HES have necessitated a more structured approach.

Anemia in Cambodia: prevalence, etiology and research needs

Anemia is a severe global public health problem with serious consequences for both the human and socio-economic health. This paper presents a situation analysis of the burden of anemia in Cambodia, including a discussion of the country-specific etiologies and future research needs. All available literature on the prevalence and etiology of anemia in Cambodia was collected using standard search protocols. Prevalence data was readily identified for pre-school aged children and women of reproductive age, but there is a dearth of information for school-aged children, men and the elderly. Despite progress in nation-wide programming over the past decade, anemia remains a significant public health problem in Cambodia, especially for women and children. Anemia is a multifaceted disease and both nutritional and non-nutritional etiologies were identified, with iron deficiency accounting for the majority of the burden of disease. The current study highlights the need for a national nutrition survey, including collection of data on the iron status and prevalence of anemia in all population groups. It is impossible to develop effective intervention programs without a clear picture of the burden and cause of disease in the country.

Effect of schistosomiasis and soil-transmitted helminth infections on physical fitness of school children in Côte d'Ivoire

Background

Schistosomiasis and soil-transmitted helminthiasis are important public health problems in sub-Saharan Africa causing malnutrition, anemia, and retardation of physical and cognitive development. However, the effect of these diseases on physical fitness remains to be determined.

Methodology

We investigated the relationship between schistosomiasis, soil-transmitted helminthiasis and physical performance of children, controlling for potential confounding of Plasmodium spp. infections and environmental parameters (i.e., ambient air temperature and humidity). A cross-sectional survey was carried out among 156 school children aged 7–15 years from Côte d'Ivoire. Each child had two stool and two urine samples examined for helminth eggs by microscopy. Additionally, children underwent a clinical examination, were tested for Plasmodium spp. infection with a rapid diagnostic test, and performed a maximal multistage 20 m shuttle run test to assess their maximal oxygen uptake (VO₂ max) as a proxy for physical fitness.

Principal Findings

The prevalence of Schistosoma haematobium, Plasmodium spp., Schistosoma mansoni, hookworm and Ascaris lumbricoides infections was 85.3%, 71.2%, 53.8%, 13.5% and 1.3%, respectively. Children with single, dual, triple, quadruple and quintuple species infections showed VO₂ max of 52.7, 53.1, 52.2, 52.6 and 55.6 ml kg⁻¹ min⁻¹, respectively. The VO₂ max of children with no parasite infections was 53.5 ml kg⁻¹ min⁻¹. No statistically significant difference was detected between any groups. Multivariable analysis revealed that VO₂ max was influenced by sex (reference: female, coef. = 4.02, p<0.001) and age (years, coef. = −1.23, p<0.001), but not by helminth infection and intensity, Plasmodium spp. infection, and environmental parameters.

Conclusion/Significance

School-aged children in Côte d'Ivoire showed good physical fitness, irrespective of their helminth infection status. Future studies on children's physical fitness in settings where helminthiasis and malaria co-exist should include pre- and post-intervention evaluations and the measurement of hemoglobin and hematocrit levels and nutritional parameters as potential co-factors to determine whether interventions further improve upon fitness.

The burden of parasitic worm infections is considerable, particularly in developing countries. It is acknowledged that parasitic worm infections negatively impact on children's school performance and physical development. A deeper understanding of these linkages is important for updating burden of disease measures. We investigated the relationship between worm infection status and physical fitness of 156 school children from Côte d'Ivoire and controlled for potential confounding of Plasmodium infection (the causative agent of malaria) and environmental parameters (temperature and humidity). Children were diagnosed for parasitic worm and Plasmodium infections, examined by a physician, and participated in a 20 m shuttle run test to assess their maximal oxygen uptake (VO₂ max) as a proxy for physical fitness. Most of the children had parasitic worms and a Plasmodium infection. Nevertheless, their physical fitness was excellent (average VO₂ max: 52.7 ml kg⁻¹ min⁻¹). The level of VO₂ max was only influenced by sex and age, but not by parasitic worms and Plasmodium infections. In future studies, the dynamics of children's physical performance should be assessed before and after control interventions, including the assessment of blood hemoglobin, hematocrit, and nutritional indicators to determine whether physical fitness in worm- and Plasmodium-infected individuals can be further improved.

Helicobacter pylori, helminth infections and growth: a cross-sectional study in a high prevalence population

AIM

Helicobacter pylori (H. pylori) infection is usually acquired in childhood and may adversely affect growth, although data are inconsistent. This study investigated growth parameters in a paediatric cohort with a high prevalence of H. pylori and helminth infection.

METHODS

A cross-sectional study of African refugee children (<16 years) recruited at their initial health assessment following resettlement in Australia. Detailed demographic, infection and anthropometric data were obtained. H. pylori infection was diagnosed by monoclonal faecal antigen enzyme immunoassay testing (MFAT). Growth restriction was defined as children with any anthropometric measures below the fifth centile for age and gender.

RESULTS

H. pylori infection was detected in 149/182 (81.9%). Children with H. pylori infection were older (mean 8.5 years, standard deviation (SD) 4.2 years vs. 5.8 years, SD 4.5 years, p < 0.001). No gender differences were observed. After adjustment for age, H. pylori did not adversely affect body mass index or other anthropometric measurements. Helminth infections were common (41.8%) but not associated with reduced growth or with H. pylori infection.

CONCLUSION

H. pylori and helminth infections are prevalent in African refugee children but neither is associated with growth restriction. Longitudinal growth velocity studies are necessary to identify any long-term consequences of H. pylori on childhood growth.

Neuroimmunoendocrine modulation in the host by helminth parasites: a novel form of host-parasite coevolution?

Helminth parasites have evolved diverse molecular mechanisms that facilitate their establishment, growth and reproduction inside an immunologically hostile environment. Thus, the physiological interactions during the course of the immune response to helminths are complex. Infection induces antigen-specific recognition by the immune system, which is consequently charged with the responsibility of marshalling the appropriate effector responses necessary to destroy the parasite, or at the very least inhibit its progression. Obviously, the immune system should accomplish this task while minimizing collateral damage to the host. As our understanding of the neuroendocrine system grows, it has become increasingly clear that this complex network of neurotransmitters, hormones, and cytokines plays an important role in mediating immunity. Helminths present an especially complex relationship between pathogen and these physiological systems, with hormonally dependent host factors such as sex and age correlated with parasite success. On top of the effect that this particular type of parasites may have on the invaded host, recent experimental evidence suggests that helminth parasites not only actively evade immune response, but are also able to exploit the hormonal microenvironment within their host to favor their establishment, growth and reproduction. This complex strategy of host-parasite relationship is much better exemplified by two helminth parasites: the trematode Schistosoma mansoni and the cestode Taenia crassiceps that respond to adrenal steroids and sexual steroids, respectively. Understanding how the host endocrine system can under certain circumstances favor the establishment of a parasitic infection opens interesting perspectives into the host-parasite relationship field.

Neuroimmunomodulation during infectious diseases: mechanisms, causes and consequences for the host

In this special issue of Neuroimmunomodulation, the reader will find reviewed some of the hottest topics in the field of neuroendocrine-immune interactions, with emphasis on infectious diseases. For instance, the role that immunoendocrine alterations have during human tuberculosis, a chronic infectious disease, is discussed, and it is concluded that these immunoendocrine interactions may play a detrimental role during the disease, in terms of the development of protective immune responses, control of tissue damage and metabolic disorders. Also, the role that neuroimmunomodulation plays in parasitic diseases is presented, and emphasizes the importance of the host-parasite neuroimmunoendocrine network during helminth infection. Moreover, the influence of beta-androstenes on resistance to viral and bacterial infections is discussed, as well as the impact of infectious diseases upon neuroendocrine circuits. Also, the reader will find contributions to the study of sex hormones and modulation of immunity against leishmaniasis, as well as recent work on the immune mechanisms associated with resistance or susceptibility to parasitic diseases during pregnancy. We hope that our readers will find the first ever special issue devoted to neuroimmunomodulation and infectious diseases fascinating and enticing.

Soil-transmitted helminth infections: ascariasis, trichuriasis, and hookworm

The three main soil-transmitted helminth infections, ascariasis, trichuriasis, and hookworm, are common clinical disorders in man. The gastrointestinal tract of a child living in poverty in a less developed country is likely to be parasitised with at least one, and in many cases all three soil-transmitted helminths, with resultant impairments in physical, intellectual, and cognitive development. The benzimidazole anthelmintics, mebendazole and albendazole, are commonly used to remove these infections. The use of these drugs is not limited to treatment of symptomatic soil-transmitted helminth infections, but also for large-scale prevention of morbidity in children living in endemic areas. As a result of data showing improvements in child health and education after deworming, and the burden of disease attributed to soil-transmitted helminths, the worldwide community is awakening to the importance of these infections. Concerns about the sustainability of periodic deworming with benzimidazole anthelmintics and the emergence of resistance have prompted efforts to develop and test new control tools.

Can worms defend our hearts? Chronic helminthic infections may attenuate the development of cardiovascular diseases

The established risk factors for atherosclerosis fail to fully explain the extent and severity of coronary artery diseases in 50% of the patients. Thus, the causative agents and processes, which may be involved in the pathogenesis of atherosclerosis, are being sought. Notoriously, atherosclerosis and cardiovascular event rates are much lower in developing countries. Clinically, severe infections by intracellular pathogens are widespread mostly in developing countries with poor sanitation, nutrition and massive worm infections. A link between atherosclerosis and helminth infections has never been examined. Based on the present knowledge of immune and infectious mechanisms related to atherosclerosis, it is proposed that chronic helminthic infections can have a significant bearing on the epidemiology of cardiovascular diseases. How can helminthic infections affect the cardiovascular risk? (1) Helminths evade or suppress host immune responses, by producing anti-inflammatory and other immunomodulatory molecules. (2) Helminths induce chronic Th2 activation, which can modify cytokine profiles and immunological responses to heat shock proteins, Chlamydia pneumoniae and cytomegalovirus. (3) The chronic Th2 profile may modulate monocyte activation and chemotaxis to inflammatory sites (atherosclerotic plaques). (4) Chronic Th2 activation may lead to a cytokine profile that could be beneficial for attenuation of atherosclerosis development (upregulation of IL-4, IL-10 and IL-13 and downregulation of proinflammatory cytokines). (5) Helminthic infections may reduce plasma LDL level not only by affecting the host nutrition, but also via modulation of naturally occurring antibodies to cholesterol. Studies are needed to clarify these suggestions. If the hypothesis that helminthic infections impact atherosclerosis is correct, it should be taken into consideration in atherosclerosis immunomodulation therapy and especially in the design of vaccines and vaccine trials.

Regulation of allergy and autoimmunity in helminth infection

Parasitic infections are a major theme in the "hygiene hypothesis", as allergies and autoimmune diseases are less prevalent in countries with higher burdens of helminths and other parasitic organisms. Helminths"-the grouping of multicellular worm parasites including nematodes, cestodes and trematodes-tend to establish long-lived, chronic infections indicating successful down-modulation of the host immune system. In this review, we describe the intricate immunology of host-helminth interactions and how parasites manipulate immune responses to enhance their survival. In so doing, they often minimise immunopathology and, it is suggested, reduce host susceptibility to, and severity of allergic and autoimmune diseases. Studies on helminth-infected communities and individuals support the hypothesis that an immuno-regulatory network promoted by parasites extends its influence to limiting allergies. Experimental models are now probing more deeply into the area of immune modulation by helminths, and we discuss the likely mechanisms by which helminths could be establishing a strongly regulatory environment. Understanding and harnessing the modulatory capacity of helminths may uncover novel therapeutic interventions, mimicking and exploiting their evolution for our benefit. Parasitic infections are a major theme in the "hygiene hypothesis", as allergies and autoimmune diseases are less prevalent in countries with higher burdens of helminths and other parasitic organisms. Helminths"-the grouping of multicellular worm parasites including nematodes, cestodes and trematodes-tend to establish long-lived, chronic infections indicating successful down-modulation of the host immune system. In this review, we describe the intricate immunology of host-helminth interactions and how parasites manipulate immune responses to enhance their survival. In so doing, they often minimise immunopathology and, it is suggested, reduce host susceptibility to, and severity of allergic and autoimmune diseases. Studies on helminth-infected communities and individuals support the hypothesis that an immuno-regulatory network promoted by parasites extends its influence to limiting allergies. Experimental models are now probing more deeply into the area of immune modulation by helminths, and we discuss the likely mechanisms by which helminths could be establishing a strongly regulatory environment. Understanding and harnessing the modulatory capacity of helminths may uncover novel therapeutic interventions, mimicking and exploiting their evolution for our benefit.

Helminth infection and cognitive impairment among Filipino children

The objective of this study was to examine the independent effect of infection with each of four helminths (Ascaris lumbricoides, Schistosoma japonicum, Necator americanus, and Trichuris trichiura) on cognitive function after adjusting for the potential confounders nutritional status, socioeconomic status (SES), hemoglobin, sex, and the presence of other helminthes. This cross-sectional study was carried out in a rural village in Leyte, The Philippines in 319 children 7-18 years old. Three stools were collected and read in duplicate by the Kato Katz method. Infection intensity was defined by World Health Organization criteria. Cognitive tests were culturally adapted and translated. Learning and memory cognitive domains were each defined by three subscales of the Wide Range Assessment of Memory and Learning, which had an inter-rater reliability >/= 0.92 and test-retest reliabilities ranging from 0.61 to 0.89. A household SES questionnaire was administered. A logistic regression model was used to quantify the association between performance in different cognitive domains (learning, memory, verbal fluency, and the Philippine Non-Verbal Intelligence Test) and helminth infections. After adjusting for age, sex, nutritional status, hemoglobin, and SES, S. japonicum infection was associated with poor performance on tests of learning (odds ratio [OR] = 3.04, 95% confidence interval [CI] = 1.1-6.9), A. lumbricoides infection was associated with poor performance on tests of memory (OR = 2.2, 95% CI = 1.04-4.7), and T. trichiura infection was associated with poor performance on tests of verbal fluency (OR = 4.5, 95% CI = 1.04-30). Helminth infection was associated with lower performance in three of the four cognitive domains examined in this study. These relationships remained after rigorous control for other helminths and important confounding covariates.

Impact of parasitic infections and dietary intake on child growth in the schistosomiasis-endemic Dongting Lake Region, China

The simultaneous impacts of parasitic infections and dietary intake on growth patterns were investigated for 427 children aged 10-13 years in the schistosomiasis-endemic Dongting Lake region of China. Height, weight, mid-upper arm circumference, and skinfold thicknesses (triceps, biceps, and subscapular) were measured, and eggs of Schistosoma japonicum, Ascaris lumbricoides, Trichuris trichiura, and Fasciolopsis buski in the collected stool samples of each subject were detected by Kato-Katz thick smear technique. Long-term dietary intake of each subject was assessed with a semiquantitative food frequency questionnaire. The results demonstrate that the study children were retarded in growth compared with the standards of Chinese rural children; among them, the girls were more frequently infected for S. japonicum and had lower intakes of protein and energy. Reduced height, weight, and mid-upper arm circumference were noted in children infected with S. japonicum, most severely in the girls with the least energy and protein intakes. Multiple stepwise regression analysis indicated that growth retardation was significantly and substantially associated with S. japonicum infection and lack of protein-energy intakes. For child health programs, regular schistosomiasis screening and treatment in schoolchildren needs to be complemented by health and nutrition education for both children and parents. Also, special attention should be paid to educating parents about the needs of girls.

Helminth parasites--masters of regulation

Immune regulation by parasites is a global concept that includes suppression, diversion, and conversion of the host immune response to the benefit of the pathogen. While many microparasites escape immune attack by antigenic variation or sequestration in specialized niches, helminths appear to thrive in exposed extracellular locations, such as the lymphatics, bloodstream, or gastrointestinal tract. We review here the multiple layers of immunoregulation that have now been discovered in helminth infection and discuss both the cellular and the molecular interactions involved. Key events among the host cell population are dominance of the T-helper 2 cell (Th2) phenotype and the selective loss of effector activity, against a background of regulatory T cells, alternatively activated macrophages, and Th2-inducing dendritic cells. Increasingly, there is evidence of important effects on other innate cell types, particularly mast cells and eosinophils. The sum effect of these changes to host reactivity is to create an anti-inflammatory environment, which is most favorable to parasite survival. We hypothesize therefore that parasites have evolved specific molecular strategies to induce this conducive landscape, and we review the foremost candidate immunomodulators released by helminths, including cytokine homologs, protease inhibitors, and an intriguing set of novel products implicated in immune suppression.

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.

Effects of two acanthocephalan parasites on the fecundity and pairing status of female Gammarus pulex (Crustacea: Amphipoda)

Acanthocephalan parasites are known to alter the reproductive biology and physiology of their hosts in various ways. In this study we investigated the influence of two acanthocephalan parasites, Pomphorhynchus laevis and Polymorphus minutus, on the fecundity and pairing success of female Gammarus pulex. The results show that P. laevis and P. minutus affect female intermediate host reproduction in different ways. Females infected with P. minutus were totally castrated, whereas those infected with P. laevis only showed reduced fecundity. The oocytes of P. laevis-infected females showed a similar structure to those of uninfected females, although infected females had a higher proportion of oocytes that had failed to reach complete maturity. In comparison, the oocytes of P. minutus-infected females demonstrate a clearly altered structure that suggests a major disruption to the process of vitellogenesis. In the field, males paired more frequently with uninfected females than with infected ones, and is a stronger effect for P. minutus-infected females than P. laevis-infected females. We suggest that the difference in pairing success of P. minutus-infected and P. laevis-infected females is a direct result of the different effects that the two parasites have on female fecundity.

Early childhood diarrhoea and helminthiases associate with long-term linear growth faltering

BACKGROUND

Although the acute mortality from diarrhoeal diseases is well recognized, the potentially prolonged impact of early childhood diarrhoea on background growth and development is often overlooked. To examine the magnitude and duration of the association of early childhood enteric infections with growth faltering in later childhood, we investigated associations of early childhood diarrhoea (0-2 years) and intestinal helminthiases with nutritional status from age 2 to 7 years.

METHODS

Twice-weekly diarrhoea surveillance and quarterly anthropometrics were followed from 1989 to 1998 in 119 children born into a Northeast Brazilian shantytown.

RESULTS

Diarrhoea burdens at 0-2 years old were significantly associated with growth faltering at ages 2-7 years, even after controlling for nutritional status in infancy, helminthiases at 0-2 years old, family income, and maternal education by Pearson correlation, multivariate linear regression, and repeat measures analysis. The average 9.1 diarrhoeal episodes before age 2 years was associated with a 3.6 cm (95% CI : 0.6-6.6 cm) growth shortfall at age 7 years. Early childhood helminthiasis was also associated with linear growth faltering and a further 4.6 cm shortfall (95% CI : 0.8-7.9 cm) at age 7 years.

CONCLUSIONS

Early childhood diarrhoea and helminthiases independently associate with substantial linear growth shortfalls that continue beyond age 6 years. Targeted interventions for their control may have profound and lasting growth benefits for children in similar settings.

Integrative neuroimmunomodulation of gastrointestinal function during enteric parasitism

Enteric helminths have a significant impact on the structure, function, and neural control of the gastrointestinal (GI) tract of the host. Interactions between the host's nervous and immune systems redirect activity in neuronal circuits intrinsic to the gut into an alternative repertoire of defensive and adaptive motor programs. Gut inflammation and activation of the enteric neuroimmune axis play integral roles in the dynamic interaction between host and parasite that occurs at the mucosal surface. Three inter-related themes are stressed in this review to underscore the pivotal role that neural control mechanisms play in the host's GI tract functional responses to enteric parasitism. First, we address the discovery that signaling molecules of both parasite and host origin can reorient the dynamic ecology of enteric host-parasite interactions. Second, we explore what has been learned from investigations of altered gut propulsive and secretomotor reflex activities that occur during enteric parasitic infections and the emerging picture derived from these studies that elucidates how nerves help facilitate and orchestrate functional reorganization of the parasitized gut. Third, we provide an overview of the direct impact that enteric parasitism has on nerve cell function and neurotransmission pathways in both the enteric and central nervous systems of the host. In summary, this review highlights and clarifies the complex mechanisms underlying integrative neuroimmunophysiological responses to the presence of both invasive and noninvasive enteric helminths and identifies directions for future research investigations in this highly important but understudied area.

Impact of iron supplementation and deworming on growth performance in preschool Beninese children

OBJECTIVE

To assess the effects of iron and deworming on linear growth performance of preschoolers.

DESIGN

Three-month randomized, double-blind and placebo-controlled trial. The children were allocated to four treatments: iron (60 mg elemental iron/day) + albendazole (200 mg/day for 3 consecutive days, repeated 1 month later), iron + albendazole-placebo, albendazole + iron-placebo or placebos. The supplementation was supervised.

SUBJECTS

A group of 177 children aged 3-5 y was selected from low-income households in a rural area in southern Bénin. A complete data set was analysed for 140 subjects. Many children were stunted (58% had height-for-age Z-score <-2), none were wasted (2% had weight-for-height Z-score < -2) and 76% were anemic (Hb < 110 g/l).

MAIN OUTCOME MEASURES

Anthropometric parameters, hemoglobin and eggs per gram feces.

RESULTS

No significant difference in changes in anthropometric parameters was observed between study groups, and also not in a sub-sample of stunted and anemic subjects. Changes in hemoglobin were highest in the iron-treated subjects at the end of the 3-month intervention period (P = 0.032). The difference between the iron and the placebo groups remained significant even 7 months later (P = 0.022). The difference was 5 g/l in both periods. Ascaris lumbricoides and hookworm infections decreased significantly in albendazole-treated subjects (P < 0.05).

CONCLUSIONS

In addition to recurrent parasitic infection burden, the children may have multiple micronutrient deficiencies. Therefore, it may be interesting to study appetite and food intake of young toddlers in relation to health and linear growth performance in poor environments.

Adaptive physiological processes in the host during gastrointestinal parasitism

Parasite infection of the gastrointestinal tract with helminths or protozoa induces detrimental effects on host tissues and host physiology, which have been extensively studied and reviewed. However, parasitism of the digestive system is also associated with adaptive, compensatory phenomena based on changes in host physiology or structures and which tend to counterbalance the negative consequences. The objective of this review is to describe these adaptive processes and their possible underlying mechanisms. Different processes which tend to attenuate the effect of either the loss of appetite, the intestinal malabsorption or the increased tissue losses have been assessed. These processes have been reported both for helminth and protozoan infections, where they present similar characteristics. The mechanisms involved in the adaptation to parasitism remain largely unidentified. The role of feedback mechanisms based on host regulation, possibly through gastrointestinal hormones, has been raised. On the other hand, some data support the proposal that parasites themselves may initiate some of the adaptive processes and consequently favour their own survival. These adaptive phenomena appear to be an essential component in the dynamic balance between host and parasites. Also, parasite infections represent unique models to study the adaptation of the gastrointestinal tract to aggressors.

Impact of intestinal helminth infection on anemia and iron status during pregnancy: a community based study in Indonesia

A cohort study was carried out in Purworejo District, Central Java, Indonesia to investigate prevalence of anemia and low iron stores during pregnancy in relation to intestinal helminth infection. 442 pregnant women were followed until 5-10 weeks postpartum, during the period of April 1996 - August 1998. Information on intestinal helminths, hemoglobin and serum ferritin was collected each trimester. Highest prevalence of anemia in pregnancy (37.1%) was found in the second trimester, while the highest prevalence of low iron stores (49.5%) was found in the third trimester. Most pregnant women (69.7%) were infected with at least one species of pathogenic intestinal helminths. The most common helminth detected was Trichuris trichiura followed by Necator americanus (hookworm) and Ascaris lumbricoides. A significant negative association was found between hookworm infection and serum ferritin at the first trimester (p = 0.010). It is concluded that hookworm infection can interfere iron stores. Other causes of anemia among pregnant women should be considered. Anthelminthic therapy could be given to infected women before conception as public health strategy to improve iron status.

Anthelmintic treatment of rural Bangladeshi children: effect on host physiology, growth, and biochemical status

BACKGROUND

The effect of helminth infestation on the nutrition, growth, and physiology of the host is still poorly understood. Anthelmintic treatment of children in developing countries has had varying success in terms of growth improvements.

OBJECTIVE

The objective of this study was to assess the effect of regular deworming on child growth, physiology, and biochemical status.

DESIGN

The study was a 12-mo longitudinal intervention in 123 Bangladeshi children aged 2-5 y. Treatment (mebendazole) or placebo tablets were administered every 2 mo for 8 mo and again at 12 mo. Weight, height, midupper arm circumference, intestinal permeability, plasma albumin, alpha(1)-antichymotrypsin, and total protein concentration were assessed every 2 mo.

RESULTS

Treatment with mebendazole reduced the prevalence of Ascaris lumbricoides from 78% to 8%, of Trichuris trichiura from 65% to 9%, and of hookworm from 4% to 0%. There was no significant difference in the growth of treated children compared with those given placebo tablets. No changes in intestinal permeability or plasma albumin were observed after deworming. Significant decreases in total protein (P<0.001) and alpha(1)-antichymotrypsin (P<0.001) were observed in the treatment group, indicating possible reductions in inflammation and immunoglobulin concentration after deworming. A significant increase in the prevalence of Giardia intestinalis (from 4% to 49%) in the treatment group was associated with a short-term reduction in weight (P = 0.02) and higher intestinal permeability (P <0.001) in infected subjects. No long-term effects of G. intestinalis on growth were observed.

CONCLUSION

Low-intensity helminth infections, predominantly of A. lumbricoides and T. trichiura, do not contribute significantly to the poor growth and biochemical status of rural Bangladeshi children.

Human eosinophil granule major basic protein and its novel homolog

Human MBP is associated with an array of in vitro cytotoxic and cytostimulatory activities, mediated in part by its strong basicity. It is most prominently found in the eosinophil, but is also present in placental X cells and placental-site giant cells during pregnancy. Pathologically, its pattern of tissue deposition and its ability to induce characteristic pathophysiologic changes, such as bronchial hyperreactivity and vasopermeability, strongly suggest a role for MBP in allergic and eosinophilic diseases. The role of MBP in protection from helminthic disease is also evident. Here, we present information on a novel homolog of eosinophil granule MBP with biologic activities similar to that of MBP. However, results from experiments on eosinophil granules suggest that the quantity of the homolog present in the eosinophil granule is significantly less than that of MBP itself. Further, preliminary experiments indicate that the two proteins are not synergistic in terms of their cytotoxic and cytostimulatory biologic activities. Future experiments must determine whether the MBP homolog is deposited at sites of tissue damage and can be detected in biologic fluids at concentrations required for biologic activity.

Effect of intestinal helminth infection on some nutritional parameters among rural villagers in Nepal

We report the prevalence of intestinal helminthiasis and its impact on health of Nepalese in two different rural Village Development Committees (VDC) in Nepal. A total of 261 school children from Okharpauwa VDC in Nuwakot district (Central Region) and 242 inhabitants of Boya VDC in Bhojpur district (Eastern Region) in Nepal were included in this study. The overall prevalence in these two different districts were 57.5% and 55.4%, respectively. Altogether four types of helminths were detected. In both districts, Ascaris lumbricoides was the commonest helminth. Mixed helminth infection in both study areas accounted for less than 5.0%. All helminth infected subjects were treated with a single dose of albendazole. Heavy Trichuris trichiura infection needed a second dose. Blood hemoglobin and serum total protein level in school children in Okharpauwa VDC increased significantly after chemotherapy (P < 0.05). Eosinophil count (10.1%; SD 5.0325) returned to normal (4.8%; SD 4.6997). Helminth infection in Boya VDC was more common in children than in adults. Serum total protein, albumin, total cholesterol and triglycerides levels were not influenced by the presence or absence of helminths among the inhabitants of Boya VDC. In both districts, more than 80.0% of the household had no latrine. In Boya VDC, 94.0% of inhabitants interviewed were not aware of other intestinal parasite other than A. lumbricoides.

Modes of action of anthelmintic drugs

Modes of action of anthelmintic drugs are described. Some anthelmintic drugs act rapidly and selectively on neuromuscular transmission of nematodes. Levamisole, pyrantel and morantel are agonists at nicotinic acetylcholine receptors of nematode muscle and cause spastic paralysis. Dichlorvos and haloxon are organophosphorus cholinesterase antagonists. Piperazine is a GABA (gamma-amino-butyric acid) agonist at receptors on nematode muscles and causes flaccid paralysis. The avermectins increase the opening of glutamate-gated chloride (GluCl) channels and produce paralysis of pharyngeal pumping. Praziquantel has a selective effect on the tegument of trematodes and increases permeability of calcium. Other anthelmintics have a biochemical mode of action. The benzimidazole drugs bind selectively to beta-tubulin of nematodes, cestodes and fluke, and inhibit microtubule formation. The salicylanilides: rafoxanide, oxyclozanide, brotianide and closantel and the substituted phenol, nitroxynil, are proton ionophores. Clorsulon is a selective antagonist of fluke phosphoglycerate kinase and mutase. Diethylcarbamazine blocks host, and possibly parasite, enzymes involved in arachidonic acid metabolism, and enhances the innate, nonspecific immune system.

Efficacy and safety of mebendazole in children with worm infestation

Children aged between 2-16 years, were screened for worm infestation. Fifty-five children fulfilling the inclusion criteria were included in the study. They were treated with mebendazole 100 mg twice daily for three consecutive days and followed-up for 15 days to assess cure rate and side effects. Fifty children completed the study with their stools being tested by direct smear and concentration methods and blood CBC done before treatment and at the end of the study. The cure rate for ascaris was 100% and for trichuris 75%. The drug was well tolerated and apart from mild diarrhoea occurring in 22% children, no untoward effects were reported. Nemazole (mebendazole) has shown promise and seems useful in treating children with worm infestation.

Relationships between soil-transmitted helminthiases and growth in urban slum schoolchildren in Ujung Pandang, Indonesia

This study examined the relationship between intestinal helminthiases and growth in urban slum schoolchildren. Children (n = 330) who received single doses of either pyrantel, albendazole, or placebo at baseline and again at 6 months were followed and examined fully at 0, 3, 6, and 12 months for helminth infections and anthropometry. Results of treatments indicated that all groups reduced their prevalence and intensity toward the period of the study. Reductions in intensity of both infections in the treatment groups were observed large in 3 and 12 months, whereas at 6 months reached mostly the initial level of infection. There was no significant difference in growth changes between the dewormed (once and twice) and the placebo groups. However, after controlling for some potential confounding factors, there was a significant relationship between reduction of A. lumbricoides infection and height gain at 3 and 12 months (both P < 0.05). In addition, there was a significant association between reduction in T. trichiura infection and increased midarm circumference at 3 and 12 months (P < 0.002 and P < 0.08, respectively). We conclude that treatment of helminth infections in school-age children may improve growth in areas where malnutrition and helminth infections are prevalent.

Worm kinetics and serum IgE in hooded lister rats infected with the acanthocephalan Moniliformis moniliformis and the nematode Nippostrongylus brasiliensis

After infection with the intestinal helminths Moniliformis moniliformis or Nippostrongylus brasiliensis, worm-specific IgE first appeared in the serum rats between days 10 and 24 p.i., varying with host age, worm species and worm dose used. The rate of increase in specific IgE was comparable regardless of the worm species, infection dose or host age and a peak response was observed about 1 month after the sera turned positive. In the M. moniliformis infections, these events took place long before the beginning of worm expulsion on day 63 in high-dose (50 worms) infections, and potentiation of heterologous IgE was not observed. In contrast, IgE stimulation by N. brasiliensis infections was detected as potentiation of anti-ovalbumin IgE, anti-M. moniliformis IgE and total IgE. Most of the total IgE in the serum of M. moniliformis-infected rats was likely to be the worm-specific IgE. Anthelminthic removal of M. moniliformis revealed that the presence of residual worms was necessary to maintain worm-specific IgE production.

Common intestinal helminths

Groups at risk for intestinal helminth infestation include international students and travelers, migrant laborers, refugees, children of foreign adoptions and the homeless. Symptoms are often minimal or vague, yet many such infections carry significant long-term morbidity. Enterobius vermicularis, the common pinworm, is usually manifested in children as anal itching and is best diagnosed by using the cellophane-tape test to recover eggs from the perianal skin. Treatment with mebendazole is indicated for the entire family. Trichuris, or whipworm, infection may be found with Ascaris infection, but whipworms are longer-lived and more likely to produce symptoms that mimic those of inflammatory bowel disease. Treatment for these parasites is mebendazole. Other significant helminthic infections, which are currently more common in immigrant populations, include hookworms (Necator americanus, Ancylostoma duodenale), threadworms (Strongyloides) and various tapeworms (Taenia, Diphyllobothrium and Hymenolepis species).

The distribution and pathobiology of Neoechinorhynchus cylindratus in the intestine of green sunfish, Lepomis cyanellus

The status of bluegill (Lepomis macrochirus) and green sunfish (Lepomis cyanellus) as homologous hosts for the acanthocephalan Neoechinorhynchus cylindratus was experimentally determined. It was found that the adult parasite did not establish in bluegills, but that these fish could serve as paratenic host. In contrast, complete growth and development to the adult stage occurred in the green sunfish. When green sunfish were intubated with 10 cystacanths/fish, the parasite exhibited a clear preference for the anterior half of the intestine; when 50 cystacanths/fish were intubated, the parasites showed a preference for the posterior half of the intestine. With repeated exposure of cystacanths, the parasites were distributed throughout the intestine. The extent of histopathology induced by N. cylindratus was related to the numbers of parasites present. In light infections (10 cystacanths), the parasite penetrated deeply into the intestinal wall and connective tissue developed around the proboscis. In infections with 50 cystacanths, the proboscis penetration was shallow and little if any connective tissue accumulated. There was also an indication that in crowded areas, the parasites appeared to change their sites of attachment frequently. In both heavy and repeated infections, the parasites evoked significant goblet cell hyperplasia and substantial quantities of mucus covered the intestinal wall. It is suggested that the sticky covering and the presumed presence of antibodies in the mucus combined to create a protective barrier thereby reducing the numbers of parasites that could attach and become established.

[Kidney reactivity in helminthiases and after anthelmintic treatment]

The paper provides and analyzes the data available in the literature and the authors' own findings of the structural and functional disturbances in the hosts' kidneys in various helminthiases and following the use of anthelminthic agents. The authors have established the common regularities of renal responses in helminthiases and revealed the specific features of responses to individual groups of anthelminthic agents depending on their dosage and use duration.

Effect of stocking rates and anthelminthic treatments on weight gains in weaned Nellore cattle on improved pasture in the Brazilian cerrado

The results are presented of 6 years of field trials with weaned Nellore cattle on improved pasture in the midwest of Brazil, using 2 stocking rates and 4 anthelminthic treatment regimes. The most profitable regime included treatments in May, June and September, which yielded an additional 41 and 42 kg of liveweight on the 2 stocking rates. No significant additional gains were obtained by treating during the rainy season, or by treating animals more than 24 months of age. The higher stocking rate (1.8 AU/ha) proved excessive on the improved pasture which deteriorated during the 6 year experimental period, yielding suboptimal liveweight gains.

Weight gain and the course of some estimators of gastrointestinal nematode infection in calves during winter housing in relation to the level of exposure during the previous grazing season

In two experiments groups of calves were exposed to different levels and patterns of infection with Ostertagia spp. and Cooperia spp. The experimental design simulated the stereotypic pattern of herbage infestation, including a normal or a delayed midsummer increase, under conditions of set-stocking. After this simulated 'first grazing season', calves were monitored throughout the subsequent winter housing period. No continuing negative effects of previous infection on growth performance were observed. Calves in all groups gained on average over 0.7 kg day-1, irrespective of previous level of exposure. Differences between the experiments with respect to either level or pattern of infection during the preceding 'first grazing season' were all, to a greater or lesser extent, reflected in faecal egg counts, pepsinogen values, gastrin values and antibody titres against Cooperia spp. or Ostertagia spp. Depending on the time of sampling, pepsinogen values and antibody titres against Ostertagia spp. particularly were useful variables for assessing differences in levels of infection to which groups of calves had been exposed.

Parasitic infection in malnourished school children: effects on behaviour and EEG

This paper describes a study of 194 children (aged 9-13) from a mountain village in Ecuador who were infected with one or more species of intestinal helminth or protozoan parasite. In addition to parasite load, the assessment consisted of a battery of psychological and neuropsychological tests, an EEG examination, measures of iodine level, presence of goitre and level of nutrition. We found that, in general, parasite infection, as measured at the baseline level, was not associated with cognitive impairment. The intensity of infection with A. lumbricoides, however, was correlated with the level of verbal ability and with inhibition-control aspects of cognitive behaviour. Multivariate analysis with level of nutrition, EEG status and parasite burden showed a consistent main effect of the degree of nutrition on neuropsychological performance, particularly the language, problem solving and inhibition-control dimensions.

Pathways to the impairment of human nutritional status by gastrointestinal pathogens

Gastrointestinal pathogens are of three varieties, those that can, and often do, take the life of the host, those that infect transiently and rarely are life-threatening, and those (parasites) that establish a relatively prolonged residence or colonization of the host's alimentary tract. In the case of the second form, if infections are recurrent, both catabolic effects during the episode and failure to digest foods and/or absorb nutrients results. Similarly, catabolic wastage through activation of the acute phase response, and interference with the host's acquisition of nutrients by maldigestion, malabsorption, intestinal losses and competition with the parasite burden can impair growth and nutrition with helminthic infections. Growth and nutrition with respect to all of the macronutrients and virtually all of the micronutrients have been documented to be adversely affected by gastrointestinal pathogens. For its burgeoning importance as a worldwide health problem, both with the HIV virus as a direct intestinal pathogen and with the opportunistic gut infections occurring in the immunocompromised host, AIDS represents the emerging context of the impairment of nutritional status by intestinal pathogens.

Production responses to internal parasite control in dairy cattle

A significant increase in milk production, averaging 164 litres per cow per lactation (a 4.8% increase), was seen after cows infected with gastrointestinal nematodes, paramphistomes and Fasciola hepatica were treated with broad-spectrum anthelmintics. Three hundred and ninety pairs of cows from eight herds with year-round calving were studied. One cow in each matched pair was given 7.5 mg/kg fenbendazole, 7.5 mg/kg levamisole hydrochloride and 15 mg/kg oxyclozanide in March, May and August of one year; the other cow in the pair received no anthelmintic. The number of nematode and trematode eggs was significantly decreased in the faeces of treated cows.

Bronchoconstriction in helminthic infection

In order to determine whether infection by helminthic parasites can be associated with a state of bronchoconstriction, we evaluated the response to the inhalation of a bronchodilator before and after long-term anthelmintic treatment of children in a urban slum of Caracas, Venezuela. In untreated children, a direct association was found between the degree of helminthic infection and the increase in peak expiratory flow rates caused by the bronchodilator. The elimination of the infections was accompanied by a significant decrease in response to the bronchodilator. These results indicate that helminthic infection could contribute to the development of asthmatic conditions in areas where these parasites are endemic.

Regulation and biological function of helminth-induced cytokine responses

The immunological hallmarks of infection with parasitic helminths, namely eosinophilia, mastocytosis and increased IgE synthesis, all appear to be induced by cytokines from the TH2 subset of CD4+ T cells: IgE production is stimulated by interleukin 4 (IL-4), eosinophilia by IL-5 and mastocytosis by IL-3 and IL-4. Here, Fred Finkelman and colleagues argue that the functional significance of the eosinophilia-mastocytosis-IgE axis in helminth infection is unclear and suggest that in some worm infections TH2-cell cytokines may contribute to host protection, while in others they may promote parasite survival.