Global numbers of infection and disease burden of soil transmitted helminth infections in 2010

Prevalence of soil-transmitted helminths after mass albendazole administration in an indigenous community of the Manu jungle in Peru

Few data are available on the epidemiology of soil-transmitted helminths (STHs) in indigenous populations of the Peruvian Amazon. While albendazole is being increasingly used in deworming campaigns, few data exist on the impact of mass drug administration in isolated populations. We studied the prevalence of STHs, anemia, and malnutrition in a Matsigenka ethnic group from the Peruvian Amazon. Participants had received two doses of albendazole on consecutive days, 3 months before and again 2 weeks before data collection. Overall, 290 subjects were included. Most were female (53.7%) and 63.9% were ≤19 years old. Half of the participants had helminth infections. Trichiuris (30.2%), hookworm (19.1%), Ascaris (17.7%), and Strongyloides (5.6%) were the most common helminths. Other helminth ova included Capillaria hepatica and Fasciola-like eggs. Subjects of 5-19 years (51.8 %) and 20-35 years (68.6 %) old had helminths more often than those under 5 years (38%) and older than 35 years (41.5%) (P  =  0.02). Anemia was detected in 41% of children and this was more common in children under 5 years that in those of 5-19 years [odd ratio (OR) = 5.68; 95% CI: 2.71-11.88]. Overall, 72.1% of children were malnourished. Stunting was common in children (70.7%), but wasting was not (2.9%). Despite repeated albendazole administration, this population continued to have a high prevalence of STHs, anemia, and malnutrition. In addition, we detected unusual organisms and organisms that do not respond to albendazole. Further studies are needed to assess the rationale and efficacy of mass chemotherapy for STHs in the Amazon.

Helminths and malaria co-infections are associated with elevated serum IgE

Background

Both helminth and malaria infections result in a highly polarized immune response characterized by IgE production. This study aimed to investigate the total serum IgE profile in vivo as a measure of Th2 immune response in malaria patients with and without helminth co-infection.

Methods

A cross sectional observational study composed of microscopically confirmed malaria positive (N = 197) and malaria negative (N = 216) apparently healthy controls with and without helminth infection was conducted at Wondo Genet Health Center, Southern Ethiopia. A pre-designed structured format was utilized to collect socio-demographic and clinical data of the subjects. Detection and quantification of helminths, malaria parasites and determination of serum IgE levels were carried out following standard procedures.

Results

Irrespective of helminth infection, individuals infected by malaria showed significantly high levels of serum IgE compared with malaria free apparently healthy controls (with and without helminth infections). Moreover, malaria patients co-infected with intestinal helminths showed high level of serum IgE compared with those malaria patients without intestinal helminths (2198 IU/ml versus 1668 IU/ml). A strong statistically significant association was observed between malaria parasite density and elevated serum IgE levels (2047 IU/ml versus 1778 IU/ml; P = 0.001) with high and low parasitaemia (parasite density >50,000 parasite/μl of blood), respectively. Likewise, helminth egg loads were significantly associated with elevated serum IgE levels (P = 0.003).

Conclusions

The elevated serum IgE response in malaria patients irrespective of helminth infection and its correlation with malaria parasite density and helminth egg intensity support that malaria infection is also a strong driver of IgE production as compared to helminths.

Influence of nutrition on infection and re-infection with soil-transmitted helminths: a systematic review

Background

The relationship between nutrition and soil-transmitted helminthiasis is complex and warrants further investigation. We conducted a systematic review examining the influence of nutrition on infection and re-infection with soil-transmitted helminths (i.e. Ascaris lumbricoides, hookworm, Trichuris trichiura and Strongyloides stercoralis) in humans. Emphasis was placed on the use of nutritional supplementation, alongside anthelminthic treatment, to prevent re-infection with soil-transmitted helminths.

Methods

We searched eight electronic databases from inception to 31 July 2013, with no restriction of language or type of publication. For studies that met our inclusion criteria, we extracted information on the soil-transmitted helminth species, nutritional supplementation and anthelminthic treatment. Outcomes were presented in forest plots and a summary of findings (SoF) table. An evidence profile (EP) was generated by rating the evidence quality of the identified studies according to the GRADE system.

Results

Fifteen studies met our inclusion criteria; eight randomised controlled trials and seven prospective cohort studies. Data on A. lumbricoides were available from all studies, whereas seven and six studies additionally contained data on T. trichiura and hookworm, respectively. None of the studies contained data on S. stercoralis. Positive effects of nutritional supplementation or the host’s natural nutritional status on (re-)infection with soil-transmitted helminths were reported in 14 studies, while negative effects were documented in six studies. In terms of quality, a high, low and very low quality rating was assigned to the evidence from four, six and five studies, respectively.

Conclusions

Our findings suggest that the current evidence-base is weak, precluding guidelines on nutrition management as a potential supplementary tool to preventive chemotherapy targeting soil-transmitted helminthiasis. Moreover, several epidemiological, immunological and methodological issues have been identified, and these should be considered when designing future studies.

Advances in the diagnosis of Ascaris suum infections in pigs and their possible applications in humans

Ascariasis is one of the most common parasitic diseases in both humans and pigs. It has been shown to cause growth deficits in both species and to impair cognitive development in children. Notwithstanding its substantial impact on pig economy and public health, diagnosis of ascariasis has mostly relied on the detection of eggs in stool and further development of novel, more sensitive methods has been limited or non-existent. Here, we discuss the currently available techniques for the diagnosis of ascariasis in pigs, their caveats, and the implications of a new serological detection technique for the evaluation of both pig and human ascariasis.

Uptake of benzimidazoles by Trichuris suis in vivo in pigs

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The low uptake of FBZ by Trichuris suis in vitro was confirmed in vivo in pigs.

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High correlation between plasma and worm concentrations of OXF and FBZSO₂.

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No correlation between plasma and worm concentrations of FBZ.

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The blood–enterocyte pathway seems important for FBZ-metabolites to reach T. suis.

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FBZ may enter T. suis from the blood–enterocyte pathway and the intestinal content.

It is recognized that the clinical efficacy of single dose benzimidazoles (BZs) against the nematode, Trichuris suis of pigs and the closely related Trichuris trichiura in humans is only poor to moderate. Recent in vitro studies have indicated that a low uptake of fenbendazole (FBZ) in T. suis may be responsible for its poor efficacy. The aim of this study was to investigate this hypothesis by measuring the concentrations of FBZ and its metabolites, oxfendazole (OXF) and FBZ sulphone (FBZSO₂), in T. suis isolated from FBZ treated pigs and in plasma of the pigs. The highest concentration of FBZ measured in T. suis was 66.6 pmol/mg dry worm tissue which was approximately half of what was measured in a previous in vitro study. The correlation between drug concentrations in plasma and in T. suis worms was highly positive for OXF (r = 0.93, P = 0.0007) and FBZSO₂ (r = 0.85, P = 0.007), but no correlation was found for FBZ. This study shows that the low uptake of FBZ observed for T. suis in vitro, also takes place in vivo. The high and significant correlations between OXF and FBZSO₂ concentrations in plasma of the pigs and T. suis (and the lack of this correlation for FBZ) suggests that the metabolites reach the worms via the blood–enterocyte interface while FBZ primarily reaches the worms via the intestinal lumen of the host.

Secretory products of helminth parasites as immunomodulators

Parasitic helminths release molecules into their environment, which are generally referred to as excretory-secretory products or ES. ES derived from a wide range of nematodes, trematodes and cestodes have been studied during the past 30-40 years, their characterization evolving from simple biochemical procedures such as SDS-PAGE in the early days to sophisticated proteomics in the 21st century. Study has incorporated investigation of ES structure, potential as vaccines, immunodiagnostic utility, functional activities and immunomodulatory properties. Immunomodulation by ES is increasingly the area of most intensive research with a number of defined helminth products extensively analyzed with respect to the nature of their selective effects on cells of the immune system as well as the molecular mechanisms, which underlie these immunomodulatory effects. As a consequence, we are now beginning to learn the identities of the receptors that ES employ and are increasingly acquiring detailed knowledge of the signalling pathways that they interact with and subvert. Such information is contributing to the growing idea that the anti-inflammatory properties of a number of ES products makes them suitable starting points for the development of novel drugs for treating human inflammatory disease.

The epidemiology of polyparasitism and implications for morbidity in two rural communities of Côte d'Ivoire

Background

Polyparasitism is still widespread in rural communities of the developing world. However, the epidemiology of polyparasitism and implications for morbidity are poorly understood. We studied patterns of multiple species parasite infection in two rural communities of Côte d’Ivoire, including associations and interactions between infection, clinical indicators and self-reported morbidity.

Methods

Between August and September 2011, two purposely selected rural communities in southern Côte d’Ivoire were screened for helminth, intestinal protozoa and Plasmodium infection, using a suite of quality-controlled diagnostic methods. Additionally, participants were examined clinically and we measured haemoglobin level, height, weight and mid-upper arm circumference to determine nutritional status. An anamnestic questionnaire was administered to assess people’s recent history of diseases and symptoms, while a household questionnaire was administered to heads of household to collect socioeconomic data. Multivariate logistic regression models were applied for assessment of possible associations between parasitic (co-)infections and morbidity outcomes.

Results

912/1,095 (83.3%) study participants had complete parasitological data and 852 individuals were considered for in-depth analysis. The rate of polyparasitism was high, with Plasmodium falciparum diagnosed as the predominant species, followed by Schistosoma haematobium, Schistosoma mansoni and hookworm. There were considerable differences in polyparasitic infection profiles among the two settings. Clinical morbidity such as anaemia, splenomegaly and malnutrition was mainly found in young age groups, while in adults, self-reported morbidity dominated. High parasitaemia of P. falciparum was significantly associated with several clinical manifestations such as anaemia, splenomegaly and fever, while light-intensity helminth infections seemed to have beneficial effects, particularly for co-infected individuals.

Conclusions

Clinical morbidity is disturbingly high in young age groups in rural communities of Côte d’Ivoire and mainly related to very high P. falciparum endemicity. Interactions between helminth infections and P. falciparum burden (parasitaemia and clinical morbidity) are evident and must be taken into account to design future interventions.