Distinct hepatic myeloid and lymphoid cell repertoires are associated with susceptibility and resistance to Ascaris infection.

The soil-transmitted helminth Ascaris lumbricoides infects ~800 million people worldwide. Some people are heavily infected, harbouring many worms, whereas others are only lightly infected. The mechanisms behind this difference are unknown. We used a mouse model of hepatic resistance to Ascaris, with C57BL/6J mice as a model for heavy infection and CBA/Ca mice as a model for light infection. The mice were infected with the porcine ascarid, Ascaris suum or the human ascarid, A. lumbricoides and immune cells in their livers and spleens were enumerated using flow cytometry. Compared to uninfected C57BL/6J mice, uninfected CBA/Ca mice had higher splenic CD4+ and γδ T cell counts and lower hepatic eosinophil, Kupffer cell and B cell counts. Infection with A. suum led to expansions of eosinophils, Kupffer cells, monocytes and dendritic cells in the livers of both mouse strains and depletions of hepatic natural killer (NK) cells in CBA/Ca mice only. Infection with A. lumbricoides led to expansions of hepatic eosinophils, monocytes and dendritic cells and depletions of CD8+, αß, NK and NK T cells in CBA/Ca mice, but not in C57BL/6J mice where only monocytes expanded. Thus, susceptibility and resistance to Ascaris infection are governed, in part, by the hepatic immune system.

2-Methyl-pentanoyl-carnitine (2-MPC): a urine biomarker for patent Ascaris lumbricoides infection.

Infections with intestinal worms, such as Ascaris lumbricoides, affect hundreds of millions of people in all tropical and subtropical regions of the world. Through large-scale deworming programs, World Health Organization aims to reduce moderate-to-heavy intensity infections below 1%. Current diagnosis and monitoring of these control programs are solely based on the detection of worm eggs in stool. Here we describe how metabolome analysis was used to identify the A. lumbricoides-specific urine biomarker 2-methyl pentanoyl carnitine (2-MPC). This biomarker was found to be 85.7% accurate in determining infection and 90.5% accurate in determining a moderate-to-heavy infection. Our results also demonstrate that there is a correlation between 2-MPC levels in urine and A. lumbricoides DNA detected in stool. Furthermore, the levels of 2-MPC in urine were shown to rapidly and strongly decrease upon administration of a standard treatment (single oral dose of 400 mg albendazole). In an Ascaris suum infection model in pigs, it was found that, although 2-MPC levels were much lower compared to humans, there was a significant association between urinary 2-MPC levels and both worm counts (p = 0.023) and the number of eggs per gram (epg) counts (p < 0.001). This report demonstrates that urinary 2-MPC can be considered an A. lumbricoides-specific biomarker that can be used to monitor infection intensity.

Neuronal specification in C. elegans: combining lineage inheritance with intercellular signaling.

The nervous system is composed of a high diversity of neuronal types. How this diversity is generated during development is a key question in neurobiology. Addressing this question is one of the reasons that led Sydney Brenner to develop the nematode C. elegans as a model organism. While there was initially a debate on whether the neuronal specification follows a 'European' model (determined by ancestry) or an 'American' model (determined by intercellular communication), several decades of research have established that the truth lies somewhere in between. Neurons are specified by the combination of transcription factors inherited from the ancestor cells and signaling between neighboring cells (especially Wnt and Notch signaling). This converges to the activation in newly generated postmitotic neurons of a specific set of terminal selector transcription factors that initiate and maintain the differentiation of the neuron. In this review, we also discuss the evolution of these specification mechanisms in other nematodes and beyond.

Parasite associations predict infection risk: incorporating co-infections in predictive models for neglected tropical diseases.

BACKGROUND: Schistosomiasis and infection by soil-transmitted helminths are some of the world's most prevalent neglected tropical diseases. Infection by more than one parasite (co-infection) is common and can contribute to clinical morbidity in children. Geostatistical analyses of parasite infection data are key for developing mass drug administration strategies, yet most methods ignore co-infections when estimating risk. Infection status for multiple parasites can act as a useful proxy for data-poor individual-level or environmental risk factors while avoiding regression dilution bias. Conditional random fields (CRF) is a multivariate graphical network method that opens new doors in parasite risk mapping by (i) predicting co-infections with high accuracy; (ii) isolating associations among parasites; and (iii) quantifying how these associations change across landscapes. METHODS: We built a spatial CRF to estimate infection risks for Ascaris lumbricoides, Trichuris trichiura, hookworms (Ancylostoma duodenale and Necator americanus) and Schistosoma mansoni using data from a national survey of Rwandan schoolchildren. We used an ensemble learning approach to generate spatial predictions by simulating from the CRF's posterior distribution with a multivariate boosted regression tree that captured non-linear relationships between predictors and covariance in infection risks. This CRF ensemble was compared against single parasite gradient boosted machines to assess each model's performance and prediction uncertainty. RESULTS: Parasite co-infections were common, with 19.57% of children infected with at least two parasites. The CRF ensemble achieved higher predictive power than single-parasite models by improving estimates of co-infection prevalence at the individual level and classifying schools into World Health Organization treatment categories with greater accuracy. The CRF uncovered important environmental and demographic predictors of parasite infection probabilities. Yet even after capturing demographic and environmental risk factors, the presences or absences of other parasites were strong predictors of individual-level infection risk. Spatial predictions delineated high-risk regions in need of anthelminthic treatment interventions, including areas with higher than expected co-infection prevalence. CONCLUSIONS: Monitoring studies routinely screen for multiple parasites, yet statistical models generally ignore this multivariate data when assessing risk factors and designing treatment guidelines. Multivariate approaches can be instrumental in the global effort to reduce and eventually eliminate neglected helminth infections in developing countries.

Ascaris lumbricoides and Ascaris suum vary in their larval burden in a mouse model.

Ascariasis is a neglected tropical disease, caused by Ascaris lumbricoides, affecting 800 million people worldwide. Studies focused on the early stage of parasite infection, occurring in the gut, liver and lungs, require the use of a mouse model. In these models, the porcine ascarid, Ascaris suum, is often used. The results obtained from these studies are then used to draw conclusions about A. lumbricoides infections in humans. In the present study, we sought to compare larval migration of A. suum and A. lumbricoides in mouse models. We used a previously developed mouse model of ascariasis, which consists of two mouse strains, where one mouse strain - C57BL/6J - is a model for relative susceptibility and the other - CBA/Ca - for relative resistance. Mice of both strains were infected with either A. suum or A. lumbricoides. The larval burden was assessed in two key organs, the liver and lungs, starting at 6 h post infection (p.i.) and ending on day 8 p.i. Additionally, we measured the larval size of each species (µm) at days 6, 7 and 8 p.i. in the lungs. We found that larval burden in the liver is significantly higher for A. lumbricoides than for A. suum. However, the inverse is true in the lungs. Additionally, our results showed a reduced larval size for A. lumbricoides compared to A. suum.

Parasite Infections, Allergy and Asthma: A Role for Tropomyosin in Promoting Type 2 Immune Responses.

INTRODUCTION: The relationship of parasite infections and promotion or protection from allergy and asthma is controversial. Currently, over 1.5 billion people are infected with parasites worldwide, and Ascaris lumbricoides is the most frequent soil-transmitted helminth. OBJECTIVES: To evaluate the biological activity of recombinant A. lumbricoides tropomyosin and investigate IgE cross-reactive responses to tropomyosins by means of microarray methodology for the detection of sensitization to allergen components. METHODS: Forty patients 12-75 years of age (25 males) with asthma and/or rhinitis and 10 nonallergic control subjects participated in this study. All patients presented positive skin tests to cockroach extracts and underwent skin prick testing (SPT) with recombinant (r) tropomyosins rPer a 7 from Periplaneta americana and rAsc l 3 from A. lumbricoides, at 10 µg/mL. IgE to cockroach and parasite tropomyosins were measured by chimeric ELISA and ImmunoCAP-ISAC, and total IgE was quantitated by ImmunoCAP. Agreement of results was assessed by κ statistics. RESULTS: Recombinant A. lumbricoides showed biological activity, inducing positive skin tests in 50% patients with asthma and/or rhinitis. IgE to cockroach and parasite tropomyosins were detected in 55-62% of patients. There was good-to-excellent agreement of results of SPT and IgE measurements by ELISA and ImmunoCAP-ISAC, with κ indices of 0.66-0.95. No skin test reactivity or IgE antibodies to tropomyosins were found in nonallergic individuals. CONCLUSIONS: Our results suggest that IgE responses to tropomyosin from A. lumbricoides may enhance reactivity to homologous allergens upon exposure by inhalation or ingestion, promoting allergic reactions and asthma, or increasing the severity of these clinical conditions.

Sustained preventive chemotherapy for soil-transmitted helminthiases leads to reduction in prevalence and anthelminthic tablets required.

BACKGROUND: The goal of soil-transmitted helminthiases (STH) control programmes is to eliminate STH-associated morbidity in the target population by reducing the prevalence of moderate- and heavy-intensity infections and the overall STH infection prevalence mainly through preventive chemotherapy (PC) with either albendazole or mebendazole. Endemic countries should measure the success of their control programmes through regular epidemiological assessments. We evaluated changes in STH prevalence in countries that conducted effective PC coverage for STH to guide changes in the frequency of PC rounds and the number of tablets needed. METHODS: We selected countries from World Health Organization (WHO)'s Preventive Chemotherapy and Transmission control (PCT) databank that conducted ≥5 years of PC with effective coverage for school-age children (SAC) and extracted STH baseline and impact assessment data using the WHO Epidemiological Data Reporting Form, Ministry of Health reports and/or peer-reviewed publications. We used pooled and weighted means to plot the prevalence of infection with any STH and with each STH species at baseline and after ≥5 years of PC with effective coverage. Finally, using the WHO STH decision tree, we estimated the reduction in the number of tablets needed. RESULTS: Fifteen countries in four WHO regions conducted annual or semi-annual rounds of PC for STH for 5 years or more and collected data before and after interventions. At baseline, the pooled prevalence was 48.9% (33.1-64.7%) for any STH, 23.2% (13.7-32.7%) for Ascaris lumbricoides, 21.01% (9.7-32.3%) for Trichuris trichiura and 18.2% (10.9-25.5%) for hookworm infections, while after ≥5 years of PC for STH, the prevalence was 14.3% (7.3-21.3%) for any STH, 6.9% (1.3-12.5%) for A. lumbricoides, 5.3% (1.06-9.6%) for T. trichiura and 8.1% (4.0-12.2%) for hookworm infections. CONCLUSIONS: Countries endemic for STH have made tremendous progress in reducing STH-associated morbidity, but very few countries have data to demonstrate that progress. In this study, the data show that nine countries should adapt their PC strategies and the frequency of PC rounds to yield a 36% reduction in drug needs. The study also highlights the importance of impact assessment surveys to adapt control strategies according to STH prevalence.

A 5 year retrospective analysis of common intestinal parasites at Poly Health Center, Gondar, Northwest Ethiopia.

OBJECTIVE: Intestinal parasites are present throughout the world in varying degrees of prevalence due to many factors. The aim of this study was to determine the 5-year trend prevalence of intestinal prevalence among patients who had been suspected for intestinal parasite infections. A retrospective study was conducted from 2009 to 2013 at Poly Health Center Gondar, Northwest Ethiopia. Samples were examined using direct saline wet mount methods. Statistical analysis was done using SPSS version 20 software and a P-value of < 0.05 was considered statistically significant. The results were presented in tables and graphs. RESULTS: During the study period, a total of 13,329 stool samples were requested for intestinal parasite diagnose and 5510 (41.3%) laboratory-confirmed cases were reported with a fluctuating trend. Ten different parasites were reported in each year with Entamoeba histolytica/dispar (16.8%) being the predominant parasite followed by Giardia lamblia (11.4%) and Ascaris lumbricoides (6.7%). Both males (49%) and females (51%) were equally affected (P = 0.14). The intestinal parasite was reported in all age groups in the area but the highest and the lowest prevalence were reported in age groups of 20-29 years and 40-49 years, respectively (26.5% vs 6.4%) (P < 0.001).

Disentangling complex parasite interactions: Protection against cerebral malaria by one helminth species is jeopardized by co-infection with another.

Multi-species interactions can often have non-intuitive consequences. However, the study of parasite interactions has rarely gone beyond the effects of pairwise combinations of species, and the outcomes of multi-parasite interactions are poorly understood. We investigated the effects of co-infection by four gastrointestinal helminth species on the development of cerebral malaria among Plasmodium falciparum-infected patients. We characterized associations among the helminth parasite infra-community, and then tested for independent (direct) and co-infection dependent (indirect) effects of helminths on cerebral malaria risk. We found that infection by Ascaris lumbricoides and Trichuris trichiura were both associated with direct reductions in cerebral malaria risk. However, the benefit of T. trichiura infection was halved in the presence of hookworm, revealing a strong indirect effect. Our study suggests that the outcome of interactions between two parasite species can be significantly modified by a third, emphasizing the critical role that parasite community interactions play in shaping infection outcomes.

The impact of seasonality on the dynamics and control of Ascaris lumbricoides infections.

Intestinal nematode infections affect a huge proportion of the world's population. Increasingly these infections, particularly amongst the poorest communities, are controlled through mass drug treatment programs. Seasonal variations of climate and behaviour in these regions can be significant, but their impact on the dynamics of infection and implications for the effectiveness of any mass drug treatment program (a pulsed reduction in worm burden in hosts) is not clearly understood. Here the effect of seasonality on the dynamics of the soil-based helminth, Ascaris lumbricoides, is investigated using a reformulated version of the Anderson-May model for macro-parasitic infections. Explicit analytical expressions are obtained for the stable oscillatory solution over the annual cycle, which provides a means of relating times of peak numbers of eggs, larvae and mature worms to seasonal variations. Numerical and analytical techniques are then used to consider the impact of seasonality on the optimal timing of drug treatment. Our results show that there is a relatively large window for the timing of optimal treatment, and the impact of repeated annual mass drug treatments can be substantially improved if they are timed to coincide with the months when the number of eggs and larvae are at their lowest - minimising reinfection. In terms of a more measurable quantity, in our example this corresponds to the months when the seasonal temperature is highest. Multiple annual treatments at (or close to) the optimal time each year are predicted to achieve local elimination in the community, whereas treatment at other times has a more limited impact. A key finding is that even for pronounced seasonality, perturbations in mean worm burden, and hence seasonal variation in observed egg output, may be small, potentially explaining why seasonal effects have been overlooked. Taken together these results suggest that seasonality of soil-transmitted helminths requires further experimental, field and mathematical study if the impact for mass drug administration programs is to be exploited.

Helminth lifespan interacts with non-compliance in reducing the effectiveness of anthelmintic treatment.

BACKGROUND: The success of mass drug administration programmes targeting the soil-transmitted helminths and schistosome parasites is in part dependent on compliance to treatment at sequential rounds of mass drug administration (MDA). The impact of MDA is vulnerable to systematic non-compliance, defined as a portion of the eligible population remaining untreated over successive treatment rounds. The impact of systematic non-compliance on helminth transmission dynamics - and thereby on the number of treatment rounds required to interrupt transmission - is dependent on the parasitic helminth being targeted by MDA. RESULTS: Here, we investigate the impact of adult parasite lifespan in the human host and other factors that determine the magnitude of the basic reproductive number R 0 , on the number of additional treatment rounds required in a target population, using mathematical models of Ascaris lumbricoides and Schistosoma mansoni transmission incorporating systematic non-compliance. Our analysis indicates a strong interaction between helminth lifespan and the impact of systematic non-compliance on parasite elimination, and confirms differences in its impact between Ascaris and the schistosome parasites in a streamlined model structure. CONCLUSIONS: Our analysis suggests that achieving reductions in the level of systematic non-compliance may be of particular benefit in mass drug administration programmes treating the longer-lived helminth parasites, and highlights the need for improved data collection in understanding the impact of compliance.

Sources of variability in the measurement of Ascaris lumbricoides infection intensity by Kato-Katz and qPCR.

BACKGROUND: Understanding and quantifying the sources and implications of error in the measurement of helminth egg intensity using Kato-Katz (KK) and the newly emerging "gold standard" quantitative polymerase chain reaction (qPCR) technique is necessary for the appropriate design of epidemiological studies, including impact assessments for deworming programs. METHODS: Repeated measurements of Ascaris lumbricoides infection intensity were made from samples collected in western Kenya using the qPCR and KK techniques. These data were combined with data on post-treatment worm expulsions. Random effects regression models were used to quantify the variability associated with different technical and biological factors for qPCR and KK diagnosis. The relative precision of these methods was compared, as was the precision of multiple qPCR replicates. RESULTS: For both KK and qPCR, intensity measurements were largely determined by the identity of the stool donor. Stool donor explained 92.4% of variability in qPCR measurements and 54.5% of observed measurement variance for KK. An additional 39.1% of variance in KK measurements was attributable to having expelled adult A. lumbricoides worms following anthelmintic treatment. For qPCR, the remaining 7.6% of variability was explained by the efficiency of the DNA extraction (2.4%), plate-to-plate variability (0.2%) and other residual factors (5%). Differences in replicate measurements by qPCR were comparatively small. In addition to KK variability based on stool donor infection levels, the slide reader was highly statistically significant, although it only explained 1.4% of the total variation. In a comparison of qPCR and KK variance to mean ratios under ideal conditions, the coefficient of variation was on average 3.6 times larger for KK highlighting increased precision of qPCR. CONCLUSIONS: Person-to-person differences explain the majority of variability in egg intensity measurements by qPCR and KK, with very little additional variability explained by the technical factors associated with the practical implementation of these techniques. qPCR provides approximately 3.6 times more precision in estimating A. lumbricoides egg intensity than KK, and could potentially be made more cost-effective by testing each sample only once without diminishing the power of a study to assess population-level intensity and prevalence.

The roundworm Strongyloides stercoralis in children, dogs, and soil inside and outside a segregated settlement in Eastern Slovakia: frequent but hardly detectable parasite.

A comparative study was carried out to evaluate the Strongyloides stercoralis infections in children and dogs inside and outside the segregated settlement in Medzev, Eastern Slovakia, and a survey of the soil within the settlement was included. Applying the Koga agar plate (KAP) culture method and microscopy examination of stool samples collected from 60 Roma and 21 nonRoma children, no larvae of S. stercoralis were detected but eggs of three nematodes (Ascaris lumbricoides, Trichuris trichiura, and Enterobius vermicularis) and cysts of two protozoan endoparasites (Giardia duodenalis and Cryptosporidium spp.) were often found. However, immunoenzymatic assay (ELISA) for the evidence of IgG antibodies against S. stercoralis showed 33.3% seroprevalence in Roma children and 23.8% prevalence in children from the majority population, attending the same school. Eosinophilia was regularly present in children with exclusive infection of S. stercoralis (eight cases) as well as in individuals suffering from mixed infections of S. stercoralis and some of the above listed parasites (16 cases); high eosinophil counts sometimes, but not always, occurred in parasitized children lacking S. stercoralis antibodies. A comparison of S. stercoralis in dogs from the settlement (40 dogs) and from a distant dog shelter (20 dogs) did not reveal remarkable differences: the direct microscopy of faecal samples revealed rhabditiform larvae in 13.3% of the dogs from the settlement (4/30) and in 10.0% of the dogs from the shelter (2/20). Out of blood samples collected from the second dog group, 55% of the dogs contained antibodies against S. stercoralis. In the soil collected from 14 various locations within the settlement, S. stercoralis larvae were observed in two samples (14.3%); however, 13 samples (92.9%) were positive for human or dog endoparasites of the genera Ancylostoma, Ascaris, Toxocara, Toxascaris, Trichuris, and Hymenolepis.

Ascaris lumbricoides egg die-off in an experimental excreta storage system and public health implication in Vietnam.

OBJECTIVES: We studied the influence of different additive materials (lime, and rice husk) and aeration conditions on Ascaris lumbricoides egg die-off in 24 vaults of an experimental excreta storage unit. METHODS: Excreta samples were collected once every two weeks over a 181-day period. Temperature, pH, and moisture content were recorded. A. lumbricoides eggs were quantitatively analyzed by the Romanenko method, which identified and counted live and dead eggs. RESULTS: From the first sampling (0 storage day) to the final sampling (181 storage days) the average percentage of viable A. lumbricoides eggs decreased gradually from 76.72 ± 11.23% (mean ± SD) to 8.26 ± 5.20%. The storage time and the high pH value significantly increased the die-off of helminth eggs. Over 181 storage days, all vaults option effectively reduced A. lumbricoides eggs die-off. CONCLUSIONS: The best vault option, with aeration and 10% lime per total weight, met the WHO standard for excreta treatment on the 111th storage day.

[Investigation on prevalence and risk factors of HIV/AIDS and Schistosoma japonicum, Ascaris lumbricoides and Trichuris trichiura infections in a rural community of southwestern China].

OBJECTIVE: To investigate the prevalence and risk factors of helminthic infections including Schistosoma japonicum, Ascaris lumbricoides and Trichuris trichiura and human immunodeficiency virus (HIV), and find out the association among them in a rural community of southwestern China. METHODS: A community-based cross sectional study was conducted. One town was selected randomly; the infections of S.japonicum, A.lumbricoides and T.trichiura were detected with the modified Kato-Katz thick smear method and HIV infection with the diagnostic Test Kit among all residents. A questionnaire survey was conducted to investigate the related risk factors. RESULTS: Among the participants, the infection rates of HIV, S.japonicum, A.lumbricoides and T.trichiura were 2.33%, 2.05%, 13.47% and 30.59% respectively; 7.08% (31/438) were infected with both A.lumbricoides and T.trichiura; 0.23% (1/438) were co-infected with HIV and A.lumbricoides, and the same with HIV and T.trichiura. The multivariate logistic regression analysis showed that sex (male, OR=3.26, 95% CI：0.97, 10.95) and drug abuse (OR=72.86, 95% CI：18.51, 286.76) were significantly associated with HIV infection. Home toilet was negatively related to A.lumbricoides infection (OR=0.52, 95% CI：0.27, 0.98) and T.trichiura infection (OR=0.48, 95% CI：0.28, 0.80). Compared with the people in Villages Four, the people living in Village One were at a higher risk for A.lumbricoides infection (OR=3.14, 95% CI：1.35, 7.27), and compared with the people living in Village Four, the people living in Village Two and Village Three were more likely to be infected with T.trichiura (OR=3.73, 95% CI：1.92, 7.26; OR=4.53, 95% CI：2.12, 9.68). The people aged between 11 and 20 years had a higher T.trichiura infection risk than the people aged more than 50 years (OR = 3.72, 95% CI：1.59, 8.67). There was a significant association between A.lumbricoides and T.trichiura infections (OR = 3.11, 95% CI：1.63, 5.93). There was no association between S.japonicum infection and related factors above mentioned. CONCLUSIONS: The infection rates of HIV, S.japonicum, A.lumbricoides and especially T.trichiura were rather high in this area, and therefore, the prevention and treatment of these diseases should be strengthened. Further studies on the relationship between HIV and the infections of helminths, especially S.japonicum are needed.

Intestinal helminth infections among inmates in Bedele prison with emphasis on soil-transmitted helminths.

BACKGROUND: Intestinal helminths infect more than two billion people worldwide. They are common in developing countries where sanitary facilities are inadequate. There is scarcity of documented data on the magnitude of intestinal helminths among inmates in Ethiopia. The aim of this study was to determine prevalence of intestinal helminth infections among inmates in Bedele prison, south-western Ethiopia. METHODS: A cross-sectional study involving 234 inmates in Bedele prison was conducted in April 2012. Socio-demographic data was collected from each study participant using semi-structured questionnaire. Fresh stool specimens were collected and processed using modified McMaster technique. RESULTS: At least one species of intestinal helminth was identified in 111 (47.4 %) of the inmates. Ascaris lumbricoides was the most predominant parasite isolated, followed by the hookworms. Most of the cases of soil-transmitted helminths (STHs) were light infections. Untrimmed hand fingernails was significantly associated with A. lumbricoides infection (AOR 0.383, 95 % CI 0.200-0.731). CONCLUSION: Intestinal helminths are common among the inmates in Bedele prison. Health information should be given to the inmates on proper personal hygiene practices with emphasis on trimming of hand fingernails. Monitoring helminth infections in the inmate population is required.

Risk Factors and Relationship Between Intestinal Parasites and the Growth Retardation and Psychomotor Development Delays of Children in Sanliurfa, Turkey.

OBJECTIVE: The objective of this study was to determine the risk factors for and relationship among parasitic infections, growth retardation, and psychomotor developmental delays in children aged 6 years and below. METHODS: This case-control study was performed in Sanliurfa in southeastern Turkey between October and December 2007. Data were collected using a structured questionnaire, anthropometry, Ankara Development Screening Inventory, and laboratory analysis of stool specimens. RESULTS: The most common parasite was Giardia intestinalis (42.53%) followed by Enterobius vermicularis (27.58%), Ascaris lumbricoides (18.39%), Hymenolepis nana (5.75%), Trichuris trichiura (3.45%), Escherichia coli (1.15%), and Blastocystis spp. (1.15%). Fifty-eight percent of all children were infected with intestinal parasites; 55.2% had only one parasite, whereas 44.8% had multiple parasites. The children infected with G. intestinalis and other intestinal parasites had significantly higher levels of growth retardation and psychomotor development delay than non-infected children. Children with parasitic infections had growth delay up to 2.9 times, general development delay up to 1.9 times, language-cognitive development delay up to 2.2 times, and fine motor development delay up to 2.9 times higher than children without any parasitic infections. However, no significant relationship among intestinal parasites, gross motor development, social-self skills, and development delay was identified. The education level of parents, poor economic situation, number of households, not washing hands, playing with soil, family history of parasitic infection were the significant risk factors for intestinal parasites. CONCLUSION: Our study indicates that the presence of either malnutrition or intestinal parasites may put a child in a high-risk group for developmental delays and growth retardation. Therefore, public health interventions can embrace nationwide deworming in children.

Spatio-temporal distribution of soil-transmitted helminth infections in Brazil.

BACKGROUND: In Brazil, preventive chemotherapy targeting soil-transmitted helminthiasis is being scaled-up. Hence, spatially explicit estimates of infection risks providing information about the current situation are needed to guide interventions. Available high-resolution national model-based estimates either rely on analyses of data restricted to a given period of time, or on historical data collected over a longer period. While efforts have been made to take into account the spatial structure of the data in the modelling approach, little emphasis has been placed on the temporal dimension. METHODS: We extracted georeferenced survey data on the prevalence of infection with soil-transmitted helminths (i.e. Ascaris lumbricoides, hookworm and Trichuris trichiura) in Brazil from the Global Neglected Tropical Diseases (GNTD) database. Selection of the most important predictors of infection risk was carried out using a Bayesian geostatistical approach and temporal models that address non-linearity and correlation of the explanatory variables. The spatial process was estimated through a predictive process approximation. Spatio-temporal models were built on the selected predictors with integrated nested Laplace approximation using stochastic partial differential equations. RESULTS: Our models revealed that, over the past 20 years, the risk of soil-transmitted helminth infection has decreased in Brazil, mainly because of the reduction of A. lumbricoides and hookworm infections. From 2010 onwards, we estimate that the infection prevalences with A. lumbricoides, hookworm and T. trichiura are 3.6%, 1.7% and 1.4%, respectively. We also provide a map highlighting municipalities in need of preventive chemotherapy, based on a predicted soil-transmitted helminth infection risk in excess of 20%. The need for treatments in the school-aged population at the municipality level was estimated at 1.8 million doses of anthelminthic tablets per year. CONCLUSIONS: The analysis of the spatio-temporal aspect of the risk of infection with soil-transmitted helminths contributes to a better understanding of the evolution of risk over time. Risk estimates provide the soil-transmitted helminthiasis control programme in Brazil with useful benchmark information for prioritising and improving spatial and temporal targeting of interventions.

Proliferative capacity and cytokine production by cells of HIV-infected and uninfected adults with different helminth infection phenotypes in South Africa.

BACKGROUND: It has been suggested that the proliferative capacity of cells from individuals with HIV or both HIV and helminth infections is attenuated and cytokine production is dysregulated. This study describes peripheral blood mononuclear cell proliferation capacity and cytokine profile from individuals with HIV or both HIV and helminth infections in South Africa. METHODS: Forty HIV-infected and 22 HIV-uninfected participants were randomly selected and stratified into different helminth infection phenotypes by egg excretion and Ascaris lumbricoides specific -immunoglobulin-E (IgE) levels. Five day cell cultures of participants, unstimulated or stimulated with Phytohaemaglutinnin, Streptokinase, HIV-1 p24 and Ascaris lumbricoides worm antigens were stained with monoclonal antibody-fluorochrome conjugates (Ki67-FITC and CTLA-APC-4). Percentage expression of Ki67 and CTLA-4 was measured to determine cell proliferation and regulation, respectively. Culture supernatants were analysed for the expression of 13 cytokines using the Bioplex (BioRad) system. Kruskal Wallis was used to test for differences in variables between helminth infected subgroups who were either having eggs in stool and high IgE (egg+IgEhi); or eggs in stool and low IgE (egg+IgElo); or no eggs in stool and high IgE (egg-IgEhi) and those without helminth infection (egg-IgElo). RESULTS: Individuals excreting eggs in stool with high serum IgE (egg+IgEhi phenotype) had potent mitogen responses but consistently produced low, but statistically non-significant antigen-specific (HIV-1 p24 (p = 0.41) and Ascaris (p = 0.19) and recall antigen (Streptokinase; p = 0.31) Ki67 responses. The group also had reduced type 1 cytokines. Individuals excreting eggs in stool with low serum IgE( egg+IgElo phenotype) had a more favourable antiviral profile, characterized by higher IFNγ, IL-2, lower IL-4 and higher IL-10 production. CONCLUSION: The findings suggest that dual HIV/helminth infection with egg excretion and/or high Ascaris IgE phenotye may be linked with poor proliferative capacity and deleterious cytokine profile with regards to HIV control.

Ascaris lumbricoides infection and its relation to environmental factors in the Mbeya region of Tanzania, a cross-sectional, population-based study.

BACKGROUND: With one quarter of the world population infected, the intestinal nematode Ascaris lumbricoides is one of the most common infectious agents, especially in the tropics and sub-tropics. Infection is caused by oral intake of eggs and can cause respiratory and gastrointestinal problems. To identify high risk areas for intervention, it is necessary to understand the effects of climatic, environmental and socio-demographic conditions on A. lumbricoides infection. METHODOLOGY: Cross-sectional survey data of 6,366 study participants in the Mbeya region of South-Western Tanzania were used to analyze associations between remotely sensed environmental data and A. lumbricoides infection. Non-linear associations were accounted for by using fractional polynomial regression, and socio-demographic and sanitary data were included as potential confounders. PRINCIPAL FINDINGS: The overall prevalence of A. lumbricoides infection was 6.8%. Our final multivariable model revealed a significant non-linear association between rainfall and A. lumbricoides infection with peak prevalences at 1740 mm of mean annual rainfall. Mean annual land surface temperature during the day was linearly modeled and negatively associated with A. lumbricoides infection (odds ratio (OR) = 0.87, 95% confidence interval (CI) = 0.78-0.97). Furthermore, age, which also showed a significant non-linear association (infection maximum at 7.7 years), socio-economic status (OR = 0.82, CI = 0.68-0.97), and latrine coverage around the house (OR = 0.80, CI = 0.67-0.96) remained in the final model. CONCLUSIONS: A. lumbricoides infection was associated with environmental, socio-demographic and sanitary factors both in uni- and multivariable analysis. Non-linear analysis with fractional polynomials can improve model fit, resulting in a better understanding of the relationship between environmental conditions and helminth infection, and more precise predictions of high prevalence areas. However, socio-demographic determinants and sanitary conditions should also be considered, especially when planning public health interventions on a smaller scale, such as the community level.