The epidemiology of soil-transmitted helminth infections in children up to 8 years of age: Findings from an Ecuadorian birth cohort

Epidemiology of giardiasis and assemblages A and B and effects on diarrhea and growth trajectories during the first 8 years of life: Analysis of a birth cohort in a rural district in tropical Ecuador

BACKGROUND

There are limited longitudinal data on the acquisition of Giardia lamblia infections in childhood using molecular assays to detect and type assemblages, and measure effects of infections on diarrhea risk and childhood growth.

METHODS

We analysed stool samples from a surveillance sample within a birth cohort in a rural district in tropical Ecuador. The cohort was followed to 8 years of age for the presence of G. lamblia in stools by quantitative PCR and A and B assemblages by Taqman assay or Sanger sequencing. We explored risk factors associated with infection using generalized estimating equations applied to longitudinal binary outcomes, and longitudinal panel data analysis to estimate effects of infection on diarrhea and growth trajectories.

RESULTS

2,812 stool samples collected between 1 month and 8 years of age from 498 children were analyzed and showed high rates of infection: 79.7% were infected at least once with peak prevalence (53.9%) at 5 years. Assemblage B was accounted for 56.8% of genotyped infections. Risk factors for infection included male sex (P = 0.001), daycare attendance (P<0.001), having a household latrine (P = 0.04), childhood (P<0.001) and maternal soil-transmitted helminth (P = 0.029) infections, and exposures to donkeys (age interaction P = 0.034). G. lamblia was associated with increased risk of diarrhea (per episode, RR 1.03, 95% CI 1.01-1.06, P = 0.011) during the first 3 years of life and a transient impairment of weight (age interaction P = 0.017) and height-for-age (age interaction P = 0.025) trajectories between 1 and 4 years of age. There was no increased risk of either assemblage being associated with outcomes.

CONCLUSION

Our data show a relatively high edemicity of G. lamblia transmission during childhood in coastal Ecuador, and evidence that infection is associated with a transiently increased risk of diarrhea during the first 3 years of life and impairment of weight and height between 1 and 4 years.

Effect of infant viral respiratory disease on childhood asthma in a non-industrialized setting

BACKGROUND

There are limited data from non-industrialized settings on the effects of early life viral respiratory disease on childhood respiratory illness. We followed a birth cohort in tropical Ecuador to understand how early viral respiratory disease, in the context of exposures affecting airway inflammation including ascariasis, affect wheezing illness, asthma, and rhinoconjunctivitis in later childhood.

METHODS

A surveillance cohort nested within a birth cohort was monitored for respiratory infections during the first 2 years in rural Ecuador and followed for 8 years for the development of wheeze and rhinoconjunctivitis. Nasal swabs were examined for viruses by polymerase chain reaction and respiratory symptom data on recent wheeze and rhinoconjunctivitis were collected by periodic questionnaires at 3, 5, and 8 years. Stools from pregnant mothers and periodically from children aged 2 years were examined microscopically for soil-transmitted helminths. Atopy was measured by allergen skin prick testing at 2 years. Spirometry, fractional exhaled nitric oxide measurement, and nasal washes were performed at 8 years. Associations between clinically significant respiratory disease (CSRD) and wheezing or rhinoconjunctivitis at 3, 5, and 8 years were estimated using multivariable logistic regression.

RESULTS

Four hundred and twenty six children were followed of which 67.7% had at least one CSRD episode; 12% had respiratory syncytial virus (RSV)+CSRD and 36% had rhinovirus (RHV)+CSRD. All-cause CSRD was associated with increased wheeze at 3 (OR 2.33 [95% confidence intervals (CI) 1.23-4.40]) and 5 (OR: 2.12 [95% CI 1.12-4.01]) years. RHV+CSRD was more strongly associated with wheeze at 3 years in STH-infected (STH-infected [OR 13.41, 95% CI 1.56-115.64] vs. uninfected [OR 1.68, 95% CI 0.73-3.84]) and SPT+ (SPT+ [OR 9.42, 95% CI 1.88-47.15] versus SPT- [OR 1.92, 95% CI 0.84-4.38]) children. No associations were observed between CSRD and rhinoconjunctivitis.

DISCUSSION

CSRD was significantly associated with childhood wheeze with stronger associations observed for RHV+CSRD in SPT+ and STH-infected children.

Prevalence and associated risk factors of intestinal parasites among schoolchildren in Ecuador, with emphasis on the molecular diversity of Giardia duodenalis, Blastocystis sp. and Enterocytozoon bieneusi

BACKGROUND

Intestinal helminths, including Soil-Transmitted Helminth (STH), and Gastrointestinal Protist (GP) infections are major contributors to the global burden of disease, particularly in low-income countries such Ecuador. Their epidemiology in these settings is largely unknown.

METHODOLOGY

This prospective cross-sectional study investigates the carriage of intestinal helminths, including STH, and GP in asymptomatic schoolchildren (3-11 years) in the Chimborazo and Guayas provinces, Ecuador. Single stool samples (n = 372) and epidemiological questionnaires on demographics and potential risk factors were collected from participating schoolchildren. Conventional microscopy examination was used as screening method, and molecular (PCR and Sanger sequencing) assays were used to further investigate the epidemiology of some GP. A multivariate logistic regression analysis was used to evaluate the strength of the association of suspected risk factors with the presence of helminths and GP.

PRINCIPAL FINDINGS

At least one intestinal parasite species was observed by microscopy in 63.2% (235/372) of the participating schoolchildren. Enterobius vermicularis (16.7%, 62/372; 95% CI: 13.0-20.9) and Blastocystis sp. (39.2%, 146/372; 95% CI: 34.2-44.2) were the most prevalent among helminths and GP, respectively. Assemblages A (50.0%), B (37.5%) and A+B (12.5%) were detected within Giardia duodenalis and ST3 (28.6%), ST1 and ST2 (26.2% each), and ST4 (14.3%) within Blastocystis sp. Three genotypes, two known (A: 66.7%; KB-1: 16.7%) and a novel (HhEcEb1, 16.7%) were identified within Enterocytozoon bieneusi. Municipality of origin, household overcrowding, and poor sanitation and personal hygiene habits were risk factors for childhood intestinal parasites colonization.

CONCLUSIONS/SIGNIFICANCE

Despite massive government drug administration programs, STH and GP infection remain a public health concern in paediatric populations living in poor-resource settings. Molecular analytical methods are required to better understand the epidemiology of these intestinal parasites. This study provides novel information on the occurrence of Blastocystis sp. and E. bieneusi genetic variants circulating in Ecuadorian human populations.

Impact of helminth-microbiome interactions on childhood health and development-A clinical perspective

Humans have co-existed with parasites for virtually the entirety of our existence as a species. Today, nearly one third of the human population is infected with at least one helminthic species, most of which reside in the intestinal tract, where they have co-evolved alongside the human gut microbiota (GM). Appreciation for the interconnected relationship between helminths and GM has increased in recent years. Here, we review the evidence of how helminths and GM can influence various aspects of childhood development and the onset of paediatric diseases. We discuss the emerging evidence of how many of the changes that parasitic worms inflict on their host is enacted through gut microbes. In this light, we argue that helminth-induced microbiota modifications are of great importance in both facing the global challenge of overcoming parasitic infections, and in replicating helminthic protective effects against inflammatory diseases. We propose that deepening our knowledge of helminth-microbiota interactions will uncover novel, safer and more effective therapeutic strategies in combatting an array of childhood disorders.

Micronutrients deficiencies and its correlation with the soil-transmitted helminthic infections among children and non-pregnant women in Nepal: findings from Nepal national micronutrient status survey

Despite having a high risk of soil-transmitted helminths (STHs) infection, no national level study has been conducted to assess incidence and correlates of STHs in Nepal. Thus, we hypothesized that micronutrients and social status are linked with incidence of STHs infection among 6-59 months children and 15-49 years non-pregnant women in Nepal and Kato-Katz technique was adopted to measure the type and intensity of STHs infections using fresh stool specimens and venous blood was used to examine micronutrients biomarkers. Anthropometric measurements such as height and weight, sociodemographic and health status were determined using structured questionnaire. Logistic regression was used to assess unadjusted and adjusted odds ratio (AOR) and the 95% CIs of ORs. The bivariate association of STHs was assessed with the covariates variables. Overall, 12% children and 19% non-pregnant women had STHs infection; A. lumbricoides was the predominant helminth in both study participants. In multivariate model; age, ethnicity, anaemia and zinc deficiency were associated with STHs infections in children. Similarly, higher odds of STHs occurrence was observed among non-pregnant women with vitamin A deficiency. Findings from this study suggest that high-risk population, with a focus on those of lower socioeconomic status should be on priority of deworming program, nutrition intervention, and mass administration of preventive chemotherapy and sanitation champions supplement to reduce the STHs infections in Nepal.

The survey of soil-transmitted helminth species abundance in Slovakia with an emphasis on parameters important for their distribution

Soil-transmitted helminths (STH) can be easily dispensable in socially disadvantaged groups. The Roma people represent the group most at risk in Slovakia. This study aimed to investigate the occurrence of STH infections in minorities living with animals under low hygienic conditions and on contaminated soil. Subsequently, we identified the risk assessment factors of the STH transmissions based on parasitological results. In our study, STHs were predominantly found among the Roma communities living in unsanitary conditions. The prevalence of Ascaris lumbricoides among the majority was 0.79%, and Trichuris trichiura was 0.05 %. On the contrary, a community-based cross-sectional survey across eastern Slovakia also found a prevalence of 22.28 and 3.47% for A. lumbricoides and T. trichiura among the Roma population. Inhabitants that belong to the Roma minority had a 37.12 infection OR times higher than non-Roma inhabitants. The Roma people living in the countryside have a 2.23-fold higher chance of getting infected with STH than Roma living in the city. Therefore, soil and domestic animals were also examined for the presence of the STH eggs to show the environmental burden. In general, the presence of STH eggs was confirmed in 26.26% of the soil examined samples. The detailed description is as follows: eggs of Toxocara spp., Trichuris spp., eggs from the family Ancylostomatidae, and Toxascaris leonina. Ascaris eggs were detected only in the soil from localities with low hygienic standards. The probability of contracting the STH eggs in segregated settlements was 15.94 times higher compared to urban or rural areas. In addition to humans, dogs can also be a source of STH eggs in the soil. The STH eggs were confirmed in 43.55% of dog droppings. The most interesting finding was that the eggs of the genus Ascaris were up to 7.93% of dog droppings from localities with a low hygienic standard were positive. This study revealed that climatic factors and the WASH conditions influenced the distribution of STHs to variable degrees. In addition, ethnicity and sanitation were crucial factors in the distribution of STH infection in eastern Slovakia.