Development of cognitive abilities of children infected with helminths through health education

Infection of Plasmodium falciparum and helminths among school children in communities in Southern and Northern Ghana

Background

Infections of Plasmodium species, Schistosoma species and soil-transmitted helminths (STH) inflict a significant burden on children mostly in deprived communities in Ghana. Despite the deployment of malaria vector control and the annual Mass Drug Administration by National Control Programmes, these infections still pose major public health concerns in Ghana. Some remote communities which are hard-to-reach are not covered by MDA campaigns which is a major challenge to meeting elimination targets. Adequate data is necessary for formulating policies and strengthening interventions to mitigate transmission. This study assessed the infection burden of Plasmodium, Schistosoma species and STH infections among school children in communities in Southern and Northern Ghana.

Method

School children living in communities in Southern (Ada Foah, Pediatorkope, Tuanikope) and Northern (Kpalsogu) Ghana were enrolled in a cross-sectional study. A total of 493 (241 males and 252 females) school children aged (2–15 years) were enrolled in the study. Stool samples were collected to screen for Schistosoma mansoni and STH infections using the formol-ether concentration technique and urine samples were also collected to screen for S. haematobium using the routine urine examination method. Plasmodium parasitaemia was determined from thick and thin finger-prick blood samples.

Results

Overall, the prevalence of P. falciparum, S. mansoni, S. haematobium, Trichuris trichiura and hookworm infections were 17.2% (95%CI 12.8–19.7), 22.6% (95%CI 25.2–32.7), 1.6% (95%CI 0.89–5.2), 1.2% (95%CI 0.78–4.8) and 1.2% (95%CI 0.78–4.8) respectively. Plasmodium falciparum infection was generally widespread in all the study sites with Ada Foah recording the highest prevalence (35.3%) and Kpalsogu recording the lowest (5.8%). Schistosoma mansoni was present in only two Southern communities with Tuanikope recording the highest prevalence of 70.3% as against 51.5% recorded in Pediatorkope. A total of 4.5% (95% CI 2.82–10.8) of the children were co-infected with P. falciparum, Schistosoma species and STHs. This occurred only in the Southern communities; of which combination of P. falciparum and S. mansoni were predominant (1.4%).

Conclusion

A relatively low burden of parasites co-infection among children only in the Southern communities was detected. However, there were a high prevalence of single infections of P. falciparum and S. mansoni in those communities. Control measures for the helminths needs to be restarted in the island communities with a high burden of S. mansoni infections and that of Plasmodium needs to be scaled up in Ada Foah where P. falciparum infections were high.

Prevalence, Risk Factors, and Coinfection of Urogenital Schistosomiasis and Soil-Transmitted Helminthiasis among Primary School Children in Biase, Southern Nigeria

Schistosomiasis and soil-transmitted helminthiasis (STH) are neglected tropical diseases (NTDs) that cause chronic infections and ill health. The study was carried out to determine the current infection status and risk factors associated with Schistosoma haematobium and soil-transmitted helminth (STH) coinfection among school children in Biase Local Government Area (LGA), Cross River State, Nigeria. A cross-sectional study was carried out. Urine and fecal samples were randomly collected from 630 school children in six villages of Biase LGA. Urine sedimentation and Kato-Katz techniques were used to diagnose urogenital schistosomiasis and STHs, respectively. A structured questionnaire was used to collect demographic information and risk factors. The prevalence of S. haematobium in Biase LGA was 6.03%, with males (27 pupils, 9.00%) significantly more (χ² = 8.903, p value = 0.003, C.I. = −82.650–120.650) infected than the females (11 pupils, 3.33%), while the prevalence of STH infection was 11.27% with no significant difference (χ² = 0.002, p value = 0.962, C.I. = −16.441–54.559) in prevalence between males (34 pupils, 11.33%) and females (37 pupils, 11.21%). Prevalence of S. haematobium and STHs ranged from 1.82 to 19.13% and from 4.55 to 19.05% within the communities, respectively, with Abini (22 pupils, 19.13%) and Adim (20 pupils, 19.05%) communities having the highest prevalence for S. haematobium and STHs, respectively. The most infected age group was 11–13 years (21 pupils, 9.68%) for S. haematobium and 14–16 years (5 pupils, 21.74%) for STHs. Ascaris lumbricoides, hookworms, and Trichuris trichiura had prevalence of 5.56%, 3.02%, and 2.70%, respectively. An overall prevalence of 7.14% and 8.41% was observed for haematuria and proteinuria, respectively. Prevalence of coinfection among the parasites was 4.76%. Male pupils (OR = 2.868, C.I.: 1.397–5.889), pupils of the age group of 11–13 years (OR = 2.496, C.I.: 1.287–4.838), school children that swim (OR = 1.527, C.I.: 0.784–2.974), those that cross streams to farm (OR = 25.286, C.I.: 4.091–156.283), those that visit stream or river severally (OR = 3.077, C.I.: 1.204–7.863), and those whose home is 1 km (OR = 3.116, C.I.: 1.292–7.518) from the stream are at higher odds of infection with S. haematobium. For STHs, male pupils (OR = 1.012, C.I.: 0.617–1.659), pupils of the age group of 11–13 years (OR = 2.609, C.I.: 1.582–4.302), pupils that walk barefoot (OR = 18.746, C.I.: 6.786–51.783), those that do not wash fruits and vegetables before eating (OR = 2.334, C.I.: 1.400–3.892), those that do not wash hands after using the toilet (OR = 1.200, C.I.: 0.730–1.973), those that eat soils (OR = 2.741, C.I.: 1.533–4.902), those that drink water from streams or rivers (OR = 189.509, C.I.: 24.807–1447.740), and those that use pit latrine (OR = 2.920, C.I.: 1.746–4.885) and/or open defecation (OR = 2.552, C.I.: 1.454–4.479) are at high odds of being infected with STHs. Urogenital schistosomiasis and soil-transmitted helminthiasis are still endemic diseases in Biase LGA. Although the degree of infection is quite low or moderate, there is a need to intensify and sustain control measures such as provision of sustainable clean water supply, health education intervention, and chemotherapy.

Impact of Helminth Infections during Pregnancy on Vaccine Immunogenicity in Gabonese Infants

Helminth infections are common in sub-Saharan Africa. Besides direct clinical effects, a bias towards a T helper type 2 (Th2) cell immune response is observed. The consequences of parasite infection during pregnancy for the mother and particularly for the fetus and the newborn can be severe and may include impaired immune response during acute infection and vaccination. Here, we present data of immune responses to vaccines given within the expanded program on immunization (EPI) of infants born to helminth infected or non-infected mothers. The study was conducted in Lambaréné and surroundings, Gabon. Maternal helminth infection was diagnosed microscopically using the Kato-Katz method for soil-transmitted helminths (STH), urine filtration for Schistosoma haematobium infections and the saponin-based method for filarial infections. Plasma antibody levels to different vaccine antigens were measured in mothers and their offspring by enzyme-linked immunosorbent assay (ELISA) at different timepoints. We found 42.3% of the mothers to be infected with at least one helminth species. Significantly lower anti-tetanus toxoid immunoglobulin (Ig) G was detected in the cord blood of infants born to helminth infected mothers. Following vaccination, immune responses of the infants to EPI vaccines were similar between the two groups at nine and 12 months. Even though infection with helminths is still common in pregnant women in Gabon, in our setting, there was no evidence seen for a substantial effect on infants’ immune responses to vaccines given as part of the EPI.

Epidemiological dynamics and associated risk factors of S. haematobium in humans and its snail vectors in Nigeria: a meta-analysis (1983-2018)

Schistosoma haematobium, a major pathogen of urogenital schistosomiasis, has been reported to be affecting an estimated 30 million people in Nigeria. Current national estimates of S. haematobium and its cercariae, in humans and snail vectors respectively, are lacking in Nigeria, hence systematic meta-analyses were conducted to understand the disease dynamics in the endemic country over a period of 35 years based on publications from five databases (AJOL, Ovid MEDLINE, Google Scholar, PubMed and Web of Science). The preferred reporting items for systematic reviews and meta-analyses (PRIMSA) checklist were used as the standard guide for the analyses. The prevalence of S. haematobium in human hosts in Nigeria using quality effects model was 32.1% (27.3-37.2), while schistosome cercariae were observed at 3.5% (0.0-11.9), 18.2% (4.7-36.8) and 18.7% (0.0-46.1) and for B. forskalii, Bulinus globosus and B. truncatus, respectively. The high report of schistosome cercariae indicates the continuous transmission of S. haematobium in humans especially with individuals who have frequent contact with freshwater. Heterogeneity of subgroup analyses (regions, zones, sex, age groups, diagnostic techniques) and risk factors (pathological signs, occupation, water sources, anthropogenic activities, treatment) were determined. The result showed prevalence of an endemic moderate class infection that has been linked to several risk factors. Therefore, there is need for increased awareness on the prevalence, transmission routes and treatment strategies to mitigate the disease in this endemic area.

Bayesian Methods for Exposure Misclassification Adjustment in a Mediation Analysis: Hemoglobin and Malnutrition in the Association Between Ascaris and IQ

BACKGROUND

Soil-transmitted helminth infections have been found to be associated with child development. The objective was to investigate hemoglobin levels and malnutrition as mediators of the association between Ascaris infection and intelligence quotient (IQ) scores in children.

METHODS

We conducted a longitudinal cohort study in Iquitos, Peru, between September 2011 and July 2016. A total of 1760 children were recruited at 1 year of age and followed up annually to 5 years. We measured Ascaris infection and malnutrition at each study visit, and hemoglobin levels were measured as of age 3. The exposure was defined as the number of detected Ascaris infections between age 1 and 5. We measured IQ scores at age 5 and used Bayesian models to correct exposure misclassification.

RESULTS

We included a sample of 781 children in the analysis. In results adjusted for Ascaris misclassification, mean hemoglobin levels mediated the association between Ascaris infection and IQ scores. The natural direct effects (not mediated by hemoglobin) (95% CrI) and natural indirect effects (mediated by hemoglobin) (95% CrI) were compared with no or one infection: -0.9 (-4.6, 2.8) and -4.3 (-6.9, -1.6) for the effect of two infections; -1.4 (-3.8, 1.0) and -1.2 (-2.0, -0.4) for three infections; and -0.4 (-3.2, 2.4) and -2.7 (-4.3, -1.0) for four or five infections.

CONCLUSION

Our results are consistent with the hypothesis that hemoglobin levels mediate the association between Ascaris infection and IQ scores. Additional research investigating the effect of including iron supplements in STH control programs is warranted.

INTESTINAL PARASITES, NUTRITIONAL STATUS AND COGNITIVE FUNCTION AMONG PRIMARY SCHOOL PUPILS IN ILE-IFE, OSUN STATE, NIGERIA

Background:

Intestinal parasites are a cause of morbidity and mortality throughout the world particularly in developing countries and they are common health problems of children. This study determined the prevalence of intestinal parasites among primary school children, assessed risk factors predisposing to infection and the nutritional status with cognitive function of the pupils.

Materials and Methods:

It was a cross sectional study and 384 pupils from six public primary schools in Ile-Ife were enrolled. Anthropometric measurements were obtained using standard procedures. The intelligence quotients of the pupils were assessed using the Draw-a-person- test. Stool samples were collected and examined. Data was processed using SPSS Inc USA version 17. Statistical analysis was done using frequency, percentages, tables and Pearson’s chi-square was used to determine the association between intestinal parasites, nutritional status and cognitive function.

Results:

The prevalence of intestinal parasites in the study population was 24% with double infection occurring in 3.2%. Ascaris lumbricoides most prevalent 22.1%, Hookworm 3.4%, Hymenolepis nana 0.3%. Intestinal parasites were present in those that use bush and refuse dump for defeacation. The nutritional status of the pupils showed 95.8% normal weight, 3.6% underweight and 0.5% overweight. In terms of cognition, 65.4% mentally deficient, 14.3% mentally dull and 20.3% average.

Conclusion:

Intestinal parasites were prevalent among primary school children and use of bush or refuse dump for defeacation was a risk factor. There was no association between intestinal parasites, nutritional status and cognition.

The effect of cumulative soil-transmitted helminth infections over time on child development: a 4-year longitudinal cohort study in preschool children using Bayesian methods to adjust for exposure misclassification

Background

Limited research has documented an association between soil-transmitted helminth (STH) infections and child development. This has recently been identified as an important knowledge gap.

Methods

A longitudinal cohort study was conducted in Iquitos, Peru, between September 2011 and July 2016. A cohort of 880 children, recruited at 1 year of age, was followed up to 5 years. STH infection was measured annually and child development was measured with the Wechsler Preschool and Primary Scale of Intelligence III (WPPSI-III) at 5 years. Linear-regression models were used to investigate the effect of the number of detected STH infections between 1 and 5 years of age on WPPSI-III scores at 5 years of age. Bayesian latent class analysis was used to adjust for exposure misclassification.

Results

A total of 781 (88.8%) children were included in the analysis. In multivariable analysis, adjusted for STH misclassification, increasing numbers of Ascaris, Trichuris, hookworm and any STH infections were associated with lower WPPSI-III scores. Among the largest observed effects were those for the effect of Ascaris infection on verbal IQ scores [difference in IQ (95% CrI) for two, three, and four or five detected infections compared with zero or one infection: -8.27 (-13.85, -3.10), -6.69 (-12.05, -2.05) and -5.06 (-10.75, 0.05), respectively]. Misclassification of STH infection generally led to a bias towards the null.

Conclusions

These results document an association between STH infection and child development. The results highlight the importance of adjusting for STH misclassification; however, future research is needed to accurately determine the sensitivity of STH diagnostic techniques. STH control in preschool children may contribute to lowering the disease burden associated with poor child development.

A longitudinal cohort study of soil-transmitted helminth infections during the second year of life and associations with reduced long-term cognitive and verbal abilities

BACKGROUND

Soil-transmitted helminth (STH) infection leads to malnutrition and anemia, and has been linked to impaired child development. Previous research on this topic is limited and mostly conducted in school-age children. The goal of this study was to determine the effect of the number of detected STH infections between one and two years of age on subsequent cognitive and verbal abilities, in a cohort of preschool children.

METHODOLOGY/PRINCIPAL FINDINGS

A longitudinal cohort study was conducted in 880 children in Iquitos, Peru between September 2011 and July 2016. Children were recruited at one year of age and followed up at 18 months and then annually between two and five years of age. STH infection was measured with the Kato-Katz technique or the direct smear technique. Child development was measured with the Bayley Scales of Infant and Toddler Development-III at the one to three-year visits and with the Wechsler Preschool and Primary Scale of Intelligence-III at the four and five-year visits. Hierarchical multivariable linear regression models were used to account for the repeated outcome measures for each child and Bayesian latent class analysis was used to adjust for STH misclassification. Children found infected with any STH infection between one and two years of age had lower cognitive scores between two and five years of age (between group score differences (95% credible intervals) for infected once, and infected two or three times, compared to never infected: -4.31 (-10.64, -0.14) and -3.70 (-10.11, -0.11), respectively). Similar results were found for Ascaris infection and for verbal scores.

CONCLUSIONS/SIGNIFICANCE

An association was found between having been infected with Ascaris or any STH between one and two years of age and lower cognitive and verbal abilities later in childhood. These results suggest that targeting children for STH control as of one year of age is particularly important.

Soil-transmitted helminth infection, loss of education and cognitive impairment in school-aged children: A systematic review and meta-analysis

BACKGROUND

Evidence of an adverse influence of soil transmitted helminth (STH) infections on cognitive function and educational loss is equivocal. Prior meta-analyses have focused on randomized controlled trials only and have not sufficiently explored the potential for disparate influence of STH infection by cognitive domain. We re-examine the hypothesis that STH infection is associated with cognitive deficit and educational loss using data from all primary epidemiologic studies published between 1992 and 2016.

METHODS

Medline, Biosis and Web of Science were searched for original studies published in the English language. Cognitive function was defined in four domains (learning, memory, reaction time and innate intelligence) and educational loss in two domains (attendance and scholastic achievement). Pooled effect across studies were calculated as standardized mean differences (SMD) to compare cognitive and educational measures for STH infected/non-dewormed children versus STH uninfected /dewormed children using Review Manager 5.3. Sub-group analyses were implemented by study design, risk of bias (ROB) and co-prevalence of Schistosoma species infection. Influential studies were excluded in sensitivity analysis to examine stability of pooled estimates.

FINDINGS

We included 36 studies of 12,920 children. STH infected/non-dewormed children had small to moderate deficits in three domains-learning, memory and intelligence (SMD: -0.44 to -0.27, P<0.01-0.03) compared to STH-uninfected/dewormed children. There were no differences by infection/treatment status for reaction time, school attendance and scholastic achievement (SMD: -0.26 to -0.16, P = 0.06-0.19). Heterogeneity of the pooled effects in all six domains was high (P<0.01; I2 = 66-99%). Application of outlier treatment reduced heterogeneity in learning domain (P = 0.12; I2 = 33%) and strengthened STH-related associations in all domains but intelligence (SMD: -0.20, P = 0.09). Results varied by study design and ROB. Among experimental intervention studies, there was no association between STH treatment and educational loss/performance in tests of memory, reaction time and innate intelligence (SMD: -0.27 to 0.17, P = 0.18-0.69). Infection-related deficits in learning persisted within design/ROB levels (SMD: -0.37 to -52, P<0.01) except for pre-vs post intervention design (n = 3 studies, SMD = -0.43, P = 0.47). Deficits in memory, reaction time and innate intelligence persisted within observational studies (SMD: -0.23 to -0.38, all P<0.01) and high ROB strata (SMD:-0.37 to -0.83, P = 0.07 to <0.01). Further, in Schistosoma infection co-prevalent settings, associations were generally stronger and statistically robust for STH-related deficits in learning, memory and reaction time tests(SMD:-0.36 to -0.55, P = 0.003-0.02). STH-related deficits in school attendance and scholastic achievement was noted in low (SMD:-0.57, P = 0.05) and high ROB strata respectively.

INTERPRETATION

We provide evidence of superior performance in five of six educational and cognitive domains assessed for STH uninfected/dewormed versus STH infected/not-dewormed school-aged children from helminth endemic regions. Cautious interpretation is warranted due to high ROB in some of the primary literature and high between study variability in most domains. Notwithstanding, this synthesis provides empirical support for a cognitive and educational benefit of deworming. The benefit of deworming will be enhanced by strategically employing, integrated interventions. Thus, multi-pronged inter-sectoral strategies that holistically address the environmental and structural roots of child cognitive impairment and educational loss in the developing world may be needed to fully realize the benefit of mass deworming programs.

Measuring the Effect of Soil-Transmitted Helminth Infections on Cognitive Function in Children: Systematic Review and Critical Appraisal of Evidence

Recently the role of soil-transmitted helminth (STH) infections in children's cognitive developmental impairment has been under scrutiny. We conducted a systematic review of the evidence for associations between STH infections and cognitive function of children using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol. We aimed to identify the domains of cognitive function in three age strata (<24months, 24-59months and ≥60months) and critically appraise the general design protocol of the studies, with a focus on the cognitive function measurement tools used. A total of 42 papers fulfilled the inclusion criteria, including 10 studies from a recent Cochrane review. Our findings demonstrate variation in tested domains, lack of consistency in the use of measurement tools and analysis of results. Cognitive function measures in children aged under 59months have been mainly limited to domains of gross motor, fine motor and language skills, whereas in children aged 60months and above most studies tested domains such as memory and processing speed. Even within the same age group the results on the association between STH infections and measures of cognitive development were often conflicting. The current study highlights the need for methodological consensus in the use of measurement tools and data analysis protocols if the effect of STH infections on cognitive function domains in children is to be correctly established. This will be an imperative next step to generate conclusive evidence of the role of STH infections in cognitive development in children.

A single-dose antihelminthic treatment does not influence immunogenicity of a meningococcal and a cholera vaccine in Gabonese school children

BACKGROUND

We recently described the effect of a single-dose antihelminthic treatment on vaccine immunogenicity to a seasonal influenza vaccine. Here we report the effect of antihelminthics on the immunogenicity of a meningococcal vaccine and a cholera vaccine in primary school children living in Lambaréné, Gabon. Since infection with helminths remains a major public health problem and the influence on cognitive and physical development as well as the immunomodulatory effects are well established, we investigated if a single-dose antihelminthic treatment prior to immunization positively influences antibody titers and vaccine-specific memory B-cells.

METHODS

In this placebo-controlled, double-blind trial the effect of a single-dose antihelminthic treatment prior to immunization with a meningococcal as well as with a cholera vaccine was investigated. Anti-meningococcal antibodies were assessed by serum bactericidal assay, cholera vaccine-specific antibody titers by Enzyme-linked Immunosorbent Assay (ELISA) at baseline (Day 0; vaccination), four weeks (Day 28) and 12weeks (Day 84) following vaccination. Meningococcal and cholera vaccine-specific memory B-cells were measured at Day 0 and 84 by vaccine-specific Enzyme-linked Immunospot (ELISpot) assay. The helminth burden of the participants was assessed four weeks before vaccination (Day -28) and at Day 84 by the Merthiolate-Iodine-Formaldehyde technique.

RESULTS

Out of 280 screened school children, 96 received a meningococcal vaccine and 89 a cholera vaccine following allocation to either the single-dose antihelminthic treatment group or the placebo group. Bactericidal antibody titers increased following immunization with the meningococcal vaccine at Day 28 and Day 84 in 68 participants for serogroup A, and in 80 participants for serogroup C. The cholera vaccine titers increased in all participants with a peak at Day 28. The number of memory B-cells increased following vaccination compared to baseline. There was no statistically significant difference in antibody and B-cell response between children receiving albendazole compared to those receiving placebo.

CONCLUSION

A single-dose treatment with albendazole prior to immunization had no effect on meningococcal or cholera vaccine immunogenicity in our study population.

Effect of Antihelminthic Treatment on Vaccine Immunogenicity to a Seasonal Influenza Vaccine in Primary School Children in Gabon: A Randomized Placebo-Controlled Trial

Background

Helminth infections are a major public health problem, especially in the tropics. Infected individuals have an altered immune response with evidence that antibody response to vaccination is impaired. Hence, treatment of helminth infections before vaccination may be a simple intervention to improve vaccine immunogenicity. In the present study we investigated whether a single-dose antihelminthic treatment influences antibody responses to a seasonal influenza vaccine in primary school children living in Gabon, Central Africa.

Methods

In this placebo-controlled double-blind trial conducted in Gabon the effect of a single-dose antihelminthic treatment with 400 mg albendazole versus a placebo one month prior to immunization with a seasonal influenza vaccine was investigated. Antiviral antibody titers against all three vaccine strains were assessed by haemagglutination inhibition (HI) test at baseline (Day 0; vaccination) and four weeks (Day 28) as well as 12 weeks (Day 84) following vaccination. Vaccine-specific memory B-cell response was measured at Day 0 and Day 84 by vaccine-specific Enzyme-linked Immunospot (ELISpot) assay. The trial is registered with the Pan African Clinical Trials Registry (PACTR) (PACTR201303000434188).

Results

98 school children aged 6–10 years were randomly allocated to receive either antihelminthic treatment or placebo and were vaccinated one month after the treatment. The prevalence of helminths at baseline was 21%. Vaccine-specific HI titers against at least one of the three vaccine strains increased at Day 28 and Day 84 in all participants. HI titers against both influenza A strains as well as memory B-cell response were modestly higher in the antihelminthic treated group compared to the placebo group but the difference was not statistically significant. Total but not specific IgA was elevated in the antihelminthic treated group compared to the control group at Day 28.

Conclusion

In our setting antihelminthic treatment had no significant effect on influenza vaccine immunogenicity. A trend towards better antiviral and vaccine immunogenicity in the antihelminthic treated group encourages studies to be conducted with alternative treatment schedules or in populations with a higher helminth burden.

Helminth infections are a major health problem in the tropics and most affected are children. The parasites are able to influence the immune system from a T-helper 1 type response to a T-helper 2 type response. There is evidence that in infected individuals the immune response following vaccination is impaired. Thus pre-treatment with a single-dose of an antihelminthic treatment before vaccination could be a simple and cost-effective intervention to improve vaccine efficacy. In the present study we investigated whether a single-dose antihelminthic treatment with albendazole influences the vaccine outcome to a seasonal influenza vaccine in primary school children living in Gabon, Central Africa. We observed a trend towards a higher anti-viral antibody titer after vaccination in the pre-treated group compared to the placebo control group, albeit not statistical significant. Furthermore we detected a higher concentration of total IgA but not of vaccine-specific IgA. In conclusion, our findings show subtle effects of antihelminthic pre-treatment but are not conclusive enough to recommend a single-dose of albendazole before vaccination to improve vaccine immunogenicity but encourage to conduct further studies in endemic areas with other treatment regiments.

Prevalence and risk factors related to intestinal parasites among children in Department of Rio San Juan, Nicaragua

BACKGROUND

The present study was carried out to assess the prevalence of intestinal parasite infections among children in Department of Rio San Juan (Nicaragua), to explore the extent of polyparasitism, and to identify the risk factors that might favour transmission of these parasites.

METHODS

A coprological study of single stool specimen, collected at random from 382 children (167 boys and 215 girls) aged 2-15 years from two municipalities, and a questionnaire, concerning demographic and epidemiological data on sanitary and behavioural habits, was filled in to identify risk factors.

RESULTS

About 93% of the children presented infection. Blastocystis hominis, the most frequently protozoa, and Trichuris trichiura, Ascaris lumbricoides and hookworm, the most prevalent helminths. Polyparasitism (85.4%[326/382]), with the highest percentages detected in females (p=0.001), in the 6-11 year age group (p<0.001) and having a rural background (p<0.001). A firm relationship between any parasite and age (OR=1.2, p=0.036) and rural background (OR=0.3, p=0.027) was detected. Living in rural areas and drinking river water were also positively associated with each of the STH species detected, and walking barefoot was also associated with hookworm infection.

CONCLUSIONS

Government efforts should be focused on controlling the risk factors associated with these enteroparasites, with health education programmes in rural areas of Nicaragua.