Risk factors for cryptosporidiosis among children in a semi urban slum in southern India: a nested case-control study

Prevalence and molecular characterization of Cryptosporidium spp. in dairy and beef cattle in Shanxi, China

Cryptosporidium spp. are key gastrointestinal protists in humans and animals worldwide. Infected cattle are considered the main source of cryptosporidiosis outbreaks in humans. However, little is known about the genetic makeup of Cryptosporidium populations in Shanxi province, China. We analyzed 858 fecal samples collected from farms in Shanxi. The presence of Cryptosporidium spp. was determined via polymerase chain reaction and subsequent sequence analysis of the small subunit rRNA gene as well as restriction fragment length polymorphism analysis. Cryptosporidium parvum was subtyped following sequence analysis of the 60 kDa glycoprotein gene (gp60). The overall prevalence of Cryptosporidium in cattle was 11.19%, with a prevalence of 13.30% and 8.67% in Lingqiu and Yingxian, respectively. The overall prevalence of Cryptosporidium in dairy and beef cattle was 10.78% and 11.50%, respectively. Cryptosporidium infection was detected across all analyzed age groups. The overall prevalence of Cryptosporidium in diarrhea and nondiarrhea samples was 18.24% and 9.72%, respectively, whereas that in intensively farmed and free-range cattle was 17.40% and 3.41%, respectively. We identified five Cryptosporidium species, with C. andersoni being the dominant species. Further, two cases of mixed infections of Cryptosporidium species were detected. All identified C. parvum isolates belonged to the subtype IIdA17G1.

Improved household flooring is associated with lower odds of enteric and parasitic infections in low- and middle-income countries: A systematic review and meta-analysis

Enteric and parasitic infections such as soil-transmitted helminths cause considerable mortality and morbidity in low- and middle-income settings. Earthen household floors are common in many of these settings and could serve as a reservoir for enteric and parasitic pathogens, which can easily be transmitted to new hosts through direct or indirect contact. We conducted a systematic review and meta-analysis to establish whether and to what extent improved household floors decrease the odds of enteric and parasitic infections among occupants compared with occupants living in households with unimproved floors. Following the PRISMA guidelines, we comprehensively searched four electronic databases for studies in low- and middle-income settings measuring household flooring as an exposure and self-reported diarrhoea or any type of enteric or intestinal-parasitic infection as an outcome. Metadata from eligible studies were extracted and transposed on to a study database before being imported into the R software platform for analysis. Study quality was assessed using an adapted version of the Newcastle-Ottawa Quality Assessment Scale. In total 110 studies were eligible for inclusion in the systematic review, of which 65 were eligible for inclusion in the meta-analysis after applying study quality cut-offs. Random-effects meta-analysis suggested that households with improved floors had 0.75 times (95CI: 0.67-0.83) the odds of infection with any type of enteric or parasitic infection compared with household with unimproved floors. Improved floors gave a pooled protective OR of 0.68 (95CI: 0.58-0.8) for helminthic infections and 0.82 OR (95CI: 0.75-0.9) for bacterial or protozoan infections. Overall study quality was poor and there is an urgent need for high-quality experimental studies investigating this relationship. Nevertheless, this study indicates that household flooring may meaningfully contribute towards a substantial portion of the burden of disease for enteric and parasitic infections in low- and middle-income settings.

Prevalence of Cryptosporidium spp. infection in working horses in Egypt.. [DOI: 10.21203/rs.3.rs-2363022/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Working horses support the livelihoods of smallholder farmers in Egypt but can pose potential zoonotic risk to their handlers such as cryptosporidiosis. Working horses were recruited into the study from 37 villages/areas in two Egyptian governorates. Faecal samples were collected from 607 horses and were examined for Cryptosporidium spp. infection using modified Zielh-Neelsen staining technique. Data about signalment, concurrent disease and level of strongyle infection were collected. The prevalence of Cryptosporidium spp. infection was calculated using a bootstrap method and potential risk factors for the infection were investigated using mixed-effects logistic regression models that included the sampling location as a random-effects variable. The prevalence of Cryptosporidium spp. infection was 28.7% (95% confidence interval = 23.5–33.9). None of the variables investigated including age and sex of the animals were associated with the risk of the infection. The study identified greater prevalence of Cryptosporidium spp. infection in the study area and further studies may be required to genotype these parasites. Personal hygiene such as hand sanitation should be practiced when managing these horses.

Benefits and Risks of Smallholder Livestock Production on Child Nutrition in Low- and Middle-Income Countries

Livestock production may improve nutritional outcomes of pregnant women and children by increasing household income, availability of nutrient-dense foods, and women's empowerment. Nevertheless, the relationship is complex, and the nutritional status of children may be impaired by presence of or proximity to livestock and their pathogens. In this paper, we review the benefits and risks of livestock production on child nutrition. Evidence supports the nutritional benefits of livestock farming through income, production, and women's empowerment. Increasing animal source food consumption requires a combination of efforts, including improved animal management so that herd size is adequate to meet household income needs and consumption and addressing sociocultural and gendered norms. Evidence supports the inclusion of behavior change communication strategies into livestock production interventions to facilitate the sustainability of nutritional benefits over time, particularly interventions that engage women and foster dimensions of women's empowerment. In evaluating the risks of livestock production, evidence indicates that a broad range of enteric pathogens may chronically infect the intestines of children and, in combination with dietary deficits, may cause environmental enteric dysfunction (EED), a chronic inflammation of the gut. Some of the most important pathogens associated with EED are zoonotic in nature with livestock as their main reservoir. Very few studies have aimed to understand which livestock species contribute most to colonization with these pathogens, or how to reduce transmission. Control at the point of exposure has been investigated in a few studies, but much less effort has been spent on improving animal husbandry practices, which may have additional benefits. There is an urgent need for dedicated and long-term research to understand which livestock species contribute most to exposure of young children to zoonotic enteric pathogens, to test the potential of a wide range of intervention methods, to assess their effectiveness in randomized trials, and to assure their broad adaptation and sustainability. This review highlights the benefits and risks of livestock production on child nutrition. In addition to identifying research gaps, findings support inclusion of poor gut health as an immediate determinant of child undernutrition, expanding the established UNICEF framework which includes only inadequate diet and disease.

Asymptomatic Intestinal Parasitic Infestations among Children Under Five Years in Selected Communities in the Ho Municipality, Ghana

Background

The study investigated intestinal parasitic infestations (IPIs) and possible risk factors associated with asymptomatic children under five (5) years in five (5) selected communities in the Ho Municipality.

Methods

The study design was cross- sectional, with a simple random sampling technique involving 150 asymptomatic children under 5 years from 5 selected communities (Klave, Hoe, Freetown, Dave and Godokpe) in the Ho Municipality. A questionnaire was used to obtain socio-demographics and other relevant parameters. Direct wet preparation, formol-ether concentration and Modified ZN staining techniques were used for the identification of intestinal parasites from participants' stool samples. The Fisher's exact test and binary logistic regression analysis were used to determine the difference in IPIs proportions and assess the risk factors associated with IPIs respectively.

Results

The overall IPIs cases was 14% (21/150). Cryptosporidium spp was most predominant [5.3% (8/150)], followed by Entamoeba spp [3.3% (5/150)], Cyclospora cayetenensis [2.7% (4/150)], Ascaris lumbricoides [1.3% (2/150)], Giardia lamblia [0.7% (1/150)] and Strongyloides stercoralis [0.7% (1/150)]. Children in rural communities (23.4%) recorded significantly higher case rate compared to those in urban communities (9.8%0), (p=0.04). Lower educational attainment of mother [OR=0.55, 95% CI (0.37 – 0.83), p-value = 0.015] and residence in rural communities [OR = 0.53, 95% CI (0.33–0.88)], p-value = 0.025] were significantly associated with IPIs.

Conclusion

Asymptomatic IPIs are quite prevalent among children under 5 years in the Ho Municipality. The study thus recommends active sensitization programs for parents/guardians on preventive measures and school health programs should be instituted in rural communities.

Molecular Epidemiology of Human Cryptosporidiosis in Low- and Middle-Income Countries

Cryptosporidiosis is one of the most important causes of moderate to severe diarrhea and diarrhea-related mortality in children under 2 years of age in low- and middle-income countries. In recent decades, genotyping and subtyping tools have been used in epidemiological studies of human cryptosporidiosis. Results of these studies suggest that higher genetic diversity of Cryptosporidium spp. is present in humans in these countries at both species and subtype levels and that anthroponotic transmission plays a major role in human cryptosporidiosis. Cryptosporidium hominis is the most common Cryptosporidium species in humans in almost all the low- and middle-income countries examined, with five subtype families (namely, Ia, Ib, Id, Ie, and If) being commonly found in most regions. In addition, most Cryptosporidium parvum infections in these areas are caused by the anthroponotic IIc subtype family rather than the zoonotic IIa subtype family. There is geographic segregation in Cryptosporidium hominis subtypes, as revealed by multilocus subtyping. Concurrent and sequential infections with different Cryptosporidium species and subtypes are common, as immunity against reinfection and cross protection against different Cryptosporidium species are partial. Differences in clinical presentations have been observed among Cryptosporidium species and C. hominis subtypes. These observations suggest that WASH (water, sanitation, and hygiene)-based interventions should be implemented to prevent and control human cryptosporidiosis in low- and middle-income countries.

Prevalence and Correlates of Cryptosporidium Infections in Kenyan Children With Diarrhea and Their Primary Caregivers

BACKGROUND

Cryptosporidium is a leading cause of diarrhea in Sub-Saharan Africa and is associated with substantial morbidity and mortality in young children.

METHODS

  We analyzed data from children aged 6-71 months presenting to 2 public hospitals in Western Kenya with acute diarrhea and their primary caregivers, including detection of Cryptosporidium by quantitative polymerase chain reaction (PCR) and immunoassay analysis in stool samples from both children and their caregivers. Associations between potential transmission sources and child/caregiver Cryptosporidium infection were evaluated using prevalence ratios (PRs). Secondary analyses evaluated host and clinical risk factors of child/caregiver Cryptosporidium infection.

RESULTS

Among 243 child-caregiver pairs enrolled, 77 children (32%) and 57 caregivers (23%) had Cryptosporidium identified by either immunoassay or PCR. Twenty-six of the 243 child-caregiver pairs (11%) had concordant detection of Cryptosporidium. Cryptosporidium infection in children was associated with detection of Cryptosporidium in caregivers (adjusted PR [aPR], 1.8; 95% CI, 1.2 to 2.6; P = .002) and unprotected water source (aPR, 2.0; 95% CI, 1.3 to 3.2; P = .003). Risk factors for Cryptosporidium detection in caregivers included child Cryptosporidium infection (aPR, 2.0; 95% CI, 1.3 to 3.0; P = .002) as well as cow (aPR, 3.1; 95% CI, 1.4 to 7.0; P = .02) and other livestock ownership (aPR, 2.6; 95% CI, 1.1 to 6.3; P = .03) vs no livestock ownership. Recent diarrhea in caregivers and children was independently associated with child and caregiver Cryptosporidium infections, respectively.

CONCLUSIONS

Our results are consistent with the hypothesis that Cryptosporidium transmission can occur directly between child-caregiver dyads as well as through other pathways involving water and livestock. Additional research into caregivers as a source of childhood Cryptosporidium infection is warranted.

Co-occurrence of and risk factors for Cryptosporidium and Giardia in brown rats from Buenos Aires, Argentina

A rodent survey was conducted in different landscape units of the city of Buenos Aires (Argentina) to determine the prevalence of Cryptosporidium and Giardia in Rattus norvegicus and to, ultimately, assess the biotic, environmental and meteorological factors that explain the variations of the likelihood of infection for both parasites in an urban environment. The results of this study revealed a ubiquitous presence of Cryptosporidium and Giardia in R. norvegicus within an urban environment with the likelihood of infection depending on environmental and meteorological conditions for both parasites. The overall prevalence was greater for Cryptosporidium (p = 50.4%) than for Giardia (20.3%). The prevalence for both parasites separately was higher in parks compared to shantytowns and scrap metal yards. Generalized Linear Mixed Models revealed that the occurrence of these parasites separately, at an individual level, was positively related with rainfall variables and that the effect of temperature depended on the landscape unit. The similarities in the transmission modes, which are affected by common extrinsic factors, may facilitate the co-occurrence of Cryptosporidium and Giardia in urban rats. Rattus norvegicus is recognized as a good model for epidemiological studies and the results of this work suggest that, from an epidemiological point of view, the probability of contact with infectious oocysts and cysts of these parasites can be modulated through environmental management and healthy behaviour towards risk factors. The information presented here will be useful to improve the understanding of the dynamics of zoonotic diseases within urban environments and to contribute to the decision-making of new and effective prophylactic measures.

Cryptosporidium Infection Increases the Risk for Chronic Diarrhea Among People Living With HIV in Southeast Asia: A Systematic Review and Meta-Analysis

We conducted a systematic review research and meta-analysis to reveal the relationship between the risk of chronic diarrhea and Cryptosporidium infection in people living with HIV in Southeast Asia. We performed online peer-reviewed literature research from January 2005 to December 2017, which included PubMed, Science Direct, ProQuest, EBSCO, Cochrane, and Web of Science databases. Calculation of size effects in the meta-analysis was performed by STATA 13.0 software to estimate relative risks (RRs) with 95% confidence intervals (CIs) for any associations. Seven cross-sectional research articles were recruited in this study based on the inclusion and exclusion criteria. Our analysis revealed a significant relationship between cryptosporidiosis and the risk of chronic diarrhea in people living with HIV, with RR = 1.325; 95% CI = 1.157 to 1.517; and P < .000. Our results suggested that cryptosporidiosis increases the risk of chronic diarrhea, and low CD4⁺ lymphocyte cell counts aggravate the degree of diarrhea. Therefore, clinicians should be more aware in treating HIV-positive people, especially those with low CD4⁺ cell counts, and we suggest that Cryptosporidium laboratory examinations be conducted immediately.

Genome-Wide Association Study of Cryptosporidiosis in Infants Implicates PRKCA

Diarrhea is a major cause of both morbidity and mortality worldwide, especially among young children. Cryptosporidiosis is a leading cause of diarrhea in children, particularly in South Asia and sub-Saharan Africa, where it is responsible for over 200,000 deaths per year. Beyond the initial clinical presentation of diarrhea, it is associated with long-term sequelae such as malnutrition and neurocognitive developmental deficits. Risk factors include poverty and overcrowding, and yet not all children with these risk factors and exposure are infected, nor do all infected children develop symptomatic disease. One potential risk factor to explain these differences is their human genome. To identify genetic variants associated with symptomatic cryptosporidiosis, we conducted a genome-wide association study (GWAS) examining 6.5 million single nucleotide polymorphisms (SNPs) in 873 children from three independent cohorts in Dhaka, Bangladesh, namely, the Dhaka Birth Cohort (DBC), the Performance of Rotavirus and Oral Polio Vaccines in Developing Countries (PROVIDE) study, and the Cryptosporidiosis Birth Cohort (CBC). Associations were estimated separately for each cohort under an additive model, adjusting for length-for-age Z-score at 12 months of age, the first two principal components to account for population substructure, and genotyping batch. The strongest meta-analytic association was with rs58296998 (P = 3.73 × 10-8), an intronic SNP and expression quantitative trait locus (eQTL) of protein kinase C alpha (PRKCA). Each additional risk allele conferred 2.4 times the odds of Cryptosporidium-associated diarrhea in the first year of life. This genetic association suggests a role for protein kinase C alpha in pediatric cryptosporidiosis and warrants further investigation.IMPORTANCE Globally, diarrhea remains one of the major causes of pediatric morbidity and mortality. The initial symptoms of diarrhea can often lead to long-term consequences for the health of young children, such as malnutrition and neurocognitive developmental deficits. Despite many children having similar exposures to infectious causes of diarrhea, not all develop symptomatic disease, indicating a possible role for human genetic variation. Here, we conducted a genetic study of susceptibility to symptomatic disease associated with Cryptosporidium infection (a leading cause of diarrhea) in three independent cohorts of infants from Dhaka, Bangladesh. We identified a genetic variant within protein kinase C alpha (PRKCA) associated with higher risk of cryptosporidiosis in the first year of life. These results indicate a role for human genetics in susceptibility to cryptosporidiosis and warrant further research to elucidate the mechanism.

Intestinal parasitic infection among household contacts of primary cases, a comparative cross-sectional study

Background

Intestinal parasitic infection affects 3.5 billion people in the world and mostly affecting the low socio-economic groups. The objectives of this research works were to estimate the prevalence and determinants of intestinal parasitic infection among family members of known intestinal parasite infected patients.

Methods and materials

A comparative cross-sectional study design was implemented in the urban and rural settings of Mecha district. The data were collected from August 2017toMarch 2019 from intestinal parasite infected patient household members. Epi-info software was used to calculate the sample size, 4531 household members were estimated to be included. Data were collected using interview technique, and collecting stool samples from each household contact of intestinal parasite patients. Descriptive statistics were used to estimate the prevalence of intestinal parasites among known contacts of intestinal parasite patients/family members. Binary logistic regression was used to identify the determinant factors of intestinal parasitic infection among family members.

Results

The prevalence of intestinal parasite among household contacts of intestinal parasite-infected family members was 86.14% [95% CI: 86.14% - 87.15%]. Hookworm infection was the predominant type of infection (18.8%). Intestinal parasitic infection was associated with sex, environmental sanitation, overcrowding, personal hygiene, residence, substandard house, role in the household, source of light for the house, trimmed fingernails, family size, regular handwashing practice. Protozoa infection was associated with habit of ingesting raw vegetable, playing with domestic animals, water source and the presence of household water filtering materials.

Conclusion

High prevalence of intestinal parasitic infection was observed among household contacts of primary cases.

Interventions to improve disposal of child faeces for preventing diarrhoea and soil-transmitted helminth infection

BACKGROUND

Diarrhoea and soil-transmitted helminth (STH) infections represent a large disease burden worldwide, particularly in low-income countries. As the aetiological agents associated with diarrhoea and STHs are transmitted through faeces, the safe containment and management of human excreta has the potential to reduce exposure and disease. Child faeces may be an important source of exposure even among households with improved sanitation.

OBJECTIVES

To assess the effectiveness of interventions to improve the disposal of child faeces for preventing diarrhoea and STH infections.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL, MEDLINE, Embase, and 10 other databases. We also searched relevant conference proceedings, contacted researchers, searched websites for organizations, and checked references from identified studies. The date of last search was 27 September 2018.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and non-randomized controlled studies (NRS) that compared interventions aiming to improve the disposal of faeces of children aged below five years in order to decrease direct or indirect human contact with such faeces with no intervention or a different intervention in children and adults.

DATA COLLECTION AND ANALYSIS

Two review authors selected eligible studies, extracted data, and assessed the risk of bias. We used meta-analyses to estimate pooled measures of effect where appropriate, or described the study results narratively. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

Sixty-three studies covering more than 222,800 participants met the inclusion criteria. Twenty-two studies were cluster RCTs, four were controlled before-and-after studies (CBA), and 37 were NRS (27 case-control studies (one that included seven study sites), three controlled cohort studies, and seven controlled cross-sectional studies). Most study sites (56/69) were in low- or lower middle-income settings. Among studies using experimental study designs, most interventions included child faeces disposal messages along with other health education messages or other water, sanitation, and hygiene (WASH) hardware and software components. Among observational studies, the main risk factors relevant to this review were safe disposal of faeces in the latrine or defecation of children under five years of age in a latrine.Education and hygiene promotion interventions, including child faeces disposal messages (no hardware provision)Four RCTs found that diarrhoea incidence was lower, reducing the risk by an estimated 30% in children under six years old (rate ratio 0.71, 95% confidence interval (CI) 0.59 to 0.86; 2 trials, low-certainty evidence). Diarrhoea prevalence measured in two other RCTs in children under five years of age was lower, but evidence was low-certainty (risk ratio (RR) 0.93, 95% CI 0.84 to 1.04; low-certainty evidence).Two controlled cohort studies that evaluated such an intervention in Bangladesh did not detect a difference on diarrhoea prevalence (RR 0.91, 95% CI 0.64 to 1.28; very low-certainty evidence). Two controlled cross-sectional studies that evaluated the Health Extension Package in Ethiopia were associated with a lower two-week diarrhoea prevalence in 'model' households than in 'non-model households' (odds ratio (OR) 0.26, 95% CI 0.16 to 0.42; very low-certainty evidence).Programmes to end open defecation by all (termed community-led total sanitation (CLTS) interventions plus adaptations)Four RCTs measured diarrhoea prevalence and did not detect an effect in children under five years of age (RR 0.92, 95% CI 0.79 to 1.07; moderate-certainty evidence). The analysis of two trials did not demonstrate an effect of the interventions on STH infection prevalence in children (pooled RR 1.03, 95% CI 0.64 to 1.65; low-certainty evidence).One controlled cross-sectional study compared the prevalence of STH infection in open defecation-free (ODF) villages that had received a CLTS intervention with control villages and reported a higher level of STH infection in the intervention villages (RR 2.51, 95% CI 1.74 to 3.62; very low-certainty evidence).Sanitation hardware and behaviour change interventions, that included child faeces disposal hardware and messagingTwo RCTs had mixed results, with no overall effect on diarrhoea prevalence demonstrated in the pooled analysis (RR 0.79, 95% CI 0.49 to 1.26; very low-certainty evidence).WASH hardware and education/behaviour change interventionsOne RCT did not demonstrate an effect on diarrhoea prevalence (RR 1.15, 95% CI 0.93 to 1.41; very low-certainty evidence).Two CBAs reported that the intervention reduced diarrhoea incidence by about a quarter in children under five years of age, but evidence was very low-certainty (rate ratio 0.77, 95% CI 0.71 to 0.84). Another CBA reported that the intervention reduced the prevalence of STH in an intervention village compared to a control village, again with GRADE assessed at very low-certainty (OR 0.17, 95% CI 0.02 to 0.73).Case-control studiesPooled results from case-control studies that presented data for child faeces disposal indicated that disposal of faeces in the latrine was associated with lower odds of diarrhoea among all ages (OR 0.73, 95% CI: 0.62 to 0.85; 23 comparisons; very low-certainty evidence). Pooled results from case-control studies that presented data for children defecating in the latrine indicated that children using the latrine was associated with lower odds of diarrhoea in all ages (OR 0.54, 95% CI 0.33 to 0.90; 7 studies; very low-certainty evidence).

AUTHORS' CONCLUSIONS

Evidence suggests that the safe disposal of child faeces may be effective in preventing diarrhoea. However, the evidence is limited and of low certainty. The limited research on STH infections provides only low and very-low certainty evidence around effects, which means there is currently no reliable evidence that interventions to improve safe disposal of child faeces are effective in preventing such STH infections.While child faeces may represent a source of exposure to young children, interventions generally only address it as part of a broader sanitation initiative. There is a need for RCTs and other rigorous studies to assess the effectiveness and sustainability of different hardware and software interventions to improve the safe disposal of faeces of children of different age groups.

An exploration of the disease burden due to Cryptosporidium in consumed surface water for sub-Saharan Africa

The protozoan pathogen Cryptosporidium is an important cause of diarrhoeal disease, but in many contexts its burden remains uncertain. The Global Waterborne Pathogen model for Cryptosporidium (GloWPa-Crypto) predicts oocyst concentrations in surface water at 0.5 by 0.5° (longitude by latitude) resolution, allowing us to assess the burden specifically associated with the consumption of contaminated surface water at a large scale. In this study, data produced by the GloWPa-Crypto model were used in a quantitative microbial risk assessment (QMRA) for sub-Saharan Africa, one of the regions most severely affected by diarrhoeal disease. We first estimated the number of people consuming surface water in this region and assessed both direct consumption and consumption from a piped (treated) supply. The disease burden was expressed in disability adjusted life years (DALYs). We estimate an annual number of 4.3 × 10⁷ (95% uncertainty interval [UI] 7.4 × 10⁶-5.4 × 10⁷) cases which represent 1.6 × 10⁶ (95% UI 3.2 × 10⁵-2.3 × 10⁶) DALYs. Relative disease burden (DALYs per 100,000 persons) varies widely, ranging between 1.3 (95% UI 0.1-5.7) for Senegal and 1.0 × 10³ (95% UI 4.2 × 10²-1.4 × 10³) for Eswatini. Countries that carry the highest relative disease burden are primarily located in south and south-east sub-Saharan Africa and are characterised by a relatively high HIV/AIDS prevalence. Direct surface water consumption accounts for the vast majority of cases, but the results also point towards the importance of stable drinking water treatment performance. This is, to our knowledge, the first study to utilise modelled data on pathogen concentrations in a large scale QMRA. It demonstrates the potential value of such data in epidemiological research, particularly regarding disease aetiology.

Anthroponotic transmission of Cryptosporidium parvum predominates in countries with poorer sanitation: a systematic review and meta-analysis

Background

Globally cryptosporidiosis is one of the commonest causes of mortality in children under 24 months old and may be associated with important longterm health effects. Whilst most strains of Cryptosporidium parvum are zoonotic, C. parvum IIc is almost certainly anthroponotic. The global distribution of this potentially important emerging infection is not clear.

Methods

We conducted a systematic review of papers identifying the subtype distribution of C. parvum infections globally. We searched PubMed and Scopus using the following key terms Cryptospor* AND parvum AND (genotyp* OR subtyp* OR gp60). Studies were eligible for inclusion if they had found C. parvum within their human study population and had subtyped some or all of these samples using standard gp60 subtyping. Pooled analyses of the proportion of strains being of the IIc subtype were determined using StatsDirect. Meta-regression analyses were run to determine any association between the relative prevalence of IIc and Gross Domestic Product, proportion of the population with access to improved drinking water and improved sanitation.

Results

From an initial 843 studies, 85 were included in further analysis. Cryptosporidium parvum IIc was found in 43 of these 85 studies. Across all studies the pooled estimate of relative prevalence of IIc was 19.0% (95% CI: 12.9–25.9%), but there was substantial heterogeneity. In a meta-regression analysis, the relative proportion of all C. parvum infections being IIc decreased as the percentage of the population with access to improved sanitation increased and was some 3.4 times higher in those studies focussing on HIV-positive indivduals.

Conclusions

The anthroponotic C. parvum IIc predominates primarily in lower-income countries with poor sanitation and in HIV-positive individuals. Given the apparent enhanced post-infectious virulence of the other main anthroponotic species of Cryptosporidium (C. hominis), it is important to learn about the impact of this subtype on human health.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3263-0) contains supplementary material, which is available to authorized users.

Socio-Behavioral Risk Factors Associated with Cryptosporidiosis in HIV/AIDS Patients Visiting the HIV Referral Clinic at Cape Coast Teaching Hospital, Ghana

Objective:

To identify the socio-behavioral risk factors associated with cryptosporidiosis among HIV/AIDS patients with chronic diarrhea symptoms visiting the HIV referral clinic at Cape Coast Teaching Hospital, Ghana.

Methods:

A cross-sectional study was conducted among 50 HIV/AIDS patients with recurrent diarrhea. Questionnaires were administered to collect social and behavioral risk factors associated with Cryptosporidium and other opportunistic protozoan parasitic infections in HIV patients. Stool samples were collected for the diagnosis of enteric protozoan pathogens using modified Ziehl-Neelsen and acid-fast staining methods. CD4⁺ cells counts of study subjects were obtained from patients clinical records. The data obtained were analyzed using Pearson chi-square and multivariate-adjusted statistics tool on SPSS 16 for Windows.

Results:

Twenty-seven (54%) of the subjects were infected with enteric protozoan pathogens. The prevalences of Cryptosporidium, Cyclospora and Microsporidium infections were 46%, 32% and 16%, respectively. Cryptosporidium infection was significantly associated with drinking water (ײ=13.528, p<0.001), Cyclospora was associated with the type of drinking water (ײ=14.931, p<0.001) and toilet facilities used by the study subjects (ײ=12.463, p<0.01), whiles Microsporidium infection was associated with hand washing behavior (ײ=12.463, p<0.01). Enteric protozoans were frequently encountered among subjects with CD4+ T-cell count <200 cells/mm³. However, coinfection of Cyclospora spp & Cryptosporidium spp was not observed in CD4⁺ cell count <200 and >500 cells/mm^3. Multivariate analysis showed that the risk factor for Cryptosporidium infection among HIV/AIDS patients was the source of drinking water (pipe borne water 76.2% prevalence: sachet water 25%; OR=0.10, 95%CI: 0.03-0.39, p<0.001).

Conclusion:

We report the risk factor for exposure of Cryptosporidium infection among HIV/AIDS patients for the first time in Ghana. The contamination of drinking water by protozoan parasites should be a public health concern. These results provide the stepping block to understand the transmission dynamics of Cryptosporidium and other opportunistic pathogens in HIV/AIDS infected patients in Ghana.

Clinical, environmental, and behavioral characteristics associated with Cryptosporidium infection among children with moderate-to-severe diarrhea in rural western Kenya, 2008-2012: The Global Enteric Multicenter Study (GEMS)

Background

Cryptosporidium is a leading cause of moderate-to-severe diarrhea (MSD) in young children in Africa. We examined factors associated with Cryptosporidium infection in MSD cases enrolled at the rural western Kenya Global Enteric Multicenter Study (GEMS) site from 2008-2012.

Methodology/Principal findings

At health facility enrollment, stool samples were tested for enteric pathogens and data on clinical, environmental, and behavioral characteristics collected. Each child’s health status was recorded at 60-day follow-up. Data were analyzed using logistic regression. Of the 1,778 children with MSD enrolled as cases in the GEMS-Kenya case-control study, 11% had Cryptosporidium detected in stool by enzyme immunoassay; in a genotyped subset, 81% were C. hominis. Among MSD cases, being an infant, having mucus in stool, and having prolonged/persistent duration diarrhea were associated with being Cryptosporidium-positive. Both boiling drinking water and using rainwater as the main drinking water source were protective factors for being Cryptosporidium-positive. At follow-up, Cryptosporidium-positive cases had increased odds of being stunted (adjusted odds ratio [aOR] = 1.65, 95% CI: 1.06–2.57), underweight (aOR = 2.08, 95% CI: 1.34–3.22), or wasted (aOR = 2.04, 95% CI: 1.21–3.43), and had significantly larger negative changes in height- and weight-for-age z-scores from enrollment.

Conclusions/Significance

Cryptosporidium contributes significantly to diarrheal illness in young children in western Kenya. Advances in point of care detection, prevention/control approaches, effective water treatment technologies, and clinical management options for children with cryptosporidiosis are needed.

Cryptosporidium is an important cause of childhood diarrhea. Research on cryptosporidiosis in countries where it is endemic remains limited; few studies have comprehensively examined risk factors for children in Kenya and similar settings. We examined characteristics associated with Cryptosporidium in children with moderate-to-severe diarrhea in rural western Kenya. We found there is little to clinically distinguish cryptosporidiosis from other childhood diarrhea in the absence of point of care diagnostics. Infants had the highest odds of Cryptosporidium infection; it has been previously established that Cryptosporidium infections in infancy can have severe consequences. Prolonged/persistent duration diarrhea and growth shortfalls were significantly more pronounced among cases with Cryptosporidium. Undernutrition and stunting in children in low- and middle-income countries have predicted decreased cognitive and school performance, thus long-term consequences could be appreciable. Using rainwater as the primary drinking water source and boiling drinking water were protective against Cryptosporidium infection, thus certain water sources may contribute to transmission. Like other studies in Kenya, we predominantly identified Cryptosporidium hominis, an anthropogenic species. Advances in point of care detection, prevention and control approaches, effective water treatment technologies, and clinical management options are needed to mitigate the potentially severe and long-term consequences of Cryptosporidium infection in children.

Risk factors for Cryptosporidium infection in low and middle income countries: A systematic review and meta-analysis

BACKGROUND

Cryptosporidium infection causes gastrointestinal disease and has a worldwide distribution. The highest burden is in developing countries.

OBJECTIVES

We sought to conduct a systematic review and meta-analysis to identify Cryptosporidium risk factors in Low and Middle Income countries (LMICs).

METHODS

Medline Ovid and Scopus databases were searched with no restriction on year or language of publication. All references were screened independently in duplicate and were included if they presented data on at least 3 risk factors. Meta-analyses using random effects models were used to calculate overall estimates for each exposure.

RESULTS

The most frequently reported risk factors in the 15 included studies were overcrowding, household diarrhoea, poor quality drinking water, animal contact, open defecation/ lack of toilet and breastfeeding. The combined odds ratio for animal contact was 1.98 (95%CI: 1.11-3.54) based on 11 studies and for diarrhoea in the household 1.98 (95%CI: 1.13-3.49) based on 4 studies. Open defecation was associated with a pooled odds ratio of 1.82 (95%CI: 1.19-2.8) based on 5 studies. Poor drinking water quality was not associated with a significant Cryptosporidium risk, odds ratio 1.06 (95%CI: 0.77-1.47). Breastfeeding was protective with pooled odds ratio 0.4 (95%CI: 0.13-1.22), which was not statistically significant.

CONCLUSIONS

Based on the included studies, crowded living conditions, animal contact and open defecation are responsible for the majority of Cryptosporidium cases in LMICs. Future studies investigating Cryptosporidium risk factors should have a good study design and duration, include appropriate number of cases, select suitable controls, investigate multiple relevant risk factors, fully report data and perform multivariate analysis.

Birth Size, Stunting and Recovery from Stunting in Andhra Pradesh, India: Evidence from the Young Lives Study

Objectives Few Indian studies have examined the relationship between birth size and stunting in children. Studies on recovery from stunting in India are even fewer. This study, thus, investigates the relationship between birth size and stunting in Andhra Pradesh, India. This study further examines the factors associated with recovery from stunting using a longitudinal data. Methods We used data from the three waves of Young Lives Study (YLS) conducted in Andhra Pradesh in the years 2002, 2006-2007, and 2009 respectively. We used data from 1965 children in wave 1 to examine the association between birth size and stunting. For examining the factors associated with recovery from stunting between 1 and 5 years of age, and between 5 and 8 years, we use data from 582 and 670 children who were stunted at age 1 and age 5 respectively. We use multivariable logistic regression models to fulfil the objectives of the paper. Results The children who were of average- or large- size at birth were significantly less likely to be stunted than children who were of small size at birth (OR 0.61 and 0.47 respectively). Children of average/tall mothers were 0.41 times less likely to be stunted than children of shorter mothers. Severely stunted children were less likely than other stunted children to recover from stunting between 1 and 5 years of age, and between 5 and 8 years. Mother's height was statistically associated with recovery. Change in wealth status of the household was statistically associated with recovery between 1 and 5 years of age. In comparison, child immunization was associated with recovery between 5 and 8 years. Conclusions for Practice This study contributes to the understanding of the impact of birth size on childhood stunting, and to the extent of recovery from stunting in India. Further follow-up is necessary to demonstrate the impact during adolescence and adulthood.

Effects of Boiling Drinking Water on Diarrhea and Pathogen-Specific Infections in Low- and Middle-Income Countries: A Systematic Review and Meta-Analysis

Globally, approximately 2 billion people lack microbiologically safe drinking water. Boiling is the most prevalent household water treatment method, yet evidence of its health impact is limited. To conduct this systematic review, we searched four online databases with no limitations on language or publication date. Studies were eligible if health outcomes were measured for participants who reported consuming boiled and untreated water. We used reported and calculated odds ratios (ORs) and random-effects meta-analysis to estimate pathogen-specific and pooled effects by organism group and nonspecific diarrhea. Heterogeneity and publication bias were assessed using I2, meta-regression, and funnel plots; study quality was also assessed. Of the 1,998 records identified, 27 met inclusion criteria and reported extractable data. We found evidence of a significant protective effect of boiling for Vibrio cholerae infections (OR = 0.31, 95% confidence interval [CI] = 0.13-0.79, N = 4 studies), Blastocystis (OR = 0.35, 95% CI = 0.17-0.69, N = 3), protozoal infections overall (pooled OR = 0.61, 95% CI = 0.43-0.86, N = 11), viral infections overall (pooled OR = 0.83, 95% CI = 0.7-0.98, N = 4), and nonspecific diarrheal outcomes (OR = 0.58, 95% CI = 0.45-0.77, N = 7). We found no evidence of a protective effect for helminthic infections. Although our study was limited by the use of self-reported boiling and non-experimental designs, the evidence suggests that boiling provides measureable health benefits for pathogens whose transmission routes are primarily water based. Consequently, we believe a randomized controlled trial of boiling adherence and health outcomes is needed.

The Influence of Household- and Community-Level Sanitation and Fecal Sludge Management on Urban Fecal Contamination in Households and Drains and Enteric Infection in Children

Urban sanitation necessitates management of fecal sludge inside and outside the household. This study examined associations between household sanitation, fecal contamination, and enteric infection in two low-income neighborhoods in Vellore, India. Surveys and spatial analysis assessed the presence and clustering of toilets and fecal sludge management (FSM) practices in 200 households. Fecal contamination was measured in environmental samples from 50 households and household drains. Enteric infection was assessed from stool specimens from children under 5 years of age in these households. The two neighborhoods differed significantly in toilet coverage (78% versus 33%) and spatial clustering. Overall, 49% of toilets discharged directly into open drains (“poor FSM”). Children in households with poor FSM had 3.78 times higher prevalence of enteric infection when compared with children in other households, even those without toilets. In the neighborhood with high coverage of household toilets, children in households with poor FSM had 10 times higher prevalence of enteric infection than other children in the neighborhood and drains in poor FSM clusters who had significantly higher concentrations of genogroup II norovirus. Conversely, children in households with a toilet that contained excreta in a tank onsite had 55% lower prevalence of enteric infection compared with the rest of the study area. Notably, households with a toilet in the neighborhood with low toilet coverage had more fecal contamination on floors where children played compared with those without a toilet. Overall, both toilet coverage levels and FSM were associated with environmental fecal contamination and, subsequently, enteric infection prevalence in this urban setting.

Cryptosporidium parvum vaccine candidates are incompletely modified with O-linked-N-acetylgalactosamine or contain N-terminal N-myristate and S-palmitate

Cryptosporidium parvum (studied here) and Cryptosporidium hominis are important causes of diarrhea in infants and immunosuppressed persons. C. parvum vaccine candidates, which are on the surface of sporozoites, include glycoproteins with Ser- and Thr-rich domains (Gp15, Gp40, and Gp900) and a low complexity, acidic protein (Cp23). Here we used mass spectrometry to determine that O-linked GalNAc is present in dense arrays on a glycopeptide with consecutive Ser derived from Gp40 and on glycopeptides with consecutive Thr derived from Gp20, a novel C. parvum glycoprotein with a formula weight of ~20 kDa. In contrast, the occupied Ser or Thr residues in glycopeptides from Gp15 and Gp900 are isolated from one another. Gly at the N-terminus of Cp23 is N-myristoylated, while Cys, the second amino acid, is S-palmitoylated. In summary, C. parvum O-GalNAc transferases, which are homologs of host enzymes, densely modify arrays of Ser or Thr, as well as isolated Ser and Thr residues on C. parvum vaccine candidates. The N-terminus of an immunodominant antigen has lipid modifications similar to those of host cells and other apicomplexan parasites. Mass spectrometric demonstration here of glycopeptides with O-glycans complements previous identification C. parvum O-GalNAc transferases, lectin binding to vaccine candidates, and human and mouse antibodies binding to glycopeptides. The significance of these post-translational modifications is discussed with regards to the function of these proteins and the design of serological tests and vaccines.

Cryptosporidiosis in children in the Indian subcontinent

Cryptosporidiosis is a leading cause of diarrheal disease among children under two in developing countries. Previous estimates have shown a high burden of cryptosporidial diarrhea in children from Sub-Saharan Africa and South Asia. Asymptomatic cryptosporidial infections which go undetected and untreated have been shown to result in significant malnutrition. In this review, we carried out a literature search of studies published on cryptosporidiosis in children in the Indian subcontinent from 1983 to 2016. Of the 154 publications identified, 54 were included for final analysis with both hospital-based and community-based studies. There were wide variations in reported prevalence rates from hospital studies and highlight the need to be carry out these studies with uniform sampling and molecular tools for detection, especially in countries with a dearth of information. Community-based studies, however, showed similarities in spite of differences in when (the late 1990s up until recently) and where (South India or Bangladesh) they were conducted. When more sensitive detection methods were used, cryptosporidial diarrhea accounted for 7%–9% of all diarrhea episodes and 20%–30% of children in these cohorts experienced at least one cryptosporidial diarrheal episode. High rates of asymptomatic infections with increased detection by serology and multiple infections (symptomatic and asymptomatic) were also documented in all cohorts. This overview brings to light the high burden of disease associated with cryptosporidiosis in children in the subcontinent and the gaps in knowledge to be addressed.

Asparagine-Linked Glycans of Cryptosporidium parvum Contain a Single Long Arm, Are Barely Processed in the Endoplasmic Reticulum (ER) or Golgi, and Show a Strong Bias for Sites with Threonine

Cryptosporidium parvum causes severe diarrhea in infants in developing countries and in immunosuppressed persons, including those with AIDS. We are interested in the Asn-linked glycans (N-glycans) of C. parvum, because (1) the N-glycan precursor is predicted to contain five mannose and two glucose residues on a single long arm versus nine mannose and three glucose residues on the three-armed structure common in host N-glycans, (2) C. parvum is a rare eukaryote that lacks the machinery for N-glycan-dependent quality control of protein folding in the lumen of the Endoplasmic Reticulum (ER), and (3) ER and Golgi mannosidases, as well as glycosyltransferases that build complex N-glycans, are absent from the predicted proteome. The C. parvum N-glycans reported here, which were determined using a combination of collision-induced dissociation and electronic excitation dissociation, contain a single, unprocessed mannose arm ± terminal glucose on the trimannosyl chitobiose core. Upon nanoUPLC-MS/MS separation and analysis of the C. parvum tryptic peptides, the total ion and extracted oxonium ion chromatograms delineated 32 peptides with occupied N-glycan sites; these were derived from 16 glycoproteins. Although the number of potential N-glycan sites with Thr (NxT) is only about twice that with Ser (NxS), almost 90% of the occupied N-glycan sites contain NxT. The two most abundant C. parvum proteins modified with N-glycans were an immunodominant antigen on the surface of sporozoites (gp900) and the possible oocyst wall protein 1 (POWP1). Seven other glycoproteins with N-glycans were unique to C. parvum; five shared common ancestry with other apicomplexans; two glycoproteins shared common ancestry with many organisms. In summary, C. parvum N-glycans are remarkable for the absence of ER and Golgi modification and for the strong bias toward occupancy of N-glycan motifs containing Thr.

Cryptosporidiosis Risk in New Zealand Children Under 5 Years Old is Greatest in Areas with High Dairy Cattle Densities

The public health risks associated with dairy farming intensification are an emerging concern. We examine the association between dairy cattle density and cryptosporidiosis risk in children <5 years old in New Zealand from 1997 to 2008, a period of rapid intensification of the dairy industry. Multi-level Poisson regression was used to model reported cryptosporidiosis (N = 3869 cases) incidence in relation to dairy cattle densities across urban and rural areas separately, after controlling for microbiological quality of public drinking water supplies and neighbourhood socio-economic factors using the Census Area Unit of residence. Within urban areas, the risk of cryptosporidiosis in children less than 5 years old was significantly, positively associated with medium and high dairy cattle density IRR 1.3 (95% CI 1.2, 1.5) and 1.5 (95% CI 1.2, 1.9) respectively, when compared to areas with no dairy cattle. Within rural areas, the incidence risk of cryptosporidiosis in children less than 5 years old were significantly, positively associated with medium and high dairy cattle density: IRR 1.7 (95% CI 1.3, 2.3) and 2.0 (95% CI 1.5, 2.8) respectively, when compared to areas with no dairy cattle. These results have public health implications for children living on and in proximity to intensively stocked dairy cattle farms.

Natural History of Cryptosporidiosis in a Birth Cohort in Southern India

In an Indian birth cohort, we demonstrate a high and early burden of cryptosporidiosis by polymerase chain reaction and serology. Reinfection was common and infections clustered in a subset of children. Prior infection provided some protection against subsequent infection, but not disease.

Background.

Cryptosporidium is a leading cause of moderate to severe childhood diarrhea in resource-poor settings. Understanding the natural history of cryptosporidiosis and the correlates of protection are essential to develop effective and sustainable approaches to disease control and prevention.

Methods.

Children (N = 497) were recruited at birth in semiurban slums in Vellore, India, and followed for 3 years with twice-weekly home visits. Stool samples were collected every 2 weeks and during diarrheal episodes were tested for Cryptosporidium species by polymerase chain reaction (PCR). Serum samples obtained every 6 months were evaluated for seroconversion, defined as a 4-fold increase in immunoglobulin G directed against Cryptosporidium gp15 and/or Cp23 antigens between consecutive sera.

Results.

Of 410 children completing follow-up, 397 (97%) acquired cryptosporidiosis by 3 years of age. PCR identified 1053 episodes of cryptosporidiosis, with an overall incidence of 0.86 infections per child-year by stool and serology. The median age for the first infection was 9 (interquartile range, 4–17) months, indicating early exposure. Although infections were mainly asymptomatic (693 [66%]), Cryptosporidium was identified in 9.4% of diarrheal episodes. The proportion of reinfected children was high (81%) and there was clustering of asymptomatic and symptomatic infections (P < .0001 for both). Protection against infection increased with the order of infection but was only 69% after 4 infections. Cryptosporidium hominis (73.3%) was the predominant Cryptosporidium species, and there was no species-specific protection.

Conclusions.

There is a high burden of endemic cryptosporidiosis in southern India. Clustering of infection is suggestive of host susceptibility. Multiple reinfections conferred some protection against subsequent infection.

Effect of pregnancy intention, postnatal depressive symptoms and social support on early childhood stunting: findings from India

BACKGROUND

According to United Nation Children's Fund, it has been estimated that worldwide about 165 million children were stunted in 2012 and India alone accounts for 38 % of global burden of stunting. This study aims to examine the effect of pregnancy intention and maternal postnatal depressive symptoms on early childhood stunting in India. We hypothesized that effect of pregnancy intention and postnatal depressive symptoms were mediated by social support.

METHODS

We used data from the first wave of Young Lives Study India. Multivariate logistic regression models (using generalized estimation equation) were used to examine the effect of pregnancy intention and postnatal depressive symptoms on early childhood stunting among children aged 5-21 months. The analysis included 1833 children (out of 2011 sample children) that had complete information on pregnancy intention, maternal depression and other variables.

RESULTS

Bivariate results indicate that a higher percent of children born after unintended pregnancy (40 %) were stunted than children of intended pregnancy (26 %). Likewise, the proportion of stunted children was also higher among women with high postnatal depressive symptoms (35 %) than the low level of depression (24 %). Results of multivariate logistic regression model indicate that children born after unintended pregnancy were significantly more likely to be stunted than children born after intended pregnancy (AOR: 1.76, CI: 1.25, 2.48). Similarly, early childhood stunting was also associated with maternal postnatal depressive symptoms (AOR: 1.53, CI: 1.21, 1.92). Moreover, the effect of pregnancy intention and postnatal depressive symptoms on early childhood stunting were not mediated by social support.

CONCLUSIONS

The findings of this study provide conclusive evidence regarding consequences of pregnancy intention and postnatal depressive symptoms on early childhood stunting in India. Therefore, there is a need to identify the women with unintended pregnancy and incorporate the promotion of mental health into their national reproductive and child health programme.

Natural History of Cryptosporidiosis in a Longitudinal Study of Slum-Dwelling Bangladeshi Children: Association with Severe Malnutrition

Background

Cryptosporidiosis is a common cause of infectious diarrhea in young children worldwide, and is a significant contributor to under-five mortality. Current treatment options are limited in young children. In this study, we describe the natural history of Cryptosporidium spp. infection in a birth cohort of children in Bangladesh and evaluate for association with malnutrition.

Methodology/Principal Findings

This is a longitudinal birth cohort study of 392 slum-dwelling Bangladeshi children followed over the first two years of life from 2008 to 2014. Children were monitored for diarrheal disease, and stool was tested for intestinal protozoa. Anthropometric measurements were taken at 3-month intervals. A subset of Cryptosporidium positive stools were genotyped for species and revealed that C. hominis was isolated from over 90% of samples. In the first two years of life, 77% of children experienced at least one infection with Cryptosporidium spp. Non-diarrheal infection (67%) was more common than diarrheal infection (6.3%) although 27% of children had both types of infection. Extreme poverty was associated with higher rates of infection (chi-square, 49.7% vs 33.3%, p = 0.006). Malnutrition was common in this cohort, 56% of children had stunted growth by age two. Children with Cryptosporidium spp. infection had a greater than 2-fold increased risk of severe stunting at age two compared to uninfected children (odds ratio 2.69, 95% CI 1.17, 6.15, p = 0.019) independent of sex, income, maternal body-mass index, maternal education and weight for age adjusted z (WAZ) score at birth.

Conclusions/Significance

Cryptosporidium infection is common (77%) in this cohort of slum-dwelling Bangladeshi children, and both non-diarrheal and diarrheal infections are significantly associated with a child’s growth at 2 years of age.

Diarrheal disease is a leading cause of death in young children worldwide. Cryptosporidium species are responsible for a large proportion of global burden of diarrhea. This study describes the natural history of cryptosporidiosis in a birth cohort of impoverished Bangladeshi children. Children were enrolled at birth and monitored for diarrhea twice a week for two years. Stool samples were tested for enteric protozoa. Children in this cohort had significant rates of malnutrition compared to the W.H.O. reference population, and extreme poverty was common. A majority of children were infected with Cryptosporidium spp, and we found that children who had at least one infection with Cryptosporidium spp during the two year follow up period were significantly more likely to have growth faltering by age 24 months. Cryptosporidiosis is a common infection in this cohort, and is associated with poverty and reduced growth during the first two years of life.