Natural History of Cryptosporidiosis in a Birth Cohort in Southern India.

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.

Etiology of diarrhea in Bangladeshi infants in the first year of life analyzed using molecular methods.

BACKGROUND: Diarrhea causes enormous morbidity and mortality in developing countries, yet the relative importance of multiple potential enteropathogens has been difficult to ascertain. METHODS: We performed a longitudinal cohort study from birth to 1 year of age in 147 infants in Dhaka, Bangladesh. Using multiplex polymerase chain reaction, we analyzed 420 episodes of diarrhea and 1385 monthly surveillance stool specimens for 32 enteropathogen gene targets. For each infant we examined enteropathogen quantities over time to ascribe each positive target as a probable or less-likely contributor to diarrhea. RESULTS: Multiple enteropathogens were detected by the first month of life. Diarrhea was associated with a state of overall pathogen excess (mean number of enteropathogen gene targets (± SE), 5.6 ± 0.1 vs 4.3 ± 0.1 in surveillance stool specimens; P < .05). After a longitudinal, quantitative approach was applied to filter out less-likely contributors, each diarrheal episode still had an average of 3.3 probable or dominant targets. Enteroaggregative Escherichia coli, Campylobacter, enteropathogenic E. coli, rotavirus, and Entamoeba histolytica were the most frequent probable contributors to diarrhea. Rotavirus was enriched in moderate to severe diarrheal episodes. CONCLUSIONS: In this community-based study diarrhea seemed to be a multipathogen event and a state of enteropathogen excess above a high carriage baseline.

Breast-feeding protects infantile diarrhea caused by intestinal protozoan infections.

This study investigated the effect of breast-feeding in protection against protozoan infection in infants with persistent diarrhea. Infants were classified into 2 groups; 161 breast-fed infants and the same number of non-breast-fed infants. Microscopic examinations of stool were done for detection of parasites and measuring the intensity of infection. Moreover, serum levels of IgE and TNF-α were measured by ELISA. Cryptosporidium spp., Entamoeba histolytica/Entamoeba dispar, Giardia lamblia, and Blastocystis sp. were demonstrated in infants with persistent diarrhea. The percentage of protozoan infections was significantly lower in breast-fed infants than that in the non-breast-fed infants. The levels of IgE and TNF-α were significantly lower in the breast-fed group than in the non-breast-fed group. There were significant positive associations between the serum levels of IgE and TNF-α and the intensity of parasite infection in the breast-fed group. It is suggested that breast-feeding has an attenuating effect on the rate and intensity of parasite infection.

Seasonal variation of enteropathogens in infants and preschoolers with acute diarrhea in western Mexico.

The present study estimates the prevalence of some enteropathogens in infants and preschoolers with acute diarrhea. From 2006 to 2007, 5459 consecutive stool samples were evaluated. Cryptosporidium parvum was the parasite identified with the higher frequency (5.1%), followed by Giardia lamblia (1.2%). Campylobacter jejuni was isolated in 858 cases (15.7%) and was the most frequent enteropathogen overall. The rates of C parvum, Shigella, and Salmonella were higher in the summer. Rotavirus had the expected winter peak and it was the third enteropathogen because of its frequency. Overall frequency of stool-reducing substances was 15.6% and was associated with a rotavirus-positive test.

Risk factors for the initial symptomatic giardia infection in a cohort of young Arab-Bedouin children.

BACKGROUND: Giardiasis is a common protozoan infection with clinical manifestations in children ranging from asymptomatic carriage to persistent diarrhoea with malabsorption. It can lead to growth and developmental retardation. AIM: The study evaluated risk factors for the initial symptomatic giardiasis (SG) episode among Arab-Bedouin children in Israel. METHODS: A community-based, prospective cohort study was conducted in Rahat, a Bedouin township in southern Israel. Infants (n=238) were followed by weekly visits from birth to age 18 months. Giardia infection was identified by antigen detection in faecal specimens. RESULTS: Approximately 26% of children experienced one or more SG episode. Mean (SD) age for first SG episode was 12.3 (3.3) months, with 95% of episodes occurring in children >6 months of age. Risk for the first SG in children >6 months of age was associated with it being spring or summer [odds ratio (OR) 6.16, p<0.001], exposure to livestock (OR 4.89, p=0.002) and prior infection with entero-aggregative Escherichia coli (EAEC) (OR 1.12 for each additional percentage in stool prevalence, p=0.02). Weight-for-age Z-scores at age 6 months were inversely related to SG risk (OR 0.62 for each unit increase in Z-score, p=0.029). CONCLUSIONS: Giardiasis is an important cause of diarrhoea in Bedouin children. Increased risk of SG in spring/summer might be linked to environmental conditions or seasonal dietary practices which increase virulence or transmission. SG in those exposed to livestock suggests that there are zoonotic risk factors or that hygiene is a causal factor. The association between EAEC infection and SG warrants further investigation.

Cryptosporidium infection in rural Gambian children: Epidemiology and risk factors.

BACKGROUND: Cryptosporidium is a major pathogen associated with diarrheal disease in young children. We studied Cryptosporidium diarrhea in children enrolled in the Global Enteric Multicenter Study (GEMS) in rural Gambia. METHODS: We recruited children <5 years of age with moderate-to-severe diarrhea (MSD) for 3 years (2008-2010), and children with either MSD or less severe diarrhea (LSD) for one year (November 2011-November 2012) at sentinel health centers. One or more randomly selected controls were matched to each case. Stool samples were tested to identify Cryptosporidium by immunoassay. A subset of randomly selected case-controls pairs were tested for Cryptosporidium species. We investigated the epidemiology of, and evaluated possible risk factors for, Cryptosporidium-positive diarrhea. RESULTS: We enrolled 1938 cases (1381 MSD, 557 LSD) and 2969 matched controls; 231/1929 (12.0%) of diarrhea cases and 141/2962 (4.8%) of controls were positive for Cryptosporidium. Most Cryptosporidium diarrhea cases (85.7%, 198/231) were aged 6-23 months, and most (81.4%, 188/231) occurred during the rainy season. Cryptosporidium hominis (C. hominis) was the predominant (82.6%) species. We found associations between increased risk of Cryptosporidium-positive MSD or LSD, or both, with consumption of stored drinking water and certain animals living in the compound-cow, cat (MSD only) and rodents (LSD only). Larger households, fowl living in the compound, and the presence of Giardia infection were associated with decreased risk of Cryptosporidium MSD and LSD. CONCLUSION: Cryptosporidium-positive diarrhea is prevalent in this setting, especially at 6-23 months of age. The preponderance of Cryptosporidium infection in the rainy season and increased risk of Cryptosporidium-positive diarrhea with consumption of stored drinking water suggest water-borne transmission. Further investigation is needed to clarify the role of animals and contamination of stored drinking water in Cryptosporidium transmission.

The seasonality of diarrheal pathogens: A retrospective study of seven sites over three years.

BACKGROUND: Pediatric diarrhea can be caused by a wide variety of pathogens, from bacteria to viruses to protozoa. Pathogen prevalence is often described as seasonal, peaking annually and associated with specific weather conditions. Although many studies have described the seasonality of diarrheal disease, these studies have occurred predominantly in temperate regions. In tropical and resource-constrained settings, where nearly all diarrhea-associated mortality occurs, the seasonality of many diarrheal pathogens has not been well characterized. As a retrospective study, we analyze the seasonal prevalence of diarrheal pathogens among children with moderate-to-severe diarrhea (MSD) over three years from the seven sites of the Global Enteric Multicenter Study (GEMS), a case-control study. Using data from this expansive study on diarrheal disease, we characterize the seasonality of different pathogens, their association with site-specific weather patterns, and consistency across study sites. METHODOLOGY/PRINCIPAL FINDINGS: Using traditional methodologies from signal processing, we found that certain pathogens peaked at the same time every year, but not at all sites. We also found associations between pathogen prevalence and weather or "seasons," which are defined by applying modern machine-learning methodologies to site-specific weather data. In general, rotavirus was most prevalent during the drier "winter" months and out of phase with bacterial pathogens, which peaked during hotter and rainier times of year corresponding to "monsoon," "rainy," or "summer" seasons. CONCLUSIONS/SIGNIFICANCE: Identifying the seasonally-dependent prevalence for diarrheal pathogens helps characterize the local epidemiology and inform the clinical diagnosis of symptomatic children. Our multi-site, multi-continent study indicates a complex epidemiology of pathogens that does not reveal an easy generalization that is consistent across all sites. Instead, our study indicates the necessity of local data to characterizing the epidemiology of diarrheal disease. Recognition of the local associations between weather conditions and pathogen prevalence suggests transmission pathways and could inform control strategies in these settings.

Lack of an adverse effect of Giardia intestinalis infection on the health of Peruvian children.

Giardia intestinalis is a common gastrointestinal protozoan worldwide, but its effects on childhood growth in developing countries are not clearly understood. The authors aimed to describe its effects on child growth. They followed 220 Peruvian children daily for diarrhea, weekly for stool samples, and monthly for anthropometry. The authors modeled the effect of nutritional status on the risk of Giardia infection and the risk of diarrhea attributable to Giardia using negative binomial regression. They modeled the effects of Giardia infection on growth using linear regression, with 85% of children becoming infected with Giardia and 87% of these becoming reinfected. In multivariable analysis, the risk of Giardia infection did not vary with weight for age (relative risk = 1.00, 95% confidence interval: 0.89, 1.12) or height for age (relative risk = 0.92, 95% confidence interval: 0.82, 1.04). Giardiasis did not affect growth at 1 or 2 months following the first infection at any age interval. The longitudinal prevalence of Giardia between 6 and 24 months of age was not associated with height gain in that interval (p = 0.981). Giardia was not associated with an increased risk of diarrhea at any age interval. Study results question the importance of Giardia as a childhood pathogen in developing countries where giardiasis is hyperendemic.

Heavy cryptosporidial infections in children in northeast Brazil: comparison of Cryptosporidium hominis and Cryptosporidium parvum.

Cryptosporidium is an important cause of infectious diarrhoea worldwide, but little is known about the course of illness when infected with different species. Over a period of 5 years, Cryptosporidium was identified in the stools of 58 of 157 children prospectively followed from birth in an urban slum (favela) in northeast Brazil. Forty isolates were available for quantification and 42 for speciation (24 Cryptosporidium hominis and 18 C. parvum). Children with C. hominis shed significantly more oocysts/ml of stool (3.5 x 10(6) vs. 1.7 x 10(6)perml; P=0.001), and oocyst counts were higher among symptomatic children (P=0.002). Heavier C. parvum shedding was significantly associated with symptoms (P=0.004), and symptomatic C. parvum-infected children were significantly more likely than asymptomatic children to be lactoferrin-positive (P=0.004). Height-for-age (HAZ) Z-scores showed significant declines within 3 months of infection for children infected with either C. hominis (P=0.028) or C. parvum (P=0.001). However, in the 3-6 month period following infection, only C. hominis-infected children continued to demonstrate declining HAZ score and asymptomatic children showed even greater decline (P=0.01). Cryptosporidium hominis is more common than C. parvum in favela children and is associated with heavier infections and greater growth shortfalls, even in the absence of symptoms.

[Animal and human Cryptosporidiosis in rural zone in Vietnam (Cu Chi district, Ho-Chi-Minh-City)]. / Cryptosporidiose animale et humaine en zone rurale au Vietnam (district de Cu Chi, Hô-Chi-Minh-ville).

A pilot study was carried out in May-June 2003 to evaluate the epidemiological situation of cryptosporidiosis in the Cu Chi district, a rural zone of Ho-Chi-Minh City Vietnam. The modified acid-fast stain of the stools revealed that 10/202 (5%) cows, 1/29 (3.5%) cattle breeders, and 2/53 (3.8%) under five year- old children with diarrhoea were infected by this germ. Unconfined cattle had a significantly higher risk of infection than penned animals (odds ratio [OR]: 8.3; 95% confidence interval [CI]: 1.06-64.7; p: 0.025).

[Role of Dientamoeba fragilis in human bowel infections]. / Dientamoeba fragilis: suo ruolo nelle infezioni intestinali umane.

During 2004, we identified 39 intestinal infections caused by Dientamoeba fragilis and 23 caused by Giardia duodenalis, on 1141 home subjects (3.4% and 2.0% respectively): D. fragilis was observed in 4.5% of O and P (29/644 subjects suffering from aspecific bowel disorders) and in 2.0% of diarrhoeas (10/497); G. duodenalis was observed in 3.1% (20/644) and in 0.6% (3/497) of cases respectively. No other pathogenic parasites were identified (only 1 case of enterobiasis in an asymptomatic child). Commensal protozoa were observed, among O and P, in 4.3% of cases (28/644). The non-pathogenic B. hominis, often associated with other protozoa, was observed in 4.1% of all 1141 cases. D. fragilis is undoubtedly more frequent in adults (36/39 cases, 92.3%) than in children (3/39, 7.7%), and is prevalent among females (24/39, 61.5%) in respect of males (15/39, 38.5%). G. duodenalis is more prevalent among adults (16/23, 69.5%) than children (7/23, 30.5%), but is more frequent among males (13/23, 56.5%) than females (10/23, 43.5%). Clinical correlations of dientamoebiasis and giardiasis are reported, seasonal and epidemiological features of these protozooses are outlined, and the authors emphasize the importance and need of Giemsa stain, among O and P and acute or prolonged diarrhoeas, on the basis of previous good direct microscopic observations of faecal specimens, for correct and complete diagnosis of intestinal infections.

Community-based monitoring of diarrhea in urban Brazilian children: incidence and associated pathogens.

Community-based monitoring was conducted in order to investigate the occurrence of diarrhea in 'sentinel areas' of Salvador, Brazil, and to establish a preliminary profile of the most common pathogens present in children's diarrhea by screening stool samples. This report describes the results obtained from twice weekly home visits to identify and follow diarrhea episodes and testing of carer-requested stool sample collection over a 6-month period. Participants were selected from a large longitudinal study in 21 areas representing the city's poorer socioeconomic and sanitary conditions. Fecal samples were examined for the presence of pathogenic bacteria, viruses and protozoa. The mean incidence of diarrhea was 4.97 episodes per child-year, and longitudinal prevalence was 13.6 days per child-year (3.7%). Pathogens were found in 44% of the fecal samples examined. Bacteria were the most frequently encountered pathogens (isolated in 22% of samples), followed by protozoa (19.5%) and viruses (16%). Viral and bacterial pathogens were associated with episodes of severe diarrhea, while viral and protozoan pathogens were associated with longer episodes. The study demonstrated the importance of a public health monitoring system based on 'sentinel areas'.

[Diarrhoea-causing agents in children aged less than five in Tunja, Colombia]. / Agentes causantes de diarrea en niños menores de 5 años en Tunja, Colombia.

OBJECTIVES: Determining the prevalence and type of infectious ADD-causing agents in a sample of children aged less than five who consulted the IPS in Tunja during 2004. MATERIAL AND METHODS: A cross-sectional study was designed. Data was obtained by surveying 129 children younger than 5 suffering from ADD. Samples of faeces were obtained following outpatient consultation at San Rafael Hospital and SaludCoop's clinic in Tunja. RESULTS: Rotavirus was found in 48.1% of cases, Shigella in 0.8%, E. coli in 13.9%, Campylobacter in 2.3%, Giardia lamblia in 12.4% and E. hitolytica in 7%. The causative agent could not be identified in 15.5% of cases. The statistical association grew with age for Rotavirus (p < 0.01), E. coli (p < 0.05) and campylobacter (p < 0.001). CONCLUSION: Rotavirus is the major causative agent of ADD in children younger than one year and, generally, in children aged less than five. The prevalence found was similar to data reported in studies carried out in Facatatativá, Bogotá, Santander, Manizales and the Chocó in Colombia and studies carried out in Venezuela, Peru and Mexico.

Use of nitazoxanide as a new therapeutic option for persistent diarrhea: a pediatric perspective.

Despite advances in the management of diarrheal disorders, diarrhea is the second most frequent illness in the world. Persistent diarrhea, common in community pediatrics, is often caused by organisms such as Giardia lamblia, Cryptosporidium parvum and, less frequently, Cyclospora, Isospora belli, and Clostridium difficile. Identifying the causative organism is often challenging, and diagnostic tests may be inaccurate and expensive and, thus, of limited benefit. Consequently, carefully chosen empiric therapy guided by a physician's clinical impressions may be a useful and cost-effective option in children with persistent diarrhea, particularly those whose signs and symptoms suggest a protozoal etiology. This article discusses the empiric use of anti-infective nitazoxanide, a thiazolide compound, in three case reports of children with persistent diarrhea, and presents an overview of the diagnostic and therapeutic issues associated with this disorder and the pharmacodynamics and pharmacokinetics of the drug.

Aetiology of acute paediatric gastroenteritis in Bulgaria during summer months: prevalence of viral infections.

Paediatric acute gastroenteritis is a global public health problem. Comprehensive laboratory investigation for viral, bacterial and parasitic agents is helpful for improving management of acute gastroenteritis in health care settings and for monitoring and controlling the spread of these infections. Our study aimed to investigate the role of various pathogens in infantile diarrhoea in Bulgaria outside the classical winter epidemics of rotavirus and norovirus. Stool samples from 115 hospitalized children aged 0-3 years collected during summer months were tested for presence of 14 infectious agents - group A rotavirus, astrovirus, Giardia, Cryptosporidium and Entamoeba using ELISAs; norovirus by real-time RT-PCR; picobirnavirus and sapovirus by RT-PCR; adenovirus using PCR, and Salmonella, Shigella, Escherichia coli, Yersinia and Campylobacter using standard bacterial cultures. Infectious origin was established in a total of 92 cases and 23 samples remained negative. A single pathogen was found in 67 stools, of which rotaviruses were the most prevalent (56.7 %), followed by noroviruses (19.4 %), enteric adenoviruses (7.5 %), astroviruses (6.0 %), bacteria and parasites (4.5 % each) and sapoviruses (1.4 %). Rotavirus predominant genotypes were G4P[8] (46.3 %) and G2P[4] (21.4 %); for astroviruses, type 1a was the most common, while the GII.4/2006b variant was the most prevalent among noroviruses. Bacteria were observed in five cases, with Salmonella sp. as the most prevalent, while parasites were found in ten stool samples, with Giardia intestinalis in five cases. The results demonstrated high morbidity associated with viral infections and that rotavirus and norovirus remain the most common pathogens associated with severe gastroenteritis during summer months in Bulgaria, a country with a temperate climate, and significant molecular diversity among circulating virus strains.

An outbreak of Cryptosporidium diarrhea in a pediatric hospital.

PIP: Physicians investigated a nosocomial diarrhea outbreak among 11 2 year old undernourished children in the nutrition service of the pediatric teaching hospital, Hospital Infantile, in Mexico City, Mexico in April 1988. Health practitioners took at least 2 stool samples from each ill child to be analyzed for Cryptosporidium oocysts. The attack rate stood st 82%. The hospital admitted a malnourished child with chronic diarrhea and pneumonia on March 22. Laboratory tests revealed that he had many Cryptosporidium oocysts and was positive for HIV. Hospital staff did not isolate him. He died on May 9 of Escherichia coli and Candida septicemia. The outbreak ended 1 week later. Laboratory tests detected Cryptosporidium oocysts in 9 cases all of whom were 3-13 months old. Further the symptoms (mean duration 14 days, fever [mean peak 38.6 degrees Celsius, and vomiting] matched those of other reported Cryptosporidium diarrhea outbreaks. The epidemic curve suggested a common source of the outbreak. Since the infants received intravenous feedings or sterilized formula, food and water could not have been the source. The physicians believed the AIDS case was that source. Direct person to person transmission was probably not responsible since each infant had his/her own separate crib. Even though the physicians could not conclusively identify the vehicle of transmission, it was most likely the hands of hospitals staff either directly by touching the infants or by contaminating the nasogastric tubes. After the outbreak, the physicians observed that only 30% of medical personnel indeed washed their hands before caring for an infant. 4 previous studies on nosocomial Cryptosporidium diarrhea outbreaks also reported the source case as immunodeficient, but these studies only included adults.^ieng

Yield from stool testing of pediatric inpatients.

OBJECTIVES: To quantify the yield from stool testing in pediatric inpatients and to identify criteria to test stool more deliberately without sacrificing diagnostic sensitivity. DESIGN: A retrospective review was performed of all stool cultures, ova and parasite examinations, and Clostridium [correction of Clostridia] difficile toxin assays performed on pediatric inpatients, aged 3 days to 18 years, at Thomas Jefferson University Hospital, Philadelphia, Pa, for 1 year. Medical records were reviewed for positive cases, each with 2 controls matched for age and test type. For this study, the term admission refers to the interval between the times each patient was admitted to and discharged from the hospital. Some patients had multiple stool tests sent to the laboratory during a single admission; some patients had more than 1 admission during the study period. Statistical analysis was performed using X2 analysis and the Student 2-tailed t test with a commercially available statistical software package (Statworks, Cricket Software, Philadelphia). RESULTS: Of 250 patient admissions to the hospital for which stool was cultured, 7 cultures (2.8%) were positive. Of 63 patient admissions having ova and parasite testing, 1 (2%) had a positive result. Clostridium [correction of Clostridia] difficile toxin assays were performed on 40 patient admissions to the hospital, and 7 (18%) had a positive result. Only 18 (3.0%) of 598 of all test results reviewed were positive. Costs of negative test results totaled $26,084. More patients (71%) with positive stool cultures than control patients (21%) had a temperature higher than or equal to 38 degrees C (X2, P < .05); however, relying on this sign missed 29% of the children with bacterial infection. A white blood cell band count of at least 0.10 was 100% sensitive and 79% specific in identifying patients with positive stool culture. There was no statistically significant relationship between stool culture results and age, total white blood cell count or white blood cell segmented neutrophil count, and no relationship between C. difficile toxin assay results and any of the above characteristics. Clostridium [correction of Clostridia] difficile was the most common pathogen identified (6 of 9) in patients developing gastrointestinal symptoms after admission; however, Salmonella enteritidis and Shigella sonnei were also significant causes (3 of 9). CONCLUSIONS: There is low yield from stool testing of pediatric inpatients: C. difficile toxin assay has the highest yield. Clostridium [correction of Clostridia] difficile testing is most valuable for children with nosocomial gastrointestinal symptoms although other bacterial pathogens do cause nosocomial symptoms in children. More selective stool testing could help us be more efficient with our patient care resources.

Cryptosporidiosis in Venezuelan children with acute diarrhea.

Thirteen of 120 Venezuelan children with acute diarrhea were found to be excreting Cryptosporidium oocysts in their stools. This confirms that Cryptosporidium can infect immunocompetent children, and the relatively high frequency found suggests that this protozoan may be an important cause of diarrhea in Venezuela.

Cryptosporidium parvum in children with diarrhea in Mexico.

Using an anti-oocyst wall monoclonal antibody-based immunofluorescence assay, the presence of Cryptosporidium parvum was evaluated in children with diarrhea from rural areas (selected from a door-to-door community survey) and from urban areas (patients attending hospitals) in the State of Puebla, Mexico. Prevalences of 9.4% in a rural population (n = 85) and 29.6% in a hospital-based urban population (n = 81). There was no consistent correlation between water source and other environmental data and the presence of C. parvum in stools. It is concluded that C. parvum may be an important pathogen associated with diarrhea in this Mexican state.