Role of protozoa as risk factors for persistent diarrhea

Spectrum of height in patients with celiac disease

BACKGROUND

Growth retardation is an important feature of celiac disease (CeD) that can lead to the failure of attainment of potential adult height. There is lack of data on the spectrum of height in treatment-naïve patients with CeD, with normal expected height at one end and short stature at the other.

METHODS

We performed a retrospective analysis of a prospectively maintained database at our center, including a total of 583 treatment-naïve patients with CeD: 419 adults (183 [43.7%] males) and 164 adolescents (12-18 years) (72 [43.9%] males). The details extracted from the database included demographic details, height, weight, body mass index, clinical symptoms, biochemical parameters, anti-tissue transglutaminase antibody anti-tTG Ab) titer, and the severity of villous abnormalities (as per modified Marsh grade). The data from Indian National Family Health Survey-4 were used as comparators.

RESULTS

Overall, 19.6% of adults and 57.9% of adolescents with CeD had short stature. While mean height of men with CeD was similar, women were taller than population controls. While a higher proportion of men with CeD had short stature as compared to the controls (32.2% vs. 20%, p<0.001), a lower proportion of women with CeD had short stature (9.7% vs. 18.9%, p<0.001). Higher proportion of adolescents with CeD had short stature compared to adults (57.9% vs. 19.6%, p<0.001). On multivariate analysis, adulthood was found to be associated with a lower prevalence of short stature.

CONCLUSIONS

Overall, 19.6% of adults and 57.9% of adolescents with CeD had short stature. While the mean height of adult men with CeD was not significantly different from the population controls, women were taller. Adolescents with CeD were significantly shorter than their peers.

Longitudinal cohort study of serum antibody responses towards Giardia lamblia variant-specific surface proteins in a non-endemic area

INTRODUCTION/AIMS

The long-term humoral immune response after a natural giardiasis infection is not well understood. The aim of this study was to evaluate longitudinal serum IgA and IgG/M responses towards conserved regions of two Giardia variant-specific surface proteins (VSP) and whether these responses differ between Giardia assemblages and durations of infection.

METHODS

We recruited thirty Giardia-positive patients, mainly returning travellers, and eighteen healthy adults presumed to be Giardia unexposed. Blood samples were collected before treatment, and at 6 weeks, 6 months and 12 months after the infection cleared. We used a multiplex bead-based flow cytometry immunoassay to measure Giardia specific IgA and IgG/M responses targeting two recombinant antigens from G. lamblia VSP proteins 3 and 5 (VSP3 and VSP5).

RESULTS

Serum levels of anti-VSP5 and anti-VSP3 IgA decreased rapidly to low levels after treatment but continued to be substantially higher than that of presumed unexposed controls even after 6 and 12 months. The IgG/M response decreased more gradually but remained significantly higher than presumed unexposed controls at all time points, except for anti-VSP3 at 12 months. There were no significant difference in responses for infections with assemblage A and assemblage B Giardia lamblia. Chronic infections (>8 weeks) were associated with a significantly lower anti-VSP5 IgG/M response.

CONCLUSION

This study describes the kinetics of the humoral immune response against two Giardia VSP proteins over one year, and the considerable cross reactivity between the two human infective Giardia assemblages. Persons with chronic Giardia infection seem to have lower levels of VSP antibodies.

Persistent diarrhea: a persistent infection with enteropathogens or a gut commensal dysbiosis?

In children from developing countries 5-10% of acute diarrhea (AD) episodes develop into persistent diarrhea (PD) defined by > 14 days of diarrhea duration. PD represents a major health burden leading to growth faltering. It is also associated with half of all diarrhea mortality. A rational intervention is thus crucial, but depends on an understanding of the pathogenesis of PD, which is still lacking. Many surveys were conducted in Latin America and in South Asia; they differ, however, with respect to enteropathogens associated with PD. Enteroaggregative strains of Escherichia coli (EAEC) were identified by several studies, but they may reflect selection by the frequent antibiotic use during the preceding AD episode. Epidemiologists have in fact identified antibiotic misuse as a major risk factor for PD. Together with the effectiveness of empirical treatment based on nutritional interventions with lactose-reduced and lactose-free diets and particularly complex plant polysaccharides from green banana, one might suspect a role of commensal gut microbiota dysbiosis instead of a persistent infection with enteropathogens in many PD cases. An analysis of the commensal gut microbiota development in persistent diarrhea during nutritional interventions is likely to increase our understanding of PD pathogenesis.

Epidemiology of Cryptosporidium in Pediatric Diarrheal Illnesses

CONTEXT

Cryptosporidium spp. is a zoonotic infection, now being recognized as a significant cause of diarrhea in both immunocompetent and immunocompromised hosts. However, there still exist significant knowledge gaps in its estimated global burden, epidemiology, diagnosis and management.

EVIDENCE ACQUISITION

A semi-systematic search was performed across PubMed to select studies on epidemiological burden of cryptosporidium diarrhea using the following keywords- ['crytosporidiosis' OR 'cryptosporidium'] AND ['diarrhea' OR 'diarrhoea']. Articles were included if participants were 'Humans', belonged to pediatric (0-18 y) age group, and were published after 1990. The results were compiled separately for acute and persistent diarrhea.

RESULTS

Cryptosporidium spp is commonly detected in stools of both cases (acute/ persistent diarrhea) and asymptomatic controls. The prevalence is higher in children with diarrhea than non-diarrheal controls (1.7-35% vs 0.3-15%); varying widely across different studies. The positivity rate is higher in younger children (<2 years) suffering from diarrhea. The main symptoms associated with cryptosporidiosis include fever, vomiting and abdominal pain with propensity for prolonged duration of diarrhea. It predisposes to malnutrition, which is also a risk factor for cryptosporidiosis. The prevalence is higher in HIV positive patients; certain socio-demographic factors play a more important role than mere geographical distribution for infection.

CONCLUSION

The high positivity rates during both acute and persistent diarrhea highlights the need to suspect this infection even in immunocompetent children.

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.

Pediatric and adult celiac disease: similarities and differences

Differences between children and adults in celiac disease (CD) presentation and epidemiology are reviewed here. Clinical manifestations, histological changes, serology, and response to gluten-free diet are similar. Differences exist in epidemiology, type of clinical presentations, coexisting diseases, complications, and association with obesity. CD is two to five times more common in children than in adults. Classical CD with gastrointestinal symptoms is more common in children whereas nonclassical CD dominates in adults. A gene dose phenomenon (double-dose HLA-DQB1 02 allele) is postulated to be responsible for this difference. Coexisting autoimmune diseases like diabetes mellitus type 1, Sjogren's syndrome, and dermatitis herpetiformis are more common in adults than in children (42 % vs. 5 %). The association of overweight/obesity and CD is stronger in adults than in children (22.5 % vs. 14 %). Besides poor compliance, pancreatic insufficiency, bacterial overgrowth, lactose intolerance, irritable bowel syndrome, lymphocytic colitis, and microscopic colitis are considered responsible for nonresponsive CD in adults but not in children. Complications like refractory sprue and small intestinal neoplasms are seen exclusively in adults. Existing diagnostic criteria (modified ESPGHAN) are not suitable for diagnosing CD in adults as the majority of cases are either nonclassical or subclinical CD.

Celiac disease presentation in a tertiary referral centre in India: current scenario

BACKGROUND

Nondiarrheal celiac disease (NDCD) is being increasingly reported but data from India is limited.

AIM

We undertook this study to compare the clinical spectrum of NDCD with that of diarrheal/classical celiac disease (CCD).

METHOD

This facility-based retrospective observational study included consecutive patients diagnosed with celiac disease (CD) (as per modified ESPGHAN criteria) from October 2009 to August 2011.

RESULTS

A total of 381 patients were diagnosed with CD during the study period. NDCD was present in 192 (51.8 %). NDCD had higher mean age at presentation (5.8 ± 2.8 vs. 6.9 ± 2.9 years respectively; p = 0.003) and longer duration of symptoms prior to diagnosis (2.9 ± 1.7 years vs. 3.6 ± 2.2 years; p = 0.02) as compared to CCD. In the NDCD group, the most frequent gastrointestinal (GI) symptoms were recurrent abdominal pain [122 (63.5 %)] and abdominal distension [102 (53.1 %)] followed by constipation [48 (25 %)], vomiting [76 (39.6 %)] and recurrent oral ulcers [89 (46.4 %)]. Vomiting and constipation were more frequently seen in NDCD as compared to CCD (p < 0.001 in both). Commonly enumerated extraintestinal manifestations in NDCD included failure to thrive [109 (56.8 %)], isolated short stature [36 (18.8 %)], persistent anemia [83 (43.2 %)] and hepatomegaly/splenomegaly or both [56 (29.2 %)]. Associated comorbidities included autoimmune thyroiditis [11 (5.7 %)], type 1 diabetes mellitus [8 (4.2 %)], bronchial asthma [23 (11.9 %)], idiopathic pulmonary hemosiderosis [4 (2.1 %)], Down's syndrome [3 (1.6 %)], alopecia areata [6 (3.1 %)], polyarthritis [2 (1.0 %)], dermatitis herpetiformis [6 (3.1 %)] and chronic liver disease [6 (3.1 %)]. The number of patients with a Marsh score IIIb and above of duodenal biopsy was significantly more in the CCD group (p < 0.001).

CONCLUSIONS

NDCD is not uncommon in India. Long-term follow up is needed to evaluate the impact of the disease and of treatment in these children.

A systematic review and meta-analysis of the association between Giardia lamblia and endemic pediatric diarrhea in developing countries

We performed a systematic literature review and meta-analysis examining the association between diarrhea in young children in nonindustrialized settings and Giardia lamblia infection. Eligible were case/control and longitudinal studies that defined the outcome as acute or persistent (>14 days) diarrhea, adjusted for confounders and lasting for at least 1 year. Data on G. lamblia detection (mainly in stools) from diarrhea patients and controls without diarrhea were abstracted. Random effects model meta-analysis obtained pooled odds ratios (ORs) and 95% confidence intervals (CIs). Twelve nonindustrialized-setting acute pediatric diarrhea studies met the meta-analysis inclusion criteria. Random-effects model meta-analysis of combined results (9774 acute diarrhea cases and 8766 controls) yielded a pooled OR of 0.60 (95% CI, .38-.94; P = .03), indicating that G. lamblia was not associated with acute diarrhea. However, limited data suggest that initial Giardia infections in early infancy may be positively associated with diarrhea. Meta-analysis of 5 persistent diarrhea studies showed a pooled OR of 3.18 (95% CI, 1.50-6.76; P < .001), positively linking Giardia with that syndrome. The well-powered Global Enteric Multicenter Study (GEMS) is prospectively addressing the association between G. lamblia infection and diarrhea in children in developing countries.

Giardiasis: a review on assemblage distribution and epidemiology in India

Giardiasis is a significant cause of diarrheal disease and associated morbidity in children and adults worldwide. In addition to diarrhea, it can also lead to malnutrition and cognitive deficits in children from developing countries. Giardia duodenalis is considered to be a species complex of several assemblages, of which assemblage A and B are predominantly associated with human infections. Assemblage type has been associated with risk of occurrence of symptoms and duration of illness. Hence genotyping of giardial isolates may help understand better the epidemiology and transmission ecology of the disease in a particular setting or area. In India, prevalence rates of Giardia infection in patients with diarrhea range from 0.4% to 70%, and asymptomatic cyst passage has been found to be as high as 50% in rural southern India. In this review, the global distribution of giardial assemblage, zoonotic transmission and the association of assemblage with disease have been discussed, followed by epidemiology of giardiasis in India.

Protection against diarrhea associated with Giardia intestinalis Is lost with multi-nutrient supplementation: a study in Tanzanian children

BACKGROUND

Asymptomatic carriage of Giardia intestinalis is highly prevalent among children in developing countries, and evidence regarding its role as a diarrhea-causing agent in these settings is controversial. Impaired linear growth and cognition have been associated with giardiasis, presumably mediated by malabsorption of nutrients. In a prospective cohort study, we aim to compare diarrhea rates in pre-school children with and without Giardia infection. Because the study was conducted in the context of an intervention trial assessing the effects of multi-nutrients on morbidity, we also assessed how supplementation influenced the relationship between Giardia and diarrhoea rates, and to what extent Giardia modifies the intervention effect on nutritional status.

METHODS AND FINDINGS

Data were collected in the context of a randomized placebo-controlled efficacy trial with 2×2 factorial design assessing the effects of zinc and/or multi-micronutrients on morbidity (n=612; height-for-age z-score <-1.5 SD). Outcomes measures were episodes of diarrhea (any reported, or with ≥3 stools in the last 24 h) and fever without localizing signs, as detected with health-facility based surveillance. Giardia was detected in stool by enzyme-linked immunosorbent assay. Among children who did not receive multi-nutrients, asymptomatic Giardia infection at baseline was associated with a substantial reduction in the rate of diarrhea (HR 0.32; 0.15-0.66) and fever without localizing signs (HR 0.56; 0.36-0.87), whereas no such effect was observed among children who received multi-nutrients (p-values for interaction 0.03 for both outcomes). This interaction was independent of age, HAZ-scores and distance to the research dispensary. There was no evidence that Giardia modified the intervention effect on nutritional status.

CONCLUSION

Although causality of the Giardia-associated reduction in morbidity cannot be established, multi-nutrient supplementation results in a loss of this protection and thus seems to influence the proliferation or virulence of Giardia or associated intestinal pathogens.

Protection against diarrhea associated with Giardia intestinalis Is lost with multi-nutrient supplementation: a study in Tanzanian children

Background

Asymptomatic carriage of Giardia intestinalis is highly prevalent among children in developing countries, and evidence regarding its role as a diarrhea-causing agent in these settings is controversial. Impaired linear growth and cognition have been associated with giardiasis, presumably mediated by malabsorption of nutrients. In a prospective cohort study, we aim to compare diarrhea rates in pre-school children with and without Giardia infection. Because the study was conducted in the context of an intervention trial assessing the effects of multi-nutrients on morbidity, we also assessed how supplementation influenced the relationship between Giardia and diarrhoea rates, and to what extent Giardia modifies the intervention effect on nutritional status.

Methods and Findings

Data were collected in the context of a randomized placebo-controlled efficacy trial with 2×2 factorial design assessing the effects of zinc and/or multi-micronutrients on morbidity (n = 612; height-for-age z-score <−1.5 SD). Outcomes measures were episodes of diarrhea (any reported, or with ≥3 stools in the last 24 h) and fever without localizing signs, as detected with health-facility based surveillance. Giardia was detected in stool by enzyme-linked immunosorbent assay. Among children who did not receive multi-nutrients, asymptomatic Giardia infection at baseline was associated with a substantial reduction in the rate of diarrhea (HR 0.32; 0.15–0.66) and fever without localizing signs (HR 0.56; 0.36–0.87), whereas no such effect was observed among children who received multi-nutrients (p-values for interaction 0.03 for both outcomes). This interaction was independent of age, HAZ-scores and distance to the research dispensary. There was no evidence that Giardia modified the intervention effect on nutritional status.

Conclusion

Although causality of the Giardia-associated reduction in morbidity cannot be established, multi-nutrient supplementation results in a loss of this protection and thus seems to influence the proliferation or virulence of Giardia or associated intestinal pathogens.

Giardia intestinalis is a well-known cause of diarrhea in industrialized countries. In children in developing countries, asymptomatic infections are common and their role as cause of diarrhea has been questioned. In a cohort of rural Tanzanian pre-school children, we assessed the association between the presence of Giardia at baseline and subsequent diarrhea risk. The study was conducted in the context of a randomised trial assessing the effect of supplementation with zinc and other micro-nutrients on malaria, and half of the children daily received a multi-nutrient supplement. Surprisingly, we found that the presence of Giardia at baseline was associated with a substantial reduction in diarrhea risk. Multivariate statistical analysis showed that this protection could not be explained by differences in age or walking distance to the dispensary between children with and without Giardia. Because we cannot exclude that children differed in other (unmeasured) characteristics, we cannot draw firm conclusions about the causality of the observed association, but our findings support the view that the parasite is not an important cause of diarrhea in highly endemic settings. Striking was that the Giardia-associated protection was lost when children received multi-nutrients. Our data do not provide information about the mechanisms involved, but suggest that multi-nutrients may influence the compositionor pathogenicity of intestinal biota.

Pathogens associated with persistent diarrhoea in children in low and middle income countries: systematic review

BACKGROUND

Persistent diarrhoea in children is a common problem in low and middle income countries. To help target appropriate treatment for specific pathogens in the absence of diagnostic tests, we systematically reviewed pathogens most commonly associated with persistent diarrhoea in children.

METHODS

We sought all descriptive studies of pathogens in the stool of children with diarrhoea of over 14 days duration in low and middle income countries with a comprehensive search of the MEDLINE, EMBASE, LILACS and WEB OF SCIENCE databases. We described the study designs and populations, assessed the quality of the laboratory tests, and extracted and summarised data on pathogens. For Escherichia coli, we calculated high and low prevalence estimates of all enteropathic types combined. Results across studies were compared for geographical patterns.

RESULTS

Nineteen studies were included. Some used episodes of diarrhoea as the unit of analysis, others used children. The quality of reporting of laboratory procedures varied, and pathogens (particularly E. coli types) were classified in different ways. As there were no apparent regional differences in pathogen prevalence, we aggregated data between studies to give a guide to overall prevalence. Enteropathic E. coli types were commonly found in children with persistent diarrhoea (up to 63%). Various other organisms, including viruses, bacteria and parasites, were detected but across all studies their prevalence was under 10%. However, these pathogens were also found in similar frequencies in children without diarrhoea.

CONCLUSION

A number of pathogens are commonly associated with persistent diarrhoea in children, but in children without diarrhoea the pathogens are found with similar frequencies. New research with carefully selected controls and standardised laboratory investigations across countries will help map causes and help explore effective options for presumptive treatment.

Post-infective diarrhoea

When diarrhoea caused by gastroenteritis persists for more than two weeks it is referred to as persistent diarrhoea in developing countries. Whilst the Control of Diarrhoeal Diseases programme has decreased mortality from acute diarrhoea, mortality from persistent diarrhoea has not been so responsive. A number of factors have been identified which are determinants for the progression of an acute episode to one which persists in developing communities. In one study from west Africa, current infection with Cryptosporidium parvum was the most significant factor. In studies from Brazil and India, continuing infection with enteropathogenic Escherichia coli was identified in 50% of infants with persistent diarrhoea. Persistent small intestinal mucosal damage is of key importance in such children. Management of established cases is complex and difficult. However, there is clear evidence that zinc is involved in the recovery of small intestinal mucosa after injury. Zinc supplementation may indeed significantly reduce the duration of persistent diarrhoea. However, the whole question of public health supplementation with zinc, vitamin A, or other supplements, is contentious at present.