Cryptosporidium, chronic diarrhoea and the proximal small intestinal mucosa

Immunity to Cryptosporidium: insights into principles of enteric responses to infection

Cryptosporidium parasites replicate within intestinal epithelial cells and are an important cause of diarrhoeal disease in young children and in patients with primary and acquired defects in T cell function. This Review of immune-mediated control of Cryptosporidium highlights advances in understanding how intestinal epithelial cells detect this infection, the induction of innate resistance and the processes required for activation of T cell responses that promote parasite control. The development of a genetic tool set to modify Cryptosporidium combined with tractable mouse models provide new opportunities to understand the principles that govern the interface between intestinal epithelial cells and the immune system that mediate resistance to enteric pathogens.

Health sequelae of human cryptosporidiosis in industrialised countries: a systematic review

BACKGROUND

Cryptosporidium is a protozoan parasite which is a common cause of gastroenteritis worldwide. In developing countries, it is one of the most important causes of moderate to severe diarrhoea in young children; in industrialised countries it is a cause of outbreaks of gastroenteritis associated with drinking water, swimming pools and other environmental sources and a particular concern in certain immunocompromised patient groups, where it can cause severe disease. However, over recent years, longer-term sequelae of infection have been recognised and a number of studies have been published on this topic. The purpose of this systematic review was to examine the literature in order to better understand the medium- to long-term impact of cryptosporidiosis.

METHODS

This was a systematic review of studies in PubMed, ProQuest and Web of Science databases, with no limitations on publication year or language. Studies from any country were included in qualitative synthesis, but only those in industrialised countries were included in quantitative analysis.

RESULTS

Fifteen studies were identified for qualitative analysis which included 3670 Cryptosporidium cases; eight studies conducted in Europe between 2004-2019 were suitable for quantitative analysis, including five case-control studies. The most common reported long-term sequelae were diarrhoea (25%), abdominal pain (25%), nausea (24%), fatigue (24%) and headache (21%). Overall, long-term sequelae were more prevalent following infection with Cryptosporidium hominis, with only weight loss and blood in stool being more prevalent following infection with Cryptosporidium parvum. Analysis of the case-control studies found that individuals were 6 times more likely to report chronic diarrhoea and weight loss up to 28 months after a Cryptosporidium infection than were controls. Long-term abdominal pain, loss of appetite, fatigue, vomiting, joint pain, headache and eye pain were also between 2-3 times more likely following a Cryptosporidium infection.

CONCLUSIONS

This is the first systematic review of the long-term sequelae of cryptosporidiosis. A better understanding of long-term outcomes of cryptosporidiosis is valuable to inform the expectations of clinicians and their patients, and public health policy-makers regarding the control and prevention of this infection. Systematic review registration PROSPERO Registration number CRD42019141311.

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.

Symptoms and risk factors of Cryptosporidium hominis infection in children: data from a large waterborne outbreak in Sweden

Cryptosporidium is a major cause of diarrheal disease worldwide. In developing countries, this infection is endemic and in children, associated with growth faltering and cognitive function deficits, with the most severe impact on those aged <2 years. Little has been reported about symptoms and risk factors for children in industrialized countries, although the disease incidence is increasing in such regions. In November 2010, a large waterborne outbreak of C. hominis occurred in the city of Östersund in Sweden. Approximately 27,000 of the 60,000 inhabitants were symptomatic. We aimed to describe duration of symptoms and the risk factors for infection with C. hominis in children aged <15 years in a Western setting. Within 2 months after a boil water advisory, a questionnaire was sent to randomly selected inhabitants of all ages, including 753 children aged <15 years. Those with ≥3 loose stools/day were defined as cases of diarrhoea. The response rate was 70.3%, and 211 children (39.9%) fulfilled the case definition. Mean duration of diarrhoea was 7.5 days (median 6, range 1-80 days). Recurrence, defined as a new episode of diarrhoea after ≥2 days of normal stools, occurred in 52.5% of the cases. Significant risk factors for infection, besides living within the distribution area of the contaminated water plant, included a high level of water consumption, male sex, and a previous history of loose stools. The outbreak was characterized by high attack and recurrence rates, emphasizing the necessity of water surveillance to prevent future outbreaks.

Cryptosporidiosis-an overview

Apicomplexan protozoan parasites of the genus Cryptosporidium infect the gastrointestinal tract and lungs of a wide variety of animals, including humans. The majority of human infections are due to either Cryptosporidium hominis (C. hominis) and/or Cryptosporidium parvum (C. parvum). The parasite has a complex life cycle that includes both asexual and sexual stages. While there are invasive free living stages, proliferation and differentiation take place within a unique parasitrophorous vacuole under the host cell brush border but outside the host cell cytoplasm. Infection is spread by environmentally resistant spores that primarily contaminate drinking water and occasionally food sources, which may cause significant outbreaks of diarrhea that generally lasts less than 2 w in immunocompetent individuals. In immunodeficient or immunosuppressed individuals, diarrhea may be copious and can result in significant morbidity and mortality, particularly in AIDS patients. Although diagnosis is relatively simple, effective drug treatment, particulary for infections in immunodeficient patients, has not been uniformly successful. This overview summarizes the species known to infect humans, aspects of the parasite life cycle, sources of infection, the pathophysiology of cryptosporidiosis, the immune response to infection, diagnosis, treatment and some aspects of cryptosporidiosis in China.

Apoptosis of intestinal crypt epithelium after Cryptosporidium parvum infection

Using a neonatal mouse model of Cryptosporidium parvum infection, we investigated whether apoptosis of epithelial cells was induced in the small intestine. At the time when the number of C. parvum oocysts in the ileum was maximal, columnar goblet cells and absorptive cells showed a decrease in the ileal epithelium that was accompanied by a significant reduction in the height of the villi. A few apoptotic epithelial cells were also observed in the vicinity of the basal crypts where C. parvum was proliferating. Morphological changes of the villous structure and apoptotic epithelial cells associated with proliferation of the parasite were scarcely detected in the duodenum, cecum, and colon of the infected mice. These findings suggest that the loss of absorptive cells and goblet cells, and the apoptosis of intestinal epithelial cells, are common events in the ileum after C. parvum infection, and that epithelial apoptosis may have a significant role in the pathogenesis of cryptosporidiosis.

Effect of nitazoxanide on morbidity and mortality in Zambian children with cryptosporidiosis: a randomised controlled trial

BACKGROUND

Cryptosporidiosis in children in developing countries causes persistent diarrhoea and malnutrition and is associated with increased mortality, but there is no effective treatment. We aimed to assess the effect of nitazoxanide-a new broad-spectrum antiparasitic drug-on morbidity and mortality in Zambian children with diarrhoea due to Cryptosporidium parvum.

METHODS

Children with cryptosporidial diarrhoea who were admitted to the University Teaching Hospital, Lusaka, Zambia, between November, 2000, and July, 2001, and whose parents consented to their having an HIV test were randomly assigned nitazoxanide (100 mg twice daily orally for 3 days) or placebo. The primary endpoint was clinical response on day 7 after the start of treatment. Secondary endpoints included parasitological response by day 10 and mortality at day 8. Analysis was by intention to treat, with exclusion of patients subsequently found to be negative for C parvum or co-infected at baseline. The trial was stratified by HIV serology.

FINDINGS

50 HIV-seropositive and 50 HIV-seronegative children were recruited for the study, four of whom were subsequently excluded. In HIV-seronegative children, diarrhoea resolved in 14 (56%) of 25 receiving nitazoxanide and 5 (23%) of 22 receiving placebo (difference 33%, 95% CI 7-59; p=0.037). C parvum was eradicated from stool in 13 (52%) of 25 receiving nitazoxanide and three (14%) of 22 receiving placebo (38%, 95% CI 14-63; p=0.007). Four children (18%) of 22 in the placebo group had died by day 8, compared with none of 25 in the nitazoxanide group (-18%, -34 to 2; p=0.041). HIV-seropositive children did not benefit from nitazoxanide. Nitazoxanide was not significantly associated with adverse events in either stratum.

INTERPRETATION

A 3-day course of nitazoxanide significantly improved the resolution of diarrhoea, parasitological eradication, and mortality in HIV-seronegative, but not HIV-seropositive, children.

Enteric pathogens, intestinal permeability and nitric oxide production in acute gastroenteritis

BACKGROUND

Aboriginal children hospitalized with diarrheal disease in northern Australia have high rates of acidosis, hypokalemia and osmotic diarrhea, as well as abnormal small bowel permeability and elevated nitric oxide (NO) production.

METHODS

In a study of 291 diarrheal admissions and 84 controls, we examined the relationship of diarrheal severity outcomes with specific enteric pathogens. NO production was measured by urine nitrate plus nitrite excretion on a low nitrate diet, small bowel permeability by the lactulose:rhamnose ratio on a timed blood specimen and stool pathogens by standard microbiologic investigations and PCR.

RESULTS

The addition of diagnostic tests for diarrheagenic Escherichia coli to standard stool microbiologic testing increased the rate of specific diagnoses from 53% to 75%, but with multiple pathogens isolated from 34%. The most frequently isolated pathogens from diarrheal patients were enteroaggregative E. coli (28.9%), rotavirus (26.5%), enteropathogenic E. coli (17.2%), Salmonella spp. (10.7%), Cryptosporidium parvum (7.2%) and Strongyloides stercoralis (7.2%). High geometric mean permeability ratios (95% confidence intervals) occurred with rotavirus (19.6; 15.3 to 25.1), enteroaggregative E. coli (21.2; 15.3 to 29.3) and Cryptosporidium (23.0; 15.1 to 35.1) compared with 9.4 (6.8 to 13.1) for no pathogens. NO production was highest for Cryptosporidium (3.7; 2.3 to 6.1) compared with 0.6 (0.4 to 1.1) for no pathogens. Multiple regression analysis revealed significant associations (P < 0.001) for rotavirus with acidosis and osmotic diarrhea, for Strongyloides with wasting and hypokalemia and for Cryptospoidium with severe and prolonged diarrhea.

CONCLUSIONS

Cryptosporidium, Strongyloides, rotavirus and enteroaggregative E. coli are important contributors to the severe manifestations of acute gastroenteritis in Australian Aboriginal children.

Tropical enteropathy: a T-cell-mediated crypt hyperplastic enteropathy

OBJECTIVE

Tropical enteropathy is widespread throughout the tropics, but its pathogenesis is unknown. T-cell activation has been demonstrated to result in enteropathy in vitro and in animal models, and occurs in untreated patients with coeliac disease. We have therefore examined the hypothesis that T-cell activation is important in the pathogenesis of tropical enteropathy.

PATIENTS AND METHODS

Healthy black Zambian subjects were compared with black and white South Africans. Quantitative microscopy was conducted on distal duodenal biopsies. Mucosal T-cell activation was quantitated by dual colour immunofluorescence staining for CD3 plus CD69 or HLA-DR. Crypt proliferation was measured by direct counting of Feulgen-stained mitotic figures, and systemic immune activation by assay of serum tumour necrosis factor alpha (TNF-alpha).

RESULTS

Villous height was reduced (P = 0.0004), crypt depth increased (P < 0.0001), and mitoses per crypt increased (P = 0.014) in black Zambians compared with black and white South Africans. Mucosal thickness was similar. Intraepithelial lymphocyte count was increased in the black groups compared with whites (P = 0.03). CD3+CD69+ (P = 0.0007) and CD3+HLA-DR+ (P < 0.0001) expression was increased in black Zambians compared with black and white South Africans. Serum TNF-alpha was similar in all groups.

CONCLUSIONS

Tropical enteropathy is associated with mucosal T-cell activation and crypt hyperplasia. Tropical enteropathy occurs in the absence of malnutrition, diarrhoea or systemic illness.

Secondary lactose intolerance in a neonatal goat

A 2-week-old Toggenburg kid was evaluated for persistent diarrhea and poor body condition. The herd had high morbidity and mortality associated with diarrhea in neonatal kids. Lactose intolerance was diagnosed on the basis of results of a lactose tolerance test and glucose absorption test. Clinically normal herdmates were used as control animals. The kid responded to lactase supplementation. Cryptosporidium organisms were detected in feces of several affected kids during episodes of acute diarrhea. Lactose intolerance was presumed to have developed secondary to intestinal cryptosporidiosis.

Enteropathy in Zambians with HIV related diarrhoea: regression modelling of potential determinants of mucosal damage

BACKGROUND

AIDS is characterised by small intestinal mucosal damage, but its aetiopathogenesis is poorly understood. Enteric infections in Africa differ from those in northern countries, where protozoan infections have been associated with severe enteropathy in AIDS patients.

AIMS

To characterise enteropathy in Zambian AIDS patients compared with local controls, and to assess relative contributions of enteric infection, nutritional impairment, and immune dysfunction.

METHODS

Computer aided mucosal morphometry of small intestinal biopsy specimens from 56 HIV infected Zambians with persistent diarrhoea and 26 diarrhoea free controls, followed by regression modelling.

RESULTS

Patients with HIV related diarrhoea had reduced villous height and increased crypt depth compared with controls. There was no difference between HIV positive and negative controls. In regression models applied to AIDS mucosal measurements, villous height and crypt depth were related to nutritional parameters and to serum soluble tumour necrosis factor receptor p55 concentration. Crypt depth was also related to lamina propria plasma cell count. Intestinal infection was found in 79%, which consisted predominantly of microsporidia in 34%, Isospora belli in 24%, and Cryptosporidium parvum in 21%, but detection of these enteropathogens was not related to severity of enteropathy.

CONCLUSIONS

Nutritional and immune disturbances were associated with enteropathy, accounting for over one third of the variation in mucosal morphometric parameters.

Enteric cryptosporidiosis in pediatric HIV infection

BACKGROUND

Enteric cryptosporidiosis is a frequent problem in adults with human immunodeficiency virus (HIV) infection, but little is known of its features in children. The aim of this study was to investigate the incidence and the clinical features of cryptosporidiosis in HIV-infected children.

METHODS

Thirty-five children with symptomatic HIV infection were screened every 2 months, and in case of diarrhea, for the presence of Cryptosporidium. Intestinal function tests were performed, and the fecal osmotic gap was measured in children with cryptosporidiosis.

RESULTS

Seventy episodes of diarrhea occurred in 16 children in a median period of 17 months. Cryptosporidium was detected in five cases, all with full-blown acquired immunodeficiency syndrome. Cryptosporidiosis was significantly more protracted than any other form of diarrhea and was associated with dehydration and severe weight loss. Intestinal function was not modified during cryptosporidiosis. Osmotic gap values were consistent with secretory rather than osmotic diarrhea. In four cases, recovery was observed without specific treatment.

CONCLUSIONS

Enteric cryptosporidiosis is a severe problem in advanced stages of HIV infection. It does not induce intestinal malabsorption. It induces diarrhea of secretory type. Recovery may be observed independently of therapy.

Reactive oxygen metabolites in piglet cryptosporidiosis

Piglet cryptosporidiosis is characterized by intestinal villous damage and malabsorption, and by reduced NaCl absorption in response to prostaglandins (PGs), which act directly on the epithelium and indirectly through enteric nerves. We hypothesized that phagocyte-derived reactive oxygen metabolite (ROM) production contributed to PG synthesis and altered transport in inflamed ileum. Ileal mucosa from control and infected piglets was analyzed for villous height, PGE2, catalase (an endogenous antioxidant), and malondialdehyde (MDA, a by-product of lipid peroxidation) from d 2-8 after infection. The response of control ileal mucosa to exogenous ROM and infected mucosa to antioxidant treatment was also studied in tissues mounted in Ussing chambers. Increased levels of MDA on d 2 preceded increased PGE2 on d 3-4, which correlated with the acute diarrheal phase; however the most severe villous atrophy (d 8) correlated with the highest levels of catalase and MDA but low levels of PGE2. Control mucosa responded to H2O2 with indomethacin- and tetrodotoxin-sensitive transient increases in short circuit current (Isc), which were accompanied by increased tissue production of 6-keto-PGF1a, the stable metabolite of PGI2; however, no increased PGE2 production was detectable. A stable analog of PGI2, carbacyclin, mimicked the transient Isc response to H2O2; however, several antioxidants failed to alter the abnormal Isc of infected tissue. These results suggest that there is evidence of increased ROM production in cryptosporidial infection and that intestinal PG synthesis and inhibited NaCl absorption may be mediated partially by ROM in this model. Additional, cooperative factors, such as PGE2 production, however, are likely needed to induce the alterations in ion transport seen in this infection.

Cryptosporidiosis in Houston, Texas. A report of 95 cases

Cryptosporidiosis is an important cause of diarrhea. We identified 95 patients with cryptosporidiosis over a 6-year period in our county hospital system, including 9 children and 86 adults infected with the human immunodeficiency virus (HIV). Risk factors included male-to-male sexual practices and Hispanic race. Diarrhea, weight loss, and gastrointestinal complaints were the most common symptoms at presentation. Among the HIV-infected adults, 20 (23%) developed biliary tract disease. Biliary involvement was associated with low CD4 counts. Treatment with paromomycin and antimotility agents was effective in reducing diarrheal symptoms in 54 of 70 (77%) patients with the acquired immunodeficiency syndrome (AIDS), although there was a high rate of relapse. Paromomycin did not prevent the development of biliary disease. Biliary disease responded to cholecystectomy or sphincterotomy with stent placement. Though often a cause of morbidity, cryptosporidiosis was only rarely the cause of death, even among patients with HIV. Cryptosporidiosis continues to be an important medical problem even in developed-countries. Current methods of prevention and treatment are suboptimal.

Jejunal water and electrolyte transport in human cryptosporidiosis

Cryptosporidiosis may have severe clinical consequences in both immunocompromised and immunocompetent individuals. However, pathophysiological mechanisms that are responsible for diarrhea are poorly understood. We performed jejunal perfusion studies in patients with human immunodeficiency virus-related cryptosporidial diarrhea to measure water and electrolyte transport in vivo. Five patients with human immunodeficiency virus-related cryptosporidiosis and nine healthy volunteers were studied using a triple-lumen steady-state jejunal perfusion technique. Stool volume measurement and distal duodenal biopsy showed that the patients had diarrhea (600-1500 ml/24 hr) and morphological abnormalities of small intestinal mucosa. Net water, sodium, and chloride movement in the jejunum was not significantly different from healthy controls. In these patients with watery diarrhea and morphological mucosal abnormalities, we found no evidence that cryptosporidial diarrhea was due to a secretory state in the proximal small intestine. We conclude that diarrhea may be due to secretion of electrolytes and water efflux more distally or to other abnormalities of gastrointestinal function.

Epithelial cell proliferation in childhood enteropathies

BACKGROUND/AIM

The aim of this study was to investigate epithelial cell turnover in childhood enteropathy to establish whether common disease related mechanisms operate. Levels of epithelial cell proliferation were measured in children with food intolerance (cows' milk protein intolerance and coeliac disease), and after infection with Giardia lamblia, Cryptosporidium, and enteropathogenic Escherichia coli.

METHODS

Comparative measures of epithelial cell proliferation were performed by recording mitotic activity and MIB-1 immunoreactivity in proximal small intestinal biopsy specimens.

RESULTS/CONCLUSIONS

A hyperplastic crypt response was evident in all of the disease states examined and was particularly pronounced in coeliac disease and in infection with enteropathogenic E coli, where mitotic and MIB-1 labelling indices were significantly raised above control values. In contrast with coeliac disease, increased crypt cell production rates in enteropathogenic E coli infection were also due to an expansion of the crypt proliferation compartment, without a comparable increase in crypt cell numbers. Crypt hyperplasia is therefore a common tissue response to mucosal damage in food allergy and infection, although disease specific mechanisms are evident.

Prevalence of Cryptosporidium in children with enteritis in southern Italy

Cryptosporidium parvum is a protozoan which causes self-limiting diarrhea in immunocompetent subjects, and severe life-threatening disease in immunocompromised patients. Cryptosporidiosis is more common in developing countries and in infants. In this paper we have evaluated the prevalence of C. parvum in 368 hospitalized children with enteritis, of whom 359 were immunocompetent and 9 HIV-infected. Stool specimens were concentrated by sedimentation and stained with a modified Ziehl-Neelsen method. Cryptosporidium parvum oocysts were found in 7 (1.90%) out of 368 subjects. Six of these were immunocompetent (with an infection rate in this population of 1.67%) and 1 HIV-infected, asymptomatic except for diarrhea. In all children symptoms of enteritis and oocyst excretion cleared within 10 days. These results indicate that the prevalence of C. parvum as a causative agent of diarrheal illness in hospitalized immunocompetent children is rather low in our region (Apulia, South Italy).

Chronic nonspecific diarrhea of childhood: pathophysiology and management

Chronic nonspecific diarrhea, or toddler's diarrhea, is a frequently encountered disorder of defecation in otherwise healthy children. Although the precise pathophysiology remains to be elucidated, evidence suggests that toddler's diarrhea primarily is a gut motility disorder, modulated by dietary factors. Although the role of low-fat diets has since long been established, the liberal consumption of fruit juices and soft drinks is considered an equally important factor. Normalization of the child's diet, especially with regard to fat, fiber, fluids, and fruit juices, usually suffices to attain resolution of the diarrhea.

Intractable diarrhoea in infancy in the 1990s: a survey in Italy

A "quick" prevalence study of intractable diarrhoea (defined as diarrhoea lasting more than 3 weeks and dependent on parenteral nutrition [PN] for more than 50% of daily caloric intake) was conducted by FAX. All 35 paediatric gastroenterology services which had been contacted answered questionnaire sent by FAX. 20 cases of intractable diarrhoea were identified in 9 centres. In 12 cases PN was administered at home, the other 8 cases being treated as inpatients for an average duration of 9.5 months. A diagnosis had been established in 11 out of 20 cases. Auto-immune enteropathy was the most frequent diagnosis (5 cases); congenital microvillous atrophy (3 cases); chronic pseudo-obstruction (2 cases) and multiple food intolerance (1 case). Undefined 9/20 cases presented atrophy of intestinal mucosa. The age of the beginning of diarrhoea varied from 2 days to 12 years, but was more than 16 months only in some cases with auto-immune enteropathy.

CONCLUSION

Intractable diarrhoea has a low prevalence in Italy and remains a rare but very intricating problem. Long-term PN is recommended in most cases: autoimmune enteropathy is the most frequent cause but in about half of the cases the aetiopathogenetic diagnosis is still not defined.

Food sensitive enteropathy: overview and update

There are two types of food sensitive enteropathy; permanent and temporary. Celiac disease belongs to the former, the temporary food sensitive enteropathies of early childhood to the latter. A food sensitive enteropathy is characterized by an abnormal small intestinal mucosa while having the offending food in the diet; the abnormality is reversed by an elimination diet, only to recur once more on challenge with the relevant food. These disorders are temporary and may follow gastroenteritis. Cow's milk sensitive enteropathy is the most frequent and best known example but soy protein, egg, fish, chicken meat, ground rice and probably gluten may also temporarily damage the small intestinal mucosa in infancy. Treatment is with an elimination diet and protein hydrolysates as a cow's milk substitute. The reason why these enteropathies are temporary has not yet been established.

Glutamine stimulates prostaglandin-sensitive Na(+)-H+ exchange in experimental porcine cryptosporidiosis

BACKGROUND/AIMS

Recent studies of piglet cryptosporidiosis showed an injury-induced impairment of sodium-glucose cotransport and a prostaglandin-mediated inhibition of neutral NaCl absorption. Because glutamine has been shown to stimulate both neutral and electrogenic Na+ absorption, this study examined the mechanism of prostaglandin-mediated inhibition of NaCl absorption and the effect of glutamine on these processes.

METHODS

Ileal mucosa from control and infected pigs was mounted in Ussing chambers for flux studies or incubated with [14C]glutamine or [14C]-glucose for metabolism studies.

RESULTS

Glucose and glutamine induced equivalent increases, 2-2.5 microEq.cm-2.h-1, in Na+ absorption and short-circuit current in control ileum. Despite a reduction in villous surface area to one third of the control, glutamine enhanced both neutral and electrogenic Na+ absorption in the infected ileum by 3.5 +/- 0.5 microEq.cm-2.h-1, whereas glucose was only half as effective (P < 0.05). In addition, glutamine was oxidized to CO2 at rates three times those of glucose. Indomethacin enhanced, whereas amiloride, prostaglandin E2, and Cl-free solutions inhibited the glutamine-induced neutral Na+ transport.

CONCLUSIONS

Glutamine-stimulated neutral Na+ absorption is mediated by a prostaglandin-sensitive apical Na(+)-H+ exchange mechanism. The heightened Na(+)-H+ exchange and tissue oxidation of glutamine suggest that glutamine is superior to glucose for use in oral rehydration solutions.

Severe cryptosporidiosis in children with normal T-cell subsets

Though Cryptosporidium spp. is considered to cause only a self-limiting illness in immunocompetent children, data from Guinea Bissau suggest that cryptosporidiosis may be a significant cause of deaths in developing countries. An impaired cellular immune function could explain the severe course of cryptosporidiosis in these children. We therefore investigated in a community study whether pre-infectious CD4/CD8 status had an impact on incidence and severity of cryptosporidiosis. Of 168 children below two years of age 21 experienced Cryptosporidium-infection within 156 days after blood sampling, but no tendencies of pre-infectious impaired cellular immune function was found in the cases compared with controls, nor did nine children who acquired persistent diarrhoea or three who died have impaired CD4/CD8 status.

Diarrhoeal disease: current concepts and future challenges. Malnutrition and infection

In individual children in developed countries it is possible to follow a sequence of infection of the gastrointestinal tract leading to chronic diarrhoea which, if it long persists, may in turn lead to undernutrition. Both in individuals and epidemiologically in developing countries it is, by contrast, often difficult to be certain whether infection precedes under-nutrition or vice versa. Chronic diarrhoea is heterogeneous and aetiology varies from community to community. Unlike acute diarrhoea, for which there is highly effective unitary therapy (oral rehydration therapy), diverse therapies are required for chronic diarrhoea based on specific diagnoses and so render community strategies difficult. The importance of adequate calorie intake is emphasized but when there is intolerance to food ingested this is counter-productive. The relative importance of post-infective food intolerance remains controversial and in many communities is unknown. Increasing emphasis is now given to the role of infection in pathogenesis of diarrhoea and malnutrition, e.g. the acquired immune deficiency syndrome and Helicobacter pylori. Hospital-based case studies including small intestinal biopsy in individual communities, by virtue of an 'iceberg effect', may prove useful for insights into aetiology and pave the way for interventions, e.g. antibiotics or dietary therapy.

Evaluation of an enzyme-linked immunosorbent assay for detection of Cryptosporidium spp. in stool specimens

We evaluated a commercially produced enzyme-linked immunosorbent assay (ELISA; LMD Laboratories, Inc.) for the detection of Cryptosporidium spp. in 296 stool specimens submitted to the Mayo Clinic parasitology laboratory for routine examination. The specimens examined were fresh (4 specimens), were stored frozen at -65 degrees C (49 specimens), or were preserved in 10% formalin (243 specimens). Results were compared with those obtained by indirect immunofluorescent antibody detection (Merifluor Cryptosporidium/Giardia; Meridian Diagnostics, Inc.). One hundred of the specimens were positive by indirect immunofluorescent antibody and ELISA, while 187 were negative by both methods; 91 of these negative stool samples contained 121 parasites of 17 different species. Eight ELISA false negatives and one false positive were observed. The ELISA sensitivity was 93%, specificity was 99%, and the positive predictive value was 99%. Storage of specimens preserved in 10% formalin or frozen fresh at -65 degrees C for up to 18 months did not appear to affect the results. There was no cross-reactivity with Giardia lamblia (54 negative specimens) or with the 16 other parasites present in the ELISA-negative stool samples. The ELISA is a fast, easy-to-read, and accurate method for the detection of Cryptosporidium spp. in stool specimens.