Etiology of outpatient pediatric nondysenteric diarrhea: a multicenter study in the United States

Enteropathogenic and enteroaggregative E. coli in stools of children with acute gastroenteritis in Davidson County, Tennessee

This prospective acute gastroenteritis (AGE) surveillance was conducted in the inpatient and emergency room settings at a referral pediatric hospital to determine the prevalence of diarrheagenic Escherichia coli (DEC) in children <12years of age with AGE in Davidson County, Tennessee. Subjects 15 days to 11 years of age, who presented with diarrhea and/or vomiting, were enrolled. Stool specimens were processed for detection of DEC using multiplex polymerase chain reaction. From December 1, 2011, to June 30, 2012, a total of 79 (38%) out of 206 stool specimens from children with AGE tested positive for E. coli. A total of 12 (5.8%) out of 206 stool specimens from children with AGE were positive for a DEC. Eight (67%) out of these 12 were positive for enteropathogenic E. coli, and the remaining 4 were positive for enteroaggregative E. coli. DEC clinical isolates clustered with known E. coli enteropathogens according to multilocus sequencing typing.

Molecular Epidemiology of Adenovirus Infection among Pediatric Population with Diarrhea in Asia

A total of 3,577 fecal specimens from infants and children with acute gastroenteritis in Japan, Korea and Vietnam during 1998 and 2001 were tested for adenovirus by the ELISA method. Of these, adenovirus was detected in 158 (4.4%). The detection rate of adenovirus was highest in Korea (8.7%, 20/231) followed by 5.0% (100/1,991) in Japan and 2.8% (38/1,355) in Vietnam. All adenoviruses were further serotyped by PCR-RFLP. The diversity of adenovirus serotypes including Ad2, 3, 5, 8, 31, 40 and 41 was demonstrated. Worth of note was a decrease in the rate of isolation of Ad40 (7.6%, 12/158) and a concomitant increase of Ad41 (63.9%, 101/158) to become the predominant serotype. Another interesting feature of the study was the presence of Ad3 (4.0% and 30%) and Ad8 (8.0% and 20%) in Japan and Korea, respectively, which is mainly associated with keratoconjunctivitis worldwide. Our result underscored the importance of adenovirus in association with acute gastroenteritis in Asian countries.

Impacts of culture-independent diagnostic practices on public health surveillance for bacterial enteric pathogens

For decades, culture has been the mainstay of diagnostic testing for bacterial enteric pathogens. This paradigm is changing as clinical laboratories adopt culture-independent methods, such as antigen-based tests and nucleic acid-based assays. Public health surveillance for enteric infections addresses 4 interrelated but distinct objectives: case investigation for localized disease control; assessment of disease burden and trends to prioritize and assess impact of population-based control measures; outbreak detection; and microbiologic characterization to improve understanding of pathogens, their virulence mechanisms, and epidemiology. We summarize the challenges and opportunities that culture-independent tests present and suggest strategies, such as validation studies and development of culture-independent tests compatible with subtyping, that could be adopted to ensure that surveillance remains robust. Many of these approaches will require time and resources to implement, but they will be necessary to maintain a strong surveillance system. Public health practitioners must clearly explain the value of surveillance, especially how outbreak detection benefits the public, and collaborate with all stakeholders to develop solutions.

Estimated burden of rotavirus-associated diarrhea in ambulatory settings in the United States

BACKGROUND

Two vaccines to prevent disease from rotavirus among young children were recently approved in the United States. Although previous studies of the burden of rotaviral disease have focused on hospitalizations, the assessment of baseline disease burden in ambulatory settings is useful for evaluating the overall impact of the vaccine.

METHODS

Outpatient and emergency department (ED) data for 1994-2006 were analyzed from 2 nationally representative databases: the National Ambulatory Medical Care Survey and the National Hospital Medical Care Survey. Visits by children (younger than 5 years) with acute gastroenteritis (AGE) were identified by using a defined set of International Classification of Diseases, Ninth Revision, Clinical Modification codes. Two previously described methods (the winter-residual-excess [WRE] and Brandt methods) were used to estimate the proportion of AGE attributable to rotavirus and to determine the annual number of visits, annual average visits, and annual visit rates in each setting.

RESULTS

The estimated average annual number of rotavirus-associated visits over the 13-year period was 782 453 outpatient visits and 164 261 ED visits from the WRE method and 665 773 outpatient visits and 205 206 ED visits from the Brandt method. This resulted in an average of 39.1 and 33.3 outpatient visits per 1000 children and 8.2 and 10.3 ED visits per 1000 children for both the WRE and Brandt methods, respectively. The average annual proportion of visits for AGE attributed to rotavirus was 34.2% (29.1% from the Brandt method) in the outpatient setting and 21.8% (27.1% from the Brandt method) in the ED, with wide variations in individual years.

CONCLUSIONS

Before the rotavirus vaccine, rotavirus seemed to be associated with a large number of outpatient and ED visits among young children. Rotavirus vaccine has the potential to reduce many outpatient and ED visits.

Cost of routine immunization of young children against rotavirus infection with Rotarix versus RotaTeq

Using a probabilistic model of the clinical and economic burden of rotavirus gastroenteritis (RVGE), we estimated the expected impact of vaccinating a US birth cohort with Rotarix in lieu of RotaTeq. Assuming full vaccination of all children, use of Rotarix - rather than RotaTeq - was estimated to reduce the total number of RVGE events by 5% and associated costs by 8%. On an overall basis, Rotarix would reduce costs by $77.2 million (95% CI $71.5-$86.5). Similar reductions with Rotarix were estimated to occur under an assumption of incomplete immunization of children.

Explaining unexplained diarrhea and associating risks and infections

Gastrointestinal illnesses are common afflictions. However, knowledge of their etiology is often lacking. Moreover, most cases of infections with reportable enteric pathogens (Campylobacter jejuni, Escherichia coli O157:H7, Salmonella, Shigella, Yersinia, Cryptosporidia and Giardia) have sporadic modes of acquisition, yet control measures are often biased towards mitigation of risks discerned by outbreak analysis. To determine the etiology of unexplained diarrhea it is important to study populations that can be matched to appropriate controls and to couple thorough classic microbiologic evaluation on receipt of specimens with archiving and outgrowth capabilities. Research evaluations should address the potential roles of a broad panel of candidate bacterial pathogens including diarrheagenic E. coli, Listeria monocytogenes, Helicobacters and jejuni Campylobacters, and also apply novel massively parallel sequencing and nucleic acid detection technologies that allow the detection of viral pathogens. To fill voids in our knowledge regarding sources of known enteric pathogens it will be critical to extend case-control studies to assess risk factors and exposures to patients with non-epidemic illnesses and to appropriate controls. By filling these gaps in our knowledge it should be possible to formulate rational prevention mechanisms for human gastrointestinal illnesses.

Cost-effectiveness and potential impact of rotavirus vaccination in the United States

OBJECTIVE

In February 2006, a safe, efficacious, orally administered pentavalent human-bovine reassortant rotavirus vaccine was licensed and recommended for routine immunization of all children in the United States. We assessed the health and economic impacts of a national rotavirus immunization program in the United States.

METHODS

Monte Carlo cost-effectiveness analyses, from health care and societal perspectives, of vaccination of a hypothetical US birth cohort of 4,010,000 children monitored from birth to 59 months of age were performed. We compared the disease and economic burden of rotavirus infection in an unvaccinated cohort of children with one vaccinated at 2, 4, and 6 months with pentavalent human-bovine reassortant rotavirus vaccine.

RESULTS

A routine rotavirus immunization program would prevent 13 deaths, 44,000 hospitalizations, 137,000 emergency department visits, 256,000 office visits, and 1,100,000 episodes requiring only home care for children <5 years of age in the United States. Assuming costs of administration of $10, the break-even price per dose of vaccine was $42 from the societal perspective and $12 from the health care perspective. From the societal perspective, at the manufacturer's price of $62.50 per dose, vaccination would cost $138 per case averted, $3024 per serious case averted, and $197,190 per life-year saved, at a total cost of $515 million to the health care system and $216 million to society. Key variables influencing the results were parental workdays lost, costs of hospitalization, emergency department visits, and child care.

CONCLUSIONS

Despite a higher burden of serious rotavirus disease than estimated previously, routine rotavirus vaccination would unlikely be cost-saving in the United States at present. Nonetheless, rotavirus vaccination may still be considered a cost-effective intervention.

Diarrhea etiology in a Children's Hospital Emergency Department: a prospective cohort study

BACKGROUND

We evaluated the frequency of recovery of pathogens from children with diarrhea who presented to a pediatric emergency department and characterized the associated illnesses, to develop guidelines for performing a bacterial enteric culture.

METHODS

We conducted a prospective cohort study of all patients with diarrhea who presented to a large regional pediatric emergency department during the period from November 1998 through October 2001. A thorough microbiologic evaluation was performed on stool specimens, and the findings were correlated with case, physician, and laboratory data.

RESULTS

A total of 1626 stool specimens were studied to detect diarrheagenic bacteria and, if there was a sufficient amount of stool, Clostridium difficile toxin (688 specimens), parasites (656 specimens), and viruses (417 specimens). One hundred seventy-six (47%) of 372 specimens that underwent complete testing yielded a bacterial pathogen (Shiga toxin-producing Escherichia coli, 39 specimens [of which 28 were serotype O157:H7]; Salmonella species, 39; Campylobacter species, 25; Shigella species, 14; and Yersinia enterocolitica, 2), a viral pathogen (rotavirus, 85 specimens; astrovirus, 27; adenovirus, 18; or rotavirus and astrovirus, 8), a diarrheagenic parasite (5 specimens); or C. difficile toxin (46 specimens). Samples from 2 patients yielded both bacterial and viral pathogens. A model to identify predictors of bacterial infection found that international travel, fever, and the passing of >10 stools in the prior 24 h were associated with the presence of a bacterial pathogen. Physician judgment regarding the need to perform a stool culture was almost as accurate as the model in predicting bacterial pathogens.

CONCLUSIONS

Nearly one-half of the patients who presented to the emergency department with diarrhea had a definite or plausible pathogen in their stool specimens. We were unable to develop a model that was substantially better than physician judgment in identifying patients for whom bacterial culture would yield positive results. The unexpectedly high rate of C. difficile toxin warrants further examination.

An updated review on Cryptosporidium and Giardia

Cryptosporidium and Giardia are two of the most commonly occurring enteric protozoans. They are responsible for diarrheal diseases that may lead to nutritional deficiencies and significant morbidity and mortality, especially among children in developing countries and patients who have immune defects. Both are difficult to diagnose with microscopic techniques. This article provides an updated review of the epidemiology, pathogenesis, clinical manifestations, and treatment of Cryptosporidium and Giardia.

Diarrhea in American infants and young children in the community setting: incidence, clinical presentation and microbiology

OBJECTIVE

The characteristics and microbiology of the full spectrum of pediatric diarrhea occurring in the U.S. community setting are not well-understood.

METHODS

Six-month prospective cohort study of 604 healthy 6- to 36-month-old children recruited by the Slone Center Office-based Research Network.

RESULTS

The incidence of parent-defined diarrhea was 2.2 episodes per person-year. The median duration of diarrhea was 2 days with a median of 6 stools per episode. Outpatient visits and hospitalization were prompted by 9.7 and 0.3% of episodes, respectively. The most common microorganisms identified in healthy baseline stools were atypical enteropathogenic Escherichia coli (12.2%), enteroaggregative Escherichia coli (3.7%), Clostridium difficile (3.5%) and Clostridium perfringens (2.9%), and each of these was no more common in diarrhea stools. In contrast, all of the viruses analyzed were more prevalent in diarrhea specimens than in baseline specimens: enteric adenovirus (5.7% diarrhea versus 1.4% baseline), rotavirus (5.2% versus 1.4%), astrovirus (3.5% versus 1.4%), Sapporo-like virus (3.0% versus 0.8%) and norovirus (1.9% versus 0.8%). A likely pathogen was detected in 20.6% of diarrhea specimens. Vomiting and > or =16 stools in an episode were predictive of isolating a pathogen from the stool, each with a relative risk of approximately 2.

CONCLUSIONS

Healthy young children in this study experienced more than 2 cases of diarrhea per person-year, but most were brief and do not require medical attention. Although most diarrhea-associated pathogens were viruses, no likely pathogen was found in almost 80% of cases; possible etiologies for these cases include currently unknown gastrointestinal infections, nongastrointestinal illnesses and dietary/environmental factors.

Viral etiology and incidence of acute gastroenteritis in young children attending day-care centers

BACKGROUND

The purpose of the study was to investigate the frequency, morbidity and cause of acute gastroenteritis in children attending day-care centers in Denmark.

METHODS

Children with acute diarrhea (> or =2 consecutive loose stools in 24 hours, with duration of < or =7 days), recruited from 19 day-care centers, were included. Gastroenteritis viruses, group A rotavirus, sapoviruses, noroviruses and astroviruses were detected with reverse transcription-polymerase chain reaction assays. In addition, stool specimens were cultured for bacterial pathogens. Children who were brought to the clinic with acute diarrhea underwent a medical evaluation, including an estimation of dehydration.

RESULTS

Two hundred seven children (median age, 20.1 months; range, 9-44 months) were enrolled. During the 6-month study period, 98 diarrheal episodes in 95 children were reported. Of these, 48 were reported retrospectively in telephone interviews. The incidence of acute diarrheal episodes was 0.08 episode per child per month. A viral etiologic agent was identified in 69% of cases. Rotaviruses were identified in 17 cases (40%), sapoviruses in 8 (19%) and astroviruses in 3 (7%). One patient had a coinfection with rotavirus and astrovirus. Campylobacter jejuni was detected in 2 patients and Clostridium difficile was found in 5 patients, all coinfected with a virus. In clinical assessments, 9 patients (18%) showed signs of dehydration and were given oral rehydration solution; 6 of these were hospitalized.

CONCLUSIONS

Acute diarrhea among children attending day-care centers was common in wintertime. Rotaviruses were, expectedly, the most common causative agents, but sapoviruses were second to rotaviruses as etiologic agents in this population.

Etiology of diarrhea in pediatric outpatient settings

BACKGROUND

The frequency with which bacteria cause diarrhea evaluated in ambulatory settings is often unknown. We attempted to determine the microbiologic etiology of diarrhea in a private pediatric practice (site A) and a clinic serving largely immigrant children (site B) and to establish guidelines for bacterial culture.

METHODS

Children with diarrhea were prospectively enrolled, and their stools were examined for diarrheagenic bacteria, viruses and parasites.

RESULTS

A total of 123 and 103 children were enrolled at sites A and B, respectively. Stools from all (100%), 126 (55.8%), 104 (46.0%) and 75 (33.2%) were tested for bacterial enteric pathogens, parasites, Clostridium difficile toxin and viruses, respectively. Of the 75 patients whose stool underwent complete testing, 36 (48%) contained at least 1 definitive or plausible pathogen. Twelve stools (5.3%) tested positive for bacteria [Campylobacter jejuni (n = 7), Yersinia enterocolitica, Shigella flexneri, Shigella sonnei, Salmonella serogroup D and Salmonella Braenderup (n = 1 each)]. One contained Blastocystis hominis, 8 contained C. difficile toxin and 16 contained viruses (9 rotavirus, 5 adenovirus and 2 astrovirus). Visible fecal blood (P = 0.029), increased stool frequency (P = 0.035), abdominal tenderness (P = 0.011) and fecal white (P < 0.001) or red blood cells (P = 0.002) were associated with bacterial infection. All children with stool yielding diarrheagenic bacteria or C. difficile toxin had at least 1 of these factors, but so did 75% of children without these agents (positive predictive value, 11%; negative predictive value, 100%; sensitivity, 100%; specificity, 25%).

CONCLUSIONS

The bacterial diarrhea prevalence is similar to that in other ambulatory studies, although the spectrum differs. Exclusion criteria for stool testing in diarrhea remain elusive. Studies to determine the etiology of unexplained diarrhea and cost-effective algorithms for diarrhea diagnosis, are needed.

Prevalence of diarrheagenic Escherichia coli in acute childhood enteritis: a prospective controlled study

OBJECTIVE

Since diarrheagenic E. coli are not identified by common clinical laboratory techniques, we hypothesized that these organisms might be an unrecognized cause of enteritis in children in the U.S.

STUDY DESIGN

1327 children with acute gastroenteritis were identified prospectively by active surveillance in the Emergency Department (ED) and the inpatient units at Cincinnati Children's Hospital Medical Center. Stool samples were evaluated for diarrheagenic E. coli using a panel of DNA probes and adherence pattern to HEp-2 cells. Stool samples from a reference group of 555 well children were studied for comparison.

RESULTS

Gene probe studies, but not HEp-2 cell adherence, demonstrated that enteroaggregative, diffusely adherent and enteropathogenic E. coli were associated with clinical illness. Each was isolated significantly more often from study subjects in the ED than controls. In children <1 year of age, enteroaggregative E. coli were isolated significantly more often from both inpatients (4.7%, Odds Ratio = 3.4, 95% confidence intervals 1.3-9.1, p <0.03) and ED patients (10.0%, Odds Ratio = 7.2, 95% confidence intervals 2.9-18.2, p <0.001) than from well children (1.4%).

CONCLUSIONS

Diarrheagenic E. coli , especially enteroaggregative E. coli , may be an important, unrecognized cause of childhood diarrhea in the U.S.

Costs associated with outpatient diarrhoea in infants and toddlers: a nationwide study of the Italian Society of Paediatric Gastroenterology and Hepatology (SIGEP)

BACKGROUND

As diarrhoea mortality is negligible in Italy, other costs should be considered when planning health strategies. Little is known about the costs associated with diarrhoea in Italian children.

AIMS

To assess the costs associated with outpatient infantile diarrhoea in Italy.

METHODS

Primary care paediatricians from five regions filled in a questionnaire for the first 10 children (1-47 months) they visited for acute diarrhoea during a 3-month period.

RESULTS

We analysed 473 questionnaires. Mean age (standard deviation) of children was 21 (11) months; mean duration of diarrhoea (standard deviation) was 4.3 (2.6) days. An overall cost of 110 (137) euro per episode was estimated, with significant difference between children younger and older than 36 months (116 euro versus 72 euro). Missed work by relatives accounts for 75% of the cost. The parents of children attending a day-care centre had an increased risk to miss work (relative risk = 2.15). A weak relationship was found between days of diarrhoea and missed work (r = 0.30); it could be estimated that the diarrhoea should be shortened by about 4 days in order to save I day of missed work.

CONCLUSIONS

Acute outpatient diarrhoea is associated with a significant financial burden in Italy. Simply shortening the diarrhoea does not seem to be the most expeditious way to reduce the cost of diarrhoea itself.

Etiology of sporadic cases of pediatric acute gastroenteritis in asturias, Spain, and genotyping and characterization of norovirus strains involved

From November 2000 to October 2001, a reverse transcription-PCR using primers directed to the norovirus RNA polymerase coding region was included in a viral and bacterial routine screening to diagnose sporadic cases of acute gastroenteritis among children in Asturias, Spain. The role of noroviruses (8.6% of the positively diagnosed cases) as the cause of sporadic pediatric gastroenteritis was evaluated with respect to the detection rates of other gastroenteritis-associated viruses and bacteria. The results indicated that noroviruses were less common than rotaviruses (36.9%), Campylobacter spp. (28.8%), and Salmonella spp. (18.4%) but more frequent than astroviruses (4.3%), adenoviruses (3.8%), and Yersinia spp. (2.2%). Mixed infections involving noroviruses were rarely observed (0.5%). The presence of a norovirus-associated pediatric gastroenteritis peak in summer, as well as the complete absence of norovirus-associated cases in colder months, challenges the view that norovirus infections exclusively have wintertime seasonality. On the other hand, phylogenetic analysis of the amplified fragments showed that the norovirus strains responsible were closely related. A further study using the full-length capsid region showed that these strains could be included into genogroup II, Bristol/Lorsdale cluster, and were closely related to the 1995 and 1996 U.S. subset of strains associated with outbreaks recorded worldwide between 1995 and 1996.

High prevalence of atypical enteropathogenic Escherichia coli (EPEC) in Norwegian children with diarrhoea

The aim of the present study was to investigate the relative contribution of enteropathogenic Escherichia coli (EPEC) as a cause of infectious diarrhoea in Norwegian children. Data from faecal specimens from children <2 years old with diarrhoea during the year 2001 were analysed. E. coli isolates with the attaching and effacing genotype (eae+) were examined for the presence of the bundle-forming pilus (bfpA) and Shiga toxin genes by PCR, and for genetic relatedness by PFGE. During the 1-year period, 598 specimens from 440 patients <2 years old were analysed. Potential enteric pathogens were identified in 124 patients (28.2 %). EPEC was the most frequently identified agent (44 patients), followed by rotavirus (41 patients), Campylobacter jejuni (17 patients) and adenovirus (17 patients). All other agents were detected in five patients or less. Only one of the eae+ E. coli isolates was classified as typical EPEC (bfpA+). Among the 43 isolates that were classified as atypical EPEC (bfpA-), eight strains belonged to EPEC serogroups, whereas the majority of strains (n = 35) were not agglutinated by EPEC antisera. None of the EPEC isolates were genetically related. This study demonstrates that atypical EPEC of non-EPEC serogroups is highly prevalent among Norwegian children with diarrhoea.

Human milk secretory antibodies against attaching and effacing Escherichia coli antigens

Secretory immunoglobulin A (sIgA) is a primary factor responsible for preventing attachment of enteropathogens to gut epithelium in breastfeeding infants. We compared the frequency of sIgA to major surface antigens of enterohemorrhagic Escherichia coli (EHEC) in milk of 123 women from the United States and Mexico to determine whether regional differences existed in the frequency of antibodies to these surface antigens. In both groups of women, milk commonly has sIgA against various EHEC lipopolysaccharides, EspA, EspB, intimin, and less frequently against Shiga toxin. The study suggests that persons living in the United States are exposed to attaching/effacing enteropathogens more frequently than is generally assumed. The low frequency of antibodies to Stx1 (in 12% of Mexican and in 22% of U.S. samples) suggests that the rare appearance of hemolytic uremic syndrome in adults is not due to neutralization of toxin at the gut level. Only anti-EspA is found in most milk samples from both populations of women. EspA may represent a useful target for an immunization strategy to prevent EHEC disease in humans.

Incidence of enteric adenovirus gastroenteritis in Iranian children

BACKGROUND

Enteric adenoviruses, i.e. adenovirus 40 (Ad40) and adenovirus 41 (Ad41), have been shown to be a substantial cause of pediatric gastroenteritis in various parts of the world, but no data are available for Iran.

OBJECTIVE

The present study was performed to determine the incidence of enteric adenoviruses in children presenting to the Children's Medical Center with gastroenteritis in Iran.

STUDY DESIGN

Stool specimens from 872 children less than 7 years of age attending the Children's Medical Center in Tehran, Iran, with gastroenteritis were tested for the presence of Ad40, Ad41, and adenovirus-genus by a monoclonal antibody-based enzyme immunoassay.

RESULTS AND CONCLUSION

6.7% of stool specimens contained enteric adenoviruses (3.3% Ad40 and 3.4% Ad41) and 2.0% nonenteric adenoviruses. Mean ages of Ad40, Ad41 and NEAd-positive children were 21, 19 and 29 months, respectively. Among the adenovirus-positive patients, 53.9% were male and 46.1% female. Watery diarrhea was present in 86.4% of children infected by adenoviruses. In conclusion, for the first time, we demonstrated the presence of enteric and nonenteric adenoviruses in a considerable proportion of stool samples from Iranian children with gastroenteritis.

Infectious diarrhea in children

Infectious diarrhea in children remains an important cause of morbidity in North America with rotavirus, nontyphoidal salmonella, Campylobacter and Giardia being the predominant pathogens in children younger than 5 years. Knowledge of the epidemiology of the diarrheal illness in a community together with the clinical information are necessary when determining the extent of investigation. Oral rehydration remains the mainstay of therapy and antibiotics are reserved for specific clinical situations and infections.

Viral causes of diarrhea

Viruses are important causes of diarrhea. In healthy adults, the main clinical manifestation is acute, self-limited gastroenteritis. Advances in molecular diagnostics have shown that epidemics of acute gastroenteritis most frequently are due to caliciviruses spread through contaminated food or through person-to-person contact. Application of similar technology is needed to make a definitive statement about the role of such candidate viruses as rotavirus, astrovirus, and adenovirus as the cause of nonepidemic acute gastroenteritis in adults. Rarely a previously healthy adult gets acute CMV colitis. CMV and EBV mainly cause diarrhea in immunocompromised patients, however. Advances in prophylaxis and treatment have reduced the frequency and severity of these diseases. Acute infantile gastroenteritis is caused by rotavirus, calcivirus, astrovirus, and adenovirus. These viral diseases of the gut are seen by the physician as routine and rare clinical problems.

Acute diarrhoea in children treated in an outpatient setting in Athens, Greece

OBJECTIVE

To describe the epidemiology and aetiology of acute diarrhoea among children treated exclusively in an outpatient setting in Greece.

METHODS

During 1999, children with acute diarrhoea who attended the emergency department of our hospital were prospectively studied. Patients requiring hospitalization were excluded. Stool specimens were tested microscopically, for bacterial enteropathogens by standard and selective medium cultures and for rotavirus and adenovirus by latex agglutination test.

RESULTS

One hundred and thirty-two children (median age: 2 years) were included in the study; an enteropathogen was detected in 63 (48%) of them. Isolates included rotavirus (19 patients), Salmonella sp (12), Campylobacter sp (10), Aeromonas sp (9), enteropathogenic Escherichia coli (6), adenovirus (6), Giardia lamblia (4), Yersinia enterocolitica (2) and Shigella sp (1). Half of the bacterial cases occurred from August to October, and two rotavirus-associated peaks occurred during February and August. Acute diarrhoea caused by viruses affected exclusively children under six years of age, mainly those attending day care centres. Macroscopic blood in stools was reported only among patients with a bacterial infection. Socioeconomic characteristics were not helpful in differentiating disease due to specific enteropathogens.

CONCLUSIONS

Bacterial enteropathogens account for a significant proportion of acute diarrhoea in children treated in the outpatient setting in Greece. Rotavirus is also a frequent cause affecting mostly younger children and those attending day care centers. The presence of blood in stools and the seasonality of bacterial infections may enable their presumptive diagnosis.

EPEC, EAEC and STEC in stool specimens: prevalence and molecular epidemiology of isolates

Stool specimens of Finns (n = 695) with (n = 603) and without (n = 92) diarrhea were studied for enteropathogenic (EPEC), enteroaggregative (EAEC) and Shiga toxin-producing (STEC) Escherichia coli by PCR. The specific isolates were subsequently investigated for their O:H serotypes and were genotyped by pulsed-field gel electrophoresis (PFGE). A subset (n = 506) of the diarrheal and all non-diarrheal specimens were also searched for conventional enteric bacterial pathogens by standard methods. Diarrheagenic E. coli were found in 5.5% and other enteric pathogens in 6.7% of the patients with and in 2.2% and 1.1% of the subjects without diarrhea, respectively. Campylobacter (3.8%), EPEC (3.2%) and Salmonella (2.0%) were the most common findings, and were detected in diarrheal patients only. STEC were associated with bloody diarrhea (8/9 isolates), whereas EAEC were equally common (1%) in diarrheal and non-diarrheal subjects. Great genomial heterogeneity was seen among diarrheagenic E. coli, and only one EPEC isolate belonged to the "classic" EPEC serogroup (O55).

Gastrointestinal infections in children

New pathogens that cause gastroenteritis in children are being recognized. Even well-recognized pathogens, such as Clostridium difficile, may require more extensive testing than was previously thought necessary. Several new tests have emerged that allow for faster identification of these pathogens so that same-day results may be possible. Probiotic therapy has emerged as a novel strategy for the treatment of gastroenteritis. New vaccines against both viral and bacterial causes of gastroenteritis are being developed. The most exciting recent advance in vaccine development may be the creation of edible vaccines.

Viral infections of the gastrointestinal tract

Viral gastroenteritis is a major public health problem worldwide, and the number of identified pathogens continuously increases. Investigators have made considerable progress toward understanding both the epidemiology and the mechanisms of virus-cell interactions, host responses, and pathogenesis. A vaccine for the most important pathogen, rotavirus, has been approved by the US Food and Drug Administration, but possible complications have temporarily curbed the use of this vaccine.

Parasitic infections of the intestines

Intestinal parasites remain extremely common worldwide. In developing countries, intestinal protozoans are important causes of childhood diarrhea. Cryptosporidiosis is a common cause of chronic diarrhea in patients with AIDS. With the advent of current active antiretroviral therapy the incidence of cryptosporidiosis in AIDS has decreased. By contrast, Cryptosporidium, Cyclospora, and Giardia outbreaks continue to be associated with contamination of food or water. The intestinal helminths Ascaris, hookworm, and Trichuris each infects over a thousand million people. While most of those infected experience only minor symptoms, recent data highlight subtle effects of parasitism on cognitive function and nutrition. Efforts at disease control in developing countries are increasingly focused on mass chemotherapy.

A multicenter randomized controlled trial of a liquid loperamide product versus placebo in the treatment of acute diarrhea in children

This randomized, double-blind, placebo-controlled trial of 48 hours' duration conducted in 13 primary care ambulatory practices in the United States and Mexico was used to compare the efficacy and safety of loperamide with placebo for the treatment of acute diarrhea in children aged 2 through 11 years. Two hundred fifty-eight children with acute nonspecific diarrhea were enrolled. Children were randomly assigned to treatment with loperamide HCl 0.5 mg/5 mL (n = 130) or placebo (n = 128). The first dose of loperamide consisted of either 1.0 mg (children 2 through 5 years of age) or 2.0 mg (children 6 through 11 years of age) of study medication under the observation of study personnel. This was followed by 1 mg after each unformed stool, with a total daily dose of up to 3.0 mg in the children 2-5 years of age, 4.0 mg in the children 6-8 years of age, and 6.0 mg in the children 9-11 years of age. The primary outcome measures were time to last unformed stool, time to first unformed stool, number of unformed stools during six consecutive 8-hour periods, and overall rating of efficacy/acceptability. Secondary outcomes included abdominal pain/cramping, vomiting, and fever. Children who received loperamide had significantly shorter time to last unformed stool (p = 0.0017) and fewer numbers of unformed stools (p = 0.0237) than children who received placebo. The end-of-study overall efficacy/acceptability rating of loperamide was significantly better than for placebo (p = 0.0107). All other clinically important outcome measures related to diarrhea relief favored loperamide. There was no significant difference in the incidence of drug-related adverse events between treatment groups, although total adverse events were reported more frequently (p = 0.048) by the loperamide group (15%) compared with the placebo group (7%). In conclusion, this controlled study provides data demonstrating that at recommend doses, loperamide is well tolerated and significantly shortens the duration and severity of symptoms of acute nonspecific diarrhea in children 2 through 11 years of age.

New causes and treatments for infectious diarrhea in children

Infectious diarrhea is a universal and important health problem in the pediatric population. An expanding number of potential viral, bacterial, and parasitic pathogens have been associated with diarrheal disease. However, the epidemiologic association of a microorganism with diarrhea is only one step in the process of identifying new pathogens. Once the virulence mechanisms of these organisms are elucidated, a causal relationship can be more readily defined. This article reviews the etiologic agents of diarrhea in the pediatric population and focuses on the newer treatment and prevention modalities, including probiotics and vaccinations, which are used increasingly to combat these diseases.