Epidemiology of diarrheal disease among children enrolled in four West Coast health maintenance organizations. Vaccine Safety Datalink Team

The role of rotavirus associated with pediatric gastroenteritis in a general hospital in Lagos, Nigeria

INTRODUCTION

Bacterial, viral and parasitic agents have been implicated and confirmed as causative agents of gastroenteritis in children with ages below 5 years old. The major role of rotavirus as causative agent is not widely recognized within the public health community, particularly in developing countries. This study examined the role of rotavirus as a causative agent of childhood gastroenteritis in infants and young children below 5 years of age in a General Hospital in Lagos, Nigeria.

METHODS

Parents and caregivers of children admitted to the hospital were interviewed using a structured questionnaire. Viral RNA was extracted from the stool samples collected and analyzed using RT-PCR for genotyping and agarose gel electrophoresis for identification of rotavirus electrophoretypes.

RESULTS

Out of the 71 samples analyzed, 16 (22.5%) were positive for rotavirus. A total of 12 (75%) males and 4 (25%) females were positive for rotavirus gastroenteritis with most cases (7, 43.8%) distributed to the 13-24 months age group, followed closely by the 1-6 months age group, with 6 cases, 37.5%. Rotavirus G2 genotype was the most prevalent strain in the hospital (10 patients, 62.5%) followed by G1 (6 patients, 37.5%). These were the only rotavirus genotypes detected in the hospital.

Burden of rotavirus hospitalisations in young children in three paediatric hospitals in the United States determined by active surveillance compared to standard indirect methods

AIM

  The number of rotavirus hospitalisations is usually estimated from assigned diagnosis codes for gastroenteritis despite lack of validation for these indirect methods. Reliable estimates before and after introduction of vaccines are needed to quantify the absolute impact of new immunisation programs.

METHODS

  This 2-year study conducted at three hospitals prior to the licensure of the rotavirus vaccines in the USA compared two indirect methods for estimating hospitalisations for rotavirus gastroenteritis with estimates derived from prospective recruitment of children presenting with diarrhoea, vomiting or fever. For active surveillance, rotavirus gastroenteritis was confirmed by demonstration of stool antigen. The indirect residual and proportional methods assumed rotavirus to have caused a proportion of hospitalisations coded as acute gastroenteritis identified from computerised records.

RESULTS

  There were 447 rotavirus hospitalisations among inpatients 31 days through 4 years of age admitted with vomiting and/or diarrhoea, compared with 306 and 228 hospitalisations identified by the two indirect methods. Only 52% of children hospitalised with gastroenteritis received a qualifying diagnosis code at discharge. Relative to active surveillance, the sensitivity and specificity (95% confidence interval (CI)) in identifying rotavirus-attributable hospitalisations was 45% (95% CI: 43-48%) and 89% (88-90%) for the residual method and 34% (30-39%) and 92% (90-94%) for the proportional method.

CONCLUSIONS

  Many children admitted to the hospital with diarrhoea, vomiting or fever were not assigned discharge codes for acute gastroenteritis. Consequently, standard indirect methods missed a substantial number of rotavirus-associated hospitalisations, thereby underestimating the absolute number of children who could potentially benefit from vaccination.

Economic analysis of rotavirus-associated diarrhea in the metropolitan Toronto and Peel regions of Ontario

OBJECTIVE

To measure the economic cost of rotavirus-associated diarrhea for a selected group of families, in a nonexperimental setting, and to estimate the factors that influence these costs.

DESIGN

Use and other socioeconomic data from a family survey (the Pediatric Rotavirus Epidemiology Study for Immunization) of children who tested positive for rotavirus were collected for the metropolitan Toronto and Peel regions of Ontario during the rotavirus season of 1997-1998. Service costs were estimated from provider data. A statistical regression analysis was used to explain the variances of provincial health care costs, prescription drug costs and indirect (work-loss) costs.

SETTING

Data were collected in hospitals, emergency rooms, paediatric practices, primary care clinics and licensed daycare centres. Hospital coverage was wide, but community coverage was not.

PATIENTS AND OTHER PARTICIPANTS

Children with diarrhea were tested for rotavirus. Those who tested positive and whose parents consented for their children to participate were included in the study.

INTERVENTIONS

None

MAIN OUTCOME MEASURES

The main outcomes were provincial health care costs, drug costs, nonmedical costs and the number of days of work missed by parents per child, as well as factors that determine these costs.

RESULTS

Children in the most severe category incurred costs of $2,663/person, and those in the least severe categories incurred costs of approximately $350/person. The most important determinant to explain provincial health care costs was the number of health problems that the child had before having rotavirus. Costs due to work loss of parents were considerable for children in all severity groups and were influenced by family working conditions.

CONCLUSIONS

When considering the economic implications of rotavirus, prior health status should be considered and indirect costs should be recognized for their importance.

An overview of the clinical use of ondansetron in preschool age children

The introduction of 5-HT₃ receptor antagonist has revolutionized the prevention and treatment of nausea and vomiting in preschool aged children. These distressing symptoms, arising from multiple etiologies such as anesthesia, chemotherapy, and viral infection, are a major concern of patients and their families. Clinical research has demonstrated the antiemetic effectiveness of ondansetron in children. Although most of these studies focus primarily on preventing vomiting across the pediatric age group, they provide strong evidence for the use of ondansetron in preschool age children. For children at high risk, pediatric practice guidelines recommend ondansetron in conjunction with other antiemetics to achieve complete control of symptoms.

The Vaccine Safety Datalink: a model for monitoring immunization safety

The Vaccine Safety Datalink (VSD) project is a collaborative project between the Centers for Disease Control and Prevention and 8 managed care organizations (MCOs) in the United States. Established in 1990 to conduct postmarketing evaluations of vaccine safety, the project has created an infrastructure that allows for high-quality research and surveillance. The 8 participating MCOs comprise a large population of 8.8 million members annually (3% of the US population), which enables researchers to conduct studies that assess adverse events after immunization. Each MCO prepares computerized data files by using a standardized data dictionary containing demographic and medical information on its members, such as age and gender, health plan enrollment, vaccinations, hospitalizations, outpatient clinic visits, emergency department visits, urgent care visits, and mortality data, as well as additional birth information (eg, birth weight) when available. Other information sources, such as medical chart review, member surveys, and pharmacy, laboratory, and radiology data, are often used in VSD studies to validate outcomes and vaccination data. Since 2000, the VSD has undergone significant changes including an increase in the number of participating MCOs and enrolled population, changes in data-collection procedures, the creation of near real-time data files, and the development of near real-time postmarketing surveillance for newly licensed vaccines or changes in vaccine recommendations. Recognized as an important resource in vaccine safety, the VSD is working toward increasing transparency through data-sharing and external input. With its recent enhancements, the VSD provides scientific expertise, continues to develop innovative approaches for vaccine-safety research, and may serve as a model for other patient safety collaborative research projects.

Unexpectedly high burden of rotavirus gastroenteritis in very young infants

BACKGROUND

The highest incidence of rotavirus gastroenteritis has generally been reported in children 6-24 months of age. Young infants are thought to be partially protected by maternal antibodies acquired transplacentally or via breast milk. The purpose of our study was to assess the age distribution of children with confirmed community-acquired rotavirus gastroenteritis presenting to an urban referral hospital.

METHODS

Children presenting to The Children's Hospital of Philadelphia with acute gastroenteritis have been monitored for the presence of rotavirus antigen in the stool by ELISA (followed by genotyping if ELISA-positive) since the 1994-95 epidemic season.

RESULTS

Over the last 12 rotavirus seasons prior to the introduction of the pentavalent rotavirus vaccine in 2006, stool specimens from 1646 patients tested positive for community-acquired rotavirus infection. Gender or age was not recorded in 6 and 5 cases, respectively. Overall, 58% of the cases occurred in boys. G1 was the predominant VP7 serotype, accounting for 72% of cases. The median (IQR) age was 11 (5-21) months. A total of 790 (48%) cases occurred in children outside the commonly quoted peak age range, with 27% in infants <6 months of age and 21% in children >24 months of age. A total of 220 (13%) cases occurred during the first 3 months of life, and the highest number of episodes per month of age [97 (6%)] was observed during the second month of life.

CONCLUSIONS

The incidence of community-acquired rotavirus gastroenteritis monitored over 12 seasons in the prevaccine era at a major university hospital was nearly constant for each month of age during the first year of life, revealing an unexpectedly high incidence of symptomatic rotavirus disease in infants <3 months old. A sizeable fraction of cases occurred in children too young to have been vaccinated according to current recommendations.

Rotavirus gastroenteritis in Norway: analysis of prospective surveillance and hospital registry data

We aimed to evaluate rotavirus morbidity and describe rotavirus epidemiology in hospitalized children in Norway to provide information before the introduction of new rotavirus vaccines. We retrospectively reviewed 14,973 gastroenteritis hospitalizations in children aged <5 y for the period 1995 to 2004, and prospectively surveyed for rotavirus in 311 children aged <5 y admitted with diarrhoea to 3 hospitals in 2006-2008. The proportion of rotavirus among all gastroenteritis hospitalizations was estimated at 14.5% from the retrospective data and at 62.9% in the prospective data. The annual incidence of rotavirus hospitalizations is estimated to be 3 per 1000 children <5 y of age, corresponding to approximately 900 (range 735-1092) hospitalizations each year. Children aged 6-23 months accounted for 61% of all confirmed rotavirus cases, and average duration of hospital stay for rotavirus cases was 1.3 days. We observed a predominance of rotavirus infections from March through May, similar to the seasonality of diarrhoea-associated hospitalizations with viral and unspecified aetiology. No rotavirus-associated deaths were reported. It is estimated that two thirds of all gastroenteritis hospitalizations in children <5 y of age may be attributable to rotavirus in Norway. Continued surveillance and further studies are needed to assess the full burden of rotavirus disease and its economic impact in Norway.

Trends in healthcare utilization for diarrhea and rotavirus disease in privately insured US children <5 years of age, 2001-2006

BACKGROUND

To assess impact of the new US rotavirus immunization program initiated in 2006, robust baseline data on diarrhea and rotavirus disease burden are needed. While several studies have assessed burden in inpatient settings, few data are available for emergency department (ED) and outpatient settings.

METHODS

We used the MarketScan databases, a large claims-based data repository, to analyze the health and economic burden of diarrhea-related healthcare encounters in children <5 years in inpatient, ED, and outpatient settings from 2001 to 2006. Because rotavirus testing and coding are not routinely performed, rotavirus burden was estimated by calculating excess diarrhea events during winter compared with summer baseline (winter residual method).

RESULTS

Between 2001 and 2006, the average annual rate of healthcare utilization for diarrhea was 1561 per 10,000 children <5 years, with a hospitalization rate of 50 per 10,000, ED visit rate of 180 per 10,000, and outpatient visit rate of 1332 per 10,000. The winter residual method attributed 53% of inpatient, 41% of ED, and 23% of outpatient diarrhea events to rotavirus. By age 5, we estimated that 1 in 74 children are admitted, 1 in 27 require ED care, and 1 in 7 are treated in outpatient settings for rotavirus illness. Median payments for rotavirus in inpatient, ED, and outpatient settings were $3135, $332, and $90, respectively.

CONCLUSIONS

Rotavirus causes substantial health and economic burden in US children, especially in ED and outpatient settings. Future monitoring through claims-based data sources should allow assessment of rotavirus vaccine impact on healthcare utilization for diarrhea.

Is environmental tobacco smoke exposure a risk factor for acute gastroenteritis in young children?

Because passive smoke exposure has not been previously linked to diarrhea diseases in children, it was hypothesized that very young children exposed to environmental tobacco smoke (ETS) exposure at home would also be more likely to develop infectious gastroenteritis (GE) than their unexposed counterparts. During 1-year period, 260 children 36 months and younger were prospectively followed up in a private pediatric practice in a southern community in the United States. Multiple logistic regression analysis showed that ETS was strongly predictive of acute GE in the univariate analysis (P = .003). Even after controlling for the various confounders, ETS exposure was still significantly associated with acute GE (relative risk = 2.55; 95% CI = 1.26-5.18). It is speculated that, similar to acute respiratory infections, the same mechanisms may explain why ETS may also be associated with acute infectious GE.

National rates of diarrhea-associated ambulatory visits in children

OBJECTIVE

To estimate national rates of ambulatory healthcare visits due to diarrhea- and rotavirus-associated illness before the introduction of rotavirus vaccine.

STUDY DESIGN

Annual rates for diarrhea-associated visits in children age < 5 years were calculated for 1995-2004 using National Ambulatory Medical Care Survey, National Hospital Ambulatory Medical Care Survey, and US Census Bureau data. Rates by age, race, and time period were compared using Poisson regression.

RESULTS

Annual rates of outpatient and emergency department (ED) visits for 1995-2004 were 955 (95% confidence interval [CI] = 803 to 1107) and 314 (95% CI = 278 to 350)/10,000 person-years, respectively. Annual outpatient (P = .470) and ED (P = .734) visit rates remained stable from 1995 to 2004. Outpatient visits were less frequent in African Americans than Caucasians (716/10,000 person-years vs 1012/10,000 person-years; P < .05; incidence rate ratio [IRR] = 0.71; 95% CI = 0.51 to 0.99), whereas ED visits were more frequent in African Americans than Caucasians (520/10,000 person-years vs 286/10,000 person-years; P < .05; IRR = 1.83; 95% CI = 1.58 to 2.11). Approximately 29% of outpatient diarrhea-associated outpatient visits (273/10,000 person-years; 95% CI = 145 to 401) and 25% of diarrhea-associated ED visits (78/10,000 person-years; 95% CI = 64 to 83) were due to rotavirus.

CONCLUSIONS

Diarrhea- and rotavirus-associated illness is associated with significant healthcare utilization. Future studies are needed to investigate factors causing differences in healthcare use by race and to explore the impact of the rotavirus vaccine.

Burden of acute gastroenteritis hospitalizations and emergency department visits in US children that is potentially preventable by rotavirus vaccination: a probe study using the now-withdrawn rotashield vaccine

BACKGROUND

With the implementation of a new rotavirus immunization program in the United States in 2006, determining the potential health benefits of rotavirus vaccination is important. We estimated the burden of acute gastroenteritis hospitalizations and emergency department visits in US children that are potentially preventable by rotavirus vaccination.

METHODS

We conducted a retrospective cohort analysis of children who in 1998-1999 were eligible to receive a now-withdrawn rotavirus vaccine (RotaShield) and were continuously enrolled in 1 of 6 managed care organizations in the Vaccine Safety Datalink. Estimates of vaccine effectiveness against all-cause gastroenteritis hospitalizations and emergency department visits adjusted according to month of birth, gender, and managed care organizations were calculated as 1 minus the risk ratio of outcomes among children in different dose groups. The burden of acute gastroenteritis prevented by vaccination was compared with the rotavirus burden estimated by 2 previously used indirect methods.

RESULTS

The effectiveness of a full 3-dose RotaShield series over a 1-year follow-up period was 83% against all-cause gastroenteritis hospitalizations and 43% against all-cause gastroenteritis emergency department visits. An increasing number of doses improved the effectiveness in preventing gastroenteritis hospitalizations, but no clear trend was observed between number of doses and effectiveness in prevention of gastroenteritis emergency department visits. The proportion of gastroenteritis hospitalizations and emergency department visits prevented by vaccination was substantially greater than the 48% to 53% of year-round hospitalizations and 33% of emergency department visits estimated to result from rotavirus by indirect methods.

CONCLUSIONS

The withdrawn rotavirus vaccine was highly effective in preventing hospitalizations and emergency department visits for all-cause acute gastroenteritis and the health benefits of vaccination against rotavirus may be greater than previously estimated.

Trends in healthcare usage attributable to diarrhea, 1995-2004

OBJECTIVE

To determine current diarrhea-associated healthcare usage rates and associated sociodemographic factors. These data can be used to determine the impact of the rotavirus vaccine.

STUDY DESIGN

Using discharge diagnosis codes, we determined diarrhea-associated visit rates for children aged 0 to 18 years enrolled in Tennessee Medicaid, 1995-2004. Poisson regression compared data across time and within strata. The winter residual excess method estimated the rotavirus burden.

RESULTS

Analyzing approximately 500 000 person-years annually, outpatient and hospitalization rates remained stable from 1995 to 2004; emergency department (ED) rates approximately doubled, incidence rate ratio (IRR): 1.92 (1.81-2.04). White children used healthcare at greater rates than black children: outpatient IRR 1.90: (1.85-1.95), ED IRR: 1.69 (1.64-1.74), and inpatient IRR: 1.82 (1.73-1.92); and rural children greater than urban: outpatient IRR 1.66 (1.62-1.70), ED IRR 1.14 (1.11-1.17), inpatient IRR 1.88 (1.80-1.97). Children aged 0 to 35 months experienced 1627 outpatient and 792 ED visits, and 148 hospitalizations per 10 000 child-years; rotavirus may have affected up to 40% of these hospitalizations.

CONCLUSIONS

Diarrhea-associated ED visit rates nearly doubled from 1995 to 2004. Future studies could explore factors resulting in increased healthcare usage by white children and those living in rural areas and document the rotavirus vaccine's impact after its release.

Burden of rotavirus disease among children visiting pediatric emergency departments in Cincinnati, Ohio, and Oakland, California, in 1999-2000

OBJECTIVE

We assessed the incidence of rotavirus disease requiring an emergency department visit among children <5 years of age.

METHODS

We conducted active surveillance for acute gastroenteritis in pediatric emergency departments in Cincinnati, Ohio, and Oakland, California, from March 1999 to May 2000, among children 2 weeks to 59 months of age with acute diarrhea and/or vomiting. We obtained clinical and demographic information from participants and tested their stool specimens for rotavirus.

RESULTS

Approximately 9% of all emergency department visits at the study sites were attributable to acute gastroenteritis. A total of 1433 children were eligible at the 2 sites; 85% were enrolled and 68% provided a stool specimen. Overall, rotavirus was detected in specimens from 27% of children (30% in Cincinnati and 24% in Oakland). Rotavirus detection was higher in bulk stools, compared with rectal swabs, at both Cincinnati (37% vs 23%) and Oakland (46% vs 18%). Patients with rotavirus had more-severe disease than did those with nonrotavirus gastroenteritis. We estimated that the mean annual incidence of emergency department visits attributable to rotavirus was 12 cases per 1000 children in Cincinnati and 15 cases per 1000 children in Oakland. Through extrapolation, we estimated that rotavirus infection causes approximately 260,910 emergency department visits per year among US children.

CONCLUSION

Active surveillance demonstrated that the burden of laboratory-confirmed rotavirus disease treated in emergency department settings among US children is substantial and greater than estimated previously.

Rotavirus vaccine introduction in the Americas: progress and lessons learned

In Latin America and the Caribbean, rotavirus causes approximately 15,000 deaths, 75,000 hospitalizations, 2 million clinic visits and 10 million cases of rotavirus diarrhea annually. Two safe vaccines are available that are effective in preventing severe illness. To date, seven countries in Latin America (Brazil, Ecuador, El Salvador, Panama, Mexico, Nicaragua and Venezuela) have introduced the vaccine. For successful rotavirus vaccine introduction, the lessons learned re-emphasize the critical need for countries to have precise plans that will ensure technical, programmatic and financial sustainability of vaccine introduction. Of these lessons learned, programmatic feasibility and financial sustainability were particularly challenging for countries that were the first to introduce a rotavirus vaccine.

Diarrhea-associated hospitalizations and outpatient visits among American Indian and Alaska Native children younger than five years of age, 2000-2004

BACKGROUND

Diarrhea accounts for many hospitalizations and outpatient clinic visits among children. American Indian and Alaska Native (AI/AN) children have experienced a greater infectious disease burden compared with the general U.S. population of children, although diarrhea-associated hospitalization rates have declined among AI/AN children.

METHODS

Hospital discharge and outpatient visit records with a diagnosis indicating a diarrhea-associated diagnosis were evaluated for AI/AN children <5 years of age, using the 2000-2004 Indian Health Service Direct and Contract Health Service Inpatient Data and outpatient visit data from the Indian Health Service National Patient Information Reporting System, and for the general U.S. population of children <5 years of age using the Kids' Inpatient Database for 2003 and National Ambulatory data for 2000-2004.

RESULTS

For 2000-2004, the diarrhea-associated hospitalization rate was similar for AI/AN children and U.S. children <5 years of age (65.9 and 79.3 of 10,000, respectively), but the rate among AI/AN infants was nearly twice the rate among U.S. infants (262.6 and 154.7 of 10,000, respectively). The rate of diarrhea-associated outpatient visits among AI/AN children was higher than for U.S. children (2255.4 versus 1647.9 of 10,000, respectively), as a result of the high rate among AI/AN infants compared with U.S. infants (6103.5 and 2956.3 of 10,000, respectively).

CONCLUSIONS

Although the diarrhea-associated hospitalization rate in AI/AN children <5 years old has declined to levels comparable with that of all U.S. children, the rate for AI/AN in infants remains higher than for U.S. infants. The diarrhea-associated outpatient visit rate for AI/AN children was higher than for U.S. children. Ongoing evaluation of hospitalization and outpatient data is important to understand the impact of rotavirus vaccine among AI/AN children.

Impact of acute rotavirus gastroenteritis on pediatric outpatient practices in the United States

OBJECTIVES

The objectives of this study were to determine the presenting symptoms, healthcare utilization, and lost time from work and day care associated with acute rotavirus gastroenteritis.

METHODS

During the winter to spring seasons of 2002-2003 or 2003-2004, children <36 months of age presenting with acute gastroenteritis to urban and suburban pediatric outpatient practices affiliated with 5 academic centers across the United States were enrolled in similarly designed studies. The case definition required >or=3 watery or looser-than-normal stools and/or forceful vomiting within a 24-hour period beginning <or=72 hours before presentation. Stool samples were tested for rotavirus antigen by standard commercial assays. Symptom frequencies for laboratory-confirmed rotavirus and nonrotavirus gastroenteritis were compared by Fisher's exact test; the number of healthcare contacts and lost days from work or day care were compared with the median 2-sample test.

RESULTS

Stool specimens were obtained from 284 of 303 (94%) participants; 115 (40%) of tested specimens were positive for rotavirus (range, 31-50% across the 5 centers). Compared with participants with nonrotavirus gastroenteritis, children with rotavirus gastroenteritis were more likely to have 1) vomiting (83% versus 66%; P = 0.003), 2) combined diarrhea and vomiting (75% versus 50%; P < 0.001), and 3) fever (60% versus 43%; P = 0.010). More time from work was lost by parents/guardians of children with rotavirus than nonrotavirus gastroenteritis (median 2 versus 0 day; P = 0.007). More day care was missed by children with rotavirus than nonrotavirus gastroenteritis (median 3 versus 1 day; P = 0.002).

CONCLUSIONS

In this multicenter study, rotavirus consistently caused a sizable proportion of cases of acute gastroenteritis seen in pediatric outpatient practices in the United States during the winter and spring. Rotavirus gastroenteritis was more frequently associated with vomiting, combined diarrhea and vomiting, fever and lost time from work and day care than nonrotavirus gastroenteritis.

Hospitalizations associated with rotavirus gastroenteritis in the United States, 1993-2002

BACKGROUND

In the United States, rotavirus gastroenteritis remains a common disease of children that results in many hospitalizations, clinic visits and medical costs. It is a common cause of morbidity and is associated with a high economic burden in developing countries. Prevention of hospitalizations is the primary target of rotavirus vaccines.

METHODS

To update estimates of rotavirus hospitalization rates in the United States, we conducted a retrospective analysis of 10 years of national hospitalization data associated with gastroenteritis and used both direct and indirect methods to estimate the percentage of cases associated with rotavirus gastroenteritis.

RESULTS

During 1993-2002, an average of 18% of all hospitalizations with gastroenteritis among children <5 years old were associated with rotavirus infection as determined by the rotavirus-specific International Classification of Diseases, 9th revision, Clinical Modification code. The annual proportion of rotavirus-associated hospitalizations increased from 15% in 1993-1995 to 21% in 2000-2002. Hospitalizations associated with rotavirus and those associated with nonspecific gastroenteritis had a marked winter-time seasonality and similar age distribution, which peaked among children between 3 and 24 months old. Using indirect estimation methods, 58,000 to 70,000 rotavirus-associated hospitalizations were estimated to occur each year in the United States.

CONCLUSIONS

Rotavirus gastroenteritis remains an important cause of hospitalizations in the United States, and the rate has not declined from 1993 through 2002.

Rotavirus vaccine: early introduction in Latin America-risks and benefits

Rotavirus infection is the cause of severe gastroenteritis of young children worldwide, leading to an estimate of 600,000 deaths a year. Efforts to develop an effective and safe vaccine resulted in licensing in 1998 of a live oral vaccine (RotaShield) that was withdrawn less than 1 year later when reports of cases of intussusception were linked to its application. This led to development of new rotavirus vaccine candidates that are currently in late phase III clinical trials. One of these vaccines, GlaxoSmithKline's Rotarix, was licensed in July 2004 to be used in Mexico. This review describes the general background for rotavirus vaccine development, the different vaccine candidates that have been tested or are currently being evaluated, the association of rotavirus vaccination with the bowel blockage known as intussuception, and discusses the benefits and risks of the fast-track introduction of Rotarix in Latin America, and particularly in Mexico.

The Rotavirus Vaccine Saga

Rotavirus is the single most common cause of acute, dehydrating gastroenteritis worldwide. This is a highly contagious and highly democratic disease. The attack rate in infants and young children is similar regardless of sanitation, socioeconomics or geography. Rotavirus vaccine development began in the early 1980s using a "Jennerian" approach based on rotaviruses that normally infect animals. Although these vaccines were found to be generally safe, protection from disease was inconsistent. The second generation of vaccines was based on the same animal viruses configured to carry the relevant coat proteins of human rotaviruses. An attenuated human rotavirus vaccine has also been developed. After close to 20 years of laboratory and clinical studies, safe and effective rotavirus vaccines are approaching regulatory approval.

Evaluation of safety, immunogenicity and efficacy of an attenuated rotavirus vaccine, RIX4414: A randomized, placebo-controlled trial in Latin American infants

BACKGROUND

A live attenuated monovalent rotavirus vaccine RIX4414 was developed with a human strain of G1P1A P[8] specificity to reduce the rotavirus burden in children.

METHODS

A double blind, randomized, placebo-controlled study evaluated the efficacy, immunogenicity, safety and reactogenicity of 2 oral doses of RIX4414 (10(4.7), 10(5.2) or 10(5.8) focus-forming units) at 2 and 4 months coadministered with routine vaccinations and oral poliovirus vaccine given for study purposes at least 14 days apart. The 2155 infants (1618 vaccine/537 placebo) enrolled in Brazil, Mexico and Venezuela were followed until 1 year of age.

RESULTS

Antirotavirus IgA seroconversion rates 2 months after dose 2 ranged between 61% (10(4.7) ffu group) and 65% (10(5.8) ffu group), and most of the infants had seroprotective levels of antibodies to coadministered routine vaccinations. The reactogenicity profile of RIX4414 was similar to that of the placebo, and no vaccination-related serious adverse events were reported. Protective efficacy against severe and any rotavirus gastroenteritis from 15 days post-dose 2 was highest in the 10(5.8) ffu group [86%; 95% confidence interval (95% CI), 63-96% and 70% (95% CI 46-84%), P < 0.001, 2-sided Fisher's exact test]. The efficacy against hospitalization was 79% (95% CI 48-92%) for pooled vaccine groups. Multiple rotavirus serotypes [G1 (50%), G9 (40%), G2, G3 and G4] were identified from gastroenteritis stools (enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction) during the study period. For severe gastroenteritis caused by G9 serotypes, the protection reached 77% (95% CI 18-96%) in the 10(5.8) ffu group, providing proof of concept that the monovalent G1P1A P[8] human rotavirus vaccine elicits cross-protection against the G9 strain. A reduction in any and severe rotavirus gastroenteritis was already observed at post-dose 1 (period: day of dose 1 to 14 days post-dose 2) in vaccinees compared with placebo recipients.

CONCLUSIONS

Two doses of RIX4414 are highly efficacious, providing cross-protection (G1 and G9 strains, prevalent during this study) and early protection against any and severe rotavirus gastroenteritis and hospitalization to infants in Latin America.

Natural rotavirus infection is not associated to intussusception in Mexican children

AIMS

To determine whether natural rotavirus infection or infection by another enteropathogen is associated to intussusception (IS); and to describe the seasonality of IS compared with severe diarrhea (SD) and rotavirus SD in Mexican children.

METHODS

A prospective, observational, multicenter and case-control study was conducted in Mexico City from December 1999 to February 2001. Cases were children younger than 1 year old hospitalized for IS; diagnosis was made by clinical features, radiologic and/or surgery findings. Controls were children younger than 1 year old hospitalized for another disease than a gastrointestinal illness (NGI). Cases and controls were paired by age and date of admission (+/-3 months; for both), in a 1:2 ratio. A surveillance of IS cases, SD and rotavirus SD episodes was conducted during the study period. Stool samples collected soon after IS resolution or at admission were tested for rotavirus, adenovirus, astrovirus, bacteria and parasites.

RESULTS

Thirty cases of IS and 60 controls with NGI were studied. Rotavirus was not detected in any case of IS. Adenovirus (17%) was the only enteropathogen detected in IS. Rotavirus (8%), adenovirus (2%), astrovirus (2%) and bacteria (2%) were detected in NGI. Rotavirus infection was not associated with IS (odds ratio, 0; 95% confidence interval, 0-2.9), whereas adenovirus infection was strongly associated as risk factor for IS (odds ratio undefined; P = 0.003), compared with NGI. Seasonal variation in admissions for IS was small, whereas admissions for SD and rotavirus SD showed a marked seasonal increase during fall-winter.

CONCLUSIONS

In Mexican children, rotavirus infection was not associated to IS; whereas a significant association was observed between adenovirus and IS. Also there was no increase in IS cases during the sharply defined fall-winter rotavirus outbreak. Observations from this controlled study suggest that natural rotavirus infection is not a risk factor for IS. This information may have implications for development of a safer and effective rotavirus vaccine.

Epidemiologic and clinical characteristics of rotavirus disease during five years of surveillance in Venezuela

BACKGROUND

To effectively introduce a rotavirus vaccine in developing countries, it is necessary to estimate the burden of rotavirus disease. Therefore we examined the epidemiologic and clinical features of rotavirus diarrhea in children younger than 5 years of age in Carabobo State and extrapolated these results to the rest of Venezuela.

METHODS

From January 1, 1998 to December 31, 2002, we conducted surveillance for rotavirus diarrhea in all children younger than 5 years of age at the Ciudad Hospitalaria Dr Enrique Tejera, in Valencia (Carabobo).

RESULTS

Rotavirus is the major cause of diarrhea in children younger than 5 years of age in Venezuela, accounting for one-fourth (23%) of all episodes of diarrhea requiring medical treatment and one-third (33%) of those requiring hospitalization. Rotavirus diarrhea was responsible for 3% of all hospitalizations and 2% of all medical visits. In Valencia, rotavirus had a marked seasonal peak during the dry and cold months of the year. Rotavirus was most frequent in children 3-23 months of age, and 61% of the cases occurred by the age of 1 year. In addition, rotavirus diarrhea was more severe in younger children. Overall, by the age of 5 years, 1 child in 72 will be hospitalized and 1 in 24 will visit the clinic for rotavirus disease. In Venezuela, we estimated that each year, 118,000 children experience rotavirus illness requiring medical care and 39,000 children require hospitalization.

CONCLUSIONS

This study confirms the significant impact of rotavirus disease in Venezuela. Rotavirus vaccines currently in development could diminish the morbidity associated with this common cause of childhood diarrheal disease.

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.

Disease burden and risk factors for hospitalizations associated with rotavirus infection among children in New York State, 1989 through 2000

OBJECTIVES

To examine trends in hospitalizations for pediatric diarrhea, ascertain the disease burden and risk factors for hospitalizations associated with rotavirus and assess the accuracy of coding for rotavirus hospitalizations in New York State.

METHODS

For 1989 through 2000, data were obtained for all diarrhea-associated hospitalizations in New York State among children 1 month through 4 years of age. Characteristics of patients hospitalized with rotavirus were compared with those for hospitalizations with diarrhea from other causes. Medical charts coded as rotavirus diarrhea were reviewed for patients who were discharged during 1997 to determine whether these diagnoses were supported with laboratory results.

RESULTS

Diarrhea was reported as a discharge diagnosis in approximately 13% of all hospitalizations for an annual incidence of 83 per 10 000 children. Viruses were the most common etiologic agents reported. Since 1993, when a rotavirus-specific code was introduced, rotavirus infection was coded for 8.7% of all diarrhea-associated hospitalizations. A total of 136 patients with diarrhea died during their hospitalization (hospital fatality rate, 1.6 per 1000), and the 12 deaths among patients with rotavirus had a distinct winter pattern. During 1997 only 46% of the hospitals reporting diarrhea in children used the specific code for rotavirus, and 12% of hospitals reported rotavirus in >30% of all diarrhea-associated hospitalizations. Infants <4 months of age were more likely than older children to be nosocomially infected with rotavirus and had a higher proportion of congenital malformations.

CONCLUSION

In New York State diarrhea is a common hospital discharge diagnosis and contributes approximately 13% of all hospitalizations among children <5 years of age. When hospitals with maximum recording were used as a reference point, >30% of diarrhea hospitalizations were recorded as likely the result of rotavirus.

Rotavirus vaccines--an update

Rotavirus vaccines offer the best hope to reduce the toll of acute rotaviral gastroenteritis in both developed and developing countries. An association with intussusception (IS) led to the withdrawal of the first licensed rotavirus vaccine in the USA in 1999, forcing a re-evaluation of the safety profile of potentially lifesaving vaccines. Development of new rotavirus vaccine candidates has continued, with a bovine-human reassortant vaccine and an attenuated human monovalent vaccine commencing Phase III trials. Several other candidates are in early Phase I and II clinical trials. The creation of innovative funding strategies to support vaccine development and production, specifically in developing countries, aim to make vaccines available where rotavirus causes the greatest impact.

Epidemiology, clinical course and impact on hospitalization costs of acute diarrhea among hospitalized children in Athens, Greece

The aim of this study was to describe the etiology, morbidity and hospitalization costs associated with acute diarrhea among hospitalized children in Greece. During 1999, 294 hospitalized children (median age 1 y) with acute diarrhea were prospectively studied. Bacterial and viral enteropathogens were detected in 100 (34%) and 37 (12.5%) patients, respectively; 17 (6%) patients had mixed infections. Isolated agents included Salmonella spp. (43 patients; 15%), rotavirus (32; 11%), Campylobacter spp. (26; 9%), enteropathogenic Escherichia coli (16; 5.5%), Shigella spp. (11; 4%), Aeromonas spp. (7; 2.5%), adenovirus (6; 2%), Yersinia enterocolitica (6; 2%), enterohemorrhagic Escherichia coli (2; 0.5%) and Giardia lamblia (1; 0.5%). Of the patients with bacterial infection, 70% were admitted between April and September 1999. A rotavirus-associated peak was noted in March. Patients with a bacterial infection were hospitalized for longer periods than those with viral infections. It is concluded that bacterial enteropathogens account for one-third of admissions due to acute diarrhea among children in Greece and are associated with significant hospitalization costs. Rotavirus is also a frequent cause of acute diarrhea necessitating hospitalization.

Biotherapeutic agents in the treatment of infectious diarrhea

Biotherapeutic agents offer unique advantages over traditional treatments for infectious diarrhea, and several have been shown to be effective (Table 4). These therapeutic microbial agents are most effective in types of infectious diseases that are associated with a disruption of the normal intestinal microecology (e.g., AAD, C. difficile disease). The impact of biotherapeutic agents on rotaviral diarrhea is of special clinical importance because this is the most common cause of pediatric diarrhea, and there is no defined treatment. Strong efforts need to be made to limit antibiotic exposure in children. Biotherapeutic agents offer a safe and effective nonantibiotic method of treating this important pathogen, especially after the withdrawal of a rotaviral vaccine from the market by the FDA. However, for many biotherapeutic agents, well-done, placebo-controlled trials still are lacking, and not all types of infectious diarrhea respond to these agents. Continued research in this innovative therapeutic area is warranted.

International variation in disease burden of rotavirus gastroenteritis in children with community- and nosocomially acquired infection

BACKGROUND

The great impact of rotavirus disease on morbidity and medical health care costs in industrialized countries together with the withdrawal of the live oral rotavirus vaccine have made a reassessment of rotavirus gastroenteritis necessary. Such a reassessment should provide sufficient data for developing alternative disease prevention strategies and for allocating resources efficiently.

OBJECTIVES

To compare characteristics and management of community- and nosocomially acquired rotavirus disease in Austria, Germany and Switzerland.

PATIENTS AND METHODS

In a prospective, population-based, trinational (Austria, Germany, Switzerland), multicenter (9 cities, 10 hospitals and 30 pediatric practices) study, a total of 174 552 children months and 78 516 hospital days were evaluated. Participants were all children 4 years of age and younger, who either presented at one of the pediatric practices with community-acquired gastroenteritis, or who had acquired gastroenteritis nosocomially. From December, 1997, to May, 1998, prospective antigen testing was done by enzyme-linked immunosorbent assay, and serotyping was done by reverse transcription polymerase chain reaction. Disease severity was scored by the Vesikari severity scale.

RESULTS

Rotavirus was detected in 29.5, 27 and 37.5% of children with community-acquired gastroenteritis and in 57, 69 and 49% of children with nosocomial gastroenteritis in Austria, Germany and Switzerland, respectively. Severity of community-acquired rotavirus gastroenteritis was more pronounced in Austria (median severity score, 11) than in Germany (median score, 9) or Switzerland (median score, 10). However, only 2% of Austrian and Swiss children compared with 12% of German children presented to their pediatricians more than four times. Nosocomially acquired rotavirus gastroenteritis was mildest in Austria but occurred within the shortest median duration of hospitalization (4 days vs. 5 and 7 in Germany and Switzerland, respectively). In a multivariant analysis age, family size, day care, breast-feeding and nationality were not predictive factors for enhanced risk to contract rotavirus infection. Alimentation was changed frequently; diet was used between 23 and 83%; special formulas were used between 10 and 57%.

CONCLUSION

The cumulative experience from three European countries suggest that rotavirus is an important cause of diarrhea in Central Europe, but significant local differences clearly demonstrate the need for obtaining national data as a reliable basis for control and prevention of the disease.

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.

Rotavirus in Ireland: national estimates of disease burden, 1997 to 1998

BACKGROUND

We estimated the disease burden caused by rotavirus hospitalizations in the Republic of Ireland by using national data on the number of hospitalizations for diarrhea in children and laboratory surveillance of confirmed rotavirus detections.

METHODS

We examined trends in diarrheal hospitalizations among children <5 years old as coded by ICD-9-CM for the period January, 1997, to December, 1998. We collated data on laboratory-confirmed rotavirus detections nationally for the same period among children <2 years old. We calculated the overall contribution of rotavirus to laboratory-confirmed intestinal disease in children <5 years old from INFOSCAN, a disease bulletin for one-third of the population. We compared data from all sources and estimated the proportion of diarrheal hospitalizations that are likely the result of rotavirus in children <5 years old.

RESULTS

In children <5 years old, 9% of all hospitalizations are for diarrheal illness. In this age group 1 in 8 are hospitalized for a diarrheal illness, and 1 in 17 are hospitalized for rotavirus by 5 years of age. In hospitalized children <2 years old, 1 in 38 have a laboratory confirmed rotavirus infection.

CONCLUSIONS

The disease burden of rotavirus hospitalizations is higher than in other industrialized countries. Access to comprehensive national databases may have contributed to the high hospitalization rates, as well as a greater tendency to hospitalize children with diarrhea in Ireland.

Intussusception among recipients of rotavirus vaccine: reports to the vaccine adverse event reporting system

BACKGROUND

Rotavirus vaccine was licensed on August 31, 1998, and subsequently recommended for routine use among infants. To assess rare adverse events, postlicensure surveillance was conducted.

OBJECTIVE

To describe the cases of intussusception among rotavirus vaccine recipients reported to the Vaccine Adverse Event Reporting System from October 1998 through December 1999.

SETTING AND PARTICIPANTS

Infants vaccinated with rotavirus vaccine in the United States.

OUTCOME MEASURES

Intussusception confirmed by radiology, surgery, or autopsy report with medical record documentation or confirmed by a primary health care provider.

RESULTS

There were 98 confirmed cases of intussusception after vaccination with rotavirus vaccine reported to the Vaccine Adverse Event Reporting System; 60 of these developed intussusception within 1 week after vaccination. Based on calculations using vaccine distribution data and intussusception incidence rates from 2 separate databases, an estimated 7 to 16 cases would have been expected to occur in the week after vaccination by chance alone.

CONCLUSION

Using a passive surveillance system for vaccine adverse events, we observed at least a fourfold increase over the expected number of intussusception cases occurring within 1 week of receipt of rotavirus vaccine. Other studies were initiated to further define the relationship between rotavirus vaccine and intussusception. In light of these and other data, the rotavirus vaccine manufacturer voluntarily removed its product from the market, and the recommendation for routine use of rotavirus vaccine among US infants has been withdrawn.

Rotavirus vaccine and intussusception. Where do we go from here?

Since the discovery of rotavirus in 1973, vaccine technology has moved from the use of monovalent attenuated animal rotavirus strains to the development of multivalent human-animal reassortment vaccines. The first licensed vaccine, a rhesus-human tetravalent vaccine, was licensed in 1998. This vaccine was withdrawn from the market a year later when it was noted that administration of vaccine was associated with an increased risk of intussusception. The future of rotavirus vaccine is dependent on the reasons for this association that have yet to be discovered.

Cost of diarrhea-associated hospitalizations and outpatient visits in an insured population of young children in the United States

OBJECTIVE

To assess the financial and clinical burden of diarrhea- and rotavirus-associated disease among a population of privately insured US children.

METHODS

For the period 1993 through 1996, we analyzed medical claims data from a large, administrative database containing information on approximately 300,000 children <5 years of age to examine trends in, and costs associated, with hospitalizations and outpatient visits for diarrhea.

RESULTS

An annual average of 1,186 diarrhea-associated hospitalizations (35 per 10,000 children <5 years) and 33 386 outpatient visits (943 per 10,000 children <5 years) were reported, accounting for 4% of all hospitalizations and 2% of all outpatient visits among children <5 years of age. Diarrhea-associated hospitalizations and outpatient visits showed a distinct winter-spring peak consistent with that of rotavirus infection. The excess of diarrhea-associated events occurring during the winter-spring peak accounted for an average of 50% of all diarrhea-associated hospitalizations and 18% of all diarrhea-associated outpatient visits. The median cost (in 1998 constant dollars) of a diarrhea-associated hospitalization was $2,307, and that for a rotavirus-associated hospitalization was $2,303. Median costs of diarrhea- and rotavirus-associated outpatient visits were $47 and $57, respectively.

CONCLUSIONS

Diarrhea is an important cause of morbidity in this insured population of young children. The epidemiologic features of diarrhea-associated events suggest that rotavirus is an important contributor to the overall morbidity from diarrhea. These disease burden and cost estimates should provide useful information with which to assess the costs and benefits of future interventions for rotavirus-associated illness.

Trends in intussusception-associated hospitalizations and deaths among US infants

CONTEXT

The newly licensed tetravalent rhesus-human reassortant rotavirus vaccine has been withdrawn following reports of intussusception among vaccinated infants.

OBJECTIVE

To describe the epidemiology of intussusception-associated hospitalizations and deaths among US infants.

DESIGN

This retrospective cohort study examined hospital discharge data from the National Hospital Discharge Survey for 1988-1997, Indian Health Service (IHS) for 1980-1997, California for 1990-1997, Indiana for 1994-1998, Georgia for 1997-1998, and MarketScan for 1993-1996, and mortality data from the national multiple cause-of-death data for 1979-1997 and linked birth/infant death data for 1995-1997.

PATIENTS

Infants (<1 year old) with an International Classification of Diseases, Ninth Revision, Clinical Modification code for intussusception (560.0) listed on their hospital discharge or mortality record, respectively.

RESULTS

During 1994-1996, annual rates for intussusception-associated infant hospitalization varied among the data sets, being lowest for the IHS (18 per 100 000; 95% confidence interval [CI] = 9-35 per 100 000) and greatest for the National Hospital Discharge Survey (56 per 100 000; 95% CI = 33-79 per 100 000) data sets. Rates among IHS infants declined from 87 per 100 000 during 1980-1982 to 12 per 100 000 during 1995-1997 (relative risk =7.6, 95% CI = 3.2-18.2). Intussusception-associated hospitalizations were uncommon in the first 2 months of life, peaked from 5 to 7 months old, and showed no consistent seasonality. Intussusception-associated infant mortality rates declined from 6.4 per 1 000 000 live births during 1979-1981 to 2.3 per 1 000 000 live births during 1995-1997 (relative risk = 2.8, 95% CI = 1.8-4.3). Infants whose mothers were <20 years old, nonwhite, unmarried, and had an education level below grade 12 years were at an increased risk for intussusception-associated death.

CONCLUSIONS

Intussusception-associated hospitalization rates varied among the data sets and decreased substantially over time in the IHS data. Although intussusception-associated infant deaths in the United States have declined substantially over the past 2 decades, some deaths seem to be related to reduced access to, or delays in seeking, health care and are potentially preventable.intussusception, hospitalizations, deaths, risk factors, infants.

Rotavirus vaccines

The past few years have seen important developments in understanding the epidemiological and virological characteristics of rotaviruses, and rapid progress has been made in rotavirus vaccine development, but further challenges remain before a vaccine is introduced into widespread use. The licensure of the first rotavirus vaccine, a tetravalent rhesus-based rotavirus vaccine, in the United States in 1998, marked a significant advance in preventing the morbidity associated with rotavirus diarrhea. The association between the tetravalent rhesus-based rotavirus vaccine and intussusception has created significant hurdles as well as new opportunities to study the pathogenesis of rotavirus and rotavirus vaccine infection. Several other rotavirus vaccine candidates are in late stages of development, and results from trials have been encouraging.

Etiology of community-acquired pediatric viral diarrhea: a prospective longitudinal study in hospitals, emergency departments, pediatric practices and child care centers during the winter rotavirus outbreak, 1997 to 1998. The Pediatric Rotavirus Epidemiology Study for Immunization Study Group

OBJECTIVE

To determine the viral etiology of community-acquired diarrhea in children admitted to hospitals and presenting in emergency departments, pediatric practices and child care centers from November 1, 1997, to June 30, 1998.

STUDY DESIGN

Children with diarrhea were identified in a prospective multisite cohort study and analyzed according to age, gender and duration of hospitalization. Stools were tested for rotavirus by enzyme immunoassay and for all other enteric viruses by electron microscopy.

RESULTS

Of the 2524 children identified with diarrhea, stools of 1386 (55%) were tested by enzyme immunoassay for rotavirus, and of these 1365 (54%) were screened by electron microscopy for all identifiable enteric viruses. Rotavirus was found in 32% (n = 437), adenovirus in 4% (n = 55), torovirus in 3% (n = 44), Norwalk-like viruses in 2% (n = 25) and astrovirus (n = 14) and calicivirus (n = 7) in fewer than 1% of the specimens tested. The proportion of rotavirus was significantly higher in children 12 to 23 months of age (43% of tested stools, n = 159) and 24 to 35 months of age (38% of tested stools, n = 64) (P < 0.001) than in any other age group. Toroviruses were found to approximately the same extent in children > or =36 months of age (6% of tested stools, n = 19) as those <36 months of age. Rotavirus (36% of tested stools, n = 375, P < 0.0005) and torovirus (4% of tested stools, n = 43, P < 0.004) were most often found in hospitalized patients. In contrast Norwalk-like viruses (P < 0.001) and astroviruses (P < 0.01) were more commonly detected in specimens from patients who presented to physicians' offices and who were symptomatic for gastroenteritis in child care centers.

CONCLUSION

This study demonstrates that although all known gastroenteritis viruses were diagnosed in symptomatic children, rotavirus was the etiologic agent in most cases of diarrhea managed in the community and in the hospital.

Cost effectiveness of rotavirus vaccination in Australia

OBJECTIVE

Rotavirus gastroenteritis causes substantial morbidity, including hospital admission, in young children. In the context of recent vaccine developments, this study aimed to estimate the cost-effectiveness of a rotavirus vaccination program in Australia.

METHOD

Standard methods of health economic evaluation were used to assess the total cost of rotavirus immunisation (as the difference between estimated vaccination program costs and the cost of disease that would be avoided by immunisation) and relate this to the number of cases of disease that would be prevented. Estimates were made from both societal and health care systems perspectives.

RESULTS

Based on Australian data on disease incidence and cost of hospitalisation, the current annual cost of rotavirus disease is about $26.0 million. Using conservative vaccine efficacy estimates, current immunization uptake rates and a cost of $30 per dose of vaccine, rotavirus immunisation would incur a net societal cost of $2.9 million ($11 per child), at a gross program cost of $21.6 million. These estimates are sensitive to two sources of uncertainty in the estimation of program delivery costs: vaccine price and whether separate immunization visits would be required.

CONCLUSION

A rotavirus immunisation program would be cost-neutral to Australian society at a vaccine price of $26 per dose (or $19 when health care system costs only are considered).

IMPLICATIONS

Rotavirus immunization may be cost-effective in Australia, but considerable uncertainty remains. Policy decisions will depend heavily on pricing of the vaccine and may also need to consider intangible costs not accounted for in this analysis.

Use of state hospital discharge data to assess the morbidity from rotavirus diarrhea and to monitor the impact of a rotavirus immunization program: A pilot study in Connecticut

OBJECTIVES

Now that rotavirus vaccines have been licensed and recommended for routine immunization of US infants, there is an urgent need for data to assess the morbidity from rotavirus diarrhea and to monitor the impact of a rotavirus immunization program. In a pilot study, we have assessed the usefulness of state hospital discharge data on diarrhea in children to provide this information by examining data from Connecticut.

DESIGN

Retrospective analysis of discharge records from acute care, nongovernmental hospitals in Connecticut. Patients. Children 1 month through 4 years of age with a diarrhea-associated diagnosis listed on the discharge record. Setting. Connecticut, 1987 through 1996.

RESULTS

During the 10-year study period, a total of 11 324 diarrhea-associated hospitalizations (49.4 hospitalizations per 10,000 children) were reported. Diarrhea-associated hospitalizations peaked during February through April, especially among children 4 to 35 months of age. The seasonality and age distribution of diarrhea-associated hospitalizations of presumed noninfectious and viral etiologies resembled those of rotavirus-associated hospitalizations. During 1993 to 1996, rotavirus was coded for 10.4% of diarrhea-associated hospitalizations increasing from 8.6% in 1993 to 14.7% in 1996. The unadjusted median cost of a diarrhea-associated hospitalization during 1987 to 1996 and 1993 to 1996 was $1,941 and $2,428, respectively.

CONCLUSIONS

Diarrhea causes substantial morbidity in children from Connecticut. The winter seasonal peak of diarrhea-associated hospitalizations in children 4 to 35 months of age coinciding with the peak of rotavirus-specific hospitalizations suggests that rotavirus is an important contributor to the overall morbidity. Although our findings suggest incomplete coding of rotavirus cases, state hospital discharge data should provide sensitive and timely information to monitor the impact of a rotavirus immunization program in Connecticut.

Microecologic approaches for traveler's diarrhea, antibiotic-associated diarrhea, and acute pediatric diarrhea

Bacterial and viral diarrhea remain important causes of morbidity and mortality throughout the world. Current concerns with medical costs, increasing frequency of antibiotic resistance, and overuse of antibiotics in general have redirected therapeutic approaches for diarrhea from traditional drugs to the use of living therapeutic organisms. Awareness of the important role of normal flora in the microecology of the intestines in fighting infection, along with the recent availability of well-controlled clinical trials for these agents, has brought microecologic therapies to the forefront of clinical practice.

Health care costs of formula-feeding in the first year of life

OBJECTIVE

To determine the excess cost of health care services for three illnesses in formula-fed infants in the first year of life, after adjusting for potential confounders.

METHODS

Frequency of health service utilization for three illnesses (lower respiratory tract illnesses, otitis media, and gastrointestinal illness) in the first year of life was assessed in relation to duration of exclusive breastfeeding in the Tucson Children's Respiratory Study (n = 944) and the Dundee Community Study (Scottish study, n = 644). Infants in both studies were healthy at birth and represented nonselected, population-based samples. Children were classified as never breastfed, partially breastfed, or exclusively breastfed, based on their feeding status during the first 3 months of life. Frequency of office visits and hospitalizations for the three illnesses was adjusted for maternal education and maternal smoking, using analysis of variance. Cost estimates, from the perspective of the health care provider/payer, were based on the direct medical costs during 1995 within a large managed care health care system.

RESULTS

In the first year of life, after adjusting for confounders, there were 2033 excess office visits, 212 excess days of hospitalization, and 609 excess prescriptions for these three illnesses per 1000 never-breastfed infants compared with 1000 infants exclusively breastfed for at least 3 months. These additional health care services cost the managed care health system between $331 and $475 per never-breastfed infant during the first year of life.

CONCLUSIONS

In addition to having more illnesses, formula-fed infants cost the health care system money. Health care plans will likely realize substantial savings, as well as providing improved care, by supporting and promoting exclusive breastfeeding.

Trends in diarrhea-associated hospitalizations among American Indian and Alaska native children, 1980-1995

OBJECTIVE

To describe trends in diarrhea- associated hospitalizations among American Indian and Alaska Native (AI/AN) children and to estimate the morbidity from rotavirus.

DESIGN

Retrospective analysis of Indian Health Service hospital discharge records.

PATIENTS

AI/AN children 1 month through 4 years of age with a diarrhea-associated diagnosis listed on the hospital discharge record.

SETTING

Hospitals on or near US Indian reservations from 1980 through 1995.

RESULTS

During 1980 through 1995, 21 669 diarrhea-associated hospitalizations were reported among AI/AN children. The annual incidence of diarrhea-associated hospitalizations declined by 76% from 276 per 10 000 in 1980 to 65 per 10 000 in 1995. The median length of hospital stay decreased from 4 days during 1980-1982 to 2 days during 1993-1995. Diarrhea-associated hospitalizations peaked during the winter months (October through March), especially among children 4-35 months of age, with the peaks appearing first in the Southwest during October and moving to the East in March. In the early years of the study (1980-1982), the rate of diarrhea-associated hospitalizations among AI/AN children (236 per 10 000) was greater than the national rate (136 per 10 000). By the end of the study period (1993-1995), the rate for AI/AN children (71 per 10 000) was similar to the national rate (89 per 10 000), although the rate for AI/AN infants remained higher than the national rate for infants.

CONCLUSIONS

Diarrhea-associated hospitalization rates for AI/AN children have declined to a level similar to that of the national population. Rotavirus may be an important contributor to diarrheal morbidity among AI/AN children, underscoring the need for vaccines against this pathogen.