Validation of Acute Gastroenteritis-related International Classification of Diseases, Clinical Modification Codes in Pediatric and Adult US Populations

International Classification of Diseases diagnostic codes are used to estimate acute gastroenteritis (AGE) disease burden. We validated AGE-related codes in pediatric and adult populations using 2 multiregional active surveillance platforms. The sensitivity of AGE codes was similar (54% and 58%) in both populations and increased with addition of vomiting-specific codes.

Evidence for Household Transmission of Rotavirus in the United States, 2011-2016

BACKGROUND

Rotavirus is a leading cause of acute gastroenteritis (AGE) in children and is highly transmissible. In this study, we assessed the presence of AGE in household contacts (HHCs) of pediatric patients with laboratory-confirmed rotavirus.

METHODS

Between December 2011 and June 2016, children aged 14 days to 11 years with AGE were enrolled at 1 of 7 hospitals or emergency departments as part of the New Vaccine Surveillance Network. Parental interviews, medical and vaccination records, and stool specimens were collected at enrollment. Stool was tested for rotavirus by an enzyme immunoassay and confirmed by real-time or conventional reverse transcription-polymerase chain reaction assay or repeated enzyme immunoassay. Follow-up telephone interviews were conducted to assess AGE in HHCs the week after the enrolled child's illness. A mixed-effects multivariate model was used to calculate odds ratios.

RESULTS

Overall, 829 rotavirus-positive subjects and 8858 rotavirus-negative subjects were enrolled. Households of rotavirus-positive subjects were more likely to report AGE illness in ≥1 HHC than were rotavirus-negative households (35% vs 20%, respectively; P < .0001). A total of 466 (16%) HHCs of rotavirus-positive subjects reported AGE illness. Of the 466 ill HHCs, 107 (23%) sought healthcare; 6 (6%) of these encounters resulted in hospitalization. HHCs who were <5 years old (odds ratio, 2.2 [P = .004]) were more likely to report AGE illness than those in other age groups. In addition, 144 households reported out-of-pocket expenses (median, $20; range, $2-$640) necessary to care for an ill HHC.

CONCLUSIONS

Rotavirus-associated AGE in children can lead to significant disease burden in HHCs, especially in children aged <5 years. Prevention of pediatric rotavirus illness, notably through vaccination, can prevent additional illnesses in HHCs.

The Norovirus Epidemiologic Triad: Predictors of Severe Outcomes in US Norovirus Outbreaks, 2009-2016

BACKGROUND

Noroviruses are the leading cause of acute gastroenteritis outbreaks worldwide. Clarifying the viral, host, and environmental factors (epidemiologic triad) associated with severe outcomes can help target public health interventions.

METHODS

Acute norovirus outbreaks reported to the National Outbreak Reporting System (NORS) in 2009-2016 were linked to laboratory-confirmed norovirus outbreaks reported to CaliciNet. Outbreaks were analyzed for differences in genotype (GII.4 vs non-GII.4), hospitalization, and mortality rates by timing, setting, transmission mode, demographics, clinical symptoms, and health outcomes.

RESULTS

A total of 3747 norovirus outbreaks were matched from NORS and CaliciNet. Multivariable models showed that GII.4 outbreaks (n = 2353) were associated with healthcare settings (odds ratio [OR], 3.94 [95% confidence interval {CI}, 2.99-5.23]), winter months (November-April; 1.55 [95% CI, 1.24-1.93]), and older age of cases (≥50% aged ≥75 years; 1.37 [95% CI, 1.04-1.79]). Severe outcomes were more likely among GII.4 outbreaks (hospitalization rate ratio [RR], 1.54 [95% CI, 1.23-1.96]; mortality RR, 2.77 [95% CI, 1.04-5.78]). Outbreaks in healthcare settings were also associated with higher hospitalization (RR, 3.22 [95% CI, 2.34-4.44]) and mortality rates (RR, 5.65 [95% CI, 1.92-18.70]).

CONCLUSIONS

Severe outcomes more frequently occurred in norovirus outbreaks caused by GII.4 and those in healthcare settings. These results should help guide preventive interventions for targeted populations, including vaccine development.

Viral Etiology of Acute Gastroenteritis in <2-Year-Old US Children in the Post-Rotavirus Vaccine Era

BACKGROUND

The rotavirus disease burden has declined substantially since rotavirus vaccine was introduced in the United States in 2006. The aim of this study was to determine the viral etiology of acute gastroenteritis (AGE) in US children aged <2 years.

METHODS

The New Vaccine Surveillance Network (NVSN) of geographically diverse US sites conducts active pediatric population-based surveillance in hospitals and emergency departments. Stool samples were collected from children aged <2 years with symptoms of AGE (n = 330) and age-matched healthy controls (HCs) (n = 272) between January and December 2012. Samples were tested by real-time reverse-transcriptase polymerase chain reaction assays {adenovirus (type 40 and 41), norovirus, parechovirus A, enterovirus, sapovirus, and astrovirus} and an enzyme immunoassay (rotavirus). All samples that tested positive were genotyped.

RESULTS

Detection rates of pathogens in children with AGE versus those of HCs were, respectively, 23.0% versus 6.6% for norovirus (P < .01), 23.0% versus 16.0% for adenovirus (P = .08), 11.0% versus 16.0% for parechovirus A (P = .09), 11.0% versus 9.0% for enterovirus (P = .34), 7.0% versus 3.0% for sapovirus (P = .07), 3.0% versus 0.3% for astrovirus (P = .01), and 3.0% versus 0.4% for rotavirus (P = .01). A high prevalence of adenovirus was detected at 1 surveillance site (49.0% for children with AGE and 43.0% for HCs). Norovirus GII.4 New Orleans was the most frequently detected (33.0%) norovirus genotype. Codetection of >1 virus was more common in children with AGE (16.0%) than in HCs (10.0%) (P = .03).

CONCLUSIONS

Norovirus, astrovirus, sapovirus, and rotavirus were detected significantly more in children with AGE than in HCs, and norovirus was the leading AGE-causing pathogen in US children aged <2 years during the year 2012.

Association of Rotavirus Vaccination With Inpatient and Emergency Department Visits Among Children Seeking Care for Acute Gastroenteritis, 2010-2016

IMPORTANCE

Rotavirus vaccines have been recommended for universal US infant immunization for more than 10 years, and understanding their effectiveness is key to the continued success of the US rotavirus vaccine immunization program.

OBJECTIVE

To assess the association of RotaTeq (RV5) and Rotarix (RV1) with inpatient and emergency department (ED) visits for rotavirus infection.

DESIGN, SETTING, AND PARTICIPANTS

This case-control vaccine effectiveness study was performed at inpatient and ED clinical settings in 7 US pediatric medical institutions from November 1, 2009, through June 30, 2016. Children younger than 5 years seeking medical care for acute gastroenteritis were enrolled. Clinical and epidemiologic data, vaccination verification, and results of stool sample tests for laboratory-confirmed rotavirus were collected. Data were analyzed from November 1, 2009, through June 30, 2016.

MAIN OUTCOMES AND MEASURES

Rotavirus vaccine effectiveness for preventing rotavirus-associated inpatient and ED visits over time for each licensed vaccine, stratified by clinical severity and age.

RESULTS

Among the 10 813 children included (5927 boys [54.8%] and 4886 girls [45.2%]; median [range] age, 21 [8-59] months), RV5 and RV1 analyses found that compared with controls, rotavirus-positive cases were more often white (RV5, 535 [62.2%] vs 3310 [57.7%]; RV1, 163 [43.1%] vs 864 [35.1%]), privately insured (RV5, 620 [72.1%] vs 4388 [76.5%]; RV1, 305 [80.7%] vs 2140 [87.0%]), and older (median [range] age for RV5, 26 [8-59] months vs 21 [8-59] months; median [range] age for RV1, 22 [8-59] months vs 19 [8-59] months) but did not differ by sex. Among 1193 rotavirus-positive cases and 9620 rotavirus-negative controls, at least 1 dose of any rotavirus vaccine was 82% (95% CI, 77%-86%) protective against rotavirus-associated inpatient visits and 75% (95% CI, 71%-79%) protective against rotavirus-associated ED visits. No statistically significant difference during this 7-year period was observed for either rotavirus vaccine. Vaccine effectiveness against inpatient and ED visits was 81% (95% CI, 78%-84%) for RV5 (3 doses) and 78% (95% CI, 72%-82%) for RV1 (2 doses) among the study population. A mixed course of both vaccines provided 86% (95% CI, 74%-93%) protection. Rotavirus patients who were not vaccinated had severe infections 4 times more often than those who were vaccinated (74 of 426 [17.4%] vs 28 of 605 [4.6%]; P < .001), and any dose of rotavirus vaccine was 65% (95% CI, 56%-73%) effective against mild infections, 81% (95% CI, 76%-84%) against moderate infections, and 91% (95% CI, 85%-95%) against severe infections.

CONCLUSIONS AND RELEVANCE

Evidence from this large postlicensure study of rotavirus vaccine performance in the United States from 2010 to 2016 suggests that RV5 and RV1 rotavirus vaccines continue to perform well, particularly in preventing inpatient visits and severe infections and among younger children.

Factors Associated With Rotavirus Vaccine Coverage

BACKGROUND

Rotavirus vaccines (RVVs) were included in the US immunization program in 2006 and are coadministered with the diphtheria-tetanus-acellular pertussis (DTaP) vaccine, yet their coverage lags behind DTaP. We assessed timing, initiation, and completion of the RVV series among children enrolled in active gastroenteritis surveillance at 7 US medical institutions during 2014-2016.

METHODS

We compared coverage and timing of each vaccine series and analyzed characteristics associated with RVV initiation and completion. We report odds ratios (ORs) and 95% confidence intervals (CIs) from multivariable logistic regression models.

RESULTS

We enrolled 10 603 children. In 2015, ≥1 dose coverage was 91% for RVV and 97% for DTaP. Seven percent of children received their first DTaP vaccine at age ≥15 weeks versus 4% for RVV (P ≤ .001). Recent birth years (2013-2016) were associated with higher odds of RVV initiation (OR = 5.72; 95% CI 4.43-7.39), whereas preterm birth (OR = 0.32; 95% CI 0.24-0.41), older age at DTaP initiation (OR 0.85; 95% CI 0.80-0.91), income between $50 000 and $100 000 (OR = 0.56; 95% CI 0.40-0.78), and higher maternal education (OR = 0.52; 95% CI 0.36-0.74) were associated with lower odds. Once RVV was initiated, recent birth years (2013-2016; OR = 1.57 [95% CI 1.32-1.88]) and higher maternal education (OR = 1.31; 95% CI 1.07-1.60) were associated with higher odds of RVV completion, whereas preterm birth (OR = 0.76; 95% CI 0.62-0.94), African American race (OR = 0.82; 95% CI 0.70-0.97) and public or no insurance (OR = 0.75; 95% CI 0.60-0.93) were associated with lower odds. Regional differences existed.

CONCLUSIONS

RVV coverage remains lower than that for the DTaP vaccine. Timely DTaP administration may help improve RVV coverage.

1112. Detection of Enteric Viruses in Children With Acute Gastroenteritis

Background

Acute gastroenteritis (AGE) is a major cause of morbidity in children. Viral pathogens are the most common infectious agents. Differences in illness characteristics of AGE with and without virus detection are poorly defined. We compared AGE illness characteristics between children with and without any-virus detected, and with single vs. multiple viruses detected.

Methods

Children between 15 days and 17 years with AGE defined as diarrhea (>3 loose stools/24 hours) or any vomiting within 10 days duration were enrolled in Vanderbilt Children’s Hospital inpatient, ED, and outpatient settings from December 2012 to November 2015. Stool specimens were tested by RT-qPCR for norovirus, sapovirus, and astrovirus and by ELISA (VP6 antigen [Rotaclone^®]) for rotavirus.

Results

Of 3,705 children enrolled, 2,892 (78%) specimens were collected. A single virus was detected in 1,109 (38%) stools [51% norovirus, 20% rotavirus, 21% sapovirus, and 8% astrovirus], viral co-detections were found in 115 (4%) stools, and 1,665 (58%) had no detected viruses. Table 1 compares children with and without any-virus detected. Children with a single-virus detected were older than those with >1 virus detected (1.8 vs. 1.5 years [P < 0.05]) with no other significant differences.

Conclusion

Children with any-virus detected had more severe symptoms, higher MVS, and more frequently reported sick contacts compared with no-virus detected. Children with no-virus detected were more likely to present with fever and higher temperatures, which may be due to bacterial organisms. These data highlight the importance of infection-prevention precautions in the community and the need for additional testing to define the etiologic spectrum of AGE in children.

Disclosures

N. Halasa, sanofi pasteur: Investigator, Research support. GSK: Consultant, Consulting fee. Moderna: Consultant, Consulting fee.

1106. Infectious Etiologies of Acute Gastroenteritis in Children during the First 100 Days Post-Allogeneic Hematopoietic Cell Transplant

Background

Acute gastroenteritis (AGE) is a frequent sequela in children undergoing hematopoietic cell transplant (HCT). Although rotavirus and norovirus have been implicated as important causes of AGE, the frequency of other pathogens is unknown. Little data exist on longitudinal prevalence of infectious AGE in HCT.

Methods

From February 2015 to May 2016, subjects <18 years undergoing allogeneic HCT were enrolled at four CDC-NVSN sites: Oakland, Kansas City, Seattle, and Nashville. Stool samples were collected at enrollment, weekly until discharge or day 100 (whichever occurred earliest), during re-admissions within the first 100 days, and day 100. AGE was defined as unexplained ≥3 episodes diarrhea and/or ≥1 episode vomiting/24 hours. Specimens were tested using Luminex xTAG Gastrointestinal Pathogen Panel (Austin, TX) and real-time PCR for adenovirus, astrovirus, norovirus, and sapovirus.

Results

Thirty-one patients were enrolled at four sites (Seattle: 13, Kansas City: 8, Oakland: 6, Nashville: (4) with median age 5 (IQR 3–10) years. Two hundred sixteen samples were obtained with median 7 samples/subject. During the first 100 days, 29 (94%) subjects met the AGE definition. Thirty-six single pathogen detections occurred in 16 (52%) subjects. Clostridium difficile was the most frequent pathogen (Figure 1), with 14 detections in nine patients, all ≥3 years; 50% of detections were asymptomatic. Seven (50%) detections occurred at HCT onset and none received targeted C. difficile therapy. Sapovirus was detected nine times in four patients, with seven (78%) detections associated with AGE symptoms. Rotavirus was detected nine times, during five symptomatic episodes, in three patients. Adenovirus was detected four times in three patients and all were symptomatic.

Conclusion

We longitudinally characterized the etiology of infectious AGE in children undergoing HCT. Despite the majority of patients meeting the definition for AGE, only half had a pathogen detected, suggesting that differentiating infectious vs. noninfectious AGE (e.g., medication induced) in this population is difficult. Although all subjects with adenovirus and most with sapovirus were symptomatic, asymptomatic C. difficile detection was common. Interestingly, norovirus was not detected. Further investigation of AGE is warranted in this population.

Disclosures

All authors: No reported disclosures.

2154. How Well Are We Estimating the True Burden of Acute Gastroenteritis? Validation of Acute Gastroenteritis-Related ICD Codes in Pediatric and Adult U.S. Populations

Background

International Classification of Diseases (ICD) diagnostic codes from acute gastroenteritis (AGE)-associated medical encounters are used for AGE disease burden estimates, yet the validity of AGE-related ICD codes in both pediatric and adult populations is unknown. We estimated the validity of AGE-related diagnostic codes in these populations using two different multi-regional AGE active surveillance platforms.

Methods

Diagnostic codes, demographic and clinical characteristics, and stool pathogen results from AGE-associated medical encounters were obtained for enrolled children <5 years old from seven sites in NVSN from December 1, 2011 to June 30, 2016, and for adult Veterans in four sites from SUPERNOVA from December 1, 2016 to February 28, 2018. SUPERNOVA also enrolled age- and time-matched non-AGE controls. Using AGE cases from the active surveillance networks, sensitivity and specificity of AGE ICD codes were estimated overall and stratified by age and health care setting using exact binomial tests.

Results

ICD codes were collected from 14,952 enrolled children <5 years old with AGE, and 625 enrolled adults (525 AGE cases and 100 controls). The sensitivity of all-cause AGE codes in children was 54% (9,127/14,952, 95% confidence interval [CI] 54–55%), and in adults was 54% (283/525; 95% CI 50–58%), with a specificity of 100% (100/100; 95% CI 97–100%). Stratified analyses demonstrated higher sensitivity of all-cause AGE codes in children in the inpatient as compared with outpatient setting: 59% (417/675; 95% CI 57–61%) vs. 53% (934/1827; 95% CI 52–54%). In adults, this trend was reversed; all-cause AGE codes had a higher sensitivity in the outpatient as compared with the inpatient setting: 72% (50/69; 95% CI 60–83%), vs. 51% (233/456; 95% CI 46–56%), respectively.

Conclusion

Across two different AGE active surveillance platforms, one enrolling only children and one enrolling only adults, the estimated sensitivity of all-cause AGE ICD codes were similarly low. This suggests that current national estimates for AGE disease burden may be underestimating the true burden of AGE pathogens in the United States, and emphasizes the importance of active, prospective surveillance.

Disclosures

All authors: No reported disclosures.

1101. Comparison of Clinical Characteristics and Demographics of GII.4 vs. Other GII Noroviruses Associated With Sporadic Acute Gastroenteritis in Children in Nashville, TN, 2012–2015

Background

Norovirus is a leading cause of acute gastroenteritis (AGE) in all age groups. Although at least 28 different genotypes infecting humans have been reported, most outbreaks over the last 15 years have been caused by genogroup II (GII) viruses, of which GII.4 viruses have caused more than 50%. Since clinical differences between different genotypes are poorly understood, we sought to compare clinical characteristics in children infected with GII.4 and non-GII.4 viruses.

Methods

Children between 15 days and 17 years who presented with AGE defined as diarrhea (≥3 loose stools in a 24 hour period) or vomiting (≥1 episodes in a 24 hour period) within 10 days duration were recruited in outpatient, emergency, and inpatient settings in Nashville, TN, during 2012–2015. Stool specimens were tested by RT-qPCR for GI and GII norovirus. Norovirus-positive specimens were genotyped by sequencing of a partial region of the capsid gene. In this study, we excluded children infected with GI, mixed GI/GII and non-typeable GII viruses.

Results

Of 3,705 AGE subjects enrolled, 2,892 (78%) specimens were collected, 637 (22%) tested norovirus-positive (567 [89%] GII, 62 [10%] GI, and 8 [1%] mixed GI/GII). Of the 567 GII viruses, 461 (81%) were able to be genotyped and of those 238/461 (51.6%) were typed as GII.4 and 223/461 (48.3%) were typed as other GII genotypes (non-GII.4, primarily GII.3 [65/ 461, 14.1%], GII.6 [48/461, 10.4%] and GII.7 [36/461, 7.8%]). Over three AGE seasons, GII.4 represented 64/117 (54%), 79/178 (44%), and 71/166 (57%), of the GII infections, respectively. Compared with non-GII.4 subjects, GII.4 subjects were more likely to be younger (15.5 vs. 21.3 months, P < 0.01), and less likely to attend daycare (23% vs. 39%, P < 0.01). GII.4 subjects also were more likely to present with diarrhea (75% vs. 57%, P < 0.01) and had higher median modified Vesikari score (7 vs. 6, P < 0.01).

Conclusion

Children infected with GII.4 viruses were younger, less likely to attend child care, more likely to present with diarrhea, and had a more severe illness compared with those with non-GII.4 infections. These data provide important information on the genotype distribution of norovirus in children with AGE in Tennessee and highlight GII.4 as the most prevalent strain.

Disclosures

N. Halasa, sanofi pasteur: Investigator, Research support. GSK: Consultant, Consulting fee. Moderna: Consultant, Consulting fee.

Evaluating Previous Antibiotic Use as a Risk Factor for Acute Gastroenteritis Among Children in Davidson County, Tennessee, 2014-2015

BACKGROUND

Epidemiologic studies that evaluate the relationship between previous antibiotic use and acute gastroenteritis (AGE) in the pediatric population are currently lacking.

METHODS

We analyzed inpatient and outpatient children with AGE and healthy controls from Vanderbilt University Medical Center between December 1, 2014, and November 30, 2015. The following 4 outcome groups were defined: overall AGE, norovirus-associated AGE, rotavirus-associated AGE, and nonnorovirus/nonrotavirus AGE. Multiple logistic regression was performed to evaluate the association between previous antibiotic use and the 4 AGE outcomes and with AGE severity.

RESULTS

Reported antibiotic use rates in the 3 months before illness onset were similar across the 4 AGE outcomes (overall AGE, 21%; norovirus-associated AGE, 23%; rotavirus-associated AGE, 28%; and nonnorovirus/nonrotavirus AGE, 22%) but were higher than that reported for healthy controls (9%). Compared with healthy controls, patients with AGE overall were 4.6 (95% confidence interval [CI], 1.8-11.4) times more likely to have reported antibiotic use in the 3 weeks before illness onset and 2.6 (95% CI, 1.7-4.1) times more likely to have reported antibiotic use within 3 months before illness onset. Similar results were found for the other specific AGE outcomes. For the overall AGE group, the odds of antibiotic use in the 3 months before illness onset was 3.5 (95% CI, 1.8-7.1) times higher for inpatients than for outpatients.

CONCLUSIONS

Previous antibiotic use among children was associated with increased odds of AGE, irrespective of etiology, and this association was stronger with more recent antibiotic use. Previous antibiotic use was associated also with more severe AGE.

Intestinal Carriage of Third-Generation Cephalosporin-Resistant and Extended-Spectrum β-Lactamase-Producing Enterobacteriaceae in Healthy US Children

BACKGROUND

The epidemiology of antibiotic-resistant Enterobacteriaceae intestinal carriage in healthy US children has not been well characterized.

METHODS

Children between 14 days and 14 years of age were enrolled during well-child visits in Oakland, California, Kansas City, Kansas, and Nashville, Tennessee, between December 2013 and March 2015. Data on recent antibiotic use by the child and travel and hospitalization history of all members of each child's household were obtained with a risk-factor survey. Stool specimens collected from the subjects were screened for extended-spectrum β-lactamase-producing (ESBL-P) bacteria using CHROMagar ESBL medium. Putative ESBL-P Escherichia coli and Klebsiella colonies underwent phenotypic confirmation by double-disk synergy testing; confirmed third-generation cephalosporin-resistant (3GCR) isolates underwent additional antibiotic-susceptibility testing.

RESULTS

In 519 subjects, the overall 3GCR Enterobacteriaceae carriage rate was 4.4% (n = 23) and ranged from 3.4% to 5.1% among the study sites. The ESBL-P Enterobacteriaceae carriage rate was 3.5% (n = 18). The rates of 3GCR Enterobacteriaceae carriage was highest in 1 to <2 year olds at 6.5%, and was 5.2% in <5 year-olds vs 1.7% in ≥5-year-olds (P = .11). 3GCR and ESBL-P Enterobacteriaceae carriage was associated with international travel within the previous year; 11.1% of ESBL-P Enterobacteriaceae carriers reported this history compared with 1.6% of noncarriers (P = .004). No other queried factor was found to increase risk. Of the 24 analyzed 3GCR isolates, 58% were multidrug resistant.

CONCLUSIONS

The 3GCR Enterobacteriaceae carriage rate exceeds 5% in healthy US children <5 years of age. International travel within the previous year increased the risk of 3GCR and ESBL-P Enterobacteriaceae carriage. In contrast, we found no differences in the rates of hospitalization or recent antibiotic exposure between carriers and noncarriers. Young children, who have the highest prevalence of colonization, might be a sentinel population to study to gain a better understanding of community sources of antibiotic-resistant Enterobacteriaceae.

Near Real-Time Surveillance of U.S. Norovirus Outbreaks by the Norovirus Sentinel Testing and Tracking Network - United States, August 2009-July 2015

Norovirus is the leading cause of endemic and epidemic acute gastroenteritis in the United States (1). New variant strains of norovirus GII.4 emerge every 2-4 years (2-4) and are often associated with increased disease and health care visits (5-7). Since 2009, CDC has obtained epidemiologic data on norovirus outbreaks from state health departments through the National Outbreak Reporting System (NORS) (8) and laboratory data through CaliciNet (9). NORS is a web-based platform for reporting waterborne, foodborne, and enteric disease outbreaks of all etiologies, including norovirus, to CDC. CaliciNet, a nationwide electronic surveillance system of local and state public health and regulatory agency laboratories, collects genetic sequences of norovirus strains associated with gastroenteritis outbreaks. Because these two independent reporting systems contain complementary data, integration of NORS and CaliciNet records could provide valuable public health information about norovirus outbreaks. However, reporting lags and inconsistent identification codes in NORS and CaliciNet records have been an obstacle to developing an integrated surveillance system.

Rotavirus Strain Trends During the Postlicensure Vaccine Era: United States, 2008-2013

BACKGROUND

Group A rotaviruses (RVA) are a significant cause of pediatric gastroenteritis worldwide. The New Vaccine Surveillance Network (NVSN) has conducted active surveillance for RVA at pediatric hospitals and emergency departments at 3-7 geographically diverse sites in the United States since 2006.

METHODS

Over 6 consecutive years, from 2008 to 2013, 1523 samples from NVSN sites that were tested positive by a Rotaclone enzyme immunoassay were submitted to the Centers for Disease Control and Prevention for genotyping.

RESULTS

In the 2009, 2010, and 2011 seasons, genotype G3P[8] was the predominant genotype throughout the network, with a 46%-84% prevalence. In the 2012 season, G12P[8] replaced G3P[8] as the most common genotype, with a 70% prevalence, and this trend persisted in 2013 (68.0% prevalence). Vaccine (RotaTeq; Rotarix) strains were detected in 0.6%-3.4% of genotyped samples each season. Uncommon and unusual strains (eg, G8P[4], G3P[24], G2P[8], G3P[4], G3P[6], G24P[14], G4P[6], and G9P[4]) were detected sporadically over the study period. Year, study site, and race were found to be significant predictors of genotype.

CONCLUSIONS

Continued active surveillance is needed to monitor RVA genotypes in the United States and to detect potential changes since vaccine licensure.

Molecular characterization of the first G24P[14] rotavirus strain detected in humans

Here we report the genome of a novel rotavirus A (RVA) strain detected in a stool sample collected during routine surveillance by the Centers for Disease Control and Prevention's New Vaccine Surveillance Network. The strain, RVA/human-wt/USA/2012741499/2012/G24P[14], has a genomic constellation of G24-P[14]-I2-R2-C2-M2-A3-N2-T9-E2-H3. The VP2, VP3, VP7 and NSP3 genes cluster phylogenetically with bovine strains. The other genes occupy mixed clades containing animal and human strains. Strain RVA/human-wt/USA/2012741499/2012/G24P[14] most likely is the product of interspecies transmission and reassortment events. This is the second report of the G24 genotype and the first report of the G24P[14] genotype combination in humans.

Estimates of Parainfluenza Virus-Associated Hospitalizations and Cost Among Children Aged Less Than 5 Years in the United States, 1998-2010

BACKGROUND

Parainfluenza virus (PIV) is the second leading cause of hospitalization for respiratory illness in young children in the United States. Infection can result in a full range of respiratory illness, including bronchiolitis, croup, and pneumonia. The recognized human subtypes of PIV are numbered 1-4. This study calculates estimates of PIV-associated hospitalizations among U.S. children younger than 5 years using the latest available data.

METHODS

Data from the National Respiratory and Enteric Virus Surveillance System were used to characterize seasonal PIV trends from July 2004 through June 2010. To estimate the number of PIV-associated hospitalizations that occurred annually among U.S. children aged <5 years from 1998 through 2010, respiratory hospitalizations from the Healthcare Cost and Utilization Project Nationwide Inpatient Sample were multiplied by the proportion of acute respiratory infection hospitalizations positive for PIV among young children enrolled in the New Vaccine Surveillance Network. Estimates of hospitalization charges attributable to PIV infection were also calculated.

RESULTS

Parainfluenza virus seasonality follows type-specific seasonal patterns, with PIV-1 circulating in odd-numbered years and PIV-2 and -3 circulating annually. The average annual estimates of PIV-associated bronchiolitis, croup, and pneumonia hospitalizations among children aged <5 years in the United States were 3888 (0.2 hospitalizations per 1000), 8481 per year (0.4 per 1000 children), and 10,186 (0.5 per 1000 children), respectively. Annual charges for PIV-associated bronchiolitis, croup, and pneumonia hospitalizations were approximately $43 million, $58 million, and $158 million, respectively.

CONCLUSIONS

The majority of PIV-associated hospitalizations in young children occur among those aged 0 to 2 years. When vaccines for PIV become available, immunization would be most effective if realized within the first year of life.

Outbreaks of Acute Gastroenteritis Transmitted by Person-to-Person Contact, Environmental Contamination, and Unknown Modes of Transmission--United States, 2009-2013

PROBLEM/CONDITION

Acute gastroenteritis (AGE) is a major cause of illness in the United States, with an estimated 179 million episodes annually. AGE outbreaks propagated through direct person-to-person contact, contaminated environmental surfaces, and unknown modes of transmission were not systematically captured at the national level before 2009 and thus were not well characterized.

REPORTING PERIOD

2009-2013.

DESCRIPTION OF SYSTEM

The National Outbreak Reporting System (NORS) is a voluntary national reporting system that supports reporting of all waterborne and foodborne disease outbreaks and all AGE outbreaks resulting from transmission by contact with contaminated environmental sources, infected persons or animals, or unknown modes. Local, state, and territorial public health agencies within the 50 U.S. states, the District of Columbia (DC), five U.S. territories, and three Freely Associated States report outbreaks to CDC via NORS using a standard online data entry system.

RESULTS

A total of 10,756 AGE outbreaks occurred during 2009-2013, for which the primary mode of transmission occurred through person-to-person contact, environmental contamination, and unknown modes of transmission. NORS received reports from public health agencies in 50 U.S. states, DC, and Puerto Rico. These outbreaks resulted in 356,532 reported illnesses, 5,394 hospitalizations, and 459 deaths. The median outbreak reporting rate for all sites in a given year increased from 2.7 outbreaks per million population in 2009 to 11.8 outbreaks in 2013. The etiology was unknown in 31% (N = 3,326) of outbreaks. Of the 7,430 outbreaks with a suspected or confirmed etiology reported, norovirus was the most common, reported in 6,223 (84%) of these outbreaks. Other reported suspected or confirmed etiologies included Shigella (n = 332) and Salmonella (n = 320). Outbreaks were more frequent during the winter, with 5,716 (53%) outbreaks occurring during December-February, and 70% of the 7,001 outbreaks with a reported setting of exposure occurred in long-term-care facilities (n = 4,894). In contrast, 59% (n = 143) of shigellosis outbreaks, 36% (n = 30) of salmonellosis outbreaks, and 32% (n = 84) of other or multiple etiology outbreaks were identified in child care facilities.

INTERPRETATION

NORS is the first U.S. surveillance system that provides national data on AGE outbreaks spread through person-to-person contact, environmental contamination, and unknown modes of transmission. The increase in reporting rates during 2009-2013 indicates that reporting to NORS improved notably in the 5 years since its inception. Norovirus is the most commonly reported cause of these outbreaks and, on the basis of epidemiologic data, might account for a substantial proportion of outbreaks without a reported etiology. During 2009-2013, norovirus accounted for most deaths and health care visits in AGE outbreaks spread through person-to-person contact, environmental contamination, and unknown modes of transmission.

PUBLIC HEALTH ACTION

Recommendations for prevention and control of AGE outbreaks transmitted through person-to-person contact, environmental contamination, and unknown modes of transmission depend primarily on appropriate hand hygiene, environmental disinfection, and isolation of ill persons. NORS surveillance data can help identify priority targets for the development of future control strategies, including hygiene interventions and vaccines, and help monitor the frequency and severity of AGE outbreaks in the United States. Ongoing study of these AGE outbreaks can provide a better understanding of certain pathogens and their modes of transmission. For example, certain reported outbreak etiologies (e.g., Salmonella) are considered primarily foodborne pathogens but can be transmitted through multiple routes. Similarly, further examination of outbreaks of unknown etiology could help identify barriers to making an etiologic determination, to analyze clinical and epidemiologic clues suggestive of a probable etiology, and to discover new and emerging etiologic agents. Outbreak reporting to NORS has improved substantially since its inception, and further outreach efforts and system improvements might facilitate additional increases in the number and completeness of reports to NORS.