Trends in Incidence of Norovirus-associated Acute Gastroenteritis in 4 Veterans Affairs Medical Center Populations in the United States, 2011-2015

BACKGROUND

Norovirus is an important cause of epidemic acute gastroenteritis (AGE), yet the burden of endemic disease in adults has not been well documented. We estimated the prevalence and incidence of outpatient and community-acquired inpatient norovirus AGE at 4 Veterans Affairs Medical Centers (VAMC) (Atlanta, Georgia; Bronx, New York; Houston, Texas; and Los Angeles, California) and examined trends over 4 surveillance years.

METHODS

From November 2011 to September 2015, stool specimens collected within 7 days of AGE symptom onset for clinician-requested diagnostic testing were tested for norovirus, and positive samples were genotyped. Incidence was calculated by multiplying norovirus prevalence among tested specimens by AGE-coded outpatient encounters and inpatient discharges, and dividing by the number of unique patients served.

RESULTS

Of 1603 stool specimens, 6% tested were positive for norovirus; GII.4 viruses (GII.4 New Orleans [17%] and GII.4 Sydney [47%]) were the most common genotypes. Overall prevalence and outpatient and inpatient community-acquired incidence followed a seasonal pattern, with higher median rates during November-April (9.2%, 376/100 000, and 45/100 000, respectively) compared to May-October (3.0%, 131/100 000, and 13/100 000, respectively). An alternate-year pattern was also detected, with highest peak prevalence and outpatient and inpatient community-acquired norovirus incidence rates in the first and third years of surveillance (14%-25%, 349-613/100 000, and 43-46/100 000, respectively).

CONCLUSIONS

This multiyear analysis of laboratory-confirmed AGE surveillance from 4 VAMCs demonstrates dynamic intra- and interannual variability in prevalence and incidence of outpatient and inpatient community-acquired norovirus in US Veterans, highlighting the burden of norovirus disease in this adult population.

Incidence, etiology, and severity of acute gastroenteritis among prospectively enrolled patients in 4 Veterans Affairs hospitals and outpatient centers, 2016-18

BACKGROUND

Acute gastroenteritis (AGE) burden, etiology, and severity in adults is not well-characterized. We implemented a multisite AGE surveillance platform in 4 Veterans Affairs Medical Centers (Atlanta, Bronx, Houston and Los Angeles), collectively serving >320,000 patients annually.

METHODS

From July 1, 2016-June 30, 2018, we actively identified AGE inpatient cases and non-AGE inpatient controls through prospective screening of admitted patients and passively identified outpatient cases through stool samples submitted for clinical diagnostics. We abstracted medical charts and tested stool samples for 22 pathogens via multiplex gastrointestinal PCR panel followed by genotyping of norovirus- and rotavirus-positive samples. We determined pathogen-specific prevalence, incidence, and modified Vesikari severity scores.

RESULTS

We enrolled 724 inpatient cases, 394 controls, and 506 outpatient cases. Clostridioides difficile and norovirus were most frequently detected among inpatients (cases vs controls: C. difficile, 18.8% vs 8.4%; norovirus, 5.1% vs 1.5%; p<0.01 for both) and outpatients (norovirus: 10.7%; C. difficile: 10.5%). Incidence per 100,000 population was highest among outpatients (AGE: 2715; C. difficile: 285; norovirus: 291) and inpatients ≥65 years old (AGE: 459; C. difficile: 91; norovirus: 26). Clinical severity scores were highest for inpatient norovirus, rotavirus, and Shigella/EIEC cases. Overall, 12% of AGE inpatient cases had ICU stays and 2% died; 3 deaths were associated with C. difficile and 1 with norovirus. C. difficile and norovirus were detected year-round with a fall/winter predominance.

CONCLUSIONS

C. difficile and norovirus were leading AGE pathogens in outpatient and hospitalized US Veterans, resulting in severe disease. Clinicians should remain vigilant for bacterial and viral causes of AGE year-round.

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.

2322. Etiology, Severity of Illness, and Risk Factors for Patients Hospitalized with Acute Gastroenteritis from Multi-Site Veteran’s Affairs (VA) Surveillance, 2016–2018: Results from SUPERNOVA

Background

The severity of acute gastroenteritis (AGE) in adult populations and the relative contribution of specific pathogens is not well characterized. In 2016, we implemented a multisite AGE surveillance platform in 4 VA hospitals (Atlanta, Bronx, Houston and Los Angeles), collectively serving > 320,000 patients annually.

Methods

Inpatient AGE cases and age- and time-matched non-AGE controls were identified through prospective screening of admissions using standardized case definitions. Stool samples were tested for 22 pathogens using the FilmArray® Gastrointestinal Panel. Medical conditions were analyzed as risk factors for AGE by multivariate logistic regression.

Results

From July 2016 to June 2018, 731 cases and 399 controls were enrolled. Risk factors for AGE cases included HIV-positive status (adjusted odds ratio [aOR] 4.6; 95% confidence interval [CI] 1.6–12.9; P < 0.01), severe kidney disease (aOR 4.5; 95% CI 2.0–9.8; P < 0.01), and immunosuppressive therapy (aOR 4.0; 95% CI 1.2–13.3]; P = 0.02). Clostridioides difficile and norovirus were the most commonly detected pathogens in cases (18% and 5%, respectively); detection of these pathogens in cases was significantly higher than detection in controls (8% and 2%, respectively; P < 0.01 for both). The median duration of hospital stay was longer for C. difficile compared with norovirus cases (5 vs. 3 days; P < 0.01), and cases with both pathogens had intensive care unit (ICU) stays (C. difficile: 18%; norovirus: 8%; P = 0.2). Fourteen deaths occurred among AGE cases; 2 were associated with C. difficile and 1 with norovirus; the remainder did not have a clear etiology or pathogen detected. C. difficile and norovirus were detected year-round with a fall and winter predominance; C. difficile prevalence was highest in October, while norovirus prevalence was six times higher in December than in summer months.

Conclusion

This surveillance platform captured cases of severe AGE, including ICU stays and deaths, among hospitalized US Veterans. C. difficile and norovirus were leading pathogens in AGE cases. These findings can help guide appropriate clinical management of AGE patients and inform public health efforts to quantify and address the associated burden of disease through targeted interventions.

Disclosures

All authors: No reported disclosures.

Active Surveillance for Norovirus in a US Veterans Affairs Patient Population, Houston, Texas, 2015-2016

Background

Norovirus is a leading cause of acute gastroenteritis (AGE); however, few data exist on endemic norovirus disease burden among adults. Candidate norovirus vaccines are currently in development for all ages, and robust estimates of norovirus incidence among adults are needed to provide baseline data.

Methods

We conducted active surveillance for AGE among inpatients at a Veterans Affairs (VA) hospital in Houston, Texas. Patients with AGE (≥3 loose stools, ≥2 vomiting episodes, or ≥1 episode of both loose stool and vomiting, within 24 hours) within 10 days of enrollment and non-AGE control patients were enrolled. Demographic data and clinical characteristics were collected. Stool samples were tested using the FilmArray gastrointestinal panel; virus-positives were confirmed by real-time reverse transcription polymerase chain reaction and genotyped by sequencing.

Results

From November 2, 2015 through November 30, 2016, 147 case patients and 19 control patients were enrolled and provided a stool specimen. Among case patients, 139 (95%) were male and 70 (48%) were aged ≥65 years. Norovirus was the leading viral pathogen detected (in 16 of 20 virus-positive case patients) and accounted for 11% of all AGE cases. No viral pathogens were detected among control patients. Incidence of norovirus-associated hospitalization was 20.3 cases/100 000 person-years and was similar among those aged <65 and ≥65 years.

Conclusions

This active surveillance platform employed screening and enrollment of hospitalized VA patients meeting a standardized AGE case definition, as well as non-AGE control patients. Data from this study highlight the burden of norovirus in a VA inpatient population and will be useful in policy considerations of a norovirus vaccine.

1648. Incidence of Norovirus and Rotavirus From Multisite Active Surveillance in Veteran’s Affairs Hospitals, December 2016–February 2018: Results From the SUPERNOVA Network

Background

Viruses are frequently implicated in acute gastroenteritis (AGE) outbreaks, yet the endemic burden of norovirus and rotavirus disease in adult populations is not well characterized. In 2016, we implemented a multisite AGE surveillance platform capturing cases and controls in 4 VA hospitals (Atlanta, Bronx, Houston, and Los Angeles), collectively serving >320,000 patients annually.

Methods

Inpatient AGE cases and age- and time-matched controls were identified through prospective screening of admissions via standardized case definitions. Outpatient cases were passively identified using stool samples submitted for routine clinical microbiological diagnostics. Samples were tested with the FilmArray Gastrointestinal Panel, followed by genotyping of virus positives. Incidence was estimated using population denominators of unique patients served annually by site.

Results

From December 1, 2016 to February 28, 2018, 875 cases (496 inpatients, 379 outpatients), and 374 controls were enrolled. Norovirus and rotavirus prevalence was highest among outpatient AGE cases (11.6% and 2.9%, respectively) followed by inpatient cases (3.4% and 1.6%, respectively); few controls were positive (norovirus, 1.3%; rotavirus, 0%). Norovirus-associated inpatient incidence was 15.2 per 100,000 population (range by site: 10.7–19.9/100,000) and rotavirus-associated inpatient incidence was 7.5 per 100,000 population (range by site: 0–12.8/100,000). The predominant norovirus genotype was GII.P16-GII.4 Sydney (50%), and rotavirus genotype was G12P[8] (83%). Norovirus was detected every calendar month and peaked in December–January, while rotavirus peaked in April. Nine deaths were documented among AGE inpatient cases, including one norovirus-associated death.

Conclusion

Implementation of a multisite AGE surveillance platform captured a wide spectrum of illness for norovirus and rotavirus in US Veterans including outpatient visits, inpatient hospitalizations, and one norovirus-associated death. Norovirus was the leading viral pathogen and was detected year-round. Ongoing surveillance using this platform will allow for further characterization of the pathogen distribution and associated AGE disease burden in adults.

Disclosures

V. Marconi, ViiV: Investigator, Research support and Salary. Bayer: Investigator, Research support. Gilead: Investigator, Research support.

652. What Is Blood Got to Do with It? Genetic Susceptibility to Norovirus and Rotavirus Infection: Results From the SUPERNOVA Network

Background

Histo-blood group antigens (HBGAs), whose expression is controlled in part by fucosyltransferase 2 (FUT2) and 3 (FUT3) genes, serve as receptors for norovirus and rotavirus. Individuals without functional FUT2 (nonsecretors) or FUT3 (Lewis-negative) genes may have decreased susceptibility to norovirus and rotavirus infections. As the prevalence of secretor and Lewis status can vary by race and ethnicity, we assessed this association in a US Veteran population.

Methods

Stool and saliva specimens were collected from acute gastroenteritis (AGE) cases and age- and time-matched controls through a multisite, active surveillance platform at four Veterans Affairs hospitals (Atlanta, Bronx, Houston, Los Angeles). Stool specimens were tested with the FilmArray Gastrointestinal Panel; norovirus and rotavirus positive specimens were genotyped. Saliva specimens were analyzed for HBGA expression by EIA using glycan-specific monoclonal antibodies and lectins. Chi-squared and Fisher’s exact tests were conducted to evaluate associations between secretor and Lewis status and infection with norovirus or rotavirus.

Results

From November 4, 2015–December 30, 2017, 670 AGE cases and 319 controls provided both stool and saliva specimens. Norovirus (21 GII.4 Sydney, 13 GII non-4, 7 GI, 10 untyped) and rotavirus (13 G12P[8], 1 G2P[4], 1 untyped) positive cases were more likely to be secretor positive (90% and 100%, respectively) compared with controls (76%) (P = 0.03 for both). Infections with GII.4 Sydney norovirus (P < 0.01) and G12P[8] rotavirus (P < 0.05) were significantly associated with secretor status. This association was not observed with other norovirus or rotavirus genotypes. No association was observed between Lewis status, race, or ethnicity and infection with norovirus or rotavirus.

Conclusion

Norovirus and rotavirus infections among a US Veteran population were associated with secretor status in a genotype-dependent manner, and with GII.4 Sydney norovirus and G12P[8] rotavirus, the most common strains. These associations are consistent with previously reported results, and suggest that the efficacy of interventions, such as vaccines, should include consideration of secretor status and predominantly circulating virus strains.

Disclosures

R. L. Atmar, Takeda Vaccines, Inc.: Investigator, Research grant. V. C. Marconi, ViiV: Investigator, Research support and Salary. Gilead: Investigator, Research support. Bayer: Investigator, Research support.

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.

Incidence of Norovirus-Associated Acute Gastroenteritis in Four Veteran’s Affairs Medical Center Populations in the United States, 2011–2015

Background

In the USA, norovirus is an important cause of epidemic acute gastroenteritis (AGE) as well as a leading cause of pediatric AGE. However, the burden of sporadic norovirus disease in US adults has not been well-documented. Our objective was to estimate the incidence of outpatient visits and hospitalizations for community-acquired norovirus AGE at four Veterans Affairs Medical Centers (VAMCs) and their associated outpatient clinics in Atlanta, GA; Bronx, New York; Houston, TX; and Los Angeles, CA.

Methods

From November 2011 to September 2015, stool specimens collected for clinician-requested diagnostic testing within 7 days of AGE symptom onset and with reported vomiting or diarrhea were tested for norovirus by real-time RT-PCR and positive samples were genotyped by Sanger sequencing. Incidence of norovirus-associated outpatient visits and hospitalizations were calculated by multiplying the prevalence of norovirus among tested specimens by AGE-coded outpatient encounters and inpatient discharges, and dividing by the unique patients served at each VAMC.

Results

1,620 stool specimens were tested from all 4 sites. Seven percent of outpatient (n = 795) samples (annual range: 3%–10%; range by site: 3%–10%) and 6% of&#x2028;(n = 825) samples from hospitalized patients tested positive for norovirus (annual range: 3%–8%; range by site: 3%–10%). Forty-four percent of norovirus-positive specimens were typed as GII.4 Sydney. Seventy-four percent of norovirus-positive specimens were collected between November and April. From 2011 to 2015, outpatient norovirus incidence was 250/100,000 population (annual range: 129 to 426/100,000; range by site: 87 to 428/100,000), and the incidence of norovirus hospitalizations was 28/100,000 population (annual range: 19 to 39/100,000; range by site: 14 to 57/100,000). By age group and setting, the highest incidence was observed among 45- to 64-year-old outpatients (370/100,000 population), and 85+-year-old inpatients (63/100,000 population).

Conclusion

This study provides estimates of the incidence of norovirus AGE outpatient visits and hospitalizations across multiple years among a geographically distributed VA population, highlighting the substantial burden of norovirus in US adults.

Disclosures

All authors: No reported disclosures.

Active Surveillance to Quantify the Burden of Norovirus in a U.S. Veterans Affairs (VA) Patient Population, Houston, 2015–2016

Background

Norovirus is the leading cause of acute gastroenteritis (AGE) outbreaks in the United States; however, little data exist on the burden of endemic norovirus disease among adults. Robust estimates of the norovirus disease burden among US adults are needed to inform assessment of potential norovirus vaccines, which are currently in development.

Methods

We conducted active surveillance for AGE at the Michael E. DeBakey Veteran’s Affairs (VA) Medical Center, where approximately 104,000 unique patients were served in 2016. Cases were defined as veterans with symptoms of AGE (≥3 loose stools, ≥2 vomiting episodes, or ≥1 episodes of both loose stool and vomiting, within 24 hours) occurring in the previous 10 days, who presented to the emergency department or outpatient clinics (outpatients), or were admitted to the hospital (inpatients). Patients without AGE symptoms in the prior 14 days were enrolled as controls. Demographic data and illness characteristics were collected from enrolled subjects, and stool samples were collected and tested using the FilmArray gastrointestinal panel. Norovirus positives were confirmed by real-time RT-PCR and genotyped after sequencing of conventional PCR products.

Results

From November 1, 2015–November 30, 2016, 130 inpatient and 85 outpatient AGE cases, along with 20 inpatient and 37 outpatient controls, were enrolled and provided a stool specimen. Among cases, 201 (93%) were male, and 94 (44%) were ≥65 years; median duration of illness was 3 days (range, 1–10 days). Norovirus was detected in 12 (9%) inpatient and 15 (18%) outpatient cases; norovirus was not detected in any controls. Incidence of norovirus-associated hospitalization was 15/100,000 population, and was similar in hospitalized cases aged <65 years (14/100,000) and ≥65 years (15/100,000). Of 22 norovirus positive specimens genotyped, 13 (59%) were GII.4 Sydney.

Conclusion

This robust, active surveillance platform employed screening and enrollment of patients in a VA population meeting a standardized AGE case definition, as well as asymptomatic controls. Data from this study highlight the burden of norovirus in adults and importance of a norovirus vaccine.

Disclosures

R. L. Atmar, Takeda Vaccines, Inc.: Research Support, Research support. B. Lopman, HHS/NIH/NIAID: Grant Investigator, Grant recipient. Bill & Melinda Gates Foundation: Grant Investigator, Grant recipient.

Impact and Effectiveness of Monovalent Rotavirus Vaccine Against Severe Rotavirus Diarrhea in Ghana

BACKGROUND

Ghana was among the first African nations to introduce monovalent rotavirus vaccine (RV1) into its childhood immunization schedule in April 2012. We aimed to assess the impact of vaccine introduction on rotavirus and acute gastroenteritis (AGE) hospitalizations and to estimate vaccine effectiveness (VE).

METHODS

Using data from 2 teaching hospitals, monthly AGE and rotavirus admissions by age were examined 40 months before and 31 months after RV1 introduction using interrupted time-series analyses. From January 2013, we enrolled children <2 years of age who were eligible for RV1 from a total of 7 sentinel sites across the country. To estimate VE, we fit unconditional logistic regression models to calculate odds ratios of vaccination by rotavirus case-patient status, controlling for potential confounders.

RESULTS

Vaccine coverage ranged from 95% to 100% for dose 1 and 93% to 100% for dose 2. In the first 3 years after vaccine introduction, the percentage of hospital admissions positive for rotavirus fell from 48% in the prevaccine period to 28% (49% adjusted rate reduction; 95% confidence interval [CI], 32%-63%) postvaccination among <5-year-olds. With high vaccine coverage, it was not possible to arrive at robust VE estimates; any-dose VE against rotavirus hospitalization was estimated at 60% (95% CI, -2% to 84%;P= .056).

CONCLUSIONS

Results from the first 3 years following RV1 introduction suggest substantial reductions of pediatric diarrheal disease as a result of vaccination. Our VE estimate is consistent with the observed rotavirus decrease and with efficacy estimates from elsewhere in sub-Saharan Africa.

Two-dose varicella vaccine effectiveness and rash severity in outbreaks of varicella among public school students

BACKGROUND

Universal 2-dose varicella vaccination was recommended in 2006 to further reduce varicella disease burden. This study examined 2-dose varicella vaccine effectiveness (VE) and rash severity in the setting of school-associated varicella outbreaks.

METHODS

A case control study was conducted from January 2010 to May 2011 in all West Virginia public schools. Clinically diagnosed cases from varicella outbreaks were matched with classmate controls. Vaccination information was collected from school, health department and healthcare provider immunization information systems.

RESULTS

Among the 133 cases and 365 controls enrolled, VE against all varicella was 83.2% [95% confidence interval (CI): 69.2%-90.8%] for 1-dose of varicella vaccine and 93.9% (95% CI: 86.9%-97.1%) for 2-dose; the incremental VE (2-dose vs. 1-dose) was 63.6% (95% CI: 32.6%-80.3%). In preventing moderate/severe varicella, 1-dose varicella vaccine was 88.2% (95% CI: 72.7%- 94.9%) effective, and 2-dose vaccination was 97.5% (95% CI: 91.6%-99.2%) effective, with the incremental VE of 78.6% (95% CI: 40.9%-92.3%). One-dose VE declined along with time since vaccination (VE = 93.0%, 88.0% and 81.8% in <5, 5-9 and ≥ 10 years after vaccination, P = 0.001 for trend). Both 1- and 2-dose breakthrough cases had milder rash than unvaccinated cases (<50 lesion: 24.6%, 49.1% and 70.0% in unvaccinated, 1-dose and 2-dose cases, P < 0.001), and no severe disease was found in 2-dose cases.

CONCLUSIONS

Two-dose varicella vaccination is highly effective and confers higher protection than a 1-dose regimen. High 2-dose varicella vaccination coverage should maximize the benefits of the varicella vaccination program and further reduce varicella disease burden in the United States.

Case-control study of hepatitis B and hepatitis C in older adults: Do healthcare exposures contribute to burden of new infections?

Reports of hepatitis B virus (HBV) and hepatitis C virus (HCV) transmission associated with unsafe medical practices have been increasing in the United States. However, the contribution of healthcare exposures to the burden of new infections is poorly understood outside of recognized outbreaks. We conducted a case-control study at three health departments that perform enhanced viral hepatitis surveillance in New York and Oregon. Reported cases of symptomatic acute hepatitis B and hepatitis C occurring in persons≥55 years of age from 2006 to 2008 were enrolled. Controls were identified using telephone directories and matched to individual cases by age group (55-59, 60-69, and ≥70 years) and residential postal code. Data collection covered exposures within 6 months before symptom onset (cases) or date of interview (controls). Forty-eight (37 hepatitis B and 11 hepatitis C) case and 159 control patients were enrolled. Case patients were more likely than controls to report one or more behavioral risk exposures, including sexual or household contact with an HBV or HCV patient, >1 sex partner, illicit drug use, or incarceration (21% of cases versus 4% of controls exposed; matched odds ratio [mOR]=7.1; 95% confidence interval [CI]: 2.1, 24.1). Case patients were more likely than controls to report hemodialysis (8% of cases; mOR=13.0; 95% CI: 1.5, 115), injections in a healthcare setting (58%; mOR=2.7; 95% CI: 1.3, 5.3), and surgery (33%; mOR=2.3; 95% CI: 1.1, 4.7). In a multivariate model, behavioral risks (adjusted OR [aOR]=5.4; 95% CI: 1.5, 19.0; 17% attributable risk), injections (aOR=2.7; 95% CI: 1.3, 5.8; 37% attributable risk), and hemodialysis (aOR=11.5; 95% CI: 1.2, 107; 8% attributable risk) were associated with case status.

CONCLUSION

Healthcare exposures may represent an important source of new HBV and HCV infections among older adults.

Challenges in confirming a varicella outbreak in the two-dose vaccine era

BACKGROUND

A second dose of varicella vaccine was recommended for U.S. children in 2006. We investigated a suspected varicella outbreak in School District X, Texas to determine 2-dose varicella vaccine effectiveness (VE).

METHODS

A varicella case was defined as an illness with maculopapulovesicular rash without other explanation with onset during April 1-June 10, 2011, in a School District X student. We conducted a retrospective cohort in the two schools with the majority of cases. Lesion, saliva, and environmental specimens were collected for varicella-zoster virus (VZV) PCR testing. VE was calculated using historic attack rates among unvaccinated.

RESULTS

In School District X, 82 varicella cases were reported, including 60 from Schools A and B. All cases were mild, with a median of 14 lesions. All 10 clinical specimens and 58 environmental samples tested negative for VZV. Two-dose varicella vaccination coverage was 66.4% in Schools A and B. Varicella VE in affected classrooms was 80.9% (95% CI: 67.2-88.9) among 1-dose vaccinees and 94.7% (95% CI: 89.2-97.4) among 2-dose vaccinees in School A, with a second dose incremental VE of 72.1% (95% CI: 39.0-87.3). Varicella VE among School B students did not differ significantly by dose (80.1% vs. 84.2% among 1-dose and 2-dose vaccinees, respectively).

CONCLUSION

Laboratory testing could not confirm varicella as the etiology of this outbreak; clinical and epidemiologic data suggests varicella as the likely cause. Better diagnostics are needed for diagnosis of varicella in vaccinated individuals so that appropriate outbreak control measures can be implemented.

Surveillance for acute viral hepatitis - United States, 2007

PROBLEM

In the United States, acute viral hepatitis most frequently is caused by infection with any of three distinct viruses: hepatitis A virus (HAV), hepatitis B virus (HBV), or hepatitis C virus (HCV). These unrelated viruses are transmitted through different routes and have different epidemiologic profiles. Safe and effective vaccines have been available for hepatitis B since 1981 and for hepatitis A since 1995. No vaccine exists against hepatitis C. HBV and HCV can persist as chronic infections and represent a leading cause of chronic liver disease and hepatocellular carcinoma in the United States.

REPORTING PERIOD COVERED

Cases in 2007, the most recent year for which data are available, are compared with those from previous years.

DESCRIPTION OF SYSTEM

Cases of acute viral hepatitis are reported voluntarily to CDC by state and territorial health departments via CDC's National Notifiable Disease Surveillance System (NNDSS). Reports are received electronically via CDC's National Electronic Telecommunications System for Surveillance (NETSS).

RESULTS

Acute hepatitis A incidence has declined 92%, from 12.0 cases per 100,000 population in 1995 to 1.0 case per 100,000 population in 2007, the lowest rate ever recorded. Declines were greatest among children and in those states where routine vaccination of children was recommended beginning in 1999. Acute hepatitis B incidence has declined 82%, from 8.5 cases per 100,000 population in 1990 to 1.5 cases per 100,000 population in 2007, the lowest rate ever recorded. Declines occurred among all age groups but were greatest among children aged <15 years. Following a peak in 1992, incidence of acute hepatitis C declined; however, since 2003, rates have plateaued. In 2007, as in previous years, the majority of these cases occurred among adults, and injection-drug use was the most common risk factor.

INTERPRETATION

The results documented in this report suggest that implementation of the 1999 recommendations for routine childhood hepatitis A vaccination in areas of the United States with consistently elevated hepatitis A rates has reduced rates of infection. In addition, universal vaccination of children against hepatitis B beginning in 1991 has reduced disease incidence substantially among younger age groups. Higher rates of hepatitis B continue among adults, particularly among males aged 30-44 years, reflecting the need to vaccinate adults at risk for HBV infection. The decline in hepatitis C incidence after 1992 was attributable primarily to a decrease in incidence among injection-drug users. The reasons for this decrease were unknown but probably reflected changes in behavior and practices among injection-drug users.

PUBLIC HEALTH ACTIONS

The expansion in 2006 of recommendations for routine hepatitis A vaccination to include all children in the United States aged 12-23 months is expected to reduce hepatitis A rates further. Ongoing hepatitis B vaccination programs ultimately will eliminate domestic HBV transmission, and increased vaccination of adults with risk factors will accelerate progress toward elimination. Further prevention of hepatitis B and hepatitis C relies on identifying and preventing transmission of HBV or HCV in hospital and nonhospital health-care associated settings. In addition, prevention of hepatitis C relies on identifying and counseling uninfected persons at risk for hepatitis C (e.g., injection-drug users) regarding ways they can protect themselves from infection. Public health management of persons with chronic HBV or HCV infection will help to interrupt the transmission to susceptible persons, and their medical management will help to reduce the development of the sequelae from chronic liver disease.

Surveillance for acute viral hepatitis--United States, 2006

PROBLEM/CONDITION

In the United States, acute viral hepatitis most frequently is caused by infection with three viruses: hepatitis A virus (HAV), hepatitis B virus (HBV), and hepatitis C virus (HCV). These unrelated viruses are transmitted through different routes and have different epidemiologic profiles. Safe and effective vaccines have been available for hepatitis B since 1981 and for hepatitis A since 1995. No vaccine exists against hepatitis C.

REPORTING PERIOD COVERED

Cases in 2006, the most recent year for which data are available, are compared with those from previous years.

DESCRIPTION OF SYSTEM

Cases of acute viral hepatitis are reported voluntarily to CDC by state and territorial epidemiologists via CDC's National Notifiable Disease Surveillance System (NNDSS). Reports are received electronically via CDC's National Electronic Telecommunications System for Surveillance (NETSS).

RESULTS

During 1995-2006, hepatitis A incidence declined 90% to the lowest rate ever recorded (1.2 cases per 100,000 population). Declines were greatest among children and in those states where routine vaccination of children was recommended beginning in 1999. An increasing proportion of cases occurred in adults. During 1990-2006, acute hepatitis B incidence declined 81% to the lowest rate ever recorded (1.6 cases per 100,000 population). Declines occurred among all age groups but were greatest among children aged <15 years. Following a peak in the late 1980s, incidence of acute hepatitis C declined through the 1990s; however, since 2003, rates have plateaued, with a slight increase in reported cases in 2006. In 2006, as in previous years, the majority of these cases occurred among adults, and injection-drug use was the most common risk factor.

INTERPRETATION

The results documented in this report suggest that implementation of the 1999 recommendations for routine childhood hepatitis A vaccination in the United States has reduced rates of infection and that universal vaccination of children against hepatitis B has reduced disease incidence substantially among younger age groups. Higher rates of hepatitis B continue among adults, particularly males aged 25-44 years, reflecting the need to vaccinate adults at risk for HBV infection. The decline in hepatitis C incidence that occurred in the 1990s was attributable primarily to a decrease in incidence among injection-drug users. The reasons for this decrease were unknown but likely reflected changes in behavior and practices among injection-drug users.

PUBLIC HEALTH ACTIONS

The expansion in 2006 of recommendations for routine hepatitis A vaccination to include all children in the United States aged 12-23 months is expected to reduce hepatitis A rates further. Ongoing hepatitis B vaccination programs ultimately will eliminate domestic HBV transmission, and increased vaccination of adults with risk factors will accelerate progress toward elimination. Prevention of hepatitis C relies on identifying and counseling uninfected persons at risk for hepatitis C (e.g., injection-drug users) regarding ways to protect themselves from infection and on identifying and preventing transmission of HCV in health-care settings.