Multistate outbreak of Salmonella enterica serotype enteritidis infection associated with pet guinea pigs

Salmonella causes about one million illnesses annually in the United States. Although most infections result from foodborne exposures, animal contact is an important mode of transmission. We investigated a case of Salmonella enterica serotype Enteritidis (SE) sternal osteomyelitis in a previously healthy child who cared for two recently deceased guinea pigs (GPs). A case was defined as SE pulsed-field gel electrophoresis (PFGE) XbaI pattern JEGX01.0021, BlnI pattern JEGA26.0002 (outbreak strain) infection occurring during 2010 in a patient who reported GP exposure. To locate outbreak strain isolates, PulseNet and the US Department of Agriculture National Veterinary Service Laboratories (NVSL) databases were queried. Outbreak strain isolates underwent multilocus variable-number tandem repeat analysis (MLVA). Traceback and environmental investigations were conducted at homes, stores, and breeder or broker facilities. We detected 10 cases among residents of eight states and four NVSL GP outbreak strain isolates. One patient was hospitalized; none died. The median patient age was 9.5 (range, 1-61) years. Among 10 patients, two purchased GPs at independent stores, and three purchased GPs at different national retail chain (chain A) store locations; three were chain A employees and two reported GP exposures of unknown characterization. MLVA revealed four related patterns. Tracebacks identified four distributors and 92 sources supplying GPs to chain A, including one breeder potentially supplying GPs to all case-associated chain A stores. All environmental samples were Salmonella culture-negative. A definitive SE-contaminated environmental source was not identified. Because GPs can harbor Salmonella, consumers and pet industry personnel should be educated regarding risks.

A large community outbreak of blastomycosis in Wisconsin with geographic and ethnic clustering

BACKGROUND

Blastomycosis is a potentially life-threatening infection caused by the soil-based dimorphic fungus Blastomyces dermatitidis, which is endemic throughout much of the Midwestern United States. We investigated an increase in reported cases of blastomycosis that occurred during 2009-2010 in Marathon County, Wisconsin.

METHODS

Case detection was conducted using the Wisconsin Electronic Disease Surveillance System (WEDSS). WEDSS data were used to compare demographic, clinical, and exposure characteristics between outbreak-related and historical case patients, and to calculate blastomycosis incidence rates. Because initial mapping of outbreak case patients' homes and recreational sites demonstrated unusual neighborhood and household case clustering, we conducted a 1:3 matched case-control study to identify factors associated with being in a geographic cluster.

RESULTS

Among the 55 patients with outbreak-related cases, 33 (70%) were hospitalized, 2 (5%) died, 30 (55%) had cluster-related cases, and 20 (45%) were Hmong. The overall incidence increased significantly since 2005 (average 11% increase per year, P < .001), and incidence during 2005-2010 was significantly higher among Asians than non-Asians (2010 incidence: 168 vs 13 per 100 000 population). Thirty of the outbreak cases grouped into 5 residential clusters. Outdoor activities were not risk factors for blastomycosis among cluster case patients or when comparing outbreak cases to historical cases.

CONCLUSIONS

This outbreak of blastomycosis, the largest ever reported, was characterized by unique household and neighborhood clustering likely related to multifocal environmental sources. The reasons for the large number of Hmong affected are unclear, but may involve genetic predisposition.

Searching for sharp drops in the incidence of pandemic A/H1N1 influenza by single year of age

Background

During the 2009 H1N1 pandemic (pH1N1), morbidity and mortality sparing was observed among the elderly population; it was hypothesized that this age group benefited from immunity to pH1N1 due to cross-reactive antibodies generated from prior infection with antigenically similar influenza viruses. Evidence from serologic studies and genetic similarities between pH1N1 and historical influenza viruses suggest that the incidence of pH1N1 cases should drop markedly in age cohorts born prior to the disappearance of H1N1 in 1957, namely those at least 52–53 years old in 2009, but the precise range of ages affected has not been delineated.

Methods and Findings

To test for any age-associated discontinuities in pH1N1 incidence, we aggregated laboratory-confirmed pH1N1 case data from 8 jurisdictions in 7 countries, stratified by single year of age, sex (when available), and hospitalization status. Using single year of age population denominators, we generated smoothed curves of the weighted risk ratio of pH1N1 incidence, and looked for sharp drops at varying age bandwidths, defined as a significantly negative second derivative. Analyses stratified by hospitalization status and sex were used to test alternative explanations for observed discontinuities. We found that the risk of laboratory-confirmed infection with pH1N1 declines with age, but that there was a statistically significant leveling off or increase in risk from about 45 to 50 years of age, after which a sharp drop in risk occurs until the late fifties. This trend was more pronounced in hospitalized cases and in women and was independent of the choice in smoothing parameters. The age range at which the decline in risk accelerates corresponds to the cohort born between 1951–1959 (hospitalized) and 1953–1960 (not hospitalized).

Conclusions

The reduced incidence of pH1N1 disease in older individuals shows a detailed age-specific pattern consistent with protection conferred by exposure to influenza A/H1N1 viruses circulating before 1957.

An outbreak of Legionnaires disease associated with a decorative water wall fountain in a hospital

OBJECTIVE

To detect an outbreak-related source of Legionella, control the outbreak, and prevent additional Legionella infections from occurring.

DESIGN AND SETTING

Epidemiologic investigation of an acute outbreak of hospital-associated Legionnaires disease among outpatients and visitors to a Wisconsin hospital.

PATIENTS

Patients with laboratory-confirmed Legionnaires disease who resided in southeastern Wisconsin and had illness onsets during February and March 2010.

METHODS

Patients with Legionnaires disease were interviewed using a hypothesis-generating questionnaire. On-site investigation included sampling of water and other potential environmental sources for Legionella testing. Case-finding measures included extensive notification of individuals potentially exposed at the hospital and alerts to area healthcare and laboratory personnel.

RESULTS

Laboratory-confirmed Legionnaires disease was diagnosed in 8 patients, all of whom were present at the same hospital during the 10 days prior to their illness onsets. Six patients had known exposure to a water wall-type decorative fountain near the main hospital entrance. Although the decorative fountain underwent routine cleaning and maintenance, high counts of Legionella pneumophila serogroup 1 were isolated from cultures of a foam material found above the fountain trough.

CONCLUSION

This outbreak of Legionnaires disease was associated with exposure to a decorative fountain located in a hospital public area. Routine cleaning and maintenance of fountains does not eliminate the risk of bacterial contamination. Our findings highlight the need to evaluate the safety of water fountains installed in any area of a healthcare facility.

Improving the evidence base for decision making during a pandemic: the example of 2009 influenza A/H1N1

This article synthesizes and extends discussions held during an international meeting on "Surveillance for Decision Making: The Example of 2009 Pandemic Influenza A/H1N1," held at the Center for Communicable Disease Dynamics (CCDD), Harvard School of Public Health, on June 14 and 15, 2010. The meeting involved local, national, and global health authorities and academics representing 7 countries on 4 continents. We define the needs for surveillance in terms of the key decisions that must be made in response to a pandemic: how large a response to mount and which control measures to implement, for whom, and when. In doing so, we specify the quantitative evidence required to make informed decisions. We then describe the sources of surveillance and other population-based data that can presently--or in the future--form the basis for such evidence, and the interpretive tools needed to process raw surveillance data. We describe other inputs to decision making besides epidemiologic and surveillance data, and we conclude with key lessons of the 2009 pandemic for designing and planning surveillance in the future.

Comparison of patients hospitalized with pandemic 2009 influenza A (H1N1) virus infection during the first two pandemic waves in Wisconsin

BACKGROUND

Wisconsin was severely affected by pandemic waves of 2009 influenza A H1N1 infection during the period 15 April through 30 August 2009 (wave 1) and 31 August 2009 through 2 January 2010 (wave 2).

METHODS

To evaluate differences in epidemiologic features and outcomes during these pandemic waves, we examined prospective surveillance data on Wisconsin residents who were hospitalized ≥ 24 h with or died of pandemic H1N1 infection.

RESULTS

Rates of hospitalizations and deaths from pandemic H1N1 infection in Wisconsin increased 4- and 5-fold, respectively, from wave 1 to wave 2; outside Milwaukee, hospitalization and death rates increased 10- and 8-fold, respectively. Hospitalization rates were highest among racial and ethnic minorities and children during wave 1 and increased most during wave 2 among non-Hispanic whites and adults. Times to hospital admission and antiviral treatment improved between waves, but the overall hospital course remained similar, with no change in hospitalization duration, intensive care unit admission, requirement for mechanical ventilation, or mortality.

CONCLUSIONS

We report broader geographic spread and marked demographic differences during pandemic wave 2, compared with wave 1, although clinical outcomes were similar. Our findings emphasize the importance of using comprehensive surveillance data to detect changing characteristics and impacts during an influenza pandemic and of vigorously promoting influenza vaccination and other prevention efforts.

Epidemiologic and clinical features among patients hospitalized in Wisconsin with 2009 H1N1 influenza A virus infections, April to August 2009

BACKGROUND

During April 15 through July 23, 2009, Wisconsin reported the most confirmed and probable cases of 2009 influenza A (H1N1) virus (2009 H1N1) infection in the United States. Preliminary reports suggest that 2009 H1N1 infection disproportionately affected minority populations.

METHODS

Prospective surveillance among all acute care hospitals in Wisconsin to detect patients hospitalized at least 24 hours with confirmed 2009 H1N1 infection during April 23 through August 15, 2009.

RESULTS

During the study interval, 252 patients were hospitalized and 11 (4%) died. Statewide hospitalization rates by age, sex, and race/ethnicity categories were highest among patients aged <1 year (21.6/100,000), females (4.9/100,000), and African Americans (36.3/100,000). The median age was 28 years: Hispanics (median age=16 years) and African Americans (24 years) were younger than non-Hispanic whites (37 years) and Asians (38 years). African Americans were more likely to have a hematologic condition and be morbidly obese (BMI > or = 40 kg/m2), and less likely to be admitted to an intensive care unit compared to other race/ethnicity groups (P<0.05). Hispanics and non-Hispanic whites were more likely to have cancer, be non-morbidly obese (BMI 30-39.9 kg/m2 or BMI percentile > or = 95%), and be hospitalized for >5 days compared to African Americans and Asians (P<0.05). There were no significant racial/ethnic differences in time from illness onset to admission or receipt of antiviral therapy, need for mechanical ventilation, acute respiratory distress syndrome, or death.

CONCLUSIONS

The first wave of the 2009 H1N1 pandemic in Wisconsin disproportionately affected hospitalized patients who were African Americans, Asians, and Hispanics compared to non-Hispanic whites. Preventive measures focused on these populations may reduce morbidity associated with 2009 H1N1 infection.

Monitoring the impact of influenza by age: emergency department fever and respiratory complaint surveillance in New York City

BACKGROUND

The importance of understanding age when estimating the impact of influenza on hospitalizations and deaths has been well described, yet existing surveillance systems have not made adequate use of age-specific data. Monitoring influenza-related morbidity using electronic health data may provide timely and detailed insight into the age-specific course, impact and epidemiology of seasonal drift and reassortment epidemic viruses. The purpose of this study was to evaluate the use of emergency department (ED) chief complaint data for measuring influenza-attributable morbidity by age and by predominant circulating virus.

METHODS AND FINDINGS

We analyzed electronically reported ED fever and respiratory chief complaint and viral surveillance data in New York City (NYC) during the 2001-2002 through 2005-2006 influenza seasons, and inferred dominant circulating viruses from national surveillance reports. We estimated influenza-attributable impact as observed visits in excess of a model-predicted baseline during influenza periods, and epidemic timing by threshold and cross correlation. We found excess fever and respiratory ED visits occurred predominantly among school-aged children (8.5 excess ED visits per 1,000 children aged 5-17 y) with little or no impact on adults during the early-2002 B/Victoria-lineage epidemic; increased fever and respiratory ED visits among children younger than 5 y during respiratory syncytial virus-predominant periods preceding epidemic influenza; and excess ED visits across all ages during the 2003-2004 (9.2 excess visits per 1,000 population) and 2004-2005 (5.2 excess visits per 1,000 population) A/H3N2 Fujian-lineage epidemics, with the relative impact shifted within and between seasons from younger to older ages. During each influenza epidemic period in the study, ED visits were increased among school-aged children, and each epidemic peaked among school-aged children before other impacted age groups.

CONCLUSIONS

Influenza-related morbidity in NYC was highly age- and strain-specific. The impact of reemerging B/Victoria-lineage influenza was focused primarily on school-aged children born since the virus was last widespread in the US, while epidemic A/Fujian-lineage influenza affected all age groups, consistent with a novel antigenic variant. The correspondence between predominant circulating viruses and excess ED visits, hospitalizations, and deaths shows that excess fever and respiratory ED visits provide a reliable surrogate measure of incident influenza-attributable morbidity. The highly age-specific impact of influenza by subtype and strain suggests that greater age detail be incorporated into ongoing surveillance. Influenza morbidity surveillance using electronic data currently available in many jurisdictions can provide timely and representative information about the age-specific epidemiology of circulating influenza viruses.

Changes in invasive Pneumococcal disease among HIV-infected adults living in the era of childhood pneumococcal immunization

BACKGROUND

Adults infected with HIV have high rates of invasive pneumococcal disease. Introduction of pneumococcal conjugate vaccine for children could affect disease among HIV-infected adults.

OBJECTIVE

To compare invasive pneumococcal disease among HIV-infected adults before and after the introduction of a pediatric conjugate vaccine.

DESIGN

Active laboratory-based surveillance in an adult population of 10.8 million, including 38,314 living with AIDS.

SETTING

7 Active Bacterial Core surveillance areas in the United States.

PATIENTS

All surveillance-area residents 18 to 64 years of age with Streptococcus pneumoniae isolated from a sterile site between 1998 and 2003.

MEASUREMENTS

Ratio of the number of cases of invasive pneumococcal disease among HIV-infected adults to the estimated number of adults 18 to 64 years of age living with AIDS; serotype-specific subset analyses; and comparison of periods before and after introduction of conjugate vaccine by using exact tests.

RESULTS

Of 8582 cases of invasive pneumococcal disease in adults, 2013 (24%) occurred among persons infected with HIV. Between baseline (1998 to 1999) and 2003, the ratio of invasive pneumococcal disease in HIV-infected adults to the number of adults living with AIDS in the surveillance areas decreased from 1127 to 919 cases per 100 000 AIDS population, a reduction of 19% (P = 0.002). Among HIV-infected adults, the ratio for disease caused by pneumococcal serotypes included in the conjugate vaccine decreased 62% (P < 0.001), although the ratio for disease caused by nonvaccine serotypes increased 44% (P < 0.001).

LIMITATIONS

Ratios are proxy measures of incidence rates. The denominator of surveillance-area residents living with HIV infection was not available.

CONCLUSIONS

Introduction of the pediatric conjugate vaccine was associated with an overall decrease in invasive pneumococcal disease among HIV-infected adults, despite increased disease caused by nonvaccine serotypes.

Declining incidence of invasive Streptococcus pneumoniae infections among persons with AIDS in an era of highly active antiretroviral therapy, 1995-2000

BACKGROUND

Our goal was to describe trends in invasive pneumococcal disease incidence among persons with acquired immunodeficiency syndrome (AIDS) since the introduction of highly active antiretroviral therapy (HAART).

METHODS

We used time-trend analysis of annual invasive pneumococcal disease incidence rates from a population-based, active surveillance system. Annual incidence rates were calculated for 5 July-June periods by use of data from San Francisco county, the 6-county Baltimore metropolitan area, and Connecticut. The numerators were the numbers of invasive Streptococcus pneumoniae infections among persons 18-64 years of age with AIDS; the denominators were the numbers of persons living with AIDS, estimated on the basis of AIDS surveillance data.

RESULTS

The annual incidence of invasive pneumococcal disease declined from 1094 cases/100,000 persons with AIDS (July 1995-June 1996) to 467 cases/100,000 persons living with AIDS (July 1999-June 2000). The annual percentage changes in incidence were -34%, -29%, -8%, and -1%. Declines were similar by surveillance area, sex, and race/ethnicity. During the final year of the study, the invasive pneumococcal disease incidence in persons with AIDS was half that of the pre-HAART era but was still 35 times higher than that in similarly aged non-HIV-infected adults.

CONCLUSIONS

In the United States, invasive pneumococcal disease incidence declined sharply across a range of subgroups living with AIDS during the period after widespread introduction of HAART. Despite these gains, persons with AIDS remain at high risk for invasive pneumococcal disease.

Low seroprevalence of IgG antibodies to Ebola virus in an epidemic zone: Ogooué-Ivindo region, Northeastern Gabon, 1997

A population-based serosurvey was performed to determine the seroprevalence of antibodies to Ebola virus (EBO) in a region that has experienced multiple epidemics of EBO hemorrhagic fever. Of 2533 residents in 8 villages, serum samples from 979 (38.6%) were tested by enzyme-linked immunosorbent assay for immunoglobulin (Ig) G and IgM antibodies to Ebola-Zaire (EBO-Z) virus. Fourteen samples (1.4%) were found positive for IgG antibodies, and 4 of these (.4%) were samples from survivors of an epidemic of EBO hemorrhagic fever. Seroprevalence based on the remaining 10 IgG-seropositive individuals with no history of exposure to EBO was 1.0% (exact binomial 95% confidence interval, 0.5%-1.9%). No serum samples were found positive for IgM antibodies to EBO-Z virus. The low seroprevalence suggests that, outside of recognized outbreaks, human exposure to EBO in this epidemic zone is rare.

Women at a sexually transmitted disease clinic who reported same-sex contact: their HIV seroprevalence and risk behaviors

OBJECTIVES

This study compares characteristics, behaviors, and human immunodeficiency virus (HIV) infection in women who reported same-sex contact and women who had sex only with men.

METHODS

Participants were patients attending a New York City sexually transmitted disease clinic. Structured questionnaires were administered by interviewers.

RESULTS

Overall, 9% (135/1518) of women reported same-sex contact; among these, 93% also reported contact with men. Women reporting same-sex contact were more likely than exclusively heterosexual women to be HIV seropositive (17% vs 11%; odds ratio [OR] = 1.7, 95% confidence interval [CI] = 1.0, 2.6), to exchange sex for money/drugs (48% vs 12%, OR = 6.7, 95% CI = 4.6, 9.8), to inject drugs (31% vs 7%, OR = 6.3, 95% CI = 4.1, 9.5), and to use crack cocaine (37% vs 15%, OR = 3.3, 95% CI = 2.2, 4.8). HIV in women reporting same-sex contact was associated with history of syphilis (OR = 8.8), sex for crack (OR = 5.7), and injection drug use (OR = 4.5).

CONCLUSIONS

In this study, women who reported same-sex contact were predominantly bisexual. They had more HIV risk behaviors and were more often HIV seropositive than women who had sex only with men. Among these bisexual women, heterosexual contact and injection drug use were the most likely sources of HIV. There was no evidence of female-to-female transmission.