1359. Human Parainfluenza Epidemiology in Homeless Shelters — King County, Washington

Background

Human parainfluenza viruses (HPIV) cause respiratory illness in individuals of all ages. However, HPIV epidemiology data in people experiencing homelessness (PEH) are limited.

Methods

We analyzed cross-sectional data from a clinical trial and SARS-CoV-2 surveillance study in 23 homeless shelters in King County, Washington from October 2019-May 2021. Questionnaires and nasal swab specimens were obtained from eligible participants at enrollment. Between October 2019-March 31, 2020, participants included those aged > 3 months with acute respiratory illness. Monthly shelter surveillance was also conducted where participants were recruited regardless of symptoms. With the community spread of SARS-CoV-2, the study design transitioned from a clinical trial to a SARS-CoV-2 surveillance study which expanded enrollment eligibility to include participants with or without symptoms from April 1, 2020, onward. Participants were not followed longitudinally but were permitted to enroll multiple times during the study period. Specimens were tested for HPIV 1-4 and other respiratory viruses using RT-PCR.

Results

Among 14,464 specimens, 32 were HPIV-positive from 29 participants (median age 9 years, range 0.3-64 years; 45% female; 28% Black; 10% with chronic conditions) of which 59% were children. Family shelters had the highest percentage of HPIV infections (Table). HPIV was detected every month before the community spread of SARS-CoV-2. All HPIV-positive samples in May 2021 came from a single family shelter (Figure). Only 67% of HPIV-positive participants had symptoms with runny nose, cough and sore throat the most commonly reported. HPIV co-detection with other respiratory viruses occurred in 19% of HPIV-positive specimens; Rhinovirus co-detection (16%) was the most common.

Human Parainfluenza Encounters by Shelter Type Before and After April 1, 2020

Human Parainfluenza Positive Samples by Shelter Type Among Unique Participants

Conclusion

HPIV affected PEH of all ages with most cases in shelters with children. Coinciding with community-wide SARS-CoV-2 mitigation efforts, the number of HPIV infections were reduced. However, a cluster of HPIV infections still occurred within one family shelter. Shelter-specific public health measures including non-pharmaceutical interventions used during the COVID-19 pandemic may reduce HPIV infections among residents.

Disclosures

Janet A. Englund, MD, AstraZeneca: Advisor/Consultant|AstraZeneca: Grant/Research Support|GlaxoSmithKline: Grant/Research Support|Meissa Vaccines: Advisor/Consultant|Merck: Grant/Research Support|Pfizer: Grant/Research Support|Sanofi Pasteur: Advisor/Consultant Helen Y. Chu, MD, MPH, Cepheid: Reagents|Ellume: Advisor/Consultant|Gates Ventures: Grant/Research Support|Merck: Advisor/Consultant|Pfizer: Advisor/Consultant.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Transmission Associated With an Indoor Music Event That Required Proof of Full Vaccination Against Coronavirus Disease 2019 (COVID-19) Prior to Entry-Seattle, July 2021

In July 2021, Public Health-Seattle & King County investigated a coronavirus disease 2019 (COVID-19) outbreak at an indoor event intended for fully vaccinated individuals, revealing unvaccinated staff, limited masking, poor ventilation, and overcrowding. Supporting businesses to develop and implement comprehensive COVID-19 prevention plans is essential for reducing spread in these settings.

Interactions among 17 respiratory pathogens: a cross-sectional study using clinical and community surveillance data

Background

Co-circulating respiratory pathogens can interfere with or promote each other, leading to important effects on disease epidemiology. Estimating the magnitude of pathogen-pathogen interactions from clinical specimens is challenging because sampling from symptomatic individuals can create biased estimates.

Methods

We conducted an observational, cross-sectional study using samples collected by the Seattle Flu Study between 11 November 2018 and 20 August 2021. Samples that tested positive via RT-qPCR for at least one of 17 potential respiratory pathogens were included in this study. Semi-quantitative cycle threshold (Ct) values were used to measure pathogen load. Differences in pathogen load between monoinfected and coinfected samples were assessed using linear regression adjusting for age, season, and recruitment channel.

Results

21,686 samples were positive for at least one potential pathogen. Most prevalent were rhinovirus (33·5%), Streptococcus pneumoniae (SPn, 29·0%), SARS-CoV-2 (13.8%) and influenza A/H1N1 (9·6%). 140 potential pathogen pairs were included for analysis, and 56 (40%) pairs yielded significant Ct differences (p < 0.01) between monoinfected and co-infected samples. We observed no virus-virus pairs showing evidence of significant facilitating interactions, and found significant viral load decrease among 37 of 108 (34%) assessed pairs. Samples positive with SPn and a virus were consistently associated with increased SPn load.

Conclusions

Viral load data can be used to overcome sampling bias in studies of pathogen-pathogen interactions. When applied to respiratory pathogens, we found evidence of viral-SPn facilitation and several examples of viral-viral interference. Multipathogen surveillance is a cost-efficient data collection approach, with added clinical and epidemiological informational value over single-pathogen testing, but requires careful analysis to mitigate selection bias.

Monitoring Incidence of COVID-19 Cases, Hospitalizations, and Deaths, by Vaccination Status - 13 U.S. Jurisdictions, April 4-July 17, 2021

COVID-19 vaccine breakthrough infection surveillance helps monitor trends in disease incidence and severe outcomes in fully vaccinated persons, including the impact of the highly transmissible B.1.617.2 (Delta) variant of SARS-CoV-2, the virus that causes COVID-19. Reported COVID-19 cases, hospitalizations, and deaths occurring among persons aged ≥18 years during April 4-July 17, 2021, were analyzed by vaccination status across 13 U.S. jurisdictions that routinely linked case surveillance and immunization registry data. Averaged weekly, age-standardized incidence rate ratios (IRRs) for cases among persons who were not fully vaccinated compared with those among fully vaccinated persons decreased from 11.1 (95% confidence interval [CI] = 7.8-15.8) to 4.6 (95% CI = 2.5-8.5) between two periods when prevalence of the Delta variant was lower (<50% of sequenced isolates; April 4-June 19) and higher (≥50%; June 20-July 17), and IRRs for hospitalizations and deaths decreased between the same two periods, from 13.3 (95% CI = 11.3-15.6) to 10.4 (95% CI = 8.1-13.3) and from 16.6 (95% CI = 13.5-20.4) to 11.3 (95% CI = 9.1-13.9). Findings were consistent with a potential decline in vaccine protection against confirmed SARS-CoV-2 infection and continued strong protection against COVID-19-associated hospitalization and death. Getting vaccinated protects against severe illness from COVID-19, including the Delta variant, and monitoring COVID-19 incidence by vaccination status might provide early signals of changes in vaccine-related protection that can be confirmed through well-controlled vaccine effectiveness (VE) studies.

Accuracy of Medical Examiner's Assessment for Near-Real-Time Surveillance of Fatal Drug Overdoses, King County, Washington, March 2017-February 2018

OBJECTIVES

Up-to-date information on the occurrence of drug overdose is critical to guide public health response. The objective of our study was to evaluate a near-real-time fatal drug overdose surveillance system to improve timeliness of drug overdose monitoring.

METHODS

We analyzed data on deaths in the King County (Washington) Medical Examiner's Office (KCMEO) jurisdiction that occurred during March 1, 2017-February 28, 2018, and that had routine toxicology test results. Medical examiners (MEs) classified probable drug overdoses on the basis of information obtained through the death investigation and autopsy. We calculated sensitivity, positive predictive value, specificity, and negative predictive value of MEs' classification by using the final death certificate as the gold standard.

RESULTS

KCMEO investigated 2480 deaths; 1389 underwent routine toxicology testing, and 361 were toxicologically confirmed drug overdoses from opioid, stimulant, or euphoric drugs. Sensitivity of the probable overdose classification was 83%, positive predictive value was 89%, specificity was 96%, and negative predictive value was 94%. Probable overdoses were classified a median of 1 day after the event, whereas the final death certificate confirming an overdose was received by KCMEO an average of 63 days after the event.

CONCLUSIONS

King County MEs' probable overdose classification provides a near-real-time indicator of fatal drug overdoses, which can guide rapid local public health responses to the drug overdose epidemic.

Streptococcus pyogenes pbp2x Mutation Confers Reduced Susceptibility to β-Lactam Antibiotics

Two near-identical clinical Streptococcus pyogenes isolates of emm subtype emm43.4 with a pbp2x missense mutation (T553K) were detected. Minimum inhibitory concentrations (MICs) for ampicillin and amoxicillin were 8-fold higher, and the MIC for cefotaxime was 3-fold higher than for near-isogenic control isolates, consistent with a first step in developing β-lactam resistance.

A Population-Based Intervention to Improve Care Cascades of Patients With Hepatitis C Virus Infection

Hepatitis C virus (HCV) infection is common in the United States and leads to significant morbidity, mortality, and economic costs. Simplified screening recommendations and highly effective direct-acting antivirals for HCV present an opportunity to eliminate HCV. The objective of this study was to increase testing, linkage to care, treatment, and cure of HCV. This was an observational, prospective, population-based intervention program carried out between September 2014 and September 2018 and performed in three community health centers, three large multiclinic health care systems, and an HCV patient education and advocacy group in King County, WA. There were 232,214 patients included based on criteria of documented HCV-related diagnosis code, positive HCV laboratory test or prescription of HCV medication, and seen at least once at a participating clinical site in the prior year. Electronic health record (EHR) prompts and reports were created. Case management linked patients to care. Primary care providers received training through classroom didactics, an online curriculum, specialty clinic shadowing, and a telemedicine program. The proportion of baby boomer patients with documentation of HCV testing increased from 18% to 54% during the project period. Of 77,577 baby boomer patients screened at 87 partner clinics, 2,401 (3%) were newly identified HCV antibody positive. The number of patients staged for treatment increased by 391%, and those treated increased by 1,263%. Among the 79% of patients tested after treatment, 95% achieved sustained virologic response. Conclusion: A combination of EHR-based health care system interventions, active linkage to care, and clinician training contributed to a tripling in the number of patients screened and a more than 10-fold increase of those treated. The interventions are scalable and foundational to the goal of HCV elimination.

Cryptic transmission of SARS-CoV-2 in Washington State

Following its emergence in Wuhan, China, in late November or early December 2019, the SARS-CoV-2 virus has rapidly spread throughout the world. On March 11, 2020, the World Health Organization declared Coronavirus Disease 2019 (COVID-19) a pandemic. Genome sequencing of SARS-CoV-2 strains allows for the reconstruction of transmission history connecting these infections. Here, we analyze 346 SARS-CoV-2 genomes from samples collected between 20 February and 15 March 2020 from infected patients in Washington State, USA. We found that the large majority of SARS-CoV-2 infections sampled during this time frame appeared to have derived from a single introduction event into the state in late January or early February 2020 and subsequent local spread, strongly suggesting cryptic spread of COVID-19 during the months of January and February 2020, before active community surveillance was implemented. We estimate a common ancestor of this outbreak clade as occurring between 18 January and 9 February 2020. From genomic data, we estimate an exponential doubling between 2.4 and 5.1 days. These results highlight the need for large-scale community surveillance for SARS-CoV-2 introductions and spread and the power of pathogen genomics to inform epidemiological understanding.

Multidrug-Resistant Salmonella I 4,[5],12:i:- and Salmonella Infantis Infections Linked to Whole Roasted Pigs from a Single Slaughter and Processing Facility

We describe two outbreaks of multidrug-resistant (MDR) Salmonella I 4,[5],12:i:- infection, occurring in 2015 to 2016, linked to pork products, including whole roaster pigs sold raw from a single Washington slaughter and processing facility (establishment A). Food histories from 80 ill persons were compared with food histories reported in the FoodNet 2006 to 2007 survey of healthy persons from all 10 U.S. FoodNet sites who reported these exposures in the week before interview. Antimicrobial susceptibility testing and whole genome sequencing were conducted on selected clinical, food, and environmental isolates. During 2015, a total of 192 ill persons were identified from five states; among ill persons with available information, 30 (17%) of 180 were hospitalized, and none died. More ill persons than healthy survey respondents consumed pork (74 versus 43%, P < 0.001). Seventeen (23%) of 73 ill persons for which a response was available reported attending an event where whole roaster pig was served in the 7 days before illness onset. All 25 clinical isolates tested from the 2015 outbreak and a subsequent 2016 smaller outbreak (n = 15) linked to establishment A demonstrated MDR. Whole genome sequencing of clinical, environmental, and food isolates (n = 69) collected in both investigations revealed one clade of highly related isolates, supporting epidemiologic and traceback data that establishment A as the source of both outbreaks. These investigations highlight that whole roaster pigs, an uncommon food vehicle for MDR Salmonella I 4,[5],12:i:- outbreaks, will need further attention from food safety researchers and educators for developing science-based consumer guidelines, specifically with a focus on the preparation process.

The projected costs and benefits of a supervised injection facility in Seattle, WA, USA

BACKGROUND

As one strategy to improve the health and survival of people who inject drugs, the King County Heroin & Opioid Addiction Task Force recommended the establishment of supervised injection facilities (SIF) where people can inject drugs in a safe and hygienic environment with clinical supervision. Analyses for other sites have found them to be cost-effective, but it is not clear whether these findings are transferable to other settings.

METHODS

We utilized local estimates and other data sources deemed appropriate for our setting to implement a mathematical model that assesses the impact of a hypothetical SIF on overdose deaths, non-fatal overdose health service utilization, skin and soft tissue infections, bacterial infections, viral infections, and enrollment in medication assisted treatment (MAT). We estimated the costs and savings that would occur on an annual basis for a small-scale pilot site given current overdose rates, as well as three other scenarios of varying scale and underlying overdose rates.

RESULTS

Assuming current overdose rates, a hypothetical Seattle SIF in a pilot phase is projected to annually reverse 167 overdoses and prevent 6 overdose deaths, 45 hospitalizations, 90 emergency department visits, and 92 emergency medical service deployments. Additionally, the site would facilitate the enrollment of 41 SIF clients in medication assisted treatment programs. These health benefits correspond to a monetary value of $5,156,019. The annual estimated cost of running the SIF is $1,222,332. The corresponding cost-benefit ratio suggests that the pilot SIF would generate $4.22 for every dollar spent on SIF operational costs. The pilot SIF is projected to save the healthcare system $534,453. If Seattle experienced elevated overdose rates and Seattle SIF program were scaled up, the health benefits and financial value would be considerably greater.

CONCLUSION

This analysis suggests that a SIF program in Seattle would save lives and result in considerable health benefits and cost savings.

Achieving an Optimal Childhood Vaccine Policy

Policies to remove parents' ability to opt-out from school immunization requirements on the basis of religious or personal beliefs (ie, nonmedical exemptions) may be a useful strategy to increase immunization rates and prevent outbreaks of vaccine-preventable disease. However, there is uncertainty about the effectiveness of this strategy and the range of possible outcomes. We advocate for a more deliberative process through which a broad range of outcomes is scrutinized and the balance of values underlying the policy decision to eliminate nonmedical exemptions is clearly articulated. We identify 3 outcomes that require particular consideration before policies to eliminate nonmedical exemptions are implemented widely and outline a process for making the values underlying such policies more explicit.

Notes from the Field: Fatal Infection Associated with Equine Exposure - King County, Washington, 2016

On March 17, 2016, Public Health-Seattle & King County in Washington was notified of two persons who received a diagnosis of Streptococcus equi subspecies zooepidemicus (S. zooepidemicus) infections. S. zooepidemicus is a zoonotic pathogen that rarely causes human illness and is usually associated with consuming unpasteurized dairy products or with direct horse contact (1). In horses, S. zooepidemicus is a commensal bacterium that can cause respiratory, wound, and uterine infections (2). The health department investigated to determine the magnitude of the outbreak, identify risk factors, and offer recommendations.

Task analysis in action: the role of information systems in communicable disease reporting

In order to improve the design of information systems for notifiable conditions reporting, it is essential to understand the role of such systems in public health practice. Using qualitative techniques, we performed a task analysis of the activities associated with notifiable conditions reporting at a large urban health department. We identified seventeen primary tasks associated with the use of the department's information system. The results of this investigation suggest that communicable disease information management takes place in a dynamic environment where changing needs may require new solutions for system users. Additionally, our work suggests that task analysis, when applied to document the use of a legacy information system, can provide local public health agencies with valuable information about their information management needs, and can become a part of their information management decision-making strategy.

A simulation study comparing aberration detection algorithms for syndromic surveillance

BACKGROUND

The usefulness of syndromic surveillance for early outbreak detection depends in part on effective statistical aberration detection. However, few published studies have compared different detection algorithms on identical data. In the largest simulation study conducted to date, we compared the performance of six aberration detection algorithms on simulated outbreaks superimposed on authentic syndromic surveillance data.

METHODS

We compared three control-chart-based statistics, two exponential weighted moving averages, and a generalized linear model. We simulated 310 unique outbreak signals, and added these to actual daily counts of four syndromes monitored by Public Health--Seattle and King County's syndromic surveillance system. We compared the sensitivity of the six algorithms at detecting these simulated outbreaks at a fixed alert rate of 0.01.

RESULTS

Stratified by baseline or by outbreak distribution, duration, or size, the generalized linear model was more sensitive than the other algorithms and detected 54% (95% CI = 52%-56%) of the simulated epidemics when run at an alert rate of 0.01. However, all of the algorithms had poor sensitivity, particularly for outbreaks that did not begin with a surge of cases.

CONCLUSION

When tested on county-level data aggregated across age groups, these algorithms often did not perform well in detecting signals other than large, rapid increases in case counts relative to baseline levels.

Evaluation of a public health Salmonella surveillance system in King County, Washington

OBJECTIVES

Salmonella infection is the most common cause of foodborne bacterial outbreaks and deaths in the United States. The effectiveness of Salmonella surveillance for detecting outbreaks depends on timeliness of reporting. We evaluated the public health Salmonella surveillance system in King County, Washington, during an outbreak and at baseline.

METHODS

We assessed the timeliness of the Salmonella surveillance system in King County using the Public Health-Seattle & King County Laboratory (County PHL) database from 1998 to 1999. We determined median days for key steps involved in the Salmonella identification and reporting process and the percentage of suspected Salmonella isolates confirmed. Time intervals for key steps during a Salmonella outbreak were compared to baseline surveillance.

RESULTS

Of the 652 suspected Salmonella isolates sent to the County PHL from 22 clinical laboratories, 617 (94.6%) were confirmed as Salmonella. Salmonella confirmation rates improved from 1998 to 1999, and 41% of the submitting laboratories, contributing 32.4% of the isolates, had 100% confirmation rates for both years. The median total identification time during the outbreak did not differ significantly from baseline (13 days vs 17 days). The time interval for serotyping contributed most to the total identification time.

CONCLUSIONS

King County's Salmonella surveillance system requires more than 2 weeks to confirm and report serotype results for Salmonella isolates. Variation in total identification time depends on serotyping time. A more detailed study of other surveillance systems may identify approaches to decrease total identification time.

An outbreak of Salmonella serotype Saintpaul in a children's hospital

OBJECTIVES

To describe a nosocomial outbreak of Salmonella serotype Saintpaul gastroenteritis and to explore risk factors for infection.

DESIGN

Case-control study.

SETTING

A 208-bed, university-affiliated children's hospital.

PARTICIPANTS

Patients hospitalized at Children's Hospital and Regional Medical Center, Seattle, Washington, during February 2001 who had stool specimens obtained for culture at least 24 hours after admission. Case-patients (n = 11) were patients with an indistinguishable strain of Salmonella Saintpaul cultured from their stool. Control-patients (n = 41) were patients hospitalized for problems other than gastroenteritis whose stool cultures were negative for Salmonella.

METHODS

Risk factors were evaluated using the chi-square test or Fisher's exact test. Continuous variables were compared using the Mann-Whitney U test. A multivariable analysis was performed using logistic regression. The predictor of interest was the receipt of enteral feeding formula mixed by the hospital.

RESULTS

Case-patients were more likely than control-patients to have received formula mixed by the hospital (OR, 4.2; 95% confidence interval, 1.04 to 17.16). Other variables evaluated were not significant predictors of Salmonella Saintpaul infection.

CONCLUSIONS

Formula mixed by the hospital appears to have been the source of this Salmonella outbreak. Strict sanitation measures must be ensured in formula preparation and delivery, and bacterial pathogens should be included in the differential diagnosis for nosocomial gastroenteritis.

Pneumocystis carinii cytochrome b mutations are associated with atovaquone exposure in patients with AIDS

This retrospective cohort study was conducted to determine whether Pneumocystis carinii cytochrome b gene mutations in patients with AIDS and P. carinii pneumonia (PCP) are associated with atovaquone exposure. Portions of the P. carinii cytochrome b genes that were obtained from 60 patients with AIDS and PCP from 6 medical centers between 1995 and 1999 were amplified and sequenced by using polymerase chain reaction. Fifteen patients with previous atovaquone prophylaxis or treatment exposure were matched with 45 patients with no atovaquone exposure. Cytochrome b coenzyme Q binding site mutations were observed in 33% of isolates from patients exposed to atovaquone, compared with 6% from those who were not (P=.018). There was no difference in survival 1 month after treatment between patients with or without cytochrome b mutations (P=.14). Thus, cytochrome b mutations are significantly more common in patients with AIDS and PCP with atovaquone exposure, but the clinical significance of these mutations remains unknown.

Reduced injection frequency and increased entry and retention in drug treatment associated with needle-exchange participation in Seattle drug injectors

The association between needle exchange, change in drug use frequency and enrollment and retention in methadone drug treatment was studied in a cohort of Seattle injection drug users (IDUs). Participants included IDUs classified according to whether they had used a needle exchange by study enrollment and during the 12-month follow-up period. The relative risk (RR) and the adjusted RR (ARR) were estimated as measures of the association. It was found that IDUs who had formerly been exchange users were more likely than never-exchangers to report a substantial (> or= 75%) reduction in injection (ARR = 2.85, 95% confidence limit [CL] 1.47-5.51), to stop injecting altogether (ARR = 3.5, 95% CL 2.1-5.9), and to remain in drug treatment. New users of the exchange were five times more likely to enter drug treatment than never-exchangers. We conclude that reduced drug use and increased drug treatment enrollment associated with needle exchange participation may have many public health benefits, including prevention of blood-borne viral transmission.