Laboratory Review of Foodborne Disease Investigations in Washington State 2007-2017.

The Washington State Department of Health Public Health Laboratories (WAPHL) has tested 11,501 samples between 2007 and 2017 for a foodborne disease using a combination of identification, serotyping, and subtyping tools. During this period there were 8037 total clinical and environmental samples tested by pulsed-field gel electrophoresis (PFGE), including 512 foodborne disease clusters and 2176 PFGE patterns of Salmonella enterica subsp. enterica. There were 2446 Shiga toxin-producing Escherichia coli samples tested by PFGE, which included 158 foodborne disease clusters and 1174 PFGE patterns. There were 332 samples of Listeria monocytogenes tested by PFGE, including 35 foodborne disease clusters and 104 PFGE patterns. Sources linked to outbreaks included raw chicken, unpasteurized dairy products, various produce types, and undercooked beef among others. As next-generation sequencing (NGS) replaces PFGE, the impact of this transition is expected to be significant given the enhanced cluster detection power NGS brings. The measures presented here will be a reference baseline in future years.

Tdap vaccine effectiveness in adolescents during the 2012 Washington State pertussis epidemic.

BACKGROUND: Acellular pertussis vaccines replaced whole-cell vaccines for the 5-dose childhood vaccination series in 1997. A sixth dose of pertussis-containing vaccine, tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis, adsorbed (Tdap), was recommended in 2005 for adolescents and adults. Studies examining Tdap vaccine effectiveness (VE) among adolescents who have received all acellular vaccines are limited. METHODS: To assess Tdap VE and duration of protection, we conducted a matched case-control study during the 2012 pertussis epidemic in Washington among adolescents born during 1993-2000. All pertussis cases reported from January 1 through June 30, 2012, in 7 counties were included; 3 controls were matched by primary provider clinic and birth year to each case. Vaccination histories were obtained through medical records, the state immunization registry, and parent interviews. Participants were classified by type of pertussis vaccine received on the basis of birth year: a mix of whole-cell and acellular vaccines (1993-1997) or all acellular vaccines (1998-2000). We used conditional logistic regression to calculate odds ratios comparing Tdap receipt between cases and controls. RESULTS: Among adolescents who received all acellular vaccines (450 cases, 1246 controls), overall Tdap VE was 63.9% (95% confidence interval [CI]: 50% to 74%). VE within 1 year of vaccination was 73% (95% CI: 60% to 82%). At 2 to 4 years postvaccination, VE declined to 34% (95% CI: -0.03% to 58%). CONCLUSIONS: Tdap protection wanes within 2 to 4 years. Lack of long-term protection after vaccination is likely contributing to increases in pertussis among adolescents.

Tri-county comprehensive assessment of risk factors for sporadic reportable bacterial enteric infection in children.

BACKGROUND: The aim of this study was to determine risk factors for childhood sporadic reportable enteric infection (REI) caused by bacteria, specifically Campylobacter, Salmonella, Escherichia coli O157, or Shigella (REI-B). METHODS: Matched case-control study. Case patients aged <19 years who were reported to 3 Washington State county health departments and matched control subjects were interviewed from November 2003-November 2005. Matched odds ratios (ORs) were calculated by using conditional logistic regression. Population attributable risk percentages were calculated for exposures associated with infection. RESULTS: Two hundred ninety-six case patients were matched to 580 control subjects. Aquatic recreation was the most important factor associated with all REI-Bs studied (beach water exposure [OR for Salmonella infection, 28.3 {CI, 7.2-112.2}; OR for Shigella infection, 14.5 {CI 1.5-141.0} or any recreational water exposure [OR for Campylobacter infection, 2.7 {CI, 1.5-4.8}; OR for Escherichia coli O157 infection, 7.4 {CI, 2.1-26.1}]). Suboptimal kitchen hygiene after preparation of raw meat or chicken (OR, 7.1 [CI, 2.1-24.1]) and consumption of food from restaurants were additional risks for Campylobacter infection. Infection with Salmonella was associated with the use of private wells as sources of drinking water (OR, 6.5 [CI, 1.4-29.7]), and the use of residential septic systems was a risk for both Salmonella (OR, 3.2 [CI, 1.3-7.8]) and E. coli (OR, 5.7 [CI, 1.2-27.2]) O157 infection. CONCLUSIONS: Overall, non-food exposures were as important as food-related exposures with regard to their contributions to the proportion of cases. Infection prevention efforts should address kitchen hygiene practices and non-food exposures, such as recreational water exposure, in addition to food-consumption risks.

Syndromic surveillance using automated collection of computerized discharge diagnoses.

The Syndromic Surveillance Information Collection (SSIC) system aims to facilitate early detection of bioterrorism attacks (with such agents as anthrax, brucellosis, plague, Q fever, tularemia, smallpox, viral encephalitides, hemorrhagic fever, botulism toxins, staphylococcal enterotoxin B, etc.) and early detection of naturally occurring disease outbreaks, including large foodborne disease outbreaks, emerging infections, and pandemic influenza. This is accomplished using automated data collection of visit-level discharge diagnoses from heterogeneous clinical information systems, integrating those data into a common XML (Extensible Markup Language) form, and monitoring the results to detect unusual patterns of illness in the population. The system, operational since January 2001, collects, integrates, and displays data from three emergency department and urgent care (ED/UC) departments and nine primary care clinics by automatically mining data from the information systems of those facilities. With continued development, this system will constitute the foundation of a population-based surveillance system that will facilitate targeted investigation of clinical syndromes under surveillance and allow early detection of unusual clusters of illness compatible with bioterrorism or disease outbreaks.