APHL 2018 Annual Meeting Poster Abstracts Background: West-Nile virus (WNV) is a flavivirus that causes flu- like symptoms in about 20% of infected humans. Cases have been reported in all of the continental United States. In < 1% of infections, neurological complications, e.g. meningitis, occur. Laboratory diagnosis of WNV infection predominantly relies on the detection of antibodies directed against the glycoprotein E. ELISA based on this highly conserved antigen are very sensitive but also cross-reactive with antibodies against other flaviviruses produced after infection or vaccination. In this study, we validated the sensitivity and specificity of a newly developed Anti-WNV ELISA based on the non-structural protein 1 (NS1) which is less conserved within the family of flaviviridae. Results: WNV-specific IgG seroconversion and/or a = 2x increase of IgG level between the two consecutive blood samplings was determined with both ELISA in all patients from collective 1 (sensitivity 100%).1.8% of healthy blood donors were reactive in the Anti-WNV NS1 ELISA compared to 2.2% in the Anti-WNV ELISA (specificity 98.2% vs. 97.8%).In collective 3 the NS1- and the glycoprotein E-based ELISA showed identical or similar reactivity with patient sera positive for antibodies against HCV (0.0%), ZIKV (90.0% vs. 95.0%) and YFV (0.0%). Major differences in cross- reactivity were observed in samples positive for anti-DENV (11.1% vs. 77.8%) and anti-TBEV (4.0% vs. 20.8%) IgG. Discussion: Both ELISA showed a high sensitivity in clinically characterized samples from WNV patients. Assay specificity was higher using NS1 as target antigen, particularly with respect to patient sera positive for antibodies against DENV and TBEV. The diagnostic strategy of measuring an acute and a follow up sample ensured detection of the infection in all WNV cases. Presenter: Oliver Sendscheid, PhD, EUROIMMUN US, Inc., Mountain Lakes, NJ, Phone: 973.656.1000 x130, Email: email@example.com Carriage of Neisseria meningitidis Among Men Who Have Sex with Men in Los Angeles County S. Buono, L. Pandes, B. Schwarz and N. Green, Los Angeles County Department of Public Health, Downey, CA Background: An ongoing outbreak of invasive meningococcal disease (IMD) has been occurring among men who have sex with men (MSM) in Southern California since 2016. The outbreak strain, Neisseria meningitidis serogroup C (NmC), has been responsible for numerous global outbreaks in this population. In order to better understand background carriage and associated risk behaviors, PublicHealthLabs @APHL APHL.org Methods: After eligibility screening and informed consent, participants completed a 20 minute online behavioral questionnaire followed by swabbing of the urethra, throat and rectum. Swabs were plated on InTray GC selective media and all plates were incubated for 24 hours at 37°C at the clinic. Specimens were then submitted to the Los Angeles County Public Health Laboratories (LACPHL) via courier for isolation and characterization of meningococci and gonococci. Suspicious colonies were isolated on Chocolate Agar and characterized by gram stain, oxidase and API NH rapid biochemical tests. N. gonorrhoeae isolates were confirmed by the Gonogen II rapid test. All N. meningitidis isolates were grouped based on reaction to serogroup-specific antisera. Results and Conclusion: From April 2017 to January 2018, 201 culture submissions were received, 8 were rejected and 192 were used in analysis. These cultures were submitted by 3 clinics and were collected from 67 participants. Of these, 3 different participants had a single positive N. gonorrhoeae at each anatomical site (1.5%). Of the 67 oropharyngeal samples received, 13.4% (N = 9) were positive for N. meningitidis in this single site. The N. meningitidis isolates were sub-typed as serogroup A (N = 2), serogroup X (N = 1), serogroup Y (N = 2), serogroup Z (N = 1), serogroup Z’/29E (N = 2) and ungroupable (N = 1). N. meningitidis was not found in any rectal or urethral sites. Interestingly, of the carriage we have isolated to date, none have been the outbreak strain from this population. Presenter: Sean Buono, Los Angeles County Department of Public Health, Downey, CA, Email: firstname.lastname@example.org Economic Impact of the 2014–2015 Multi-state Measles Outbreak on the Local and State Public Health Sector in California HON. MENTION 2018 J. Diaz-Decaro 1 , 2 , R. Basurto-Davila 3 , N. Green 1 , 2 ; 1 Los Angeles County Public Health Laboratories, Downey, CA, 2 UCLA Fielding School of Public Health, Los Angeles, CA, 3 Los Angeles County Department of Public Health, Downey, CA Background: Measles outbreaks are a recurring economic issue for public health infrastructure. In December 2014, several individuals were exposed visiting the Disney theme park area in California resulting in 131 confirmed measles cases throughout California, with additional cases in other US states, Canada and Mexico. An understanding of the economic impact of this outbreak on the California public health system is needed to evaluate response costs to local and state communicable disease control programs (CDCPs) and public health laboratories (PHLs). Methods: Surveys were sent to local and state CDCPs and PHLs representing all California counties and health jurisdictions. Survey data was used to model the outbreak using confirmed measles cases in each county (x1) and spatial variables associated with measles transmission: county distance from epicenter (x2) and population density per county (x3). Using Poisson regression, we estimate the expected number of epidemiological measles contacts in California counties. To estimate local response costs, observed Los Angeles County data was used as a proxy and adjusted to account for variations in CDCP and PHL response by county. Summer 2018 LAB MATTERS 67 Methods: For this study the following human sera collectives were used: 1) Paired samples from nine meningitis patients with suspected WNV infection from Algeria. Samples were consecutively collected early after symptom onset at an interval of 4-8 days. WNV infections were confirmed by either detection of viral RNA or IgG seroconversion. The presence of antibodies against WNV was additionally confirmed by a Flavivirus IFA mosaic (EUROIMMUN AG, Germany).2) Samples from 500 healthy blood donors. 3) 90 patients tested positive for antibodies against Dengue (DENV, n=27), Hepatitis C (HCV, n=6), Zika (ZIKV, n=20), Tick borne encephalitis (TBEV, n=25) or Yellow fever virus (YFV, n=12) with ELISA or neutralization test. Samples were analyzed with the Anti- WNV NS1 ELISA IgG and a commercial Anti-WNV ELISA IgG based on glycoprotein E (EUROIMMUN AG, Germany). A 2x titer increase of IgG level in two consecutive samples was defined as significant. the Los Angeles County Department of Public Health began a study to describe IMD carriage in three anatomical sites as well as risk behaviors among MSM during the outbreak.