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 protected]
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,
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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: [email protected]
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.