FW: Arboviral Surveillance Report Week 1336
Maffei, Joanne
From: Christine Scott-Waldron [mailto:Christine.S...@LA.GOV]
Sent: Monday, September 16, 2013 11:57 AM
To: Christine Scott-Waldron
Subject: Arboviral Surveillance Report Week 1336
DHH ID Epidemiology Section is updating you that West Nile virus activity continues this year. The number of neuroinvasive cases is much lower than experienced in Louisiana last year.
West Nile virus infections have occurred periodically in Louisiana for the last 10 years, with occasional outbreaks.
Persons of all ages are considered equally susceptible to infection. The majority of all persons infected are completely asymptomatic (80-90%). A smaller proportion of persons (10-20%) present with febrile, influenza-like illness with abrupt onset of fever, headache, sore throat, backache, myalgia, arthralgia, fatigue, a mild transient rash and lymphadenopathy. A minority of infected people have acute aseptic meningitis or encephalitis (0.2% younger than 65 years old, 2% older than age 65). People over 50 with certain medical conditions, such as cancer, diabetes, hypertension, kidney disease, and organ transplants are at greater risk for serious illness or even death.
Attached is the pdf version of the Weekly Report for CDC week 36 ending September 7, 2013.
This report includes 34 cases, 18 neuroinvasive disease, 13 fever, and 3 asymptomatic cases (4 blood donors). We are also reporting 1 deaths which occurred within 2 weeks of onset.
In most patients, infection with WNV and many of the other arboviruses that cause encephalitis is clinically inapparent or causes a nonspecific viral syndrome. Numerous pathogens cause encephalitis, aseptic meningitis and febrile disease with clinical symptoms and presentations similar to those caused by WNV and should be considered in the differential diagnosis. Definitive diagnosis of WNV can only be made by laboratory testing using specific reagents.
The front-line screening assay for laboratory diagnosis of human WNV infection is the IgM assay. Currently, the FDA has cleared four commercially-available test kits from different manufacturers, for detection of WNV IgM antibodies.
Among the most sensitive procedures for detecting WNV in samples are those using RT-PCR to detect WNV RNA in human CSF, serum and other tissues. While these tests can be quite sensitive, virus isolation and RT-PCR to detect WNV RNA in sera or CSF of clinically ill patients have limited utility in diagnosing human WNV neuroinvasive disease due to the low level viremia present in most cases at the time of clinical presentation. Virus isolation or RT-PCR on serum may be helpful in confirming human WNV infection in immunocompromised patients when antibody development is delayed or absent.
I have attached some articles for your reference.
Thanks,
Chrissie
Christine Scott-Waldron, MSPH
Public Health Epidemiologist
Infectious Disease Epidemiology Section
Louisiana Office of Public Health
1450 Poydras Street, Room 2161-B
New Orleans, LA 70112
Email: christine.s...@la.gov
Phone: 504-568-8301
Fax: 504-568-8290
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