Graduation Year

2008

Document Type

Thesis

Degree

M.S.P.H.

Degree Granting Department

Global Health

Major Professor

Lillian M. Stark Ph.D.

Keywords

Flavivirus, Alphavirus, Arboviruses, Surveillance, MAC-ELISA

Abstract

Eastern Equine Encephalitis virus has a human mortality rate of 30% of those cases diagnosed, while 30% of those surviving infection remain with neurological sequelae for life (CDC.gov, 2007). The use of sentinel chickens for surveillance of arboviruses that are known to use birds as a reservoir host, such as St. Louis Encephalitis (SLE), West Nile (WN) virus, Eastern Equine Encephalitis (EEE) and Highlands J (HJ) virus, in Florida began with the Sentinel Chicken Arboviral Surveillance Network in 1978 (Day and Stark, 1996). This network enables the activation of an early warning system for citizens, as well as, county epidemiologists and those in mosquito control, allowing for a coordinated effort of disease prevention.

Methods currently used at the Florida Department of Health, Tampa Branch Laboratory include screening of submitted sera for antibodies to these arboviruses of epidemiologic importance by way of the hemagglutination inhibition test (HAI), and confirmation by the IgM antibody capture enzyme-linked immunosorbent assay (MAC-ELISA) and Plaque Reduction Neutralization test if the MAC-ELISA proves to be negative. While these tests combined are providing the results needed, the time to result can be a week or greater depending on the initial screening result in the HAI tests. The Microsphere Assay Technology provides an accurate, more rapid (a day or two instead of a week or more) detection method including both a screening and confirmation protocol specifically designed to test for antibody to EEE in sentinel chicken sera.

Two sera out of the thousands tested that were tested by HAI shown to be negative in standard testing, resulted as positive by the MIA method and therefore indicated a missed positive. The sensitivity and specificity, positive and negative predictive values of this new protocol as compared with MAC-ELISA as a reference standard indicated that both tests were remarkably similar; Providing sensitivity near 80%, specificity and PPV at 99%, and negative predictive values at 90% for MAC-ELISA and 94% for the MIA. Finally it was determined that Highlands J virus will not have any impact on the testing protocol and results of this test.

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