So far, WNV detection in cerebrospinal fluid or serum by means of IgM or Immunoglobulin M antibody is the most effective clinical diagnosis (Martin et al. , 2002). The IgM antibody-capture ELISA or enzyme-linked immunoabsorbent assay is described as a method with simplicity, enough sensitivity, and applicability for cerebrospinal fluid and serum samples (Martin et al. , 2002). In fact, in the 1999–2000 New York city outbreaks IgM antibody was detected on 95% of the infected individuals through their cerebrospinal fluid samples (Martin et al., 2002).
Such detection denotes infection in the central nervous system for IgM antibody is unable to pass through the blood-brain barrier. As well, in 90% of the serum samples collected within eight days of symptoms manifestation, IgM will positively be detected (Martin et al. , 2002). However, there are two crucial considerations that must be made in the serologic test interpretation.
One is the antigenic similarities among faviviruses for vaccination against or previous infections with Japanese encephalitis and other flavivirus-related viral stain may result to positive in WNV IgM antibody test (Martin et al. , 2002). On the other hand, the specific test, plaque reduction neutralization for flavivirus of anthropod origins, can be employed to differentiate IgM antibody-capture ELISA and other assays’ false-positive results (Martin et al.
, 2002). It also facilitates serologic cross-reaction differentiation in flaviviruses, but some may still have vague results in cross reaction with a neutralizing body. Since the IgM antibody exhibits more than six months persistence as majority of the infected individuals were asymptomatic, it is possible that IgM from a previous infection, which is different from the present conditions can still be detected (Martin et al. , 2002).
The elevation of neutralizing antibody titer specific to WNV in the serum of convalescent and acute disease patients is a direct indication of acute infection (Martin et al. , 2002). The West Nile virus, nucleic acid, or any other viral antigen can be detected not only from blood or cerebrospinal fluid but also in tissues and other body fluids (Martin et al. , 2002). Even though the nucleic acid amplification procedure can be utilized as a diagnostic tool, it is not recommended for routine testing due to its low sensitivity.
On the contrary, in the United States cases, poor results of viral stain detection in brain tissue or cerebrospinal fluid were observed; thus, nucleic acid amplification such as real-time PCR of polymerase chain reaction was employed that eventually resulted to 10% and 55% positive results on serum and cerebrospinal fluid samples, respectively (Martin et al. , 2002). Prevention and Treatment At present, WNV vaccines for humans are still in the perfection process (Zielinski-Gutierrez, 2004). In vitro, the efficacy of high doses of interferon-?
2b and ribavirin were observed but the clinical trials failed to elicit similar physiological response (Martin et al. , 2002). For example, both of these drugs were administered to a comatose patient but failed to make physiological improvements. At worse, ribavirin caused high fatality rate to Israel patients as compared to those who did not receive ribavirin treatment (Martin et al. , 2002). Nonetheless, osmotic, antiseizure, and steroid treatments in WNV cases have not yet explored (Martin et al. , 2002).
Thus, the government is relying on the intensification of public support for the WNV control and prevention. The public thrust envisioned for the vector reduction of mosquitoes thru the support communities and local authorities and prevention of human-mosquito vector contact is by means of barrier method, mosquito repellents, and avoidance of the natural habitat of mosquitoes (Zielinski-Gutierrez, 2004). Along with these, proper reporting of WNV infection cases and timely submission of specimen for laboratory analysis would facilitate clinical diagnosis and documentation (Zielinski-Gutierrez, 2004).