Across several states, reported cases of West Nile virus (WNV) have surged this summer. As of Aug. 28, 2012, a record-breaking 1,590 human cases of WNV have been reported in the U.S. during 2012, including 65 deaths, according to the Centers for Disease Control and Prevention (CDC).
Though it's the outbreaks of West Nile virus that are grabbing headlines this summer, a little recognized but powerful weapon is helping physicians respond to the onslaught—the clinical laboratory test that detects the virus.
The WNV lab test is performed when a person who may have had recent exposure to the virus shows possible signs and symptoms of an infection. The test is able to confirm whether the infection exists, allowing physicians to take action to control its impact. In severe cases, this might include hospital care where patients can receive supportive treatment including intravenous fluids, help with breathing, and nursing care.
Clinicians perform WNV clinical lab tests to diagnose a current or recent infection. The test measures antibodies produced by the body's immune system in response to the infection. Most people develop these antibodies within eight days of being infected with the virus. The lab test also helps to distinguish WNV from other infections, such as bacterial meningitis, in people who are seriously ill.
A technique called a nucleic acid amplification test (NAAT) is sometimes used. Because it measures the West Nile virus's genetic material, the test can detect an infection before the antibody test. This test is routinely used to screen donated units of blood, as well as donated tissue and organs. It also can be used to test birds and mosquito pools for WNV – often before any people have been identified with the disease – which helps health officials track the virus's spread through the community or region.
"The West Nile virus test is an essential tool in helping physicians determine for certain whether the virus is present," says Alan Mertz, president of the American Clinical Laboratory Association. "The test was developed quickly to respond to WNV when it first appeared in the U.S."
The test is a good example of the kind of innovative tests that clinical laboratories have discovered quickly in response to new and emerging medical crises, says Mertz – such as HIV, herpes meningitis, SARS, H1N1 and avian influenza.
Source: American Clinical Laboratory Association