Public health investigations generally follow certain steps to investigate a public health problem. Explain the steps public health officials took to diagnose West Nile virus.

WNV-specific IgM antibodies are usually detectable 3 to 8 days after onset of illness and persist for 30 to 90 days, but longer persistence has been documented. Therefore, positive IgM antibodies occasionally may reflect a past infection. If serum is collected within 8 days of illness onset, the absence of detectable virus-specific IgM does not rule out the diagnosis of WNV infection, and the test may need to be repeated on a later sample.

Explanation:

I can't say by steps I wrote here by explaining.

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either two or three

the right answer is: time