These very early - stage cases of HIV infection had an average of five days between the last negative and the first positive blood test. (sciencedaily.com)
A study published in the December 2010 Journal of Proteome Research finds that «potential» celiac patients with positive blood tests but negative biopsies actually have the same distinctive metabolic fingerprint as diagnosed celiacs. (verywellhealth.com)
Such evidence includes a positive blood test for antibodies to the measles virus, a documented previous case of measles, or the individual's being born before 1957 when measles infection was extremely common. (sciencedaily.com)