The definition of seropositive is the results of a blood test that show the presence of a specific antibody in the blood serum.
A blood test that shows you have a specific viral disease is an example of something that would be described as a seropositive test.
being or having a positive test result for the presence of a specific antibody in the serum of the blood
Indicating a positive reaction to a serological blood test, especially one testing for the presence of antibodies.
From sero- +"Ž positive.