0 showing a negative result of a blood test for a particular antibody (= a substance in the blood that fights a disease):
All 28 children followed for 12 months became seronegative, thus excluding a congenital infection.
This was the number of individuals that were seronegative when captured prior to that period and were recaptured after that period.
The period of time it took for eight seropositive herds to become seronegative during the observation period varied from 2 to 22 months.
Two approaches were taken to designate sera as seropositive or seronegative.
In total, 341 (221 seronegative and 120 seropositive) students were followed up clinically and serologically during a subsequent outbreak.
Six out of nine seronegative herds, which became seropositive, returned to their negative status after 3-7 months.
Two control flocks per case were randomly selected from the flock population that was seronegative for 1997 and 1998 in the same province.
Remitting seronegative, symmetrical synovitis with pitting edema - 13 additional cases.
