Can an animal testing positive ever test negative on future tests?
It is unlikely that a CAE virus infected adult goat which has tested positive would ever test negative in the sensitive cELISA test. Occasionally a very young animal, fed heat-treated colostrum containing CAE antibodies may test positive and later negative from the decline of passively acquired antibodies in the colostrum. In some goats, seroconversion may be delayed for months after exposure. These “silently” infected animals test negative for antibody until the viral infection is activated by stress or other factors. It has not been determined whether these goats were infectious to other goats during the time they harbored the virus but remained seronegative.
Goats infected with CAE virus are infected for life. Thus a goat tested true positive by the CAEV cELISA test would not later clear the CAE virus infection. Occasionally a very young animal, fed heat-treated colostrum containing CAE antibodies may test positive and later negative from the decline of passively acquired antibodies in the colostrum. In some goats, seroconversion may be delayed for months after exposure. These “silently” infected animals test negative for antibody until the viral infection is activated by stress or other factors. It has not been determined whether these goats were infectious to other goats during the time they harbored the virus but remained seronegative. Lastly, although the CAEV cELISA test is a USDA licensed test showing excellent ability to detect CAE virus antibody true positive results it is not perfect test. The commercial manufacturer of the cELISA test publishes a test specificity of 99.6%, which means 4 in 1000 tests could generated a false posit
