A positive result on a screening test for HTLV-I antibody should be

A positive result on a screening test for HTLV-I antibody should be

• A. Followed by PCR
• B. Validated by viral culture
• C. Confirmed by Western blot
• D. Considered highly specific for HTLV-I infection

Answer: (C)

Screening tests for HTLV-I antibodies are designed to be sensitive, but they can produce false positives due to cross-reactivity. To confirm true infection, a separate test with higher specificity is used. The Western blot serves this role because it analyzes antibodies against multiple HTLV-I proteins, and a characteristic pattern of reactivity confirms HTLV-I infection rather than a nonspecific or cross-reactive result. Viral culture isn’t practical for diagnosis here, since HTLV-1 is slow to grow and culture isn’t a reliable routine confirmatory method. PCR can detect viral DNA and is useful in certain situations, but it isn’t the standard confirmatory test after a serologic screen. Additionally, even Western blot results need careful interpretation, as some cases can be indeterminate.

Screening tests for HTLV-I antibodies are designed to be sensitive, but they can produce false positives due to cross-reactivity. To confirm true infection, a separate test with higher specificity is used. The Western blot serves this role because it analyzes antibodies against multiple HTLV-I proteins, and a characteristic pattern of reactivity confirms HTLV-I infection rather than a nonspecific or cross-reactive result. Viral culture isn’t practical for diagnosis here, since HTLV-1 is slow to grow and culture isn’t a reliable routine confirmatory method. PCR can detect viral DNA and is useful in certain situations, but it isn’t the standard confirmatory test after a serologic screen. Additionally, even Western blot results need careful interpretation, as some cases can be indeterminate.