False-positive reaction between syphilis and hepatitis C infection

Area of Science:

• Infectious Diseases
• Hepatology
• Immunology

Background:

• Limited data exist on cross-reactivity between hepatitis C virus (HCV) and syphilis serological tests.
• Understanding false-positive rates is crucial for accurate diagnosis and treatment initiation.

Purpose of the Study:

• To investigate the false-positivity of syphilis tests in HCV-infected patients.
• To examine the false-positivity of anti-HCV tests in patients with syphilis.
• To assess the validity of serological tests in co-infected or suspected patients.

Main Methods:

• Study included 50 anti-HCV positive patients, 21 VDRL positive patients, and 50 healthy controls.
• Syphilis screening used Venereal Disease Research Laboratory (VDRL) and T. pallidum hemagglutination (MHA-TP) tests.
• Hepatitis C screening used ELISA for HCV antibody; positive cases were tested for HCV RNA via PCR.

Main Results:

• False-positive VDRL reactions were observed in HCV patients, and false-positive anti-HCV tests in syphilitic patients.
• Four syphilis patients had positive anti-HCV with negative HCV-RNA.
• 10% of HCV patients showed positive VDRL but were negative for MHA-TP, indicating false-positivity.

Conclusions:

• Positive anti-HCV in syphilis patients and positive VDRL in HCV patients may be false-positive results.
• Therapeutic interventions should be confirmed with treponemal tests (e.g., MHA-TP) or PCR.
• Potential interactions between VDRL, HCV-ELISA, and IgM/IgG antibodies warrant further investigation.