The RPR screening test is similar to the older VDRL test as both measure reaginic antibodies. These antibodies are usually produced during infection with syphilis as a result of the interaction of the bacteria which causes syphilis (Treponema pallidum) and one's own body. This test is a useful screening tool for syphilis, yet its ability to detect syphilis depends on the stage of the disease. In the earliest stage of syphilis (primary syphilis) this test is positive approximately 60% of the time. Its usefulness increases with later stages such as secondary syphilis and latent syphilis where it may be positive 70-90% of the time. In the final stages (tertiary syphilis) this test is usually positive in only 60% of cases. There are several conditions which may cause a false positive test - such as HIV, lyme disease, mycoplasma pneumonia, malaria and systemic lupus erythematosus. Therefore, this screening test if found to be positive must be confirmed by a more specific test for syphilis such as FTA-ABS .