HIV in Blood VS. HIV in Semen
A guide to the difference between HIV in blood versus semen, the PCR semen test, “sperm washing,” and how SPAR developed the most stringent safety standards for semen testing in the world.
HIV in Blood VS. HIV in Semen
Research shows that HIV levels in blood do not predict HIV levels in semen (references). This is believed to be because the organs that produce semen may act as a separate site of infection. Semen viral burden differs from blood viral burden, even in men receiving treatment. For this reason, SPAR relies on semen testing and uses only sperm from samples that test undetectable for HIV in fertility attempts.
Data compiled by BRF scientists between 2000 and 2024 shows that HIV can be present in semen even when it is undetectable in blood. Key findings include:
- 2000–2006: 19% of semen specimens from 262 men entering SPAR tested positive for HIV, despite undetectable viral RNA in blood.
- 2007–2011: 18% of semen specimens from 368 men tested positive.
- 2012–2020: 16% of semen specimens from 652 men tested positive, even with more widespread use of antiviral therapy.
- 2022-2024: 11% of semen specimens from 156 men with negative blood-viral burden tested positive for HIV (reference).
All men eventually produced at least two semen specimens that tested undetectable for HIV.
This important finding—that HIV can appear intermittently in semen—is the reason SPAR tests every specimen individually. Learn more about HIV and Semen Biology
Cytomegalovirus (CMV)
Semen testing results from 2020 to 2024 revealed that, in addition to HIV, another virus—cytomegalovirus (CMV)—was detected in twice as many semen specimens. The risk of CMV transmission through semen is not well understood, but CMV is the most common infectious cause of birth defects in the US, frequently hearing and/or vision loss. 2024 publication | More references for CMV