transient Increases (“Blips”) in Viral Load

Transient Increases (“Blips”) in Viral Load

Several studies have observed that individuals on effective ART who achieve long-term suppression of viral load to undetectable levels may exhibit periodic temporary increases in plasma viral load (blips). These are generally small increases ( between approximately 50 and 1000 copies/mL), and are estimated to last for short periods (<3 href="http://www.cdc.gov/hiv/topics/treatment/resources/factsheets/art.htm#18">18-20]. Because they are transient in nature, they may be missed on routine viral load testing. Currently, there are insufficient data to make statements regarding the magnitude of transmission risk related to viral load blips. However, it is conceivable that transient increases might correlate with increases in genital fluid viral load, and with enhanced sexual transmission risk.

Correlation Between Plasma and Genital Fluid Viral Load and Resistance to ART

Although ART reduces viral load in both plasma and seminal fluid, undetectable plasma viral load may not always predict undetectable seminal fluid viral load. A recent review of 19 studies, which compared plasma and seminal fluid viral loads, indicates that while blood and genital fluid viral load are often correlated, this is not always the case [21]. Thus, a person with an undetectable plasma viral load may still shed virus in genital fluid at higher levels, which poses risk for transmission.

Several additional factors may affect genital fluid viral load. For example, sexually transmitted infections (STIs) such as gonorrhea and chlamydia have been shown to transiently increase viral load in genital fluids [22-23]. Individuals with active STIs may therefore be more infectious, despite a low or undetectable plasma viral load. Moreover, as individuals with STIs may not have any symptoms, it may be impossible for either partner to be aware of this increased risk.