Vaginal and cervical secretions

There is generally a strong association between levels of HIV in the blood and in the female genital tract, and the virus is most likely to be ‘shed’ in the cervical and vaginal fluids  when a woman has a high blood viral load.¹ However, as with men, viral load may be higher or lower in the genital fluids compared with the blood.

Unlike blood viral load, HIV viral load in the female genital tract varies over the course of the menstrual cycle, even among women on treatment. One study showed that cervical virus levels were lowest at the stage of luteinising hormone surge (before ovulation) and then increased before the onset of the next menses.² Other studies have reported a correlation between shedding and menstrual cycle,³ but this has not been found in all studies.^{4 5 6}

Some research suggests that use of hormonal contraceptives can also increase genital shedding of HIV.⁷

Antiretroviral therapy usually reduces HIV viral load in cervical and vaginal fluids. In one recent study, for example, HIV viral load in cervical and vaginal fluids declined steeply within two to four days of starting treatment, and became undetectable within two weeks. But a proportion of women with undetectable blood viral load – perhaps one-third – still shed HIV in their genital secretions despite otherwise effective antiretroviral therapy, posing a continued risk for sexual and mother-to-child transmission.^{8 9}