Menopause Increases Risk of STIs: Understanding the Biological and Behavioral Factors

Diagnosis for sexually transmitted infections (STIs) are on the rise among older adults. The Centers for Disease Control and Prevention reports a significant increase in the number of people older than 65 diagnosed with chlamydia, gonorrhoea, or syphilis in the U.S. between 2010 and 2023. 

Data also suggests that women over 50 are at greater risk for HIV than younger women

There are several reasons for this trend. Limited understanding of STIs in this age group, infrequent condom use, and increased availability of medications such as Viagra and Cialis for erectile dysfunction, and oestrogen creams and tablets for vaginal dryness contribute to this issue. 

Additionally, many older adults are reluctant to discuss their sexual history with partners and healthcare providers, leading to misconceptions about their sexual activity.

As an infectious disease scientist, I explore the biological reasons why postmenopausal women are more susceptible to STIs. My recent research indicates that menopause is associated with the loss of the genital tract's protective barrier, which is crucial in defending against microbial pathogens that cause STIs.

Menopause: A Natural Part of Aging

Menopause is defined as the stage in a woman's life when she has no menstrual periods for 12 consecutive months, typically occurring between ages 45 and 55 in the U.S. By 2030, an estimated 1.2 billion women worldwide will be menopausal or postmenopausal. 

Menopause results from a decline in oestrogen production from the ovaries, leading to diminished vaginal lubrication and tissue elasticity. 

This can cause genitourinary syndrome of menopause (GSM), characterised by symptoms such as vaginal dryness, irritation, painful sex, and frequent urinary tract infections. Approximately half of postmenopausal women experience GSM.

Biological Changes and Increased STI Risk

Research from my lab has shown that menopause compromises the structural integrity of the vaginal lining. The vaginal surface consists of multiple layers of epithelial cells held together by adhesion molecules, including the proteins desmoglein-1 (DSG1) and desmocollin-1 (DSC1). 

These proteins strengthen the vaginal lining and prevent pathogens from accessing deeper tissues, thereby reducing the risk of infection.

To investigate how menopause affects the vaginal lining, we compared DSG1 and DSC1 levels in vaginal tissue from postmenopausal and premenopausal women. Postmenopausal women exhibited significantly lower levels of these proteins. 

We also modelled the loss of ovarian oestrogen production in mice by surgically removing their ovaries, finding that mice without ovaries had reduced DSG1 and DSC1 proteins in their vaginal tissue and were more susceptible to herpes simplex virus type 2 (HSV-2) and less able to clear chlamydia infections. 

Conversely, applying oestrogen cream restored the integrity of the vaginal lining and protected these mice from HSV-2 infection.

The Importance of Addressing STI Risks in Older Adults

Understanding the behavioural and biological risk factors contributing to STI susceptibility can help clinicians and public health officials address the increasing STI rates among older adults. 

Our studies indicate that the loss of vaginal lining integrity after menopause is a significant factor. Oestrogen-containing compounds used to alleviate GSM symptoms may also reduce STI susceptibility in older adults. 

Healthcare providers can help mitigate STI risks among older adults by consistently counselling them about safe sex practices and offering routine STI screening.