Why STIs are increasing in older adults after menopause

Diagnoses of sexually transmitted infections, or STIs, are rising among older people.

According to the Centers for Disease Control and Prevention, the number of US adults aged over 65 diagnosed with chlamydia, gonorrhoea and syphilis rose by around threefold, fivefold and sevenfold respectively between 2010 and 2023.

Evidence also indicates that women aged over 50 face a higher risk of HIV than younger women.

Why STIs are increasing in older adults

Several factors may explain why these infections are increasingly prevalent in older adults. They include limited awareness of STIs within this age group, less frequent condom use, and wider access to medicines for conditions that can otherwise restrict sexual activity later in life. These include Viagra and Cialis for erectile dysfunction, alongside oestrogen creams and tablets for vaginal dryness.

Many older people are uncomfortable discussing their sexual history with either partners or healthcare professionals. This can reinforce the mistaken assumption that they are monogamous or not sexually active.

As an infectious disease scientist, I study the largely overlooked biological factors that may make postmenopausal women more vulnerable to STIs.

My recently published study found that menopause is linked to deterioration of the genital tract's protective barrier, a vital defence against the microbial pathogens responsible for STIs.

Menopause: A natural part of ageing

Menopause is defined as the point in a woman's life after 12 uninterrupted months without a menstrual period. In the US, it typically starts between the ages of 45 and 55. By 2030, an estimated 1.2 billion women around the world will be menopausal or postmenopausal.

It occurs when the ovaries cease producing oestrogen, which may reduce vaginal lubrication and the elasticity of vaginal tissue.

This may lead to genitourinary syndrome of menopause, or GSM, a condition associated with vaginal dryness and irritation, painful sex, and recurrent urinary tract infections. Approximately half of postmenopausal women experience GSM.

Menopause and the vaginal protective barrier

Beyond these harmful effects on vaginal health, research from my laboratory has shown that menopause can also weaken the structural integrity of the tissue that lines the vagina.

The vaginal surface consists of several layers of epithelial cells, which are joined by many adhesion molecules. These include the proteins desmoglein-1, or DSG1, and desmocollin-1, or DSC1. By reinforcing the vaginal lining, these proteins limit pathogens' ability to reach deeper tissues and therefore lower the likelihood of infection.

To investigate menopause's effects on the vaginal lining, we compared levels of DSG1 and DSC1 in vaginal tissue from premenopausal and postmenopausal women. DSG1 and DSC1 levels were substantially lower in postmenopausal women.

We also modelled the loss of ovarian oestrogen production seen in postmenopausal women by surgically removing mice's ovaries. Vaginal tissue from mice without ovaries likewise contained significantly lower levels of DSG1 and DSC1 proteins than tissue from mice whose ovaries remained intact.

The mice without ovaries were also more susceptible to herpes simplex virus type 2, or HSV-2, infection and were less able to eliminate chlamydia infection from the lower genital tract. In contrast, treating mice without ovaries with oestrogen cream restored the integrity of their vaginal lining and provided complete protection from HSV-2 infection.

Too important to ignore

A full understanding of both behavioural and biological factors that increase susceptibility to STIs could enable clinicians and public health officials to address the alarming growth in STIs among older adults.

Taken together, our research shows that the vaginal lining loses integrity following menopause. More research is required, but our laboratory's findings indicate that oestrogen-containing treatments used to ease vaginal irritation and other symptoms of genitourinary syndrome of menopause may also lower older adults' susceptibility to STIs.

Meanwhile, healthcare professionals can reduce STI risk in older adults by routinely providing advice on safer sex and offering regular STI screening.

Thomas L. Cherpes, Associate Professor of Otolaryngology, The Ohio State University

This article is republished from The Conversation under a Creative Commons licence. Read the original article.