Public Release:  Genital-only screening misses many cases of gonorrhea and chlamydia in women

Johns Hopkins Medicine

Current public health guidelines recommend that only gay men and people with HIV should be routinely screened for extragenital gonorrhea and chlamydia, given the high burden of these sexually transmitted infections (STIs) in this at-risk population.

However, a new Johns Hopkins Medicine study that looked at over 10,000 people who attended an STI clinic in Baltimore has found that the occurrence of gonorrhea or chlamydia in extragenital areas like the throat or rectum is also significant in women, particularly younger women. The findings will be published in the May issue of Sexually Transmitted Diseases.

If the women examined in this study had only received genital STI tests -- as is the standard recommendation -- nearly 14 percent of chlamydia infections and more than 30 percent of gonorrhea infections would have been missed.

"Gonorrhea and chlamydia are treatable infections, but we can only treat the cases we know about," says Khalil Ghanem, M.D., Ph.D., an assistant professor of medicine and corresponding author of this study. "If we want to effectively control the spread of these two diseases, we need to ensure that testing guidelines are as rigorous as possible."

Gonorrhea and chlamydia are common bacterial infections that are generally not fatal but can cause serious short- and long-term health problems if left untreated. Both conditions can be effectively managed with antibiotics, though as with other bacteria, some antibiotic resistance can occur.

"However, when these infections occur in extragenital areas, they are typically asymptomatic," notes Joshua Trebach, a third-year student at the Johns Hopkins University School of Medicine, who undertook this surveillance project along with Ghanem. "These types of infections pose a large and hidden public health threat, because they can be transmitted to unwitting sexual partners and form an active infection."

But while this new study indicates that routine extragenital screening would be valuable from a public health perspective, Ghanem notes that whether routine screening can be cost-effective is another matter.

The total prevalence of extragenital gonorrhea or chlamydia among the more than 4,000 women screened was 2.4 percent and 3.7 percent, respectively. By comparison, the extragenital rates for gay men, considered a risk group that needs routine screening, were 18.9 percent for gonorrhea and 11.8 percent for chlamydia. "This means we'd need to screen more women for extragenital infections, which may come with a higher price tag," says Ghanem.

"Cost-effectiveness analysis is an area we should definitely pursue," he continues. "Young women in particular might benefit, as our analysis found that women who were 18 or younger had nearly fourfold increased odds of being diagnosed with an extragenital infection."

Ghanem, Trebach and colleagues developed their findings using health records from 10,389 people (4,402 women, 5218 heterosexual men and 769 gay men) who attended either the Baltimore City Health Department Eastern Health District or the Druid STD Clinic between June 2011 and May 2013. All of the people included in the study had reported recent exposure to oral and/or anal sexual intercourse.

The study also found that heterosexual men had extragenital rates of 2.6 percent and 1.6 percent for gonorrhea and chlamydia, respectively. However, because of budget constraints, the clinics did not test these men for genital chlamydia, so detailed comparisons could not be made.

While this analysis was focused on sexual health clinics, the authors believe it could have broader implications, as doctors in other areas like emergency medicine often encounter women complaining of pain or irritation that may be connected with an STI.

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Additional Johns Hopkins investigators involved in this study were C. Patrick Chaulk, Kathleen Page and Susan Tuddenham.

Johns Hopkins Medicine
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