How chlamydia can infect the anus from JUST oral sex

Chlamydia can infect the anus even if a person has only performed oral sex, research suggests.

A study of nearly 200 men found two had the sexually-transmitted infection (STI) in their rectums despite them denying ever receiving anal intercourse.

The infected men did, however, admit to performing cunnilingus, the research adds. 

Researchers from the US believe the chlamydia bacteria may enter the body via the mouth and survive the harsh conditions of the gut, before going on to infect other parts of the body.

The research was carried out by Indiana University and led by Dr Teresa Batteiger, an assistant professor of clinical medicine in the department of infectious diseases. 

Chlamydia is the most common STI in the US, with more than 1.7million cases being reported in 2017 alone, Centers for Disease Control and Prevention statistics show.

The infection also made up 46 per cent of all STIs in the UK in 2015, with a total of 200,288 cases, according to the sexual-health charity FPA.

Left untreated, the infection can spread to other parts of the body, leading to pelvic inflammatory disease, inflammation of the testicles and even infertility.

However, up to 70 per cent of infected women and half of infected men show no obvious signs of the STI. Symptoms can include pain when urinating, unusual discharge and discomfort during sex.

The researchers claim women ‘frequently’ develop chlamydia infections in their rectums despite them maintaining they have not engaged in anal sex. 

These infections may come about after vaginal secretions ‘spread’ to the anus.

However, this ‘autoinoculation’ is ‘unlikely’ in men, the researchers wrote in the journal Sexually Transmitted Diseases.

Heterosexual males also ‘frequently perform oral sex’ but ‘rarely participate in receptive anal exposure behaviours’, they added.

To uncover how straight men may become infected with rectal chlamydia, the researchers analysed 197 males of different sexual orientations.

The men presented to an STI clinic in Indianapolis with non-gonococcal urethritis (NGU).

NGU occurs when the tube that carries urine from the bladder out of the body becomes inflamed but the STI gonorrhoea is not to blame. 

Symptoms include a white, cloudy discharge; a burning sensation when urinating; and an irritated tip of the penis. 

The men provided urine samples and rectal swabs, which were tested for the bacteria behind chlamydia and gonorrhoea.

The participants also completed surveys about their symptoms and sexual orientation. 

And they gave ‘detailed’ explanations on their ‘recent and lifetime oral and anal sexual behaviours’. 

Of the 135 participants who identified as straight, 84 claimed to have performed cunnilingus in their lifetime but never to have received anal sex. 

Results found the chlamydia infection was in the rectums of two (2.4 per cent) of these 84 men.

All of the men who denied receiving anal sex tested negative for gonorrhoea and MG.

Among the gay and bisexual participants, 9.7 per cent had chlamydia in their rectums, while 4.8 per cent were infected with gonorrhoea and 4.8 per cent with MG.  

‘We detected rectal chlamydia infections in heterosexual men who reported cunnilingus but denied receptive anal behaviors,’ the researchers wrote. 

‘Oral sex may be a risk factor for rectal chlamydia infection via oral inoculation of the gastrointestinal tract.’ 

Previous reports state chlamydia can lie dormant in the gut, before reappearing up to 80 years after a patient has been ‘cured’ of the infection.

The bacteria has also been known to survive in the gastrointestinal tract of animals since as early as the 1950s.