Chlamydia is Australia's most common STI, with over 100,000 diagnoses reported in 2024, especially affecting young people (15-29 years). While overall rates are stable, about 1 in 20 young Australians screened in general practice test positive, though many cases (over half) go undiagnosed. Aboriginal and Torres Strait Islander peoples experience significantly higher rates, roughly double that of non-Indigenous Australians.
We recruited young people from general practice settings across rural, regional and metropolitan Australia. Participants completed a questionnaire and were tested for chlamydia. Of 4284 participants, 197 tested positive for chlamydia (5%). Prevalence was similar in men (5%) and women (4%).
The human papillomavirus (HPV) is the most common STI in the United States. There are more than 40 different strands of HPV and many do not cause any health problems. In 90% of cases, the body's immune system clears the infection naturally within two years.
Chlamydia is one of the most common sexually transmitted infections, affecting about 4.2% of women and 2.7% of men worldwide.
Not as fast-growing but still the most widespread STI is chlamydia, which had 101,742 diagnoses in Australia last year, including around 50% among people aged 20 to 29 years. Meanwhile, the 757 HIV diagnoses recorded in 2024 represented a 27% fall over the past 10 years.
In general: It is possible to get some STIs in the mouth or throat after giving oral sex to a partner who has a genital or anal/rectal STI. It is possible to get certain STIs on the genitals and genital areas after receiving oral sex from a partner with a mouth or throat infection.
Chlamydia is easily cured by a course of antibiotics. Treatment is doxycycline 100mg twice a day for 7 days. Another treatment is a single dose of azithromycin 1g. Your doctor will provide you with a prescription for the antibiotic.
Syphilis and gonorrhea are ancient afflictions. Now, however, Chlamydia is prevalent and has become the most common bacterial STD.
Chlamydia is known as a “silent” infection because most infected people have no symptoms. If symptoms do occur, they may not appear until several weeks after exposure. Even when it causes no symptoms, chlamydia can damage a woman's reproductive organs.
Nearly every sexually active person will have HPV at some point. It is the most common sexually transmitted infection in the U.S. More than 40 types of HPV can be spread sexually. You can get them through vaginal, anal, or oral sex. You can get them by skin-to-skin contact, too.
The CDC estimates that one in five Americans has an STD. Young adults from ages 20 to 34 have the highest rates of infection.
The highest country-specific rates of over 250 cases per 100 000 population were in Denmark, Finland, Iceland, Norway and Sweden – countries that together reported 57% of chlamydia cases in 2022.
The college said the rise in cases could be attributed to changing sexual practices, including reduced use of condoms across a range of demographics. That reduced use could be due to a range of factors, including a decreased concern about infection, Keighley said.
However, Mississippi has the second-highest chlamydia rate nationwide (only behind Louisiana) and the highest total STD rate among all the top 10 states.
Human Papillomavirus (HPV)
HPV8 is the most common STI. More than 40 HPV types exist, and all of them can infect both men and women.
Chlamydia can cause serious problems if left untreated, particularly among women. Women may develop pelvic inflammatory disease (PID), can experience abdominal and pelvic pain, and in later stages develop infertility and ectopic pregnancy (a pregnancy that occurs outside the womb).
The most common and effective treatment is a 7-day course of doxycycline. A single dose of azithromycin may be given but it is less effective than 7 days of doxycycline. For LGV, you need 21 days of doxycycline treatment. All sex partners should be checked, tested, and treated.
The primary reason STIs often go undetected is simple: many don't cause noticeable symptoms. Research from the National Institute of Health confirms this silent epidemic: Chlamydia: Studies across five countries found that between 31.2% to 100% of those with chlamydia reported no symptoms at all.