Sexually transmitted infections stop their upward trend in 2025 after breaking records

The results of the 2025 Report on Epidemiological Surveillance of Sexually Transmitted Infections (STIs) in Spain reveal a certain stabilization of the trend towards high levels observed in previous reports: the rates remain high, but the increase that has been observed in recent years slows down, and in some cases slight decreases are observed, from record levels.

The report, published this Thursday by the Carlos III Health Institute (ISCIII) through its National Epidemiology Center (CNE), in coordination with the Ministry of Health, confirms the presence of more infections in men than in women and a greater impact on young adults.

STIs are a group of pathologies of infectious origin in which the main route of acquisition is sexual relations, although they may have other modes of transmission. They are caused by different microorganisms, which can be viruses, bacteria, protozoa or ectoparasites. There are more than 20 STIs described and some of the best known are syphilis, chlamydiasis, gonorrhea, human immunodeficiency virus (HIV) infection, human papillomavirus (HPV), genital herpes virus, trichomoniasis, pubic pediculosis or scabies.

The report reveals that, within the growing trend of gonococcal infection (gonorrhea) and syphilis observed since the beginning of the 2000s, in this last year the rates seem to stabilize, with data very similar to those of 2024. In 2025, 37,467 cases of gonococcal infection were reported (rate: 76.26 per 100,000 inhabitants) and only a dozen more cases than the previous year. For 11,879 cases of syphilis (rate: 24.18 per 100,000 inhabitants), 85 cases less than in 2024.

Meanwhile, the rates of lymphogranuloma venereum have decreased compared to previous years, from 2,039 diagnoses to 1,824. Regarding chlamydia cases, they continue to rise (42,820, compared to 44,511 the previous year), but with a smaller increase than in previous years. Data on new HIV diagnoses are also stable.

However, the new report reveals that these sexual infections remain at a high level and have grown exponentially in the last thirty years. Thus, if gonorrhea had a rate of 11.69 per 100,000 inhabitants, this rate has risen in 2025 to 76.26 per 100,000 inhabitants. The increase is also noticeable in syphilis, jumping from a rate of 2.57 per 100,000 inhabitants to 24.28 people per 100,000.

Men and young people, the most affected

The results confirm that for all STIs, a greater impact is still observed in men than in women and that the majority of cases would be in young adults, the population with the highest infection rates, although differences are observed depending on the disease.