Cases of syphilis and gonorrhea have risen by one fifth in England in just one year, mostly among gay men, according to a report released Wednesday by Public Health England (PHE).

The new report reveals a 20 percent increase in syphilis cases between 2016 and 2017, from 5,955 cases to 7,137 cases, with the vast majority (5,592 cases, or 78 percent) in gay, bisexual, and other “men who have sex with men” (MSM).

The past year’s increase in syphilis diagnoses follows a 10-year upward spiral, with the number of cases increasing by 148 percent relative to 2008 — from 2,874 to 7,137 cases during this period.

PHE said that the number of syphilis diagnoses in 2017 was “the largest annual number reported since 1949.”

A similar trend can be noted in cases of another sexually transmitted infection (STI): gonorrhea.

There were 44,676 diagnoses of gonorrhea reported in 2017, which represents a 22 percent increase from 2016 (36,577 cases). Of these, roughly half the diagnoses (21,346) involved men who have sex with men, up from 17,626 in 2016.

While among MSM syphilis and gonorrhea showed the highest increases in 2017, a third type of venereal disease—chlamydia—also registered significant one-year growth of 17 percent, from 12,626 to 14,765 cases. Chlamydia accounted for 31 percent (15,284) of all new cases of STI’s in men who have sex with men.

According to the PHE report, the sharp increases in bacterial STIs among gay men may be due in part to “an increase in the number of condomless, anal intercourse partners as a result of behaviours such as HIV seroadaptive behaviours, group sex facilitated by geosocial networking applications, and ‘chemsex.’”

STIs among MSM

Despite the notable increases in new cases of syphilis and gonorrhea, the overall number of new STI diagnoses in England actually decreased slightly in 2017, due to a decline in the number of cases of genital warts and non-specific genital infections (NSGI), as well as a slight drop (2 percent) in chlamydia diagnoses among 15- to 24-year-olds.

PHE announced it is working with partner organizations to develop an action plan to address the rise in the number of cases of syphilis and gonorrhea. The plan will aim to increase numbers and frequency of tests in populations at higher risk of infection, to promote early detection and treatment.

“MSM should test annually for HIV and STIs and every three months if having condomless sex with new or casual partners,” PHE stated.

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