Broader outbreaks of syphilis fueled a 5% increase in sexually transmitted diseases in 2019 when compared with 2018, the Minnesota Department of Health reported Wednesday.

Exactly what the numbers will look like by the end of 2020 is unclear, with the global COVID-19 pandemic reducing person-to-person interaction and sexual activity levels and affecting STD testing as well. But the 2019 numbers show the acceleration of a trend, with STD levels increasing by only 3% in 2018.

“We don’t have any hard data about the impact COVID has had on sexual behavior or even on STD testing rates since we do not get negatives,” said Christine Jones, manager for the Health Department’s STD section. “I don’t think it’s safe for us to make any conclusions.”

While there were more cases of chlamydia (24,535) and gonorrhea (8,063) in 2019, the one-year increase in syphilis cases affected the overall increase in STDs.

Overall case numbers increased by 23% to 1,127 in 2019 for syphilis, an infectious disease caused by a bacteria spread through sexual activity. The state reported detecting 385 cases of syphilis in 2019 that were at the primary or secondary stages of infection, a 32% increase.

While syphilis is treatable with antibiotics, it can cause a variety of complications including cognitive deficits and vision and hearing loss when the infection is neglected and reaches later stages.

The Health Department reported using a new analytical method for tracking outbreaks of syphilis, which have increased among men who have sex with other men, as well as homeless people and women who are pregnant or of childbearing age.

The state has been tracking a syphilis outbreak in north-central Minnesota since 1996, but cases increased in the Twin Cities as well.

“We are now able to identify hot spots earlier than before and complete a more real-time look into what is going on in these areas,” said Dr. Ruth Lynfield, state epidemiologist.

The release of state STD data usually occurs in the spring but was delayed as the Health Department shifted personnel in its response to COVID-19.

Stay-home orders, bar closures and other pandemic response measures have likely reduced sexual encounters. Indiana University researchers reported in the journal Leisure Sciences that 43% of people had reductions in the quality of their sex lives and that the frequency of encounters decreased as well in 2020.

State officials couldn’t say how that affected STD numbers but said it is possible that confirmed results will decline just because many clinics are now testing only symptomatic patients.

There is no proof that the SARS-CoV-2 coronavirus that causes COVID-19 can be sexually transmitted, but sexual partners would be within the risk zone of 6 feet in which they could spread respiratory droplets carrying the virus by breathing, talking or coughing.