Portland is seeing a spike in HIV cases, one that Multnomah County health officials believe is tied to methamphetamine and injection drug use.

Multnomah County has seen 42 new cases of HIV in the past 18 months. That number is nearly double the 25 reported cases in 2016 and 2017 combined, according to the Multnomah County Health Department.

This comes after a five-year decrease in cases due to antiviral treatment, preventative medicine, sex education and needle exchange programs.

In a press release, the county said that users of methamphetamines and injectable drugs face the highest risk of infection and make up a significant portion of the cases. The disease can also be spread sexually. The new cases are not confined to one gender, sexuality, housing situation or place.

"We know that historically, we have not had a lot of transmission," said Kim Toevs, the Communicable Disease and STD Program director at the Multnomah County Health Department during a press conference on Thursday. "Transmission through syringes, and sharing syringes, scares us because it's the most effective way to transmit HIV, unfortunately. It's easier to transmit HIV through sharing a syringe than through sexual activity, so we are concerned that it could rapidly spread locally."

Cases of Syphilis and Shigella, diseases with common risk factors to HIV, also continue to increase. In 2018, 87 women in Multnomah County reportedly contracted Syphilis compared to 52 the previous year. Shigella, a bacteria which can be spread through unwashed hands or sexual activity, had 95 cases in 2018, up from a previous average of 20 per year.

The county and the CDC recommend HIV testing, generally, for anyone who is sexually active who has not confirmed their partner's status and anyone who shares needles. A list of public testing centers, free safe sex supplies and needle exchanges can be found on Multnomah County's website.

The county has not determined whether the situation is a short-term outbreak, or part of a larger trend. According to the press release, the Communicable Disease and Sexually Transmitted Disease Programs are currently collaborating with local health and outreach programs to increase testing and prevention.