BISMARCK, ND (KXNET) — Bismarck-Burleigh Public Health is offering walk-ins for sexual transmitted infections (STI) testing, and certain screenings are completely free to the public. Research shows certain STIs have continued to increase over the years in North Dakota. STIs come in many forms and can have a range of health effects; however, officials say they can be treated. Bismarck-Burleigh Public Health is offering affordable and confidential testing for chlamydia, gonorrhea, syphilis, HIV, and Hepatitis C. They say that HIV and Hepatitis C testing is free, but other tests may come with lab fees. Walk-ins are welcome on Tuesdays from 8:30 a.m. to 11 a.m. But Bismarck-Burleigh Public Health says that appointments are required for other days and hours of operation.