A second case of an adult in Denver with the measles was reported Wednesday by the Denver Department of Public Health & Environment and the Colorado Department of Public Health & Environment.

The person, who is a household contact of the first Denver case earlier this month, has been in quarantine during his or her infectious period and there is no risk to the general public at this time, according to a news release from DDPHE Wednesday morning.

The case is the fourth in Colorado this year and the second in Denver. The other cases in the state involved a deli worker in Pueblo and an individual in Archuleta County.

The case in Pueblo and the first case in Denver involved people who had travelled to an area of Chihuahua, Mexico, which is experiencing an ongoing measles outbreak, and were diagnosed with measles shortly thereafter. The first case in Denver involved an infant who had travelled to the region with family.

All four cases in Colorado have been confirmed by DDPHE in the past month.

Measles is a highly contagious but preventable respiratory illness that is transmitted through direct contact with infected droplets or airborne when a person breathes, coughs or sneezes. Symptoms typically emerge within two weeks of exposure with a spotty red rash. In rare cases, measles can cause swelling of the brain and death.

Measles can cause serious infection in people who haven’t had the MMR vaccine, the release notes. Two doses of the vaccine are about 97% effective in preventing the disease; the Center for Disease Control recommends children get one dose between 12 and 15 months of age, and a second between 4-and-6 years old.