State health officials urge individuals to get an extra mumps vaccine as the number of cases in Hawaii continues to rise.

The total number of confirmed mumps cases has reached 770 as of Thursday. The state Department of Health describes the outbreak of the disease as the worst in Hawaii in “several decades” as the state typically has fewer than 10 mumps cases year.

The outbreak began in March 2017 with two clusters of cases involving nine people. By late October, the number of cases surged to 500.

A majority of the recent mumps cases, the health department said, involve adults ranging in age from 20 through their early 40s, and adolescents age 10 and older.

Symptoms include swollen glands of the ears or jaw, fever, muscle aches, headaches, loss of appetite and fatigue. Complications from the disease include orchitis, oophoritis, meningitis, encephalitis and hearing loss.

State Epidemiologist Dr. Sarah Park strongly recommend individuals to get the “outbreak dose” of the MMR (measles, mumps and rubella) vaccine, especially those who reside, work or socialize in crowded settings.

“It’s also important to stay home when sick and even consider methods of social distancing which includes avoiding crowded settings and gatherings, and not hugging or kissing when greeting others,” Park said in a news release.

A gathering — whether at school, work, church or social event — has been the common denominator for those who became exposed to the disease, based on a number of cases the health department has tracked.

Similar outbreaks have occurred in Washington, Texas, Arkansas, Missouri and New York where each state reported more than 300 cases in 2017, according to the Centers for Disease Control and Prevention.

Health officials said those who had two doses of the mumps vaccine can still get the disease, especially if they have prolonged and close contact with an infected person.

To locate a pharmacy that has the mumps vaccine available, visit http://health.hawaii.gov/docd/vaccinesimmunizations/vaccine-locators/ or call the Aloha United Way information line at 211.

For more information, go to http://health.hawaii.gov/docd/advisories/mumps/.