(Reuters) - California has confirmed more cases of measles in people who visited Disneyland or its adjacent California Adventure park last month, health officials said on Monday, raising the number of infected people to 26. A total of 22 cases in California have been linked with visits to the Anaheim parks between Dec. 15 and Dec. 20, including one that arose from direct contact with an infected person, the California Department of Public Health said. Additionally, two cases have been confirmed in Utah and one case has been confirmed in both Colorado and Washington state, the department said. Four other possible measles cases are currently under investigation, the department said, adding that six of those who were sickened were eventually hospitalized. Walt Disney Parks and Resorts officials have said that the company is working with the California health department to provide information and assistance. Measles is a sometimes deadly viral disease that typically begins with fever, cough, runny nose and red eyes, and is followed by the appearance of a red rash that typically starts on the face and spreads downward. There is no specific treatment and most people recover within a few weeks. But in poor and malnourished children and people with reduced immunity, measles can cause serious complications including blindness, encephalitis, severe diarrhea, ear infection and pneumonia. In 2013, more than 70 percent of global measles deaths were in six countries - India, Nigeria, Pakistan, Ethiopia, Indonesia and the Democratic Republic of Congo.