An ongoing measles outbreak in Clark County, Washington has led the Department of Health to declare a public health emergency.
In the latest update, 23 cases of measles have been confirmed and health officials are investigating two more suspected cases.
The majority of cases are in children aged 1 to 10. Four cases are in children and teens aged 11 to 18, and one person aged 19 to 29 has been infected, according to CBS News.
Measles, which is easily preventable by vaccine, is an extremely contagious infection and can be very serious for small children.
Symptoms include cough, runny nose, inflamed eyes, sore throat, fever, and a red, blotchy skin rash. They usually develop 10 to 12 days after exposure and can last anywhere from 7 to 10 days.
Measles typically spreads to others through coughing and sneezing making it so contagious that if on person has it, 90 percent of the people close to that person who are not immune will also become infected, according to the Centers for Disease Control and Prevention.
The large number of measles cases in Clark County is a result of children skipping the vaccine because of their parent's religious or philosophical beliefs. In fact, eighteen states in the U.S. currently permit non-medical exemptions from childhood vaccinations due to philosophical beliefs.
An analysis published last June in the journal PLOS Medicine identified 15 metropolitan clusters or "hotspots" of higher rates of vaccination exemptions. The Portland, Oregon, area, just across the Columbia River from Clark County, being one of those hotspots.
"As larger unvaccinated populations grow, particularly in highly mobile cities, the potential for vaccine-preventable disease outbreaks grows," study authors Peter Hotez and Melissa Nolan said in a joint statement. "Measles outbreaks are of particular concern because measles is so highly transmissible and is associated with high morbidities, leading to hospitalization and sometimes permanent neurological injury or even death."
People who believe they may have measles and are experiencing symptoms should not go directly to doctor's offices, urgent care centers, or emergency rooms (unless experiencing a medical emergency) without calling in advance in order to avoid exposing others in the waiting room.