Thousands of cheerleaders who attended a national competition last month recently received some not-so-cheery news: They may have been exposed to mumps.

Officials at the Texas Department of State Health Services sent letters to people who attended the competition — called the National Cheerleaders Association (NCA) All-Star National Championship — alerting them that a person contagious with mumps was at the event.

More than 23,000 cheerleaders and 2,600 coaches attended the championship, which took place in Dallas, according to the NCA.

Officials said that attendees of the competition should be on the lookout for symptoms of mumps for the next few weeks.

Mumps is a contagious viral disease that causes swelling of the salivary glands, leading to puffy cheeks. It can also cause fever, headache, fatigue and loss of appetite, according to the Centers for Disease Control and Prevention (CDC).

The virus is spread through saliva and respiratory droplets, meaning that people with mumps can infect others by coughing, sneezing or talking. People may also become infected by sharing items such as cups or eating utensils, or by touching surfaces that are contaminated with the virus.

Once people are infected with the virus, symptoms usually take 16 to 18 days to appear, but it may take as long as 25 days to show symptoms.

People typically receive two doses of the mumps vaccine (which is part of the measles, mumps and rubella shot) in childhood, and the vaccine is up to 88% effective at preventing the disease.

But even vaccinated people can become infected with mumps, particularly if they are exposed to a relatively high amount of the virus, which could happen during a mumps outbreaks in close-quarter living spaces such as dorms.

Most people who get mumps recover from the virus in a few weeks. But the illness can sometimes lead to complications, including inflammation of the testicles in men who have reached puberty; inflammation of the brain; inflammation of the membranes covering the brain and spinal cord (meningitis); inflammation of the ovaries; and deafness.

Attendees of the NCA competition are being told to contact their health care provider if they experience symptoms of mumps.