Medical experts have issued a warning against the growing popularity of measles parties in California, ABC News reported.

According to officials from the state's Department of Public Health, some parents hold such gatherings to intentionally expose their children to measles and other diseases. The rationale behind measles parties is that once children get infected with the disease, they will develop immunity against it.

However, health officials strongly urge parents to avoid participating in a measles party because it could endanger the wellbeing of their children.

The Centers for Disease Control and Prevention (CDC) mentioned that exposing young children, particularly those who are under five years old, to measles could lead to other grave illnesses such as pneumonia or brain swelling. It could even cause death according to the CDC.

In addition, the California Department of Public Health reminded the public the measles parties only contribute to the spread of the disease.

"[The department] strongly recommends against the intentional exposure of children to measles as it unnecessarily places the exposed children at potentially grave risk and could contribute to further spread of the outbreak," the department said in a statement.

As a safer solution to the outbreak, health officials emphasized that vaccination is still the most effective defense against measles. The CDC recently reported that the number of confirmed measles cases is now 121 and the outbreak has spread to 17 states in the country.

The concept behind measles parties stemmed from pox parties, which gained popularity in the U.S. during the 1980s, according to the LA Times. During that time, the country has not yet developed a vaccine against the chickenpox. In response to the growing number of outbreak cases, parents organized parties so their children will contract the disease.

However, despite the development of the chickenpox vaccine in 1995, some parents in the country still continue to hold pox parties for their children.