Mumps Cases Rise in the US Despite Vaccine Protection

Health officials in the United States have reported a recent rise in mumps/">mumps cases, drawing attention to another vaccine-preventable disease after measles. In Maryland, authorities confirmed 26 cases of mumps so far in 2026, including 19 confirmed and seven probable infections. Nationally, the US Centers for Disease Control and Prevention (CDC) recorded 34 cases across 11 jurisdictions by late February. Although vaccination has dramatically reduced mumps over the past decades, occasional outbreaks continue to occur.

Understanding the Mumps Virus

Mumps is a contagious viral disease caused by the mumps virus, which belongs to the paramyxovirus family. It mainly affects the salivary glands, especially the parotid glands located near the ears. The infection spreads through respiratory droplets and saliva when an infected person coughs, sneezes, talks or shares utensils and drinks. One of the major challenges in controlling mumps is that infected individuals can spread the virus several days before symptoms appear and remain contagious for about five days after gland swelling begins.

Symptoms and Disease Progression

The most noticeable symptom of mumps is swelling of one or both parotid glands, resulting in puffy cheeks and jaw pain. Other symptoms may include fever, headache, muscle aches, fatigue and loss of appetite. Symptoms usually appear two to three weeks after exposure to the virus. In young children, the illness is often mild and sometimes even asymptomatic. However, adolescents and adults are more likely to experience more severe symptoms, which is why outbreaks often occur in schools, colleges and other close-contact settings.

Possible Complications and Risk Groups

Although most people recover without long-term effects, mumps can occasionally lead to serious complications. These include orchitis, an inflammation of the testicles that may rarely affect fertility, and oophoritis, which is inflammation of the ovaries. The infection can also affect the nervous system, causing meningitis or, in rare cases, encephalitis. Another uncommon but serious complication is permanent hearing loss. Individuals who are not vaccinated face the highest risk of infection and complications.

Important Facts for Exams

• Mumps is a viral disease caused by a member of the paramyxovirus family.
• The infection spreads through respiratory droplets and saliva.
• The MMR vaccine protects against measles, mumps and rubella.
• Two doses of the MMR vaccine are about 86% effective in preventing mumps infection.

Role of Vaccination and Continued Outbreaks

The measles, mumps and rubella (MMR) vaccine remains the most effective method of preventing mumps. Two doses of the vaccine provide about 86 per cent protection, while a single dose offers around 72 per cent protection. However, because no vaccine provides complete immunity, breakthrough infections can still occur in vaccinated individuals. These cases are usually milder and less likely to cause severe complications, but they can still contribute to outbreaks, particularly in crowded environments where close contact facilitates transmission.