Mumps is a viral infection that affects the salivary glands, causing them to become swollen and painful. It is a highly contagious disease that spreads through contact with infected saliva or respiratory secretions. Mumps is most common in children, but can also affect adults who have not been vaccinated. Symptoms of mumps include fever, headache, muscle aches, and loss of appetite. Treatment typically involves rest, hydration, and pain relief medication.