Of the basic types of meningitis (bacterial, viral, or fungal), viral meningitis is the most common. In the U.S., viral meningitis causes 25,000 to 50,000 hospitalizations each year, according to the Centers for Disease Control and Prevention (CDC). It’s mostly caused by a group of viruses known as enteroviruses, which are more prevalent in the summer and fall. In most cases, though, the disease is mild. Most infected children and adults don’t need to be hospitalized or receive any medical treatment, says Dr. Offit. They get better on their own within seven to 10 days.

Bacterial meningitis is less common, but it’s a greater threat because it’s more likely to leave children with permanent disabilities or be fatal. Three of the most common types of bacteria that cause meningitis include Haemophilus influenzae type b (Hib), pneumococcus, and meningococcus. Hib and pneumococcal disease are more likely in kids under age 5. Meningococcal meningitis is the most common in children under age 2 and adolescents. “Although children under age 2 are more likely to get infected with meningococcal bacteria, they’re not as likely to die from it as the adolescent,” says Dr. Offit. Teens and young adults who share close quarters such as dorm rooms, cabins, or barracks with people from other parts of the country are particularly at risk. Why? “Under those circumstances, you’re more likely to come in contact with types of meningococcal bacteria you haven’t encountered before,” he says.

What are the symptoms? You might think that meningitis is only associated with a red or purple rash, but that's actually not a common symptom. Whether meningitis is viral, bacterial, or fungal, the typical symptoms are similar, and they may include fever (100.4 degrees or higher), severe headache, stiff neck, inability to tolerate bright light, irritability, listlessness, lethargy, nausea, vomiting, or seizures. (In babies, additional symptoms include inconsolable crying or refusal to eat. It could even be difficult to wake meningitis-infected babies.) Symptoms don’t vary based on the age of your child, but you’ll have to do more interpreting the younger your child is. A baby, for example, won’t be able to tell you her neck is stiff or that she’s crying because she’s ill, not colicky, says Dr. Offit. Symptoms tend to be the most pronounced with the bacterial form of the disease. “There’s more inflammation, so the symptoms are more severe,” Dr. Offit says. The disease is detected through a spinal tap; spinal fluid is collected and sent to the lab, where it’s analyzed to see if bacteria are present and what type it is.