Spinal meningitis is an infection that causes inflammation of the meninges, the three protective membranes surrounding the brain and spinal cord. The term “spinal meningitis” is informal. In medicine, the condition is simply called meningitis, because it affects the same continuous membrane system whether it involves the brain or the spinal cord. Bacterial meningitis is the most dangerous form and can be fatal within hours of the first symptoms.
What the Meninges Are and Why They Matter
Your brain and spinal cord are wrapped in three layers of tissue: the dura (outermost), arachnoid (middle), and pia (innermost). Between the arachnoid and the pia sits a fluid-filled gap called the subarachnoid space, which contains cerebrospinal fluid. This fluid cushions and nourishes the central nervous system.
When bacteria, viruses, or fungi enter that space, they trigger an inflammatory response. The resulting swelling increases pressure inside the skull, which can damage brain tissue, block normal fluid drainage, and disrupt blood flow. That pressure is what makes bacterial meningitis so dangerous so quickly.
Bacterial, Viral, and Fungal Types
Bacterial meningitis is the most severe type. In the United States, the leading bacterial cause is Streptococcus pneumoniae, which also carries the highest mortality rate worldwide. Other common culprits include Neisseria meningitidis (the “meningococcal” bacterium), Haemophilus influenzae, and Listeria monocytogenes, which is more likely to affect adults over 60, pregnant women, and people with weakened immune systems. Newborns face a distinct risk from group B streptococcus, a bacterium that can pass from mother to baby during birth.
Viral meningitis is far more common and usually less severe. Enteroviruses cause the majority of cases, though herpesviruses, mumps, measles, and mosquito-borne viruses like West Nile can also be responsible. Most people with viral meningitis recover on their own within a couple of weeks.
Fungal meningitis is uncommon and typically affects people with compromised immune systems, such as those with uncontrolled diabetes or organ transplant recipients. Cryptococcus and Coccidioides are among the most frequent fungal causes.
How It Spreads
Bacterial and viral meningitis can both spread from person to person, but the routes differ. The bacteria behind most cases of bacterial meningitis live in the nose and throat and travel through respiratory droplets or saliva. Coughing, kissing, or sharing utensils can transmit them. Many people carry these bacteria without ever getting sick. Group B streptococcus, by contrast, lives in the gut or vagina and passes to babies during delivery.
If someone in your household is diagnosed with bacterial meningitis, close contacts are often offered preventive antibiotics to clear the bacteria from the nose and throat before they can cause illness. Fungal meningitis is not contagious between people.
Recognizing the Symptoms
The classic trio of symptoms is fever, neck stiffness, and altered mental status (confusion, drowsiness, or difficulty staying alert). However, all three appear together in only about 41% of bacterial meningitis cases, so waiting for the full set can be dangerous. Other common signs include severe headache, nausea, vomiting, and sensitivity to light.
In infants, the signs look different. A bulging soft spot on the head, poor feeding, irritability, and a high-pitched cry may be the only clues. Young children often can’t describe neck stiffness, so unexplained fever with unusual sleepiness or fussiness warrants immediate medical attention.
Two physical signs are closely associated with meningitis. In one, bending the neck forward causes the knees to flex involuntarily. In the other, straightening the knee while the hip is bent to 90 degrees causes pain or resistance. Neither sign is present in every case, but either one in a febrile patient raises strong suspicion.
How It’s Diagnosed
The definitive test is a lumbar puncture, commonly called a spinal tap. A needle draws a small sample of cerebrospinal fluid from the lower back, and the lab analyzes it for signs of infection. One of the most important clues is glucose level: in bacterial meningitis, the sugar content in cerebrospinal fluid drops below 50% of the blood glucose level, sometimes extremely low. In viral meningitis, glucose typically stays normal. Both types elevate the protein concentration in the fluid. The lab also looks for bacteria directly and runs cultures to identify the exact organism.
Treatment and What to Expect
Bacterial meningitis is a medical emergency. Death can occur within hours of symptom onset, so treatment starts immediately, often before test results come back. Intravenous antibiotics are the cornerstone, and anti-inflammatory steroids may be given alongside the first antibiotic dose to reduce swelling and lower the risk of neurological damage and death. The specific antibiotics may be adjusted once the lab identifies the exact bacterium. Patients with risk factors for Listeria, such as being over 60 or pregnant, receive an additional antibiotic to cover that possibility.
Viral meningitis, by comparison, usually doesn’t require specific antiviral treatment. Rest, fluids, and over-the-counter pain relief are the standard approach, and most people improve within 7 to 10 days. Herpes-related meningitis is an exception and does require antiviral medication.
Fungal meningitis requires long courses of antifungal treatment, often administered intravenously at first, then continued by mouth for weeks or months.
Long-Term Complications
Surviving bacterial meningitis does not always mean a full recovery. Up to 30% of survivors experience some form of neurological or behavioral aftereffect, and studies following children five or more years after their illness found that nearly half still had some type of lasting consequence.
Hearing loss is one of the most common outcomes. In one study of children who survived pneumococcal meningitis, 33% had measurable hearing loss, and 18% still had it at follow-up one to two years later. Vision problems, cognitive difficulties, seizures, and motor impairments are also reported. A study of children in Bangladesh found that 41% of pneumococcal meningitis survivors had mental development deficits and 35% had psychomotor delays at their 12- to 24-month follow-up.
Behavioral effects are significant too. A UK survey found that 46% of parents whose children had meningitis as infants reported behavioral problems when those children became teenagers, compared to 21% in a control group. Adults are not immune to these lasting effects either. Even those considered to have made a “good” recovery can experience cognitive impairment, cranial nerve problems, and difficulty with language or coordination. Over one-third of adults who survived tuberculous meningitis had residual neurological issues a year later.
Vaccines That Prevent Meningitis
Vaccination is the most effective way to prevent bacterial meningitis. Two vaccine types target the meningococcal bacteria specifically.
- MenACWY vaccine: Recommended for all adolescents at age 11 to 12, with a booster at 16 because protection fades over time. If the first dose is given between ages 13 and 15, the booster should come at 16 to 18. If the first dose is given at 16 or later, no booster is needed. Children as young as 2 months may need a multi-dose series if they have specific risk factors.
- MenB vaccine: Covers serogroup B, which the MenACWY vaccine does not. The CDC recommends a shared decision between the patient (or parent) and clinician about whether this vaccine makes sense, typically for adolescents and young adults. The standard schedule is two doses six months apart, though students heading to college in less than six months can receive a three-dose series for faster protection.
Beyond the meningococcal vaccines, routine childhood vaccines against Haemophilus influenzae type b and Streptococcus pneumoniae have dramatically reduced meningitis cases in young children over the past several decades. Pregnant women are also screened for group B strep in many countries and given antibiotics during labor if they test positive, which has brought the neonatal infection rate down to roughly 0.34 to 0.37 cases per 1,000 live births in the United States.