Meningitis is an infection of the meninges, which are membranes that surround the brain and spinal cord. Anyone, including adults, can develop meningitis. However, the risk is higher in people with weakened immune systems and in young children.

Signs and symptoms of meningitis include:

Meningitis often occurs due to pathogens such as viruses, bacteria, and fungi, and so the type of treatment a person receives will vary.

Read on to learn more about meningitis in adults, including the causes, symptoms, and treatment options.

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Meningitis is a condition that causes inflammation of the meninges. The meninges form a protective membrane that surrounds the brain and spinal cord, and contribute to the blood-brain barrier.

Meningitis often occurs when viruses, bacteria, and fungi infect the meninges, resulting in inflammation and swelling.

The condition can be fatal, because as the meninges swell, they begin to press on the brain and spinal cord, disrupting crucial biological processes.

Cancer, autoimmune disorders, and reaction to medication can sometimes also cause meningitis. When this happens, a person has noninfectious meningitis.

Learn more about types of meningitis here.

Meningitis has many causes, including viruses, bacteria, fungi, and parasites. However, when a pathogen is not the cause of meningitis, a person has noninfectious meningitis.

Infectious causes

The following pathogens can cause meningitis:

  • Viruses: Non-polio enteroviruses, which are similar to the common cold, tend to cause viral meningitis. Usually, these viruses are mild and go away on their own, but sometimes, meningitis develops as a complication. Other viruses that can lead to meningitis are mumps, chickenpox, measles, and flu.
  • Bacteria: The most common type of bacteria that cause meningitis are Streptococcus pneumoniae, group B Streptococcus, Neisseria meningitidis, Haemophilus influenzae, and Listeria monocytogenes. Some of these bacteria spread through contaminated food, but usually, the bacteria transmit from person to person.
  • Fungi: The main types of fungi that cause meningitis areCryptococcus neoformans, Coccidioides immitis, Aspergillus, and Candida. Sources of these fungi include wood, soil, and pigeon droppings.

Parasites and ameba can also cause meningitis, but cases are rare.

Noninfectious causes

An adult may develop noninfectious meningitis from a health condition such as cancer.

Other noninfectious causes include:

Symptoms of meningitis can differ between adults and children.

Typically, symptoms will not all present at once. A person will usually notice a gradual decline in their well-being.

In adults, meningitis symptoms may present as:

Meningitis affects adults and children in the same way. However, symptoms can manifest differently in very young children.

For example, an adult may complain about a stiff neck, while a baby will arch their back and cry.

Newborns also do not always present with fever or hypothermia, and overall, they show more subtle signs of infection.

While a lot of people make a full recovery from meningitis, some do not.

A person’s recovery depends on a number of factors, such as how quickly they receive treatment and how severe their infection is.

For instance, bacterial meningitis is the most serious form of the condition and can leave people with permanent health problems.

Other serious complications of meningitis include:

To confirm a diagnosis of meningitis, a doctor will first conduct a physical examination and look out for signs of, for example, meningeal irritation, back pain, and light sensitivity. They will also closely examine a person’s skin to check for discoloration and rashes.

After the physical exam, a doctor will request a sample of the person’s cerebrospinal fluid to confirm the presence of meningitis-causing viruses, bacteria, and fungi.

A doctor will not usually administer any treatment until they are sure of the cause. However, in urgent circumstances, they will assume a person has bacterial meningitis and immediately treat them with antibiotics.

According to current treatment protocols, in cases of bacterial meningitis, a doctor will consider a person’s age and medical history before administering a suitable antibiotic.

Adults aged 18–49 years will usually receive either ceftriaxone or vancomycin through a needle into a vein, or intravenously (IV).

People over the age of 50 years or those with weakened immune systems will also receive ceftriaxone IV or vancomycin IV, but a doctor may also consider ampicillin IV.

To reduce meningeal inflammation, a person may receive steroid therapy. However, more research is necessary to determine whether steroids are an effective and safe method to treat bacterial meningitis.

In cases of fungal meningitis, a doctor will administer antifungal drugs to clear the infection.

Most incidences of viral meningitis resolve on their own without treatment.

Recovery times differ between individuals and depend on the cause of meningitis:

  • Viral meningitis: People typically recover within 7–10 days and tend not to have any lasting complications.
  • Bacterial meningitis: Recovery times for bacterial meningitis vary, and some people can begin to feel better in as little as 2–3 days. However, they may need long-term treatment if they experienced serious complications.
  • Fungal meningitis: People with underlying health conditions, such as cancer, will usually take a while to recover from fungal meningitis and may require long-term treatment.

Meningitis can affect people of any age, including adults. The three main causes of meningitis are viral, bacterial, and fungal infections.

Adults with weakened immune systems are most at risk of serious meningitis complications, especially if they develop a bacterial infection of the meninges.

Doctors diagnose meningitis in adults using a combination of physical exams and cerebrospinal fluid screening.

Viral meningitis often resolves on its own within 7–10 days and leaves no lasting complications. However, bacterial and fungal meningitis may require long-term treatment.