Meningitis is a potentially life-threatening infection of the meninges, the tough layer of tissue that surrounds the brain and the spinal cord — that occurs when the tissue surrounding the brain and spinal cord becomes inflammed. The swelling from this inflammation can harm or destroy nerve cells and cause bleeding in the brain. A number of things can cause this condition, from an infection to a traumatic injury to the head or spine. The bacterial form of this condition has a high death rate if left untreated, so it requires immediate medical attention. If not treated, meningitis can lead to brain swelling and cause permanent disability, coma, and even death.
Meningitis can be caused by a variety of things, including bacteria (the most serious), viruses, fungi, reactions to medications, and environmental toxins such as heavy metals. Although bacterial and fungal meningitis require extended hospitalization, meningitis caused by viruses can often be treated at home and has a much better outcome.
The most common cause of meningitis usually results from a viral infection, but the cause may also be a bacterial infection. Less commonly, a fungal infection may cause meningitis. Because bacterial infections are the most serious and can be life-threatening, identifying the source of the infection is an important part of developing a treatment plan.
The most serious form of meningitis, bacterial meningitis, occurs in about 3,000-5,000 people in the United States every year.
Approximately 20%-25% of the time, even with treatment, bacterial meningitis can be fatal. If bacterial meningitis progresses rapidly, in 24 hours or less, death may occur in more than half of those who develop it, even with proper medical treatment.
Acute bacterial meningitis usually occurs when bacteria enter the bloodstream and migrate to the brain and spinal cord. But it can also occur when bacteria directly invade the meninges, as a result of an ear or sinus infection or a skull fracture.
A number of strains of bacteria can cause acute bacterial meningitis. The most common include:
Streptococcus pneumoniae (pneumococcus). This bacterium is the most common cause of bacterial meningitis in infants, young children and adults in the United States. It more commonly causes pneumonia or ear or sinus infections.
Neisseria meningitidis (meningococcus). This bacterium is another leading cause of bacterial meningitis. Meningococcal meningitis commonly occurs when bacteria from an upper respiratory infection enter your bloodstream. This infection is highly contagious. It affects mainly teenagers and young adults, and may cause local epidemics in college dormitories, boarding schools and military bases.
Haemophilus influenzae (haemophilus). Before the 1990s, Haemophilus influenzae type b (Hib) bacterium was the leading cause of bacterial meningitis in children. But new Hib vaccines — available as part of the routine childhood immunization schedule in the United States — have greatly reduced the number of cases of this type of meningitis. When it occurs, it tends to follow an upper respiratory infection, ear infection (otitis media) or sinusitis.
Listeria monocytogenes (listeria). These bacteria can be found almost anywhere — in soil, in dust and in foods that have become contaminated. Contaminated foods have included soft cheeses, hot dogs and luncheon meats. Many wild and domestic animals also carry the bacteria. Fortunately, most healthy people exposed to listeria don't become ill, although pregnant women, newborns and older adults tend to be more susceptible. Listeria can cross the placental barrier, and infections in late pregnancy may cause a baby to be stillborn or die shortly after birth. People with weakened immune systems, due to disease or medication effect, are most vulnerable.
Each year, viruses cause a greater number of cases of meningitis than do bacteria. Viral meningitis is usually mild and often clears on its own within two weeks. A group of viruses known as enteroviruses are responsible for about 30 percent of viral meningitis cases in the United States. As many viral meningitis episodes never have a specific virus identified as the cause, determining how many people get viral meningitis is difficult because it often remains undiagnosed and is easily confused with the flu.
The prognosis for viral meningitis is much better than that for bacterial meningitis, with most people recovering completely with simple treatment of the symptoms. Because antibiotics do not help viral infections, they are not useful in the treatment of viral meningitis.
The most common signs and symptoms of enteroviral infections are rash, sore throat, diarrhea, joint aches and headache. These viruses tend to circulate in late summer and early fall. Viruses such as herpes simplex virus, La Crosse virus, West Nile virus and others also can cause viral meningitis.
Chronic forms of meningitis occur when slow-growing organisms invade the membranes and fluid surrounding your brain. Although acute meningitis strikes suddenly, chronic meningitis develops over two weeks or more. Nevertheless, the signs and symptoms of chronic meningitis — headaches, fever, vomiting and mental cloudiness — are similar to those of acute meningitis. This type of meningitis is rare.
Fungal meningitis is relatively uncommon and causes chronic meningitis. Occasionally it can mimic acute bacterial meningitis. Cryptococcal meningitis is a common fungal form of the disease that affects people with immune deficiencies, such as AIDS. It's life-threatening if not treated with an antifungal medication.
Meningitis can also result from noninfectious causes, such as drug allergies, some types of cancer, inflammatory diseases such as lupus, traumatic injury to the head or spine, reaction to certain medications or medical treatments, and environmental toxins such as heavy metals.
Symptoms of meningitis can develop over several hours, or they may take one to two days. Common symptoms (in people over the age of two) include high fever, headache, and stiff neck. In some forms of the disease, symptoms may also include distinctive rashes. More severe meningitis symptoms include nausea, vomiting, confusion, and sleepiness. In newborns and small infants, the classic symptoms may be absent or difficult to detect.
Meningitis should be treated as a medical emergency because bacterial meningitis can lead to septicemia (blood poisoning), which can be fatal.
Common meningitis symptoms in anyone over the age of two years include:
High fever
Headache
Stiff neck.
These symptoms can develop over several hours, or they may take one to two days. Symptoms of meningitis may also include distinctive rashes in some forms of the disease. Symptoms of meningococcal meningitis may be associated with kidney and adrenal gland failure and shock.
More severe symptoms may include:
Nausea
Vomiting
Confusion
Sleepiness
Discomfort looking into bright lights.
As meningitis progresses, patients of any age may have seizures.
In newborns and infants, the classic meningitis symptoms of fever, headache, and neck stiffness may be absent or difficult to detect.
Instead, infants with meningitis may only appear slow or inactive, or be irritable, have vomiting, or be feeding poorly.
Bacterial meningitis is the more serious form of the condition. The symptoms usually begin suddenly and rapidly get worse. If you suspect a case of bacterial meningitis, you should phone 911 immediately to request an ambulance.
There are some early warning signs that you may notice before the other symptoms appear.
Early warning signs
Bacterial meningitis has a number of early warning signs that can occur earlier than the other symptoms. These are:
pain in the muscles, joints or limbs, such as in the legs or hands
unusually cold hands and feet, or shivering
pale or blotchy skin and blue lips
The presence of a high temperature (fever) plus any of the above symptoms should be taken very seriously. Phone 911 immediately to request an ambulance.
Early symptoms
The early symptoms of bacterial meningitis are similar to those of many other conditions, and include:
a severe headache
fever
nausea (feeling sick)
vomiting (being sick)
feeling generally unwell
Later symptoms
As the condition gets worse it may cause:
drowsiness
confusion
seizures or fits
being unable to tolerate bright lights (photophobia) – this is less common in young children
a stiff neck – also less common in young children
a rapid breathing rate
a blotchy red rash that does not fade or change color when you place a glass against it – the rash is not always present
Babies and young children
The symptoms of bacterial meningitis are different in babies and young children. Possible symptoms include:
becoming floppy and unresponsive, or stiff with jerky movements
becoming irritable and not wanting to be held
unusual crying
vomiting and refusing feeds
pale and blotchy skin
loss of appetite
staring expression
very sleepy with a reluctance to wake up
Some babies will develop a swelling in the soft part of their head (fontanelle).
Most people with viral meningitis will have mild flu-like symptoms, such as:
headaches
fever
generally not feeling very well
In more severe cases of viral meningitis symptoms may include:
neck stiffness
muscle or joint pain
nausea (feeling sick)
vomiting (being sick)
diarrhea (passing loose, watery stools)
photophobia (sensitivity to light)
Unlike bacterial meningitis, viral meningitis does not usually lead to septicemia (blood poisoning).
The complications of meningitis can be severe. The longer you or your child has the disease without treatment, the greater the risk of seizures and permanent neurological damage, including:
Hearing loss
Blindness
Memory difficulty
Loss of speech
Learning disabilities
Behavior problems
Brain damage
Paralysis
Other complications may include:
Kidney failure
Adrenal gland failure
Shock
Death
People with suspected meningitis or septicemia (blood poisoning) need to be admitted to hospital for treatment immediately, wherever they are. For bacterial meningitis, strong doses of intravenous antibiotics are required. Viruses cannot be killed by antibiotics, so most treatment for viral meningitis does not involve medications to kill the virus. Depending on the source of infection, infected sinuses may need to be drained as part of treatment.
Someone with bacterial meningitis will require urgent treatment in hospital. If they have severe meningitis, they may need to be treated in an intensive care unit (ICU). Antibiotics (medication for infections caused by bacteria) will be used to treat the underlying infection. These will be given intravenously (through a vein in your arm).
At the same time you may also be given:
oxygen
intravenous fluids (through a vein)
steroids or other medication to help reduce the inflammation (swelling) around your brain
If the antibiotics work well, you should spend about a week in hospital, or maybe less. But if you are severely ill you may need to stay in hospital for weeks or even months.
Meningococcal disease (the combination of meningitis and septicemia) can cause some long-term complications.
If you or your child has bacterial meningitis, your doctor may also recommend treatments for:
Brain swelling
Shock
Convulsions
Dehydration
Infected sinuses or mastoids — the bones behind the outer ear that connect to the middle ear — may need to be drained. Infected fluid that has accumulated between the skull and the membranes that surround the brain also may need to be drained surgically.
Antibiotics can't cure viral meningitis, and most cases improve on their own in a week or two without therapy. If the cause of your meningitis is a herpes virus, there's an antiviral medication available.
Viral meningitis can either be:
severe
mild
The treatment for both severe and mild meningitis is described below.
Severe viral meningitis
If the symptoms of viral meningitis are severe enough to require admission to hospital, the condition will be treated in the same way as bacterial meningitis with antibiotics.
Once a diagnosis of viral meningitis has been confirmed, the antibiotics will be withdrawn. However, intravenous fluids will be continued to support the body as it recovers.
In very severe cases, where someone is in hospital with viral meningitis, anti-viral medicines may be given.
Mild viral meningitis
Most people with viral meningitis will not require hospital treatment. Viral meningitis is usually mild and can be treated at home with:
plenty of rest
painkillers for the headache
anti-emetics (anti-sickness) medicine for the vomiting
Most people recover within 5 to 14 days.
Other types of meningitis
If the cause of your meningitis is unclear, your doctor may start antiviral and antibiotic treatment while a cause is being determined.
Fungal meningitis treatments are associated with harmful side effects, so treatment is often deferred until a laboratory can confirm the cause is fungal.
Non-infectious meningitis due to allergic reaction or autoimmune disease may be treated with cortisonelike medications. In some cases, no treatment may be required, because the condition can resolve on its own. Cancer related meningitis requires therapy for the individual cancer.
Most cases of meningitis are isolated and the risk of the infection spreading is low.
However, if someone is thought to be particularly at risk of infection, they can be given a dose of antibiotics as a precautionary measure. For example, a young child who has spent a large amount of time in close contact with another child who has developed bacterial meningitis.
Not completing the childhood vaccine schedule increases your risk of meningitis. So do a few other risk factors:
Age. Most cases of viral meningitis occur in children younger than age 5. In the past, bacterial meningitis also usually affected young children. But since the mid-1980s, as a result of the protection offered by current childhood vaccines, the median age at which bacterial meningitis is diagnosed has shifted from 15 months to 25 years.
Living in a community setting. College students living in dormitories, personnel on military bases, and children in boarding schools and child care facilities are at increased risk of meningococcal meningitis, probably because the bacterium is spread by the respiratory route and tends to spread quickly wherever large groups of susceptible teenagers or young adults congregate.
Pregnancy. If you're pregnant, you're at increased of contracting listeriosis — an infection caused by listeria bacteria, which may also cause meningitis. If you have listeriosis, your unborn baby is at risk, too.
Working with animals. People who work with domestic animals, including dairy farmers and ranchers, have a higher risk of contracting listeria, which can lead to meningitis.
Compromised immune system. Factors that may compromise your immune system — including AIDS, diabetes and use of immunosuppressant drugs — also make you more susceptible to meningitis. Removal of your spleen, an important part of your immune system, also may increase your risk.
Meningitis typically results from contagious infections. Common bacteria or viruses that can cause meningitis can spread through coughing, sneezing, kissing, or sharing eating utensils, a toothbrush or a cigarette. You're also at increased risk if you live or work with someone who has the disease.
These steps can help prevent meningitis:
Wash your hands. Careful hand washing is important to avoiding exposure to infectious agents. Teach your children to wash their hands often, especially before they eat and after using the toilet, spending time in a crowded public place or petting animals. Show them how to wash their hands vigorously, covering both the front and back of each hand with soap and rinsing thoroughly under running water.
Stay healthy. Maintain your immune system by getting enough rest, exercising regularly, and eating a healthy diet with plenty of fresh fruits, vegetables and whole grains.
Cover your mouth. When you need to cough or sneeze, be sure to cover your mouth and nose.
If you're pregnant, take care with food. Reduce your risk of listeriosis if you're pregnant by cooking meat thoroughly and avoiding cheeses made from unpasteurized milk.
Some forms of bacterial meningitis are preventable with the following vaccinations:
Haemophilus influenzae type b (Hib) vaccine. Children in the United States routinely receive this vaccine as part of the recommended schedule of vaccines, starting at about 2 months of age. The vaccine is also recommended for some adults, including those who have sickle cell disease or AIDS and those who don't have a spleen.
Pneumococcal conjugate vaccine (PCV7). This vaccine is also part of the regular immunization schedule for children younger than 2 years in the United States. In addition, it's recommended for children between the ages of 2 and 5 who are at high risk of pneumococcal disease, including children who have chronic heart or lung disease or cancer.
Pneumococcal polysaccharide vaccine (PPSV). Older children and adults who need protection from pneumococcal bacteria may receive this vaccine. The Centers for Disease Control and Prevention recommends the PPSV vaccine for all adults older than 65, for younger adults and children who have weak immune systems or chronic illnesses such as heart disease, diabetes or sickle cell anemia, and for those who don't have a spleen.
Meningococcal conjugate vaccine (MCV4). The Centers for Disease Control and Prevention recommends that a single dose of MCV4 be given to children ages 11 to 12 or to any children ages 11 to 18 who haven't yet been vaccinated. However, this vaccine can be given to younger children who are at high risk of bacterial meningitis or who have been exposed to someone with the disease. It's approved for use in children as young as 9 months old. It's also used to vaccinate healthy people who have been exposed in outbreaks but have not been previously vaccinated.