Meningitis is a dangerous inflammation of the meninges, the protective membranes that surround the central nervous system (brain and spinal cord).
Meningitis can produce numerous mild symptoms, including fever, nausea, headache, stiff neck, light sensitivity, and skin rash.
In more severe cases, it can cause confusion, seizures, stroke, brain damage, and death.
It's unknown exactly how many people suffer from meningitis each year.
However, in 2013 meningitis resulted in 303,500 deaths worldwide, according to a 2014 report in the medical journal The Lancet.
Meningitis isn't the same as encephalitis or myelitis, an inflammation of the brain or spinal cord, respectively (or encephalomyelitis, a simultaneous inflammation of the brain and spinal cord).
Most often, the meninges will become inflamed when the fluid surrounding the central nervous system is infected.
Viral meningitis is the most common form of the disease, according to the Centers for Disease Control and Prevention (CDC), and is most often caused by non-polio enteroviruses, such as echnoviruses and coxsackievirus A and B.
Numerous other viruses may cause it as well, however, including the mumps, measles, HIV, West Nile, and herpes viruses.
Bacterial meningitis is rare, but often severe and life threatening.
In the United States, the leading causes of bacterial meningitis are Haemophilus influenzae type b, Streptococcus pneumoniae (called pneumococcus meningitis), group B Streptococcus, Listeria monocytogenes, and Neisseria meningitidis (meningococcal meningitis).
Unlike viral and bacterial meningitis, fungal meningitis generally caused by Cryptococcus, Histoplasma, Blastomyces, Coccidioides, or Candida fungi isn't contagious.
It usually occurs when fungi travel through the blood to the spinal cord.
The microscopic ameba (a single-celled organism) Naegleria fowleri can cause a rare form of parasitic meningitis called primary amebic meningoencephalitis, in which the brain is also inflamed.
Other parasites, including Angiostrongylus cantonensis and Gnathostoma spinigerum, can also cause meningitis, particularly a form called eosinophilic meningitis, in which the cerebrospinal fluid contains a high amount of eosinophil white blood cells.
There are also numerous non-infectious causes of meningitis.
For instance, various health issues, particularly inflammatory or autoimmune conditions, can lead to meningitis. These conditions include:
A wide range of medications can also result in meningitis, such as:
Additionally, you can get meningitis after a head injury or brain surgery.
Vaccines are available to prevent you from getting certain bacterial and viral infections that can cause meningitis, including meningococcus, pneumococcus, mumps, and measles.
Skipping your vaccinations increases your chances of getting these types of meningitis.
Spending time or living in close quarters with other people, such as in dorm rooms, day care settings, or military barracks, can also increase your risk of catching bacterial and viral meningitis from other people.
If you have a weakened immune system, such as from medications, HIV/AIDS, diabetes, pregnancy (especially for listeria), alcoholism, spleen removal, or recent organ or bone marrow transplants, youre also at an increased risk for infectious meningitis.
Infants are at an increased risk for bacterial meningitis, and children under 5 years old have a higher chance of contracting viral meningitis.
Premature babies with very low birth weights may be more prone to fungal meningitis in particular, Candida blood stream infections that spread to the brain.
Exposure to the meningitis-causing parasite, Naegleria fowleri, which thrives in warm, freshwater locales such as hot springs, lakes, and poorly maintained swimming pools, can increase your chance of developing a very rare form of parasitic meningitis called primary amebic meningoencephalitis (PAM).
You can become infected with A. cantonensis and G. spinigerum parasites from eating certain raw or undercooked meat, such as snails, pigs, chickens, and freshwater fish, frogs, and shrimp, particularly while in Southeast Asian countries.
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There are numerous issues that can cause the meninges, or protective membranes around the brain and spinal cord, to become inflamed, a condition called meningitis.
Viral infections, particularly from non-polio enteroviruses, most commonly cause meningitis, according to the Centers for Disease Control and Prevention (CDC).
But other types of infections, including those from a wide variety of bacteria, fungi, and parasites, can also cause meningitis.
There are also many non-infectious causes of meningitis, including head injury, brain surgery, and certain cancers.
Despite the range of causes, however, the symptoms of meningitis are generally the same.
A sudden onset of fever, severe headache, and stiff neck is typically the initial sign of meningitis in children and adults.
Other common symptoms may follow, including:
Along with these common symptoms, people with viral meningitis may also experience lethargy (lack of energy), decreased appetite, and sleeping problems, such as sleepiness and difficulty fully rousing from sleep.
The symptoms of bacterial meningitis typically develop between three and seven days, and may appear quickly or over several days, according to the CDC.
In addition to the common symptoms listed above, meningococcal meningitis meningitis caused by the bacteria Neisseria meningitidis can cause certain types of rashes, including purpura (purple, bruise-like spots) and petechia (pinpoint red spots).
The later stages of bacterial meningitis can cause severe and life-threatening symptoms, including seizures, coma, and stroke; it can even result in death.
Survivors of severe bacterial meningitis (and sometimes viral meningitis) may suffer from a host of complications, including:
An infection from the microscopic ameba (a single-celled organism) Naegleria fowleri can cause a very rare form of parasitic meningitis called primary amebic meningoencephalitis, or PAM, in which the brain is also inflamed.
The initial symptoms of PAM headache, fever, stiff neck, nausea, and vomiting begin within the first seven days of becoming infected with the parasite. As the infection progresses, it can cause:
Without treatment, PAM usually results in death about five days after symptoms start, according to the CDC.
Signs and symptoms of meningitis in newborns include:
Blood tests, imaging tests, and lumbar punctures are all used to diagnose meningitis.
Standard blood tests can reveal if you have antibodies or foreign proteins that are indicative of an infection.
X-ray images and computed tomography (CT) scans can reveal if you have inflammation, particularly of your meninges.
These tests can also show if you have other health problems, such as brain damage and internal bleeding, and if you have any issues that may make a lumbar puncture unsafe to perform, including abscesses and brain inflammation.
The meninges will become inflamed if there's an infection of the cerebral spinal fluid.
Lumbar punctures, also called spinal taps, allow doctors to collect a sample of the fluid that bathes the brain and spinal cord to test for infection, by looking at the ratios of white blood cells, blood, protein, and glucose.
The spinal fluid can also be examined to identify infectious organisms, and to see what type of medication would be most effective against that organism.
Lumbar punctures and subsequent tests can also determine what kind of infection bacterial, viral, fungal is present.
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In its early stages, meningitis typically causes a sudden onset of fever, severe headache, and stiff neck.
Though the most common type of meningitis, viral meningitis, is generally mild and resolves on its own, it's important to see a doctor if you're experiencing these symptoms.
This is because other types of meningitis particularly bacterial meningitis and some forms of parasitic meningitis can be severe, rapidly progressing, and even life threatening.
If your doctor suspects you have meningitis, he or she will likely put you on a round of broad-spectrum antibiotics to fight potential non-viral types of infectious meningitis.
A lumbar puncture, or spinal tap, is the primary diagnostic tool for meningitis, and it involves collecting and analyzing cerebral spinal fluid.
Once a diagnosis is made, your doctor will provide a more specific treatment.
Antibiotics cannot kill viruses. If you have viral meningitis, you will be taken off whatever antibiotic therapy you may have been using.
There is no specific treatment for viral meningitis, which is often mild.
Most of the time, people recover from their viral meningitis in seven to 10 days, with little more than rest, over-the-counter fever reducers/pain medications, and proper fluid intake.
However, if you have meningitis caused by a herpes virus or influenza, your doctor may prescribe an antiviral medication.
For instance, the antiviral drugs ganciclovir (Cytovene) and foscarnet (Foscavir) are sometimes used to treat Cytomegalovirus meningitis in people with weakened immune systems (from HIV/AIDS or other issues), infants born with infection, or severely ill individuals.
In some cases, acyclovir (Zovirax) may be used to treat meningitis from the herpes simplex virus, although it appears to have a positive effect only when given very early in the illness.
Influenza may be treated with one of several different licensed antiviral agents, including peramivir (Rapivab) and oseltamivir (Tamiflu).
If you have bacterial meningitis, you will be treated with one or more antibiotics that target the bacteria causing your infection.
These antibiotics commonly include:
A number of other antibiotics may also be used, such as meropenem and the aminoglycoside antibiotics tobramycin (Tobi, Tobrex) and gentamicin (Garamycin, Gentak).
Ciprofloxacin (Cipro) and rifampin (Rifadin) are sometimes given to family members of people with bacterial meningitis to help protect them from catching the infections.
Fungal meningitis is treated with long courses of high-dose IV antifungal medications.
These medications are often part of the azole class of antifungal drugs, such as fluconazole (Diflucan), which is used to treat infections from Candida albicans, the fungus behind yeast infections.
Depending on the type of infection, other antifungals may also be used.
For example, amphotericin B (Ambisome, Amphotec) is the most common treatment for cryptococcal meningitis, caused by the fungus Cryptococcus neoformans.
Amphotericin B may also be used to treat a rare type of parasitic meningitis caused by Naegleria fowleri.
Alternatively, the antifungal agent miconazole and the antibiotic rifampin may be used.
However, infections from this single-celled ameba are often fatal, even when treatment is administered.
In addition to the above medications, corticosteroids may be used to reduce meningitis inflammation.
Diazepam (Valium) or phenytoin (Dilantin) can help treat seizures, which may occur with bacterial and N. fowleri infections.
There are a number of noninfectious causes of meningitis, including cancers, autoimmune disorder, and medications.
Doctors typically treat these forms of meningitis by tackling the underlying cause.
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The causes of meningitis fall into two broad categories: infectious (from viruses and microbes) and non-infectious.
Vaccines cannot protect you from the non-infectious causes of meningitis, which include cancer, autoimmune disorders, and certain medications.
However, vaccines can protect you from the three most common bacteria that cause meningitis in children and adult Neisseria meningitidis, Haemophilus influenzae type b (Hib), and Streptococcus pneumoniae and certain meningitis-causing viruses.
Meningococcal disease is any illness caused by N. meningitidis.
At least 13 different serogroups, or strains, of N. meningitidis have been identified so far, with five of them (A, B, C, Y, and W-135) causing the vast majority of meningococcal disease cases in the world, according to the Immunization Action Coalition.
In the United States, the meningococcal polysaccharide vaccine (Menomune), which has been available since the 1970s, protects against groups A, C, Y, and W-135.
It's the only meningococcal vaccine licensed for people older than 55, though it can be used for anyone age 2 or older, according to the Centers for Disease Control and Prevention (CDC).
The meningococcal conjugate vaccine (Mentactra, Menveo) also protects against these four strains.
Its recommended for everyone between 9 months and 55 years old (Menveo can be given to children as young as 2 months old).
An initial dose should be given between the ages of 11 and 12, with a booster shot at age 16; no booster shot is needed if the first dose is given after age 16.
These vaccines contain the bacteria's outer polysaccharide capsule, or sugar coat. This polysaccharide is an antigen, or a substance that causes the immune system to make protective antibodies.
Mentactra and Menveo are "conjugate" vaccines because they're made by chemically binding the polysaccharide to a carrier protein, increasing the vaccine's effectiveness.
The Food and Drug Administration (FDA) recently approved the first two vaccines for N. meningitidis group B Trumenba and Bexsero for people between 10 and 25 years old.
The first Hib conjugate vaccine became available in 1987.
Today, six Hib vaccines are available, some of which are combined with other vaccines. MenHibrix, for example, protects against Hib and meningococcal groups C and Y.
The vaccines are given in three or four doses, depending on the brand. They're recommended for all U.S. children under age 5, and the first dose is usually given at 2 months of age.
Pneumococcal disease is an illness caused by S. pneumoniae.
Approved in 2010, the pneumococcal conjugate vaccine (Prevnar 13) protects against 13 types of pneumococcal bacteria.
It's recommended for all children younger than 5 years of age, adults older than 65 years of age, and people older than 6 years old who have certain risk factors.
The pneumococcal polysaccharide vaccine (Pneumovax), approved in 1983, protects against 23 types of pneumococcal bacteria.
It's recommended for all adults who are at least 65 years old, and everyone older than age 2 with a high risk of pneumococcal disease due to health issues and medications.
No vaccines are available to protect against non-polio enteroviruses, by far the most common cause of viral meningitis.
However, vaccines can prevent other meningitis-causing viruses, including mumps, measles, influenza, and chickenpox (varicella).
The measles-mumps-rubella-varicella (MMRV) vaccine, approved in 2005, protects against three meningitis-causing viruses. Separate MMR and varicella vaccines are also available.
The vaccines are recommended for all children, with the first of two doses given between 12 and 15 months of age.
The CDC recommends that everyone over 6 months old get a flu vaccine every season.
Routine shots of the vaccine are necessary because the formulation of the vaccine is updated yearly to account for the ever-evolving flu viruses.
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Meningitis is an inflammation of the membranes surrounding the brain and spinal cord.
Bacterial meningitis, a form of meningitis that stems from a bacterial infection, is relatively rare.
It affects roughly 4,100 people (and kills about 500) each year in the United States, according to a 2011 report in the New England Journal of Medicine.
Bacterial meningitis is usually severe, according to the Centers for Disease Control and Prevention (CDC).
The disease can cause symptoms such as seizures and coma as well as various complications, including brain damage, hearing loss, and learning disabilities.
Pneumococcal meningitis, caused by Streptococcus pneumoniae, is the most common type of bacterial meningitis in children and adults in the United States, accounting for 61 percent of all cases, according to a report in the journal Clinical Microbiology Reviews, followed by meningococcal meningitis, caused by Neisseria meningitidis.
Listeria monocytogenes meningitis tends to affect older adults, as do pneumococcal and meningococcal meningitis.
Pregnant women, infants, and people with weak immune systems are also at higher risk of developing meningitis from Listeria monocytogenes.
Both pneumococcal and meningococcal meningitis are unusual in infants, who are more likely to develop meningitis from Streptococcus agalactiae (also called group B Strep), Escherichia coli, and Listeria monocytogenes infections.
Haemophilus influenzae type b, (also called Hib), was once a common cause of meningitis in the United States, particularly among infants and children.
This agent used to be responsible for up to 48 percent of all bacterial meningitis cases, according to the Clinical Microbiology Reviews study.
The Hib vaccine has virtually eliminated Hib meningitis in infants and children in the United States though Hib is still a major cause of pediatric meningitis around the world.
Other bacteria including Salmonella, Staphylococcus aureus, and Pseudomonas aeruginosa can also cause meningitis, particularly in people with weakened immune systems or those who have had head trauma or brain surgery.
Bacterial meningitis is passed to other people through the exchange of saliva or mucus, such as through kissing, coughing, or sneezing.
Risk factors for bacterial meningitis include:
Additionally, pregnant women are at an increased risk for Listeria monocytogenes infections which comes from eating foods (soft cheeses, hot dogs, lunch meats) contaminated with the bacteria and can pass the bacteria to their newborns, potentially resulting in neonatal meningitis.
Similarly, newborns can get a group B Strep infection, and subsequently meningitis, from their mothers during birth.
Vaccines can protect you from certain pneumococcal, meningococcal, and Hib infections.
Additionally, preventative antibiotics can help protect you from becoming infected with N. meningitidis or Hib if you have close contacts with someone with those forms of meningitis.
The CDC also recommends maintaining healthy habits (i.e., quit smoking and avoid cigarette smoke), getting an adequate amount of sleep, and keeping your distance from people who are sick.
There are a number of ways for pregnant women to reduce their risk of getting a Listeria infection and passing it on to their newborns, including:
Bacterial meningitis is effectively treated with appropriate antibiotics, which can reduce the death risk to below 15 percent (the risk is higher for young infants and the elderly), according to the CDC.
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Though bacteria and viruses are often thought of as being behind common infections and illnesses, other microbes, such as fungi, can also cause disease.
The fungus Candida albicans, for example, frequently causes yeast infections.
If a fungal infection spreads to the central nervous system (CNS, made up of the spinal cord and brain) through the blood, it can cause fungal meningitis, an inflammation of the protective membrane surrounding the CNS.
Fungal meningitis is not contagious it cannot be directly passed from one person to another and is very rare among people with healthy immune systems, according to the Centers for Disease Control and Prevention (CDC).
Most often, it affects people with weakened immune systems from:
The overall prevalence of fungal meningitis is unclear, but certain forms of the disease are somewhat common among high-risk populations.
For instance, Cryptococcus neoformans is the most common cause of fungal meningitis, according to the Meningitis Research Foundation.
Worldwide, the fungus causes nearly 1 million cases of cryptococcal meningitis in people living with HIV/AIDS each year, according to a 2009 report in the journal AIDS.
Cryptococcus neoformans is found in the droppings of wild birds.
You can become infected with the fungus if you inhale soil particles contaminated with the droppings.
However, only in very rare cases will someone with a healthy immune system develop cryptococcal meningitis, the CDC notes.
The aforementioned C. albicans can cause meningitis, generally in premature babies with very low birth weights. The fungus is usually acquired in hospital settings.
Histoplasma is a meningitis-causing fungus that lives in the environment, usually in soil that has high concentrations of bird or bat droppings.
It's harmless in people with normal immune systems, according to the Meningitis Research Foundation.
In the United States, Histoplasma is predominately found in central and eastern regions, such as the Ohio and Mississippi River valleys.
It's also found in certain areas of Central and South America, Africa, Asia, and Australia.
Blastomyces and Coccidiodes are soil-living fungi that can get into the body and cause meningitis (in rare cases) when their spores are inhaled after their environment is disturbed.
Blastomyces are found in soil full of decaying organic matter in Midwestern states, while Coccidiodes are found in soil of endemic areas, which includes the Southwestern United States and parts of Central and South America.
Certain people have a higher risk of getting a Coccidiodes infection (also called valley fever), including:
Other fungi can also cause meningitis: In 2012, there was a multistate fungal meningitis outbreak, mostly caused by steroid injections contaminated with the fungus Exserohilum rostratum, according to the CDC.
People with fungal meningitis often experience similar symptoms to other forms of meningitis, including:
Treating fungal meningitis involves killing the underlying infection that is, a long course of antifungal medications (specific to the fungus) that is usually given intravenously in the hospital.
There are no vaccines to prevent against the meningitis-causing fungi.
Preventing fungal meningitis generally involves avoiding the various soils in which the fungi live this is especially important for people who have weakened immune systems.
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Viral meningitis is a virus-borne inflammation of the protective membranes surrounding the brain and spinal cord (the meninges).
It's far less severe than bacterial meningitis, and generally only produces mild symptoms such as headache, nausea, bright-light sensitivity, and lethargy.
Viral meningitis is the most common type of meningitis, and the majority of cases are due to non-polio enteroviruses, notes the Centers for Disease Control and Prevention (CDC).
In fact, according to a 2006 report in the journal Antimicrobial Agents and Chemotherapy, enteroviruses alone cause an estimated 75,000 cases of meningitis in the United States each year.
There are a number of viruses that can cause meningitis.
Enteroviruses, which include the Coxsackie and Echovirus groups of viruses, may account for up to 80 percent of viral meningitis cases in adults, according to a 2008 article in the British Medical Journal (BMJ).
The general population may also get meningitis from HIV and various herpes viruses, including:
People who aren't up to date on their vaccinations may get meningitis from the influenza, mumps, and measles viruses.
People who have a weakened immune system may get meningitis from cytomegalovirus, and those who have contact with rodent feces or urine may get it from lymphocytic choriomeningitis virus.
In addition to rodents, certain insects can also transmit viruses that cause meningitis, such as:
Viral meningitis is contagious, because the viruses that cause the disease are generally easily passed between people.
Enteroviruses are present in the feces, mucus, and saliva of infected people, and are transmitted through direct contact with an infected person or surface.
In temperate climates, the viruses spread most during summer and autumn, and infection rates are high all year long in tropical and subtropical climates, according to the BMJ report.
Only a small number of people infected with enteroviruses will get meningitis, according to the CDC.
Children under age 5 and people with weakened immune systems from diseases, medications, and/or recent surgeries and transplants are most likely to get meningitis from enteroviruses.
The herpes simplex virus is the second-most-common cause of viral meningitis in adolescents and adults in developed countries, according to the BMJ report.
It can be passed to other people via contact with an infected area of skin during an outbreak (when the virus is active).
Other meningitis-causing viruses are spread in different ways.
For instance, mumps, measles, and influenza are easily spread between the unvaccinated through coughing and sneezing, while HIV is spread through sex and sharing drug needles (the virus is present in blood, breast milk, and seminal, vaginal, and rectal fluids).
No specific treatment exists for viral meningitis, and most cases clear up within seven to 10 days.
However, antiviral medications may help people with meningitis from herpes viruses and influenza (antibiotics, on the other hand, aren't effective against viruses).
Infants under 1 month and people with weakened immune systems are most likely to suffer severe symptoms, according to the CDC, and may need comfort care to control symptoms.
Vaccines can prevent some types of viral meningitis, though this doesn't include enterovirus meningitis.
In this case, avoiding close contact with those with enteroviruses and touching your face with unwashed hands can help minimize your chances.
If you're already infected, you can prevent the spread of the virus by frequently washing your hands, disinfecting surfaces, staying away from people, and coughing and sneezing into a cloth or tissue (not your hands).
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