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We are now wrapping up our final blog of the Meningitis series by discussing the last four, rare types of meningitis - fungal, parasitic, amebic, and non-infectious. We have already discussed the two most common forms, one being the severe, and potentially fatal bacterial meningitis, and the other being the less severe, but still serious viral meningitis. Let's take a look at the rest of the types, beginning with:
Fungal Meningitis is rare and usually caused by fungus spreading through the blood to the spinal cord. Although anyone can develop fungal meningitis, people who have weak immune systems, such as those with an HIV infection or cancer, are at an increased risk. The most common cause of fungal meningitis for people with weak immune systems is Cryptococcus.
Fungal meningitis is not spread from person to person. The disease can develop after a fungus spreads through the bloodstream from elsewhere in the body, to the brain or spinal cord, or from an infection next to the brain or spinal cord. Someone may also develop fungal meningitis after taking certain medications that weaken the immune system, such as: prednisone, medications given after an organ transplant, anti-TNF medications, or medications given for treatment of rheumatoid arthritis, or other autoimmune conditions.
Different types of fungus are transmitted in several ways:
- Cryptococcus is thought to be acquired through inhaling soil contaminated with bird feces.
- Histoplasma is found in environments with heavy contamination of bird or bat feces, particularly in the Midwest.
- Blastomyces is thought to exist in soil that is rich in decaying organic matter in the Midwest, particularly, in the Northern Midwest.
- Coccidioides is found in the soil of endemic areas, particularly the Southwestern United States, and parts of Central and South America.
When these environments are disturbed, the fungal spores can be inhaled. Meningitis results from the fungal infection spreading from the lungs to the spinal cord. Unlike the fungi above, Candida, which also causes meningitis, is usually acquired in a hospital setting.
Certain diseases, medications, and surgical procedures may weaken the immune system and increase the risk of getting a fungal infection, thus leading to fungal meningitis. Premature babies with very low birth weights are also at an increased risk for getting Candida - the blood stream infection that may spread to the brain.
Living in certain areas of the United States may increase the risk for fungal lung infections, which can also cause meningitis. Living in the Midwestern or Southwestern United States is where the above fungi likely live.
In addition to those with weakened immune systems, pregnant women in their third trimester, African Americans, and Filipinos are also more likely to develop Coccidiodes infection, also called valley fever.
Signs, Symptoms, & Treatment
Signs and symptoms of fungal meningitis may include:
If meningitis is suspected, samples of blood or cerebrospinal fluid are collected and sent to a lab for testing. To confirm fungal meningitis, specific lab tests can be performed, depending on the type of fungus suspected.
Fungal meningitis is treated with long courses of high dose antifungal medications, usually administered through an IV in the hospital. The length of treatment depends on how strong the immune system is and the type of fungus that caused the infection. For those with weak immune systems, or other diseases, treatment is often longer.
No specific activities are known to cause fungal meningitis. Avoiding soil and other environments that are likely to contain fungus is the best preventative. People with weak immune systems should try to avoid digging and dusty activities, as well.
Various parasites can cause meningitis or can affect the brain or nervous system in other ways. Overall, parasitic meningitis is much less common than viral and bacterial meningitis.
Some parasites can cause a rare form of meningitis called eosinophilic meningitis, eosinophilic meningoencephalitis, or EM, with increased levels of eosinophils, which is a type of white blood cell, in the fluid around the brain and spinal cord. EM can also be caused by other types of infections, and can have non-infectious causes, such as medications.
There are 3 main parasites that cause EM in some infected people, and they are:
- Angiostrongylus cantonensis (neurologic angiostrongyliasis)
- Baylisascaris procyonis (baylisascariasis; neural larva migrans)
- Gnathostoma spinigerum (neurognathostomiasis)
How Do These Parasites Spread?
These parasites normally infect animals, not people, and they are not spread from one person to another. People get infected by ingesting something that has the infectious form or stage of the parasite.
For example: People can get infected with A. Cantonesis by ingesting raw or undercooked snails or slugs, or by eating contaminated produce. People get infected with B. Procyonis by accidentally ingesting infectious parasite eggs in raccoon feces or in something contaminated with raccoon feces. Lastly, people can get infected with G. Spinigerum in various ways, such as eating raw or undercooked freshwater fish, eels, frogs, poultry, or snakes.
As for risks, some people may have increased risk for infection because of where they live or travel.
People in many parts of the world have gotten infected with A. Cantonensis - especially, but not only, in parts of Asia and the Pacific Islands, including Hawaii. B. Procyonis is found in raccoons in parts of the United States, especially in the mid-Atlantic, Northeastern, and Midwestern regions, as well as parts of California. People in these areas, especially young children, who put dirt or animal waste in their mouth, or who spend time around raccoons are at an increased risk for Baylisacaris infection. The neurologic form of G. Spinigerum infection is most common in Southeast Asia, especially in Thailand.
Symptoms & Treatment
As with meningitis caused by other infections, people who develop symptomatic EM from these parasites can have a headache, stiff neck, nausea, vomiting, sensitivity to light, and confusion. Other symptoms - depending on the type of parasite, can include tingling or painful feelings in their skin and low grade fevers.
All 3 of these parasites sometimes infect the eye(s), and can cause severe illness, such as: loss of coordination and muscle control, weakness or paralysis, coma, permanent disability, or death. If you think you or your child might have meningitis, see a healthcare professional right away for the appropriate testing and clinical management.
If meningitis is suspected, samples of blood and CSF (cerebrospinal fluid) are collected and sent for laboratory testing to look for evidence of infection with these parasites and to rule out other causes. It often is hard to find these parasites in the CSF or in other parts of the body, but the person’s travel/exposure history may provide helpful clues, along with the findings of clinical examinations, laboratory testing, and scans.
The most common types of treatment for EM caused by these parasites are for the symptoms, such as: pain medication for headaches or medications to reduce the body's reaction to the parasite - rather than for the infection itself.
Primary amebic meningoencephalitis (PAM) is a very rare form of parasitic meningitis that causes a brain infection that is usually fatal. PAM is caused by the microscopic ameba, Naegleria fowleri when water containing the ameba enters the body through the nose.
Naegleria fowleri is found around the world. In the United States, the majority of infections have been linked to swimming in warm freshwater located in southern-tier states, like Florida and Texas. The ameba can be found in:
- Bodies of warm freshwater, such as lakes and rivers
- Naturally hot water, such as hot springs
- Warm water discharge from industrial plants
- Untreated geothermal drinking water sources
- Swimming pools that are poorly maintained, minimally chlorinated, or un-chlorinated
- Water heaters. This ameba grows best at higher temperatures up to 115 degrees Fahrenheit (46 degrees Celsius), and can survive for short periods at higher temperatures.
Naegleria fowleri is not found in salt water, such as the ocean.
How it Spreads
Naegleria fowleri infects people by entering the body through the nose. This typically occurs when people go swimming or diving in warm freshwater places, like lakes and rivers. The Naegleria fowleri ameba travels up the nose to the brain where it destroys the brain tissue.
You cannot be infected with Naegleria fowleri by drinking contaminated water. In very rare instances, Naegleria infections may also occur when contaminated water enters the nose. PAM cannot be spread from one person to another.
In its early stages, symptoms of PAM are similar to symptoms of bacterial meningitis. Initial symptoms of PAM start 1 to 7 days after infection. The initial symptoms include headache, fever, nausea, vomiting, and stiff neck. Later symptoms include confusion, lack of attention to people and surroundings, loss of balance, seizures, and hallucinations. After the start of symptoms, the disease progresses rapidly and usually causes death within about 5 days.
PAM is rare, with no more than 8 cases reported each year in the United States. The early symptoms of PAM are more likely to be caused by other more common illnesses, such as bacterial or viral meningitis. People should seek medical care immediately whenever they develop symptoms as those listed above.
Naegleria fowleri infects people when water containing the ameba enters the body through the nose. Infection is rare and typically occurs when people go swimming or diving in warm freshwater places, like lakes and rivers. Very rarely, infections have been reported when people submerge their heads, cleanse their noses or irrigate their sinuses using contaminated tap or faucet water. Naegleria fowleri can grow in pipes, hot water heaters, and water systems, including treated public drinking water systems. Personal actions to reduce the risk of Naegleria fowleri infection should focus on limiting the amount of water going up the nose and lowering the chances that Naegleria fowleri may be in the water.
Non-infectious meningitis causes include:
- Certain drugs
- Head Injury
- Brain Surgery
This type is not spread from person to person, and mimics all of the same symptoms as bacterial or viral meningitis.