What is Meningitis?
Inflammation of brain and spinal cord membranes, typically caused by an infection.
Meningitis is usually caused by a viral infection but can also be bacterial or fungal. Vaccines can prevent some forms of meningitis.
Types of Meningitis
- Viral meningitis. Viral meningitis is the most common type of meningitis
- Bacterial meningitis. Bacterial meningitis is contagious and caused by infection from certain bacteria
- Fungal meningitis. Fungal meningitis is a rare type of meningitis
- Parasitic meningitis
- Non-infectious meningitis
What is viral meningitis?
Viral meningitis (when meningitis is caused by a virus) is the most common type of meningitis. Most people get better on their own without treatment. However, anyone with symptoms of meningitis should see a doctor right away because any type of meningitis can be serious. Babies younger than 1 month old and people with weakened immune systems are more likely to have severe illness from viral meningitis.
Causes
Non-polio enteroviruses are the most common cause of viral meningitis.
Other causes
- Mumps virus
- Herpesviruses, including Epstein-Barr virus, herpes simplex viruses, and varicella-zoster virus (which causes chickenpox and shingles)
- Measles virus
- Influenza virus
- Arboviruses, such as West Nile virus
- Lymphocytic choriomeningitis virus
Who is at risk?
- Children younger than 5 years old
- People with weakened immune systems caused by diseases, medications (such as chemotherapy), and recent organ or bone marrow transplantations
Most people with mild viral meningitis usually get better on their own within 7 to 10 days.
Initial symptoms of viral meningitis are similar to those for bacterial meningitis. However, bacterial meningitis is usually severe and can cause serious complications, such as brain damage, hearing loss, or learning disabilities. The pathogens (germs) that cause bacterial meningitis can also be associated with another serious illness, sepsis. Sepsis is the body’s extreme response to infection. Without timely treatment, sepsis can quickly lead to tissue damage, organ failure, and death.
Common symptoms in babies
- Fever
- Irritability
- Poor eating
- Sleepiness or trouble waking up from sleep
- Lethargy (a lack of energy)
Common symptoms in children and adults
- Fever
- Headache
- Stiff neck
- Photophobia (eyes being more sensitive to light)
- Sleepiness or trouble waking up from sleep
- Nausea
- Irritability
- Vomiting
- Lack of appetite
- Lethargy (a lack of energy)
Treatment
In most cases, there is no specific treatment for viral meningitis. Most people who get mild viral meningitis usually recover completely in 7 to 10 days without treatment. Antiviral medicine may help people with meningitis caused by viruses such as herpesvirus and influenza.
Antibiotics do not help viral infections, so they are not useful in the treatment of viral meningitis. However, antibiotics do fight bacteria, so they are very important when treating bacterial meningitis.
People who develop severe illness, or are at risk for developing severe illness, may need care in a hospital.
What is bacterial meningitis?
Bacterial meningitis is serious. Some people with the infection die and death can occur in as little as a few hours. However, most people recover from bacterial meningitis. Those who do recover can have permanent disabilities, such as brain damage, hearing loss, and learning disabilities.
Causes
Mainly the causes of meningitis are:
- Streptococcus pneumoniae
- Group B Streptococcus
- Neisseria meningitidis
- Haemophilus influenzae
- Listeria monocytogenes
- Escherichia coli
Some causes of bacterial meningitis are more likely to affect certain age groups:
- Newborns: Group B Streptococcus, S. pneumoniae, L. monocytogenes, E. coli
- Babies and young children: S. pneumoniae, N. meningitidis, H. influenzae, group B Streptococcus, M. tuberculosis
- Teens and young adults: N. meningitidis, S. pneumoniae
- Older adults: S. pneumoniae, N. meningitidis, H. influenzae, group B Streptococcus, L. monocytogenes
Meningitis symptoms include sudden onset of
- Fever
- Headache
- Stiff neck
There are often other symptoms, such as
- Nausea
- Vomiting
- Photophobia (eyes being more sensitive to light)
- Altered mental status (confusion)
Newborns and babies may not have, or it may be difficult to notice the classic symptoms listed above. Instead, babies may
- Be slow or inactive
- Be irritable
- Vomit
- Feed poorly
- Have a bulging fontanelle (the “soft spot” on a baby’s head)
- Have abnormal reflexes
What is Cryptococcus meningitis?
Cryptococcal meningitis is a type of meningitis caused by a fungus called Cryptococcus. This type of meningitis mainly affects people with weakened immune systems due to another illness. If not treated, cryptococcal meningitis can have lasting consequences and can even be fatal.
In most cases, cryptococcal meningitis is caused by the fungus Cryptococcus neoformans. This fungus is found in soil around the world. Cryptococcus gattii can also cause meningitis, but this form can cause disease in patients with a normal immune system as well.
Is Cryptococcus meniningitis contagious?
Cryptococcosis is not contagious, meaning it cannot spread from person-to-person. Cryptococcal meningitis specifically occurs after Cryptococcus has spread from the lungs to the brain. Meningitis can also be caused by a variety of other organisms, including bacteria, viruses, and other fungi.
Symptoms
Symptoms of cryptococcal meningitis often develop gradually, within a few days to weeks of exposure to the fungus.
A person with cryptococcal meningitis may develop the following symptoms:
- headache
- nausea and vomiting
- fatigue
- confusion or hallucinations
- personality changes
- sensitivity to light
- fever
- stiff neck
- blurred vision
It may be difficult for someone to tell if they have symptoms of cryptococcal meningitis. Many of the symptoms may be similar to the side effects of a medication they may be taking to treat an underlying condition.
If left untreated, cryptococcal meningitis can lead to more serious symptoms, including:
- fluid on the brain
- coma
- hearing loss
Cryptococcal meningitis can be fatal if not treated quickly, especially in people with HIV or AIDS.
Diagnosis
The definitive diagnosis of cryptococcal meningitis is made by culture from the CSF. The opening pressure should be measured along with India ink evaluation, cryptococcal antigen testing, fungal culture, and routine spinal fluid studie.
Management of Cryptococcus meningitis.
Cryptococcal meningitis is treated with antifungal drugs such as amphotericin, fluconazole, and flucytosine (induction therapy); recurrence of the infection is prevented by taking fluconazole daily for life or until the immune system recovers.
Current guidelines recommend 2 weeks of amphotericin B (0.7–1.0 mg/kg per day) intravenously in combination with flucytosine 100mg/kg/day as first line therapy for treatment of cryptococcal meningitis.
Oral fluconazole, 200 mg/d, is the most effective maintenance therapy for AIDS-associated cryptococcal meningitis [17, 24] (AI). A randomized comparative trial demonstrated the superiority of fluconazole (200 mg/d) over amphotericin B (1 mg/kg/w) as maintenance therapy.
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Food for thoughts.
Amphotericin B is toxic, because mammalian and fungal membranes are similar in structure and composition, this is one mechanism by which amphotericin B causes cellular toxicity. Amphotericin B molecules can form pores in the host membrane as well as the fungal membrane. This impairment in membrane barrier function can have lethal effects.
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