Meningitis

Types of Meningitis

1. Viral Meningitis (Aseptic Meningitis):

   • Cause: Most commonly caused by viruses, including enteroviruses (like coxsackievirus and echovirus), mumps virus, herpes simplex virus (HSV), varicella-zoster virus (VZV), and human immunodeficiency virus (HIV).
   • Course: Viral meningitis is typically less severe than bacterial meningitis. It often resolves on its own, though symptoms can last for several weeks. It may still cause significant discomfort but generally does not lead to long-term complications.
   • Transmission: Often spread through direct contact with respiratory droplets, fecal matter, or bodily fluids of an infected person.

2. Bacterial Meningitis:

   • Cause: Bacterial infections are the most severe form of meningitis and require urgent medical treatment. The most common bacteria responsible for bacterial meningitis include:
     • Streptococcus pneumoniae: The most common cause in adults and children over 2 years old.
     • Neisseria meningitidis (meningococcus): A leading cause of bacterial meningitis, especially in adolescents and young adults.
     • Haemophilus influenzae type b (Hib): Previously a leading cause of bacterial meningitis in children, now much less common due to widespread vaccination.
     • Listeria monocytogenes: A cause of meningitis in newborns, the elderly, and immunocompromised individuals.
     • Group B Streptococcus: A common cause of neonatal meningitis.
   • Course: Bacterial meningitis is a medical emergency. It can progress rapidly and can be fatal if not treated promptly with antibiotics. Even with treatment, bacterial meningitis can cause severe complications like brain damage, hearing loss, and seizures.
   • Transmission: Typically transmitted through respiratory droplets from coughing, sneezing, or kissing, and sometimes through contact with contaminated surfaces or bodily fluids.

3. Fungal Meningitis:

   • Cause: Fungal infections are rare but can cause meningitis, especially in immunocompromised individuals (e.g., people with HIV/AIDS or those on immunosuppressive medications). Common causes include Cryptococcus (particularly in HIV/AIDS patients), Histoplasma, and Coccidioides.
   • Course: Fungal meningitis usually develops slowly and can be treated with antifungal medications, but it can be difficult to treat, especially in immunocompromised patients.

4. Parasitic Meningitis:

   • Cause: Meningitis caused by parasites is rare but can occur. Naegleria fowleri is a brain-eating amoeba that can cause a severe, often fatal form of meningitis, typically through contaminated water entering the nose (e.g., swimming in warm freshwater lakes).
   • Course: Parasitic meningitis is typically severe and may not respond to standard treatments. Prompt diagnosis and treatment are crucial.

5. Non-Infectious Meningitis:

   • Cause: This type of meningitis can result from conditions other than infection, such as autoimmune diseases (e.g., lupus), certain cancers (e.g., leukemia), or a side effect of medications (e.g., certain antibiotics or immunosuppressive drugs).
   • Course: The treatment depends on the underlying cause and may include steroids, chemotherapy, or other targeted therapies.

Symptoms of Meningitis

Symptoms of meningitis can develop rapidly (over hours) or more slowly, depending on the cause (especially in viral vs. bacterial meningitis). Common symptoms include:

• Fever
• Headache (often severe)
• Neck stiffness (one of the hallmark symptoms)
• Nausea and vomiting
• Photophobia (sensitivity to light)
• Altered mental status (confusion, drowsiness, difficulty concentrating)
• Seizures
• Rash (more common in meningococcal meningitis)
• Cold hands and feet or a purple or red rash (in cases of meningococcemia, where bacteria spread in the bloodstream, often seen in Neisseria meningitidis infections)
• Sleepiness or trouble waking up
• Muscle aches or joint pain
• Rapid breathing

In infants and young children, additional symptoms can include:

• Poor feeding
• High-pitched crying
• Bulging fontanelle (the soft spot on a baby’s head)
• Lethargy or difficulty waking

Diagnosis of Meningitis

To diagnose meningitis, healthcare providers rely on several key tests:

1. Medical History and Physical Examination:

   • The doctor will look for typical signs and symptoms (e.g., fever, neck stiffness, altered mental status) and assess for risk factors like recent exposure to sick individuals, immunocompromised status, or vaccination history.

2. Lumbar Puncture (Spinal Tap):

   • This is the definitive test for meningitis. A needle is inserted into the lower back to collect cerebrospinal fluid (CSF) from around the spinal cord. The fluid is then analyzed for:
     • White blood cells (increased in infections)
     • Glucose levels (typically low in bacterial meningitis, normal or slightly low in viral meningitis)
     • Protein levels (increased in both bacterial and viral meningitis)
     • Culture and PCR testing to identify bacteria, viruses, or fungi in the CSF

3. Blood Cultures:

   • Blood samples may be taken to identify the infection and detect the presence of bacteria or fungi in the bloodstream.

4. Imaging:

   • In some cases, imaging (such as a CT or MRI scan) may be done to rule out other potential causes of symptoms, such as brain abscesses or tumors.

5. PCR Testing:

   • Polymerase chain reaction (PCR) can detect specific viral or bacterial DNA in the CSF, providing quick and accurate identification.

Treatment of Meningitis

The treatment approach depends on the cause of meningitis:

1. Bacterial Meningitis:

   • Antibiotics: Treatment must begin as soon as bacterial meningitis is suspected. The choice of antibiotics will depend on the type of bacteria. Common antibiotics include:
     • Ceftriaxone or Cefotaxime (broad-spectrum antibiotics)
     • Vancomycin (to cover resistant bacteria like Streptococcus pneumoniae or Staphylococcus aureus)
     • Penicillin or Ampicillin (for Listeria and Group B Streptococcus infections)
   • Corticosteroids: Dexamethasone is often given along with antibiotics to reduce inflammation and the risk of neurological complications, especially in cases caused by Streptococcus pneumoniae.
   • Supportive Care: Hospitalization for IV fluids, pain management, and monitoring for complications is essential.

2. Viral Meningitis:

   • No specific antiviral treatment exists for most viral causes, but supportive care is crucial, including hydration, pain relievers (acetaminophen or ibuprofen), and anti-nausea medications.
   • In cases caused by herpes simplex virus (HSV), acyclovir (an antiviral) may be given.

3. Fungal Meningitis:

   • Antifungal medications like amphotericin B and fluconazole are used to treat fungal infections.

4. Parasitic Meningitis:

   • Treatment depends on the specific parasite involved. Some parasitic infections are difficult to treat and may require a combination of antiparasitic medications or experimental therapies.

5. Non-Infectious Meningitis:

   • Treatment will depend on the underlying cause (e.g., autoimmune conditions may be treated with corticosteroids or immunosuppressive drugs).