Meningitis

The human is subjected to a wide variety of Pathological conditions that can be explained through proper and thorough testing. Meningitis is another disease which was poorly understood in the past but now in the 21st century we understand it in a more proper way.

What is Meningitis?

Meningitis is a form of an inflammation on the layers covering and enclosing our brain. There are 3 of these layers, known as meninges, around our brain. "Meninges" comes from the Greek word for “membrane” and which refered to the three membranes which wrap the brain and spinal cord.

The membrane layers from the outside towards the inside are the: 

1.    dura mater
2.    Arachnoid mater
3.    Pia mater

What are the causes for Meningitis?

Most commonly, meningitis is contracted through either Viral or Bacterial pathogens. Other causes also include:
•    Cancer (genetic or acquired due to exposure to carcinogens)
•    Chemical irritation through inadequate exposure
•    Fungi or spores of fungi
•    Drug allergies and/or drug interaction rendering the immune system susceptible to disease

Bacterial Meningitis:

Bacterial meningitis is the most common type of meningitis. The types of bacteria that cause bacterial meningitis vary according to the infected individual's age group. It can lead to death or permanent disability. It is a medical emergency and must be treated promptly and aptly. It is deadly if left poorly treated. Between 5 to 40 percent of children and 20 to 50 percent of adults with this condition die. This figure is applicable even when proper treatment is provided. 

The following are the types of causative agents of Bacterial meningitis:

1.    Streptococcus pneumoniae causing pneumococcal meningitis
2.    Neisseria meningitidis causing meningococcal meningitis
3.    Staphylococcus aureus causing staphylococcal meningitis

Viral Meningitis:

The most common cause of aseptic meningitis (aseptic meningitis means the meningitis that is caused by anything other than the bacteria that usually causes meningitis) is viral meningitis. This type of meningitis can include meningitis caused by the following:

1.    Drugs
2.    Disorders that are not infections
3.    Other organisms.

Viruses which are susceptible at causing this are listed below:
1.    Enteroviruses, 
2.    Herpes simplex virus (generally type 2)
3.    Varicella zoster virus 
4.    Arboviruses (acquired from a mosquito or other insect)
5.    Influenza virus. 

Herpes Simplex Virus Type-2 (HSV-2), which causes genital herpes, is a major cause in causing meningitis. HSV-2 can also cause symptoms of typical meningitis. HSV-2 meningitis usually occurs when the virus first infects the body. Genital symptoms and meningitis symptoms may and will manifest at the same time. Symptoms of meningitis may appear before or after the genital symptoms, and some people can have meningitis symptoms but not have any genital symptoms. After symptoms disappear, HSV-2 remains in the body in a dormant state. However, it can become reactivate again periodically and manifest symptoms. Thus, meningitis due to HSV-2 as a causative agent can manifest itself again and recur.

The varicella-zoster virus causes chickenpox and meningitis. The varicella-zoster virus remains in the body in an inactive form. The virus may never cause symptoms again, or it may reactivate many years later. When it reactivates, it causes herpes zoster known as shingles and may lead to meningitis. 

Symptoms of Meningitis:

The first symptoms include:

• Fever
• Vomiting
• Headache
• Feeling unwell
• Limb pain
• Pale skin
• Cold hands and feet
• Rash
• Neck stiffness
• Photophobia
• Confusion

Septicemia may occur with or without meningitis. Not everyone manifests all of the symptoms and they can show up in any idiosyncratic sequence.
In adults, the most early symptoms of meningitis is a severe headache which occurs in more than approximate to almost 90% of cases of bacterial meningitis, followed by stiffness of the neck basically known as the inability to flex the neck forward passively due to increased neck muscle tone and tautness. The classic trio of signs consists of stiffness of the neck, rapid onset of high grade fever, and changed mental perception; however, all three features are present in only 40–45% of bacterial meningitis cases .If none of the three signs are present, acute meningitis is highly unlikely. Other signs linked with meningitis include photophobia meaning intolerance to bright light and strobing light and phonophobia meaning intolerance to loud noises and sharp noises. Small children often do not exhibit these symptoms as one cannot accurately note these symptoms in a child and may only be irritable and look unwell. The fontanelle known as the soft spot on the top of a baby's head may bulge and rise up in infants aged up to 6 months. Other features that distinguish meningitis from less severe illnesses in young children are pain in legs, cold legs and feet, and an abnormal skin tone and/or rash.

Transmission of Meningitis

Transmission of meningitis can be done in several ways, depending on the virus. It can spread through the bloodstream from an infection in another part of the body which is the most common way. You may come in contact with contaminated stool, which occurs most commonly when infected people do not wash their hands after a bowel movement or when they swim in a public swimming pools. It can also transmit during sexual intercourse or other genital contact with an infected person. Insect bites such as a mosquito or spread through the air by inhaling the virus. It may also result due to contact with dust or food contaminated by the urine or stool of infected mice, pet hamsters or any sort of rodents. 

Diagnosis of meningitis

The physician or pediatrician can diagnose meningitis by checking your medical history, a physical exam and certain confirmatory diagnostic tests. During the exam, the doctor may look for signs of infection around the head, ears, throat and skin along the spine.

Your doctor may also order some lab tests such as:

Blood cultures - A blood sample is placed in a culture supportive media in a dish to see if it grows microorganisms, particularly the relevant bacteria. A sample may also be examined via slide and stained, then verified under a microscope to note if bacteria are present.

Imaging/Computerized tomography (CT)/magnetic resonance imaging (MRI) scans of the head may confirm swelling and/or inflammation. X-rays or CT scans of the chest or sinuses also may show infection that may be linked with meningitis.

Spinal tap (lumbar puncture) is used for a definitive diagnosis of meningitis. We need a spinal tap to collect cerebrospinal fluid. People having meningitis, the CSF often shows a low glucose level along with an increased WBC count.