Meningitis is the inflammation of the meninges – the protective membranes of the brain and spinal cord – which triggers symptoms such as headaches, fever, and a stiff neck.
The inflammation largely affects the arachnoid layer – the hollow middle layer of the brain that’s filled with cerebrospinal fluid (CSF) – when bacteria, viruses, fungi, or parasites invade it through blood vessels that are present throughout this layer.
Once these microbes reach the CSF they can then infect the inner layer pia, which secretes the CSF, as well as the outer dura layer.
However, these infectious organisms can also enter the brain externally due to any brain injury, skull fracture, lumbar puncture, or during brain surgery. Certain medications can also inflame all or any of the protective layers of the brain.
The prevalence of meningitis is higher in newborns, children, teenagers, and young adults, but can affect individuals of any age. Detecting the organism causing the meningitis at the earliest is most important as the severity of infection and treatment is dependent on this.
Meningitis can be a serious and life-threatening condition if not treated immediately and adequately, even if in some cases symptoms can improve without treatment in a few weeks.
The typical symptoms of meningitis may develop as early as two days to a week after the organism causing the condition infests you. According to WHO, the average gestation period is four days after which you start noticing symptoms such as headaches, followed by fever, neck rigidity, and inability to flex the neck forward. Other symptoms that can help identify meningitis are:
- Fever of different grades
- Cold hands and feet
- Vomiting and nausea
- Increased breathing rate
- Muscle or joint pain with stiffness
- Pale or blotchy skin
- Intolerance to bright lights
- Sleepiness or difficulty in waking up
UK’s National Health Service recommends getting immediate medical help if an individual develops any of these symptoms which can appear in any order. Moreover, newborns and children are at greater risk as they cannot always tell what is going wrong, but one can look for some specific identifiers such as:
- Refusing feeds
- Being irritable
- Having high pitched cry
- Become floppy or unresponsive suddenly
- Observing bulged soft spot on the top of the head
Causes and Types of Meningitis
Meningitis may be caused by several factors. Bacterial meningitis which accounts for relatively fewer cases, can cause more severe infections when compared to viral meningitis. The World Health Organization (WHO) reveals that even with early diagnosis and timely treatment, five to ten percent of individuals who contract meningitis die. Even among the survivors, around 10-20% of them develop lifelong complications like brain damage, hearing loss, and learning disabilities.
Bacterial meningitis is the leading cause of death by meningitis. The infection, if not treated, can often lead to death within just a few hours. Most individuals recover from this condition, but one in ten of them develop permanent brain damage, hearing loss and learning disabilities due to the infection.
Bacteria like Streptococcus pneumoniae, Streptococcus, Neisseria meningitidis, Haemophilus influenza type B (HiB), Listeria monocytogenes, Escherichia coli, and Mycobacterium tuberculosis cause majority of infections after entering the brain either by sepsis or due to bad hygiene.
When the bacteria enter the bloodstream and cause an infection that spreads to other parts of the body, it is referred to as septicemia which triggers sepsis which is the body’s reaction to the infection.
According to WHO, Neisseria meningitidis that causes meningococcal meningitis can potentially cause a large epidemic. Nearly five to ten percent of the population carries this bacterium in their throat at any given point in time.
Mycobacterium tuberculosis, which causes tuberculosis (TB), can stay dormant for years in the body and can affect the brain and spinal cord later in life. Being hard to treat after its onset, an early diagnosis is the only method to prevent meningitis caused by this bacterium.
Meningitis-causing bacteria can spread through:
- Mothers to babies during birth (Streptococcus, E.coli)
- Through close contact with a person who coughs or sneezes (HiB, M. Tuberculosis, S. Pneumonia)
- By coughing, kissing or living together with an infected person (N. Meningitidis)
- By food prepared by people who do not wash hands after using the toilet (E.coli)
- By eating contaminated food (E.coli, L. monocytogenes)
The US Center for Disease Control and Prevention (CDC) warns that pregnant women are at increased risk of getting Listeria infection due to L. Monocytogenes bacteria that may not or may show flu-like symptoms. This can lead to miscarriage, stillbirth, premature delivery, or life-threatening condition of the newborn.
Here’s a link to know more about foods that likely contain the L. monocytogenes bacteria and possible preventive steps.
Viruses are the biggest contributors to meningitis in humans. Most individuals infected with meningitis-causing viruses recover by themselves without any treatment, or with only supporting treatments, within a few weeks. However, the CDC and WHO recommend seeing a doctor right away if an individual begins to show symptoms of meningitis, as it could be of a serious variety.
Non-polio enteroviruses are the leading cause of viral meningitis, but only a small number of individuals infected with it will develop meningitis. There are several other viruses that can cause meningitis. They are:
- Mumps virus
- Epstein-Barr virus
- Herpes simplex virus that causes cold sores and genital herpes
- Varicella Zoster virus that causes chicken pox and shingles
- Measles virus
- West Nile virus, transmitted by a mosquito bite
While anyone can get infected with viral meningitis, children below the age of five years and people with a compromised immune system can get more severely ill. Close contact with an infected individual can make you sick, but not everyone who will contract the virus will develop meningitis.
Here’s an explanation by the CDC that provides more information on how each of these viruses spreads.
Fungal meningitis is caused when a fungal infection from any point in the body spreads to the brain and spinal cord. Though it is rare, fungal meningitis can make an individual dangerously ill. However, it is non-communicable and cannot spread to others even when in proximity.
There are several varieties of fungi that can cause meningitis and each has its own unique way of spreading. The most common meningitis causing fungi are:
- Cryptococcus which is abundantly present in the environment around us.
- Histoplasma which is found in the feces of birds and bats or in soil containing large amounts of these.
- Blastomyces is present in moist soil and decaying leaves or woods.
- Candida is usually found over the skin and lives inside the body but can cause meningitis if it enters into the bloodstream or organs.
Anyone can develop this condition, but people who have weakened immune systems are at increased risk. Individuals with HIV or cancer, those in post-surgical recovery, individuals on medications like steroids and immunosuppressants, those with low birth weight or who were prematurely born, and those living near the fungus source are at increased risk of developing this form of meningitis.
Parasitic meningitis is less common than other forms and is not contagious. Primary amebic meningoencephalitis (PAM) and Eosinophilic meningitis or meningoencephalitis (EM) are rare, but the most common forms of parasitic meningitis.
The parasites causing this form of meningitis enter the human body by eating meat or food infected with parasites. There are several parasites that affect humans, but the ones that account for majority of cases are:
- Angiostrongylus cantonensis: It can infect a person when they eat raw or undercooked snails and slugs, or food contaminated with the parasite.
- Baylisascaris procyonis: It infects when a person accidentally ingests the eggs of the parasite which are found in feces of certain species of monkey and environment contaminated with this.
- Gnathostoma spinigerum: It infects a person when they eat raw or undercooked freshwater fish, eels, frogs, and poultry.
The deadly Naegleria Fowleri parasite, while it is rare, accounts for some of the most severe cases of meningitis. According to the CDC, 34 cases were reported between 2009 to 2019, with only three people who contracted it survived. The reason for this is it’s extremely hard to diagnose the condition and a person can die of brain damage within a week if not treated promptly.
Fowleri is found in warm freshwater lakes, rivers, hot springs, untreated geothermal drinking water sources, unhygienic swimming pools, and soil. The parasite enters the body when a person ingests infected water through their mouth or nose.
People who consume exotic meats and children who might inadvertently put contaminated objects in their mouth are at greater risk of contracting N. Fowleri. However, there are several cases where the mode of contracting the parasite are not known.
Diagnosis and Prevention
An early and confident diagnosis is key to treating meningitis successfully, since therapies to treat the condition are heavily dependent on what is causing the condition. The most prominent diagnostic methods are:
- Analyzing symptoms and their severity
- Understanding past medical history, dietary history, recent travel history and family medical history.
- Blood tests to check for bacteria, viruses or any other microscopic organisms causing the condition.
- Extracting cerebrospinal fluid (CSF) from the lumbar region of the spine and checking for the presence of any organisms, white blood cell count, glucose content level and colour of the CSF itself.
- Imaging techniques like MRI and CT scans can be used for a more thorough picture of the location an extent of damage.
One can prevent developing meningitis by getting themselves vaccinated with meningococcal vaccine, pneumonia vaccine, Hib vaccine and BCG vaccines, to name a few. However, even vaccines do not provide 100% protection from the different varieties of microbes that cause meningitis, though they greatly reduce the changes.
The US CDC also recommends having some antibiotics after consulting your health care practitioner if you have been in close contact with a person infected with N.meningitides and Hib.
Avoiding smoking, getting plenty of rest, consuming appropriate amounts of water, avoiding close contact with sick persons, washing hands regularly especially before meals, and covering your mouth while coughing or sneezing are some healthy habits a person can adopt to prevent contracting the condition.
The approach to treat meningitis is solely dependent on understanding the vector that is causing the condition in the first place.
For meningitis caused by bacteria, antibiotics such as Cephalosporins, Chloramphenicol, and Steroids are the primary approach to treatment, and this should be started as early as possible. Any delay in starting this treatment could lead to more severe illness, and in severe cases coma and death.
When it comes to meningitis caused by viruses, the condition usually improves by itself in a few weeks and only therapies to subside symptoms are used.
Use of long-course, high-dose antifungals such as amphotericin-B and Flucytosine are the primary ways to treat an individual with fungal meningitis.
There is no specific treatment for parasitic meningitis. Some pills are prescribed to manage the headaches and vomiting. Doctors may also prescribe medications to reduce the body’s reaction to the parasite causing the infection which may help some people.