Meningitis is a rare, but severe and fatal disease. The mortality rate is 10 percent, and 40 percent of the cases result in permanent disabilities, like cognitive (learning) difficulty, audio-visual problems, liver and kidney failure, and loss of limbs. Meningitis is caused by inflammation and swelling of the protective membranous layers covering the brain and spinal cord and cerebrospinal fluid. Meningitis may be bacterial as well as viral.

What is Meningitis?

The word Meningitis has been derived from Meninges. Meninges are the protective membranes wetted with cerebrospinal fluid, that surround the brain and spinal cord. Meningitis is a bacterial, viral, fungal, or amoebic infection, that affects the protective membrane of the brain and spinal cord. The infection causes swelling and inflammation in the membranes and abnormal cell count in cerebrospinal fluid.

The inflammation in Meninges causes severe headaches, a stiff neck, and high-temperature fever. Most Meningitis incidents are the result of viruses and bacteria, but fungi, amoeba, head injuries, and the use of certain types of drugs can also cause meningitis.

All cases of Meningitis must be treated timely. Some viral infections improve on their own without treatment, while others require emergency antibiotic treatment, or else can cause death. Bacterial meningitis is the most dangerous infection, which causes serious complications. Seek immediate medical care, if you suspect you or someone else has meningitis.

Meningitis Symptoms

Early symptoms of meningitis resemble those of flu and mild fever, however, with the passage of time (several hours or a couple of days), the signs get harsh.

• Sudden and severe headache and pain in the neck.
• Sudden high fever with high temperature.
• Stiff neck with pain.
• Nausea in common, vomiting in special cases.
• Confusion or trouble concentrating.
• Seizures occur in most cases of bacterial meningitis.
• Sleepiness/drowsiness and trouble waking.
• Sensitivity to light or a dislike of bright lights is an early warning sign of meningitis.
• Loss of appetite or thirst.
• In some cases of Bacterial Meningitis (Meningococcal Disease), skin rashes do appear.

Types of Meningitis

There are 7 types of meningitis. Some are infectious, while others are non-infectious. Any type of infection that causes harm to the meninges, is known as Meningitis. Even malaria can cause meningitis. Categorization of Meningitis is made on the basis of types of pathogens.

1. Bacterial Meningitis
2. Viral Meningitis
3. Fungal Meningitis
4. Parasitic Meningitis
5. Chronic Meningitis
6. Amoebic Meningitis
7. Non-infectious Meningitis

Bacterial Meningitis

Acute Bacterial meningitis (ABM) is very serious and requires medical attention as soon as possible. In this case, bacteria enter the bloodstream and travel to the brain and spinal cord, and attack the cerebrospinal fluid and meninges. Following are the types of meningitis, which are caused by several strains of bacteria:

Haemophilus Meningitis:

Haemophilus influenzae type b (Hib) bacterium was once the leading cause of bacterial meningitis in children. Before the Hib vaccines that have greatly reduced the number of cases, it was the leading cause of bacterial meningitis.

Meningococcal Meningitis:

Meningitis caused by the bacteria Neisseria meningitidis is known as Meningococcal Meningitis. These bacteria generally cause upper respiratory tract infections, but they can also cause meningitis, once they enter the bloodstream. Vaccines can help protect from meningitis, however, the contagious nature of the disease can still affect the vaccinated person. A person with close contact with an affected person should take antibiotics to prevent it.

Pneumococcal Meningitis:

Pneumococcal meningitis is caused by Streptococcus pneumoniae bacteria (also called pneumococcus, or S pneumoniae). This type of bacteria is the most common cause of bacterial meningitis in adults. It is the second most common cause of meningitis in children older than the age of 2 years.

Group B Streptococcus Pneumococcal Meningitis

This type of Meningitis is caused by the action of Group B streptococci (bacteria). General mothers pass these bacteria to their babies during birth.

Listeria Meningitis: 

Listeria Monocytogenes is responsible for this type of Meningitis. These bacteria can be found in unpasteurized milk/cheeses, ice cream, raw or processed vegetables/fruits, undercooked poultry, sausage, smoked fish, hot dogs, and lunchmeats. Pregnant women, newborn babies, and older aged people are more susceptible to this disease. As Listeria Monocytogenes can pass through the placenta, therefore late pregnancy babies may be victims of this disease. Moreover, it is the responsible pathogen in 20% of cases of bacterial meningitis in both neonates and adults older than 50 years.

E-Coli Meningitis:

E-Coli Meningitis is caused by a bacterium known as “Escherichia coli”. It was found to be a disease in immunocompromised patients and the elderly age group. E-coli is the most common pathogen causing meningitis among the neonatal age group. It is one of the rare causes of meningitis in immune-competent adults.

Bacterial meningitis symptoms

Symptoms are almost the same in all types of meningitis, but as far as Bacterial Meningitis is concerned, the symptoms are more severe and life-threatening. The most common symptoms of bacterial meningitis are:

Symptoms in Adults

• • Bacterial meningitis symptoms develop suddenly
  • Stiff neck with severe pain
  • Headaches
  • Sensitivity to light from the very initial stage
  • High fever with Shivering
  • Feeling confused or sleepy
  • Bruising easily all over the body due to blood clotting
  • A rash on the skin
  • Weak with limited range of motion
  • Seizures (if the meningitis is advanced)

Symptoms in Infants

• • Irritability
  • Vomiting from a high fever
  • Excessive crying episodes
  • Swelling of the soft spot of the skull
  • Lack of sleep, and difficulty waking
  • Lack of appetite
  • Seizures

Symptoms of Meningitis usually appear suddenly in a couple of hours. If your think your baby is showing the above signs, avail of emergency medical aid right away. The use of adequate antibiotics can surely reduce the risk of death.

Risk Factors of Bacterial Meningitis

There are certain factors that increase the risk of infection to develop meningitis.

• Age Factor: Babies compared with older people are more susceptible to being the victim of meningitis. Usually, neonatal babies have greater chances to suffer from bacterial meningitis, however people of all ages can not be excluded from the risk of any bacterial infection to develop meningitis.
• Group setting: The chances of the spread of Meningococcal disease are greater in people living in groups, like college hostels, combined apartments, and other gatherings.
• Certain medical conditions: Certain medical conditions like HIV infection, cerebrospinal fluid leak, or lacking spleen increases the risk of meningitis.
• Working with pathogens causing meningitis: Microbiologists and laboratory staff are routinely exposed to “Neisseria meningitidis”. Having close contact with the pathogen may increase the risk of meningitis.
• Travel: Travelers traveling to meningitis-prone-belts, like sub-Saharan Africa, and Mecca (during pilgrimage)may be at increased risk for meningococcal disease.

Viral Meningitis

Meningitis which is caused by any kind of viral infection is known as Viral Meningitis. Viral Meningitis is the most common type of meningitis, is less severe, and goes away on its own, but still, any type of meningitis can be risky. Babies less than one month of age, and people with weak immunity, have greater chances of having life-threatening meningitis. In other words, meningitis for neonates and immunocompetent persons may cause serious complications and even death.

Causes of Viral Meningitis

Non-polio enteroviruses are the most common cause of viral meningitis almost all over the world. Only a small number of enteroviruses can develop meningitis. The most common viruses which can cause meningitis are as under;

• Mumps virus: Mumps Virus causes illness in glands present on each side of the face.
• Herpesviruses: Herps Simplex Viruses and varicella-zoster virus cause chickenpox and shingles.
• Measles virus: Measles is an acute viral illness, characterized by its prodromal stage of high fever and malaise, pre-eruptive stage (pathognomonic enanthema) with cough, conjunctivitis, and coryza, followed by the eruptive/convalescent stage.
• Influenza virus: There are four types of influenza viruses; A, B, C, and D. All these viruses cause flu, which can be mild to severe with high fever. Influenza viruses may cause meningitis.
• Arboviruses: Abroviruses are a group of viruses spread and transmitted by the bite of insects. Diseases like California encephalitis, Chikungunya, dengue, Eastern equine encephalitis, Powassan, St. Louis encephalitis, West Nile, Yellow Fever, and Zika, are caused by Abroviruses.
• Lymphocytic choriomeningitis virus: Lymphocytic choriomeningitis is a disease caused by LCMV. It is an infectious disease with symptoms of meningitis (fever, headache, stiff neck, etc.), encephalitis (drowsiness, confusion, sensory disturbances, and/or motor abnormalities, such as paralysis), or meningoencephalitis (inflammation of both the brain and meninges).

Viral meningitis symptoms

Symptoms of viral meningitis are almost the same as those of Meningococcal, but still, the condition caused by viral infection is milder.

Symptoms in Children and Adults

• High Fever
• Severe Headache
• Painful and Stiff neck
• Eyes being sensitive to light (photophobia)
• Sleepiness or trouble waking up from sleep
• Persistent Nausea, and vomiting
• Irritability, malaise, and uneasiness
• Joint swelling and stiffness with limited range of motion
• Lack of appetite
• Lethargy (a lack of energy)

Symptoms in neonates and babies

• Fever
• Irritability
• Poor eating
• Vomiting (rare cases)
• Sleepiness or trouble waking up from sleep
• Lethargy, drowsiness

Note: The difference between the symptoms of Bacterial and Viral Meningitis is a Bacterial Meningitis has more chances of Seizures.

Risk Factors of Viral Meningitis

People of any age can be victims of Viral Meningitis, however, there are some factors that can cause the risk of the disease;

• Neonates i.e under 1 month of age
• Infants under 5 years of age
• People with the incompetent immune system
• People under medication and therapy
• People with recent surgery, organ transplantation, and bone marrow replacement

Fungal Meningitis

Fungal meningitis is caused by the spread of fungal infection to the brain and spinal cord from anywhere else in the body. Cryptococcus, Histoplasma, Blastomyces, Candida, and Coccidioides cause fungal infection, which later can develop into Meningitis. Fungal Meningitis spreads in different ways;

1. Cryptococcus lives in environments all through the world and is the biggest cause for developing a meningitic condition.
2. Histoplasma is a different fungus, which is abundantly found in areas with a large number of birds and bats. It is found in the dropping of birds and bats.
3. Blastomyces Fungus is found in soils of marshes, and moist land. It is also found in decaying leaves and wood in moist areas.
4. Coccidioides Fungus lives in dust and soils of warm, arid, and desert regions of the western hemisphere.
5. Candida fungi are a type of fungi, which lives inside and on our bodies. In general, candida is not harmful. It becomes harmful when enters the bloodstream and organs.

Fungi are microorganisms and can not be seen with the naked eye. They can only be seen under a microscope. Fungi can enter our bodies through breathing. They reach our brain and spinal cord by means of the bloodstream and cause meningitis.

Risk Factors of Fungal Meningitis

Although anyone can suffer from a fungal infection, however, there are some factors that increase the risk of fungal infection.

1. People with incompetent immune systems are vulnerable to fungal infection
2. Long-term use of corticosteroids is more likely to increase your chance of getting a fungal infection.
3. Certain health conditions like HIV and Cancer may reduce our immune power and can put us at high risk of fungal infection.
4. Certain medications like anti-TNF and surgical procedures may weaken your immune system, and increase the risk of fungal infection.
5. Premature babies with very low birth weights are also at increased risk for getting Candida bloodstream infections, which may spread to the brain and cause meningitis.
6. Soils of certain areas in the United States are rich in fungi. People living in those areas of the United States may fall at risk of fungal infection, which may proceed to an infection in the meninges.

Signs and Symptoms

Like bacterial and viral meningitis, fungal meningitis has the following symptoms:

• High Fever
• Severe Headache
• A stiff neck is a key symptom of all types of meningitis
• Nausea and vomiting
• Photophobia (eyes’ sensitivity to light)
• Altered mental status (confusion)

How to Prevent Fungal Meningitis

There are several preventive and preemptive measures to protect against fungal infection. People with weak immune systems should take the following precautionary steps;

• People working in dust and excavating sites should protect themselves against breathing the dust by wearing an N95 mask.
• During a dust storm, stay inside and get the windows closed, so that dust and dirt may be inhaled.
• Protect your nose and mouth against dust/ dirt while working in fields.
• Wash your injuries with antiseptic soaps to prevent the skin from developing an infection.
• After having been infected with a fungal infection, take antifungal medicines as per the prescriptions of your physician.

Chronic Meningitis

Chronic meningitis is defined as an inflammatory cerebrospinal fluid (CSF) profile that persists for at least 1 month. The presentation often includes headache, nausea, vomiting, cranial neuropathies, symptoms of elevated intracranial pressure, or focal neurologic deficits. The most common etiologies of chronic meningitis fall into 3 broad categories: infectious, autoimmune, and neoplastic. Evaluation of the patient with suspected chronic meningitis should include a detailed history and physical examination as well as repeated CSF diagnostics, serologic studies, and biopsy of the brain or other abnormal tissue (eg, lymph node or lung), when indicated. Early identification of the etiology and rapid treatment are crucial for improving morbidity and mortality, but potential infectious and neoplastic conditions should be excluded prior to empirically starting steroids or immunosuppressive medications.

Parasitic Meningitis

There are some parasites, which cause an eosinophilic meningitic infection. These parasites cause meningoencephalitis. When both the meninges of the brain and the spinal cord are infected, the condition is known as Meningoencephalitis. Three types of parasites are responsible for Meningoencephalitis.

• Angiostrongylus cantonensis: Angiostrongylus cantonensis is a parasitic nematode that causes angiostrongyliasis, the most common cause of eosinophilic meningitis in Southeast Asia and the Pacific Basin. The nematode commonly resides in the pulmonary arteries of rats, giving it the common name rat lungworm. Angiostrongylus Cantonensis causes baylisascariasis meningitis or neural larva migrans
• Baylisascaris procyonis: Baylisascaris procyonis, also known by the common name of raccoon roundworm, is a roundworm nematode, found ubiquitously in raccoons, the definitive hosts. It is named after H. A. Baylis, who studied them in the 1920s–30s, and Greek askaris. Gnathostoma spinigerum causes neurognathostomiasis meningitis.
• Gnathostoma spinigerum: It is a type of parasitic nematode that causes gnathostomiasis meningitis in humans, also known as its clinical manifestations are creeping eruption, larva migrans, Yangtze edema, Choko-Fuschu Tua chid, and wandering swelling. Gnathostomiasis in animals can be serious, and even fatal.

How Parasitic Meningitis Spreads?

These parasites do not directly infect humans. They infect animals, and then humans when they eat infected animals. Generally, there are three types of parasites, which affect animals first, and then transmit to humans. When humans eat the uncooked/undercooked meat of infected animals, the risk of infection is increased.

• Angiostrongylus cantonensis: People can get infected by eating raw or undercooked snails or slugs or contaminated produce.
• Baylisascaris procyonis: People get infected by accidentally ingesting infectious parasite eggs. These eggs can be found in raccoon feces and environments (such as dirt) contaminated with raccoon feces.
• Gnathostoma spinigerum: People can get infected by eating raw or undercooked freshwater fish or eels, frogs, poultry, or snakes. The infection causes meningitis.

Note: Parasitic meningitis is not contagious, and does not transmit from person to person.

Risk Factors of Parasitic Meningitis

• People living in Southeast Asia, Pacific Islands, and Hawaii have the risk of infection of Angiostrongylus cantonensis.

• Baylisascaris procyonis infects raccoons in almost all of the United States, especially Midwest, Northeast, Middle Atlantic, and West Coast. A raccoon is a greyish-brown American mammal that has a foxlike face with a black mask and a ringed tail. People in these areas who spend time around raccoons are at increased risk for Baylisascaris infection. Young children and babies are at more risk when they touch their soil-contaminated fingers in the mouth and nose.
• Countries of Southeast Asia particularly Thailand and Japan are prone to the infection of Gnathostoma spinigerum. The neurologic form of Gnathostoma spinigerum develops meningitis fever.

Signs and Symptoms

Like bacterial and viral meningitis, parasitic meningitis has the following symptoms:

• High Fever
• Severe Headache
• A stiff neck is a key symptom of all types of meningitis
• Nausea and vomiting
• Photophobia (eyes’ sensitivity to light)
• Altered mental status (confusion)

Amoebic Meningitis

An amoeba namely Naegleria Flowleri causes primary amebic meningoencephalitis (PAM); a rare brain infection, which affected 160 people from 1962 (when first time detected) to 2023. Most of the cases resulted in death. Only four victims survived.

Spread and Sources of Amoebic Meningitis

Naegleria fowleri lives in warm fresh water and soil around the world. It infects people via their noses. It only survives at higher temperatures (45 celsius), and lives for a short period of time. It lives in;

• Warm and freshwater lakes, streams, ponds, and rivers.
• Hot water springs/ geysers.
• Warm waste water of industries and power stations.
• Unchlorinated warm tap water, warm swimming pools, and other recreational points.
• The soil of the regions with hot climatic conditions.

Spread of Amoebic Meningitis

Naegleria fowleri is the amoeba that infects the brain and spinal cord meninges by entering the body through the nose. This amoeba travels from warm waters, where people take baths, to their noses. This typically happens when people go swimming or diving, and when they put their heads under fresh water of lakes and ponds, rivers and streams. The ameba then travels up the nose to the brain, where it causes damage to the meninges and brain, and causes serious illness until death.

Signs and Symptoms of Amoebic Meningitis

Like bacterial and viral meningitis and parasitic meningitis, amoebic meninges has the following initial signs but later the symptoms may aggravate and worsen the condition. It results in death in most cases. There have been only 4 survivals among 160 cases recorded in USA since 1962, it first time detected:

• High Fever
• Severe Headache
• A stiff neck is a key symptom of all types of meningitis
• Nausea and vomiting
• Photophobia (eyes’ sensitivity to light)
• Altered mental status (confusion)

Later symptoms include:

• Extra Stiff neck
• Altered mental status (confusion)
• Lack of attention to people and surroundings
• Seizures
• Hallucinations
• Coma

Non-infectious Meningitis

Diseases due to pathogens that spread between people are known as infectious diseases. While the diseases developed as a result of some injury, surgery, or some other non-pathogenic cause, are non-infectious diseases. These conditions remain confined to the affected person and never spread from person to person. There are many non-infectious causes behind the development of meningitis. Among these cancers/tumors, lupus, certain medicines, head injuries, and surgeries are notable.

Signs and Symptoms of Non-infectious Meningitis

The following signs and symptoms are common in non-infectious meningitis:

• Mild to high Fever
• Headache
• Stiff neck
• Nausea
• Vomiting
• Photophobia (eyes being more sensitive to light)
• Altered mental status (confusion)

The non-infectious meningitis cases are controllable if they are timely medicated. There had been 10 million reported cases of non-infectious meningitis in 2020 worldwide. Even with advanced medication, the mortality rate of the disease is 25%, that is because of the severity of the injury.

Is Meningitis Contagious?

• Bacterial Meningitis is Contagious: Bacterial meningitis is a serious illness and can be life-threatening. It’s most often caused by Neisseria meningitidis or Streptococcus pneumoniae. Both are contagious. Meningococcal bacteria can’t survive outside the body for long, so you’re unlikely to get it from being near someone who has it.
• Viral Meningitis is Contagious: People can spread the viruses that cause viral meningitis to other people. If you have close contact with someone who has viral meningitis, they may spread the virus to you. However, you are not likely to develop meningitis. That’s because most people infected with these viruses will not develop meningitis.
• Fungal Meningitis is not contagious: Fungal meningitis does not spread between people. The fungus Candida can also cause meningitis. Candida normally lives inside the body and on the skin without causing any problems. However, in certain patients who are at risk, Candida can enter the bloodstream or internal organs and cause an infection.
• Amoebic/Parasitic Meningitis is not Contagious: Parasitic meningitis is extremely rare and life-threatening. It’s caused by a microscopic amoeba called Naegleria fowleri. This parasite enters the body through the nose, usually in contaminated lakes and rivers. You can’t get it by drinking contaminated water and it isn’t contagious.
• Non-infectious Meningitis is not Contagious: Meningitis isn’t always the result of an infection. It can develop as a result of head injury or brain surgery. It can also be caused by certain medications, lupus, or cancer. Non-infectious meningitis is not contagious.

Meningitis Vaccine/Shots

Currently, there are five vaccines treating five types of infection that cause meningitis;

• Meningococcal vaccines
• Pneumococcal vaccines
• Other meningitis vaccines
• Men ACWY for travel
• European Immunisation Week 2021

Meningococcal vaccines