Overview

Are you interested in learning more about meningitis and how it can affect adults? Have you or your loved ones suffered from meningitis? In this article, we will explore how meningitis manifests in adults, its types and treatment.

To start, we will talk about the definition of meningitis. So, what is meningitis? It is an infection of the meninges which are protective membranes that surround the brain and spinal cord.¹ Once the infection happens, the meninges will swell and cause pressure on either the brain or spinal cord, which can lead to life-threatening conditions.² Meningitis affects more than 2.5 million people around the globe annually, with 2 out of 10 patients being left with a brain injury or amputation and 1 out of 10 cases leading to death. ³ Hence, it is important to understand, diagnose and treat meningitis properly. 

There are multiple causes for meningitis such as bacterial, viral and even fungal infections.⁴ Although other causative agents like cancer, autoimmune disease, and certain drugs can also give rise to meningitis.^4,5 To further elaborate, the following sections will cover the required information.

Types of meningitis

Bacterial meningitis

Bacterial meningitis is one of the multiple types of meningitis, and even though it is less common than the viral type, it is often the more serious one. ² It can lead to death within a few hours, however, most people recover from bacterial meningitis.⁶ Some of the people who do recover may end up having permanent disabilities.⁶

There are multiple causative agents for bacterial meningitis such as:⁶

• Streptococcus pneumoniae
• Group B Streptococcus
• Escherichia coli
• Haemophilus influenzae
• Neisseria meningitidis
• Listeria monocytogenes

People who have bacterial meningitis end up having typical meningitis symptoms which will be discussed in the symptoms section.⁶ It can affect people of various ages, but some people are more susceptible than others; such as immunocompromised patients, people who have a cerebrospinal fluid leak, or do not have a spleen.⁶

Bacterial meningitis spreads through close contact, respiratory droplets from sneezing or coughing, the exchange of respiratory or throat fluids (e.g., saliva), or consuming contaminated food when proper hand hygiene is not followed after using the bathroom.⁶

It’s important to treat bacterial meningitis early on as it can lead to complications such as seizures, coma, and even death.⁶ It can also lead to a life-threatening illness called sepsis.⁶

Viral meningitis

Viral meningitis is the most common type of meningitis with most people getting better on their own and not requiring treatment.⁷ Many viruses can cause meningitis, and some include:⁷

• Non-polio enteroviruses (most common)
• Mumps
• Measles
• Influenza virus
• Herpes viruses like Epstein-Barr virus, herpes simplex viruses or varicella-zoster virus (which cause chickenpox and shingles)

Similarly to bacterial meningitis, the symptoms will usually be that of a typical meningitis infection.⁷ 

Also, anyone can get viral meningitis but some people are at more risk; such as people whose immunity has been compromised by disease, people who have to take medications like chemotherapy or steroids and organ or bone marrow transplant patients who have a weaker immune system.⁷

Viral meningitis can be transmitted through multiple ways. For example, it can spread through close contact or sharing respiratory secretions (saliva or spit) or bodily secretions (faeces, nasal secretions, fluid from blisters), coughing or sneezing, or from specific animal exposure and their secretions like urine, faeces or even bites.⁷

Fungal meningitis

Compared to bacterial and viral meningitis, meningitis due to fungi is quite rare.⁸ It is more commonly associated with people who have a weakened immune system such as people who have decreased immunity in the later stages of an HIV infection.⁹

When a person’s immunity is weakened, this gives the fungi the ability to spread anywhere in the body, including the brain and spine.⁸ Fungal spores, when inhaled, can cause a lung infection.⁸ This infection then spreads and goes into the brain/spinal cord and leads to meningitis.⁸

There are multiple causative agents such as:⁸

• Cryptococcus
• Coccidioides
• Histoplasma
• Candida
• Blastomyces

Sometimes, fungal infections can occur if medical equipment is not cleaned properly, leading to an increased risk of getting an infection during a medical procedure.⁸

The symptoms of fungal meningitis include the common symptoms of meningitis.⁸

As mentioned previously, people who have weakened immunity are more at risk for fungal meningitis, and this weakened immunity can be due to:⁸

• HIV infection
• Cancer
• Medications that affect immunity such as steroids (e.g. prednisone), anti-tumour necrosis factor medications and medicine that is given for organ transplantation

It is interesting to note that although we can get fungal infections from the environment, our bodies (such as candida in our gut entering the bloodstream) or medical procedures, the fungal infection does not spread between people.⁸

Parasitic meningitis

Parasites can cause meningitis and other nervous system symptoms.¹⁰ It is less likely to cause meningitis when compared to bacterial or viral meningitis although some people may be at more risk due to where they live or travel.¹⁰ Meningitis due to parasites can be called EM in short and is of two types: eosinophilic meningitis or eosinophilic meningoencephalitis.¹⁰

Multiple parasites can cause meningitis including:¹⁰

• Angiostrongylus cantonensis (A. cantonensis in short) - rat lungworm
• Baylisascaris procyonis (B. procyonis in short) - racoon roundworm 
• Gnathostoma spinigerum (G. spinigerum in short)

In this type of meningitis, patients exhibit typical meningitis symptoms but can also develop eye infections, or even have tingling/painful feeling in their skin (which is generally associated with A. cantonensis).¹⁰ Sometimes, parasitic meningitis can lead to complications such as loss of muscle control and coordination, paralysis, coma, permanent disability or even death.¹⁰ Hence, it is important to understand the risk factors associated with it.

Some people may be at more risk for these types of infections due to where they live or what animals they touch – for example, A. cantonensis is more seen in Southeast Asia and Pacific Islands such as Hawaii. ¹⁰ B. procyonis is more commonly seen to be transmitted through racoons.¹⁰ While G. spinigerum is most commonly seen in Southeast Asia, especially in Thailand and Japan.¹⁰

These parasites infect animals rather than humans and transmit to humans through ingestion of contaminated food or being exposed to the infected animal.¹⁰ For example: eating raw or undercooked snails/slugs, freshwater fish, eels, frogs, poultry or snakes, or touching contaminated objects such as dirt that has contaminated racoon faeces.¹⁰

Symptoms

Multiple signs and symptoms can arise from meningitis such as:^4,11

• Fever
• Headache
• Stiff neck
• Nausea and vomiting
• Light sensitivity/photophobia
• Confusion
• Rash
• Seizures
• Quick breathing
• Pale, mottled or blotchy skin

Diagnosis

Several tests are performed to diagnose meningitis. These tests include:¹²

• Physical examination and looking out for the symptoms
• Blood tests to check for bacteria or viruses
• A lumbar puncture where a sample of the cerebrospinal fluid is taken to be tested for any viruses or bacteria
• CT scan to check for any issues with the brain or to detect any swelling

Treatment

Treatment of meningitis is based on the type and cause, for example:^7,8,12

• Bacterial meningitis can be fatal and will need treatment using antibiotics right away
• Antiviral medications are used for severe viral meningitis, although it is mostly a self-limiting infection and will resolve on its own within 7-10 days
• A high dose of antifungal medication is used for fungal meningitis through vein injection, followed by oral antifungal medicine
• Hydration through administration of intravenous fluid injection and giving oxygen mask in case of breathing difficulties
• Steroids are given to decrease the swelling in the brain

Prevention

There are some steps that we can take to avoid and prevent meningitis from occurring such as:^6,7,8,10

• Vaccination against bacterial meningitis is the most efficient method to protect against certain infections
• Washing hands often and keeping good hygiene practices
• Avoid close contact with sick individuals
• Clean and disinfect surfaces regularly
• Avoid eating raw or undercooked foods
• Avoid contact with raccoons and their faeces
• Staying inside during dust storms and closing windows to avoid inhaling fungal spores, or wearing N95 masks

Summary

Meningitis can be a serious infection if left untreated which can result in permanent disability or even death. Anyone can get meningitis, but some individuals are at an increased risk compared to others. It is important to understand the causing agent of meningitis, whether it is bacterial, viral, fungal or parasitic so that we can treat it appropriately and have the best outcome possible for our health. While viral meningitis is self-limited and resolves on its own, bacterial meningitis can impose a serious health risk that requires immediate treatment and care. Hence, it is important to stay aware of this illness and be vigilant regarding our health.