Overview

Meningitis, which is usually a life-threatening disorder, is characterised by inflammation of the protective membranes, known as the meninges, covering the brain and spinal cord. These include the dura mater, arachnoid mater and pia mater. Meningitis is caused by bacterial, viral or fungal infections and very rarely by parasites. Meningitis can affect anyone, but it is most common in babies, young children, teenagers and young adults.

This article aims to divulge the key causes and symptoms of meningitis to provide people with the knowledge to protect themselves and their loved ones. Understanding these causes and symptoms is essential, as early detection is key to survival. This is because meningitis is a fast killer that can lead to death within 24 hours!¹ By understanding and recognising these signs and symptoms, individuals can seek prompt medical attention and potentially prevent severe complications like sepsis, brain damage or nerve damage.

Meningitis causes

Bacterial meningitis

Bacterial meningitis is caused by bacterial infections. Its annual incidence in the UK is estimated at 1.24 per 100,000 adults.² It is a relatively rare type of meningitis but the most fatal, often killing patients within 24 hours. This is because most bacterial meningitis cases are acute, meaning the symptoms are severe and appear suddenly.

Bacteria commonly associated with bacterial meningitis:

Streptococcus pneumoniae

The transmission route usually involves direct person-to-person contact with respiratory droplets from infected individuals. This is the leading cause of bacterial meningitis in adults, responsible for 75-80% of all bacterial meningitis cases and with a mortality rate of 15%.³ However, a vaccine can prevent this infection. 

Neisseria meningitidis

Transmission involves close person-to-person contact, particularly inhaling respiratory droplets from infected individuals. This type of bacterial meningitis is highly contagious and commonly affects teenagers and young adults. A vaccine can prevent this infection.

Haemophilus influenzae

The transmission route involves direct person-to-person contact with respiratory droplets from infected individuals. This used to be a common cause of bacterial meningitis, but the Haemophilus influenzae type b vaccine has greatly reduced the number of cases. In Pakistan, haemophilus influenzae meningitis was reduced by 89% and 93% in comparison with community and hospital controls (respectively) when the vaccine was introduced.⁴ 

Listeria monocytogenes

This bacteria is acquired through the consumption of contaminated foods, often unpasteurised cheese or hot dogs. Individuals infected with this bacteria typically experience fever and diarrhoea. However, in young, elderly and immunocompromised patients it causes meningitis.⁵

Viral meningitis

As you might have guessed, viral meningitis is caused by viral infections. The estimated annual incidence of viral meningitis in the UK is 2.73 per 100,000 adults.² Most cases of meningitis are caused by a viral infection. However, viral meningitis is almost never life-threatening and can usually be resolved on its own with supportive care.

Viruses commonly associated with viral meningitis:

Enteroviruses

Enteroviruses are common viruses, prevalent in the summer and early fall in temperate parts of the world. Enteroviruses account for 80% of all cases of viral meningitis in adults.⁶ The most common enteroviruses that cause viral meningitis are coxsackie or echovirus groups.⁶ These enteroviruses are typically transmitted through an oral route via dirty hands, polluted water and food, or through a fecal-oral route.

Herpes viruses

These include the herpes simplex virus type 1 and 2. The herpes simplex virus type 2 is often the leading cause of viral meningitis, accounting for 31% of cases.⁶ It ranks second among the most common causes of viral meningitis in adolescents and adults in developed countries. Herpes simplex 1 virus type accounts for 4% of viral meningitis cases.⁶

Varicella-zoster virus

This virus commonly causes chickenpox or shingles. However, in immunocompromised patients, it can cause meningitis, accounting for 11% of viral meningitis cases.⁶

Fungal meningitis

This type of meningitis caused by fungal pathogens is relatively rare. However, unlike viral meningitis, it can be life-threatening. Additionally, it doesn’t spread from person to person.

Fungus commonly associated with fungal causes

Cryptococcus neoformans

This is the most common cause of fungal meningitis, accounting for 70% of cases worldwide.⁷ This fungus is commonly associated with HIV-associated meningitis due to HIV/ AIDS patients being immunodeficient. It is usually spread through inhalation of spores found in bird dropping or soil. Once it enters the body, it spreads to the central nervous system (CNS) resulting in inflammation of the meninges. 

Candida species

Candida fungus (candida albicans and non-albicans), are commonly associated with meningitis in premature babies with very low birth weight, individuals with compromised immune systems,⁸ and people undergoing chemotherapy or long-term corticosteroid therapy. Candida species live within the body and on the skin, but they can enter the bloodstream in certain people and spread to the meninges to cause inflammation (meningitis).

Parasitic meningitis

This is a very rare form of meningitis caused by parasites. Like fungal meningitis, parasitic meningitis does not spread from person to person. 

Parasites commonly associated with parasitic causes:

Naegleria fowleri

This parasite is an amoeba (single-celled living organism) found in warm freshwater environments like rivers, lakes and hot springs. Naegleria fowleri is often referred to as a ‘brain-eating amoeba’ due to the parasite travelling to the brain and spreading to the meninges. It leads to a rare type of meningitis, called primary amebic meningitis, which features a high mortality rate.⁹ This type of meningitis has specific symptoms like hallucinations, loss of balance and lack of attention or focus.

Angiostrongylus cantonensis

This parasite is known as the rat lungworm because is a nematode (roundworm) that usually infects rats. Human infection is usually a consequence of the ingestion of infected snails, prawns, crabs or contaminated fruits and vegetables.

Other meningitis causes

Meningitis can also have noninfectious causes such as drug allergies to non-steroidal anti-inflammatory drugs or antibiotics, some types of cancer, inflammatory diseases like sarcoidosis, and chemical reactions.

Meningitis symptoms

Common symptoms of bacterial, viral, fungal and parasitic meningitis include: 

• Fever (a body temperature over 37.5^oC degrees): this is often the earliest symptom of meningitis. It is caused by the body’s release of small chemicals called pyrogens which act on the hypothalamus to make your body temperature higher. This occurs to create an environment less favourable for the pathogen to replicate
• Headache: This is another early symptom of meningitis. It is caused by the possible stimulation of nerve endings in the walls of blood vessels supplying the meninges
• Nausea and vomiting: these often result from increased intracranial pressure (pressure within the skull and on the brain tissue), a phenomenon that can activate the vomiting centre in the brainstem. Furthermore, systemic inflammation can cause vomiting
• Stiff neck (nuchal rigidity): this is a classic symptom of meningitis. It is caused by the inflamed nerve roots and meninges of the cervical region getting stretched. This activates a protective muscle spasm which causes neck stiffness
• Sensitivity to bright lights (photophobia): this is often thought to arise due to irritation of the basal meninges (meninges around the brain’s base) around the diaphragma sellae

Additional symptoms

• Altered mental state
• Seizures (fits)
• Small round spots (petechiae) that look like a skin rash but do not fade when a glass is rolled over them. This often occurs in bacterial meningitis caused by neisseria meningitidis
• Lack of appetite

It is important to remember that symptoms can appear in any order and some may never appear. If you suspect you have measles, a disease that can lead to meningitis, call 999 for an ambulance or go to your local A&E. Similarly, if you have been in contact with someone with meningitis seek medical attention.

FAQ’s

Is meningitis contagious? 

Bacterial and viral meningitis are contagious and can spread through respiratory droplets or close person-to-person contact. This includes sneezing, coughing and kissing. However, fungal and parasitic meningitis are usually not contagious.

Can meningitis be diagnosed? 

Diagnosis consists of a physical examination, a blood test, an analysis of cerebrospinal fluid obtained through a lumbar puncture and medical imaging tests like CT scans or X-rays.

What should I do if I suspect meningitis? 

Seek immediate medical attention if someone or yourself is showing symptoms of meningitis. Early diagnosis is vital to prevent death and/or life-changing complications. 

Summary

This article aimed to cover the causes and symptoms of meningitis in detail to provide people with the knowledge to protect themselves and their loved ones. This is critical because an early diagnosis and prompt treatment greatly improve patient outcomes and reduce the likelihood of long-term complications. By raising awareness, and promoting vaccination and hygiene practices, the global burden of meningitis can be minimised.