From the Guidelines
Meningitis is caused by a variety of infectious agents, including bacteria, viruses, fungi, and parasites, as well as non-infectious triggers, with the most common causes being Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae type b for bacterial meningitis, and enteroviruses, herpes simplex virus, and arboviruses for viral meningitis. The causes of meningitis can be broadly categorized into:
- Bacterial meningitis, which is commonly caused by Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae type b 1
- Viral meningitis, which is frequently caused by enteroviruses, herpes simplex virus, and arboviruses 1
- Fungal meningitis, which typically affects immunocompromised individuals and is caused by Cryptococcus, Candida, and Histoplasma 1
- Parasitic meningitis, which is rare but can be caused by organisms like Angiostrongylus cantonensis 1
- Non-infectious causes, including certain medications (NSAIDs, antibiotics), autoimmune conditions (lupus, sarcoidosis), and cancers that spread to the meninges 1
The likelihood of any specific aetiology depends on a range of factors, including age, immune status, and travel history, as outlined in Table 2 of the UK Joint Specialist Societies guideline on the diagnosis and management of acute meningitis and meningococcal sepsis in immunocompetent adults 1. For example, young adults are more likely to have viral meningitis, while older adults are more likely to have pneumococcal disease. Additionally, individuals with compromised immune systems, such as those with HIV or taking immunosuppressive medications, are at increased risk of certain types of meningitis, such as cryptococcal meningitis 1.
It is essential to note that the treatment of viral meningitis is generally supportive, with analgesia and fluids if necessary, and that antibiotics should be stopped once a viral diagnosis is made 1. In cases of suspected encephalitis, such as changes in personality, behavior, or cognition, or altered conscious level, intravenous aciclovir should be given for suspected HSV encephalitis, and the British Infection Association/Association of British Neurologists guidelines on the management of encephalitis should be followed 1.
In terms of prevention, vaccination against certain types of bacteria, such as Streptococcus pneumoniae and Neisseria meningitidis, can help reduce the risk of meningitis 1. Additionally, practicing good hygiene, such as frequent handwashing, and avoiding close contact with individuals who are sick can also help prevent the spread of meningitis-causing agents.
Overall, the causes of meningitis are diverse and depend on various factors, and a thorough understanding of these factors is essential for accurate diagnosis and effective treatment.
From the Research
Causes of Meningitis
Meningitis is a serious condition that affects the central nervous system, caused by inflammation of the meninges, which is the membrane surrounding the brain and spinal cord. The causes of meningitis can be categorized into:
- Bacterial infections: Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae are the principal causes of bacterial meningitis 2, 3, 4, 5
- Viral infections: Many viruses, such as enteroviruses, herpesviruses, and influenza viruses, can cause meningitis, with enteroviruses being the underlying cause of most viral meningitis cases worldwide 6
- Fungal infections: Although less common, fungal infections can also cause meningitis 6
Bacterial Meningitis Causes
The main bacterial causes of meningitis are:
- Streptococcus pneumoniae
- Neisseria meningitidis
- Haemophilus influenzae
- Streptococcus agalactiae (group B Streptococcus) 2, 3, 4, 5
Impact of COVID-19 on Meningitis Incidence
The COVID-19 pandemic has led to a significant reduction in the incidence of invasive diseases due to Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis, likely due to the introduction of COVID-19 containment measures and public information campaigns 5