302 Viral meningitis and measles Flashcards
What is the definition of meningitis?
Inflammation of the meninges and subarachnoid space – classic triad of symptoms: headache, fever and neck stiffness — and pleocytosis (an increased cell count, particularly of leukocytes) in the CSF
What is the definition of encephalitis?
Inflammation of the brain cortex parenchyma - behavioural changes, focal neurological abnormalities and impairment of consciousness
What is the definition of meningoencephalitis?
Central nervous system infection with clinical features of both meningeal and parenchymal disease
What is the definition of aseptic meningitis?
inflammation of the meninges not due to pyogenic bacteria
Which pathogen causes the deadliest meningitis?
Streptococcus pneumoniae (20-37%) in high income countries and 51% in low income
What is the most common pathogen causing meningitis in neonates?
Streptococcus agalactiae (group B streptococcus, GBS) and Escherichia coli
What is the most common pathogen causing meningitis in adults?
Staphylococcus pneumoniae
Listeria monocytogenes is the third most common cause of meningitis in adults and is commonly associated with old age (>60 years) and an immunocompromised state
What are the clinical characteristics of meningitis in different ages?
Neonates: nonspecific symptoms: irritability, poor feeding, respiratory distress, pale or marble skin and hyper- or hypotonia
-low diagnostic accuracy
Children: fever, chills, vomiting, photophobia and severe headache; the younger the patient with bacterial meningitis, the more subtle and atypical are the symptoms
Adults: headache, fever, neck stiffness and altered mental status are common signs and symptoms at admission
Which bacteria is a petechial and purpuric rash associated with?
Pneumococcal meningitis
A petechial rash is identified in 20–52% of patients and is indicative of meningococcal infection in over 90% of patients
What are the abnormalities found in the CSF when someone has bacterial meningitis?
pleocytosis of mainly polymorphic leukocytes, low glucose concentration, low CSF to blood glucose ratio and elevated protein levels
What lab test help distinguish between bacterial and viral meningitis?
Serum concentrations of C-reactive protein (CRP) and pro-calcitonin are highly discriminatory between paediatric bacterial and viral meningitis
Blood cultures are valuable for detection of the causative organism
What are some non-infectious causes of meningitis?
Drug-induced (e.g., amoxicillin, nonsteroidal anti-inflammatory medications or trimethoprim-sulfamethoxazole), neoplastic, neurosarcoidosis, rheumatoid arthritis, systemic lupus erythematosus, or vasculitis (e.g., Kawasaki disease)
During which seasons is viral meningitis more common?
Viral meningitis exhibits a summer-to-fall seasonality in temperate climates and a year-round incidence in tropical and subtropical areas
Causative pathogens are primarily transmitted through the faecal-oral route, and less commonly via respiratory secretions
What are the main causes of viral meningitis?
Enteroviruses
Non-polio humanenteroviruses (NPEV)are the leading recognizable cause of viral meningitis (Picornaviridae)
Herpes simplex (0.5-18%)
Mumps virus
What are some meningeal clinical signs?
Kernig’s sign – With the patient’s hips and knees flexed, a positive sign is when the patient resists extension of the knee. The test was originally performed with a patient seated on the edge of the bed and feet dangling over the side
Brudzinski’s sign – Flexion of the supine patient’s neck causes the patient to flex both hips and knees; therefore, retracting the legs toward the chest
Nuchal rigidity – Neck stiffness denoting involuntary resistance to passive neck flexion
