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Questions and Answers
Which virus accounts for more than 85% of cases of acute viral meningitis?
Which organism is a common bacterial cause of pyogenic meningitis?
Which of the following organisms is associated with eosinophilic meningitis?
What type of cells predominates in the CSF during acute viral meningitis?
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Which virus is NOT generally considered a cause of acute viral meningitis?
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What is the primary cause of meningococcal meningitis?
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What are some common underlying conditions that increase the risk of pneumococcal pneumonia?
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Which molecular method can simultaneously detect multiple agents of meningitis in CSF?
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What is a key characteristic of Neisseria meningitidis under microscopic examination?
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What is the estimated mortality rate for meningococcal disease?
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Study Notes
Overview of Meningitis
- Acute Viral Meningitis: Caused predominantly by enteroviruses (>85%), including herpesviruses, arboviruses, HIV, mumps, and occasionally lymphocytic choriomeningitis virus.
- Chronic Bacterial Meningitis: Often linked to Streptococcus pneumoniae as the most common agent; can also be caused by meningococcus, Group B Streptococcus, Listeria monocytogenes, and gram-negative bacilli such as Escherichia coli.
Parasitic Agents of Meningitis
- Toxoplasma gondii: Causes toxoplasmosis associated with meningitis.
- Free-living amoebae: Known to cause infections leading to meningitis.
- Trypanosoma brucei: Responsible for African sleeping sickness, which can affect central nervous system.
- Angiostrongylus cantonensis: Associated with eosinophilic meningitis.
- Gnathostoma spinigerum: Causes a type of infection linked to meningitis.
- Cysticercosis, schistosomiasis, echinococcal disease: Other notable parasitic infections that can involve the central nervous system.
- Toxocara canis and Trichinella: Also related to meningitis cases.
Fungal Agents
- Cryptococcus neoformans: A significant fungal cause of meningitis, particularly in immunocompromised individuals.
- Candida albicans, Blastomyces dermatitidis, Histoplasma capsulatum, Coccidioides immitis, Aspergillus species: Other fungi linked with meningitic symptoms.
Molecular Diagnosis
- Molecular Methods: Highly sensitive techniques offering rapid results compared to cultures, facilitating the detection of bacteria in CSF.
- BioFire FilmArray: An automated multiplex PCR system that can identify 14 common meningitis pathogens within 1 hour.
- Commonly Targeted Genes: Include capsule transport gene (ctrA) and sodC for Neisseria meningitidis.
Meningococcal Meningitis
- Causative Agent: Neisseria meningitidis (meningococcus), characterized by its gram-negative diplococci morphology.
- Epidemiology: Annually, nearly 500,000 cases worldwide with a mortality rate of 5-16%.
- Outbreaks: Group W can lead to significant outbreaks, notably during mass gatherings like the Hajj pilgrimage.
- Persistent Cases in India: Annual sporadic cases primarily in North India, with a surge in reported cases in Bihar (2015) exceeding 12,000.
Risk Factors and Transmission
- Age: Highest incidence in children (3 months to 5 years) and adolescents (15-25 years).
- Risk Factors: Overcrowded settings, smoking, recent respiratory infections, and complement deficiencies promote both colonization and disease progression.
- Infection Spread: Droplet inhalation from nasopharyngeal carriers is a primary transmission route.
Vaccine Prophylaxis
- Meningococcal Vaccines: Available as bivalent (serogroups A and C) or quadrivalent (serogroups A, C, Y, and W135) formulations.
- Administration Schedule: Two doses for young children (3–18 months) or a single dose for older children/adults.
- Efficacy: Vaccines have >95% protective efficacy lasting 3-5 years.
Clinical Manifestations and Case Fatality
- Common Presentations: Include meningitis, bacteremia, and pneumonia, with case fatality rates of approximately 4.7% for pneumococcal infections and 2.8% for meningococcal cases.
- Neonatal Disease: Early-onset and late-onset listeriosis have specific clinical presentations affecting both mother and fetus, with potential complications including fetal complications in mothers.
Other Notable Bacterial Agents
- Mycobacterium tuberculosis: Recognized for causing meningitis.
- Borrelia burgdorferi: Associated with Lyme disease.
- Treponema pallidum: Related to tertiary syphilis.
- Rare Bacterial Agents: Includes Nocardia, Actinomyces, Tropheryma whipplei, Leptospira, and Brucella.
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Description
Explore the various agents responsible for acute viral meningitis, including common causes and specific examples like mumps and herpesviruses. This quiz provides insights into the connection between viral and chronic meningitis. Test your knowledge on these critical pathogens.
