20 terms

13: Aseptic meningitis/Encephalitis, Leptospirosis, Cryptococcal Meningitis

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Aseptic meningitis (neurology)
A meningeal reaction in the CSF sometimes occurring in the absence of an infecting organism.
▫ It can be due to a virus, foreign substance, diagnostic or therapeutic procedure, or to a tumor or a septic focus within the skull or spinal canal.
Aseptic meningitis (virology)
most often in those under 30 years of age. Peak time for infection is in late summer. Majority of cases are caused especially by the mumps virus and the enterovirus group (including polio, coxsackieviruses and echoviruses)
Enteroviruses (Aseptic Meningitis)
-account for 80 to 85% of all cases of aseptic meningitis for which an etiologic agent is identified
-Infections are often initially indistinguishable on clinical grounds from those due to bacterial pathogens
▫ there is specific treatment for the bacterial pathogen but not for the viral pathogen
-Self-limiting
HSV aseptic meningitis
▫ is most commonly associated with primary genital infection with HSV2, developing in 36% of women and 13% of men concomitant with primary infection
▫ Primary genital infection with HSV1 and nonprimary genital infection with HSV1 or 2 rarely result in meningitis
Encephalitis
(due to herpesviruses, arboviruses, rabies virus, flaviviruses [West Nile encephalitis, Japanese encephalitis], and many others) produces disturbances of the sensorium, seizures, and many other manifestations
• Patients are more ill than those with aseptic meningitis
• Cerebrospinal fluid may be entirely normal or may show some lymphocytes and in some instances (eg, herpes simplex) red cells as well.
Picornaviruses
▫ Enterovirus (polio, coxasackie, echo)*
▫ Rhinovirus (common cold)
▫ Heparnavirus (hepatitis A; HAV)
▫ Cardiovirus (cause encephalomyelitis and myocarditis)
▫ Apthovirus (foot and mouth disease of cattle)
Primary infection (EV)
▫ Lymphoid tissue and mucosa of tonsils & pharynx
▫ Virus then spreads to M cells and Peyers patches
and enterocytes of the intestinal mucosa
▫ Results in primary viremia
Secondary infection (EV)
(in absence of serum antibody)
▫ Virus spreads to receptor-bearing target tissues resulting in a secondary viremia and symptoms
IgA
secretory antibody response is transitory but can prevent the initiation of infection
IgG
Serum antibody blocks viremic spread to target tissue, preventing disease
Coxsackie Group A (1-24)
• Cause vesicular rash around the mouth and on the hands or soles of feet (hand-foot-and- mouth disease), and sore throat, herpes- like vesicles in the buccal mucosa (herpangina)
▫ often A16 is cause
• Can cause aseptic meningitis
• Can cause acute hemorrhagic conjunctivitis (A24 specifically)
• No commercially available vaccine
Hand, Foot, Mouth Disease (HFMD)
viral infection with a typical rash and mouth lesions (herpangina = painful blisters in mouth); note lesions on hands and feet can be on the palms or soles
• It is caused by coxsackie virus infection (most commonly by A16)
• The most susceptible are infants and toddlers. Adults usually are only carriers.
Coxsackie Group B (1-6)
• Can cause pleurodynia (severe paroxysmal pain arising from the muscles between the ribs; aka Devil's grip, epidemic myalgia), myocarditiss*, pericarditis and dilated cardiomyopathy leading to heart failure.
• Can cause aseptic meningitis
• No commercially available vaccine
Echovirus
(Enteric Cytopathic Human Orphan Viruses)
• Types 1-34
• A leading cause of
viral meningitis.
• Also cause a rash.
• No commercially available vaccine
Pleconaril
- for infants and those who are immunodeficient
▫ an orally administered antiviral agent that inhibits enterovirus replication by a capsid- binding mechanism wherein it prevents uncoating of the viral RNA
▫ It attains several-fold higher concentrations within the CNS than in serum
Paralytic Poliomyelitis
• 85% caused by Poliovirus Type 1
• Occurs in <2% of infected persons
• Paralysis appears 3-4 days after minor illness or after non-paralytic poliomyelitis due to destruction of anterior horn cells of spinal cord and motor cortex of brain
• Paralysis is usually a flaccid paralysis due to lower motor neuron damage
▫ Can also involve a painful spasm of non-paralyzed muscles similar to a charley horse
• Maximal involvement within a few days after the paralytic phase begins
• Maximal recovery within 6 months
Bulbar Poliomyelitis
• More severe than paralytic polio
• May involve muscles of pharynx, vocal cords
and respiratory muscles
• Patients are maintained in chambers that
provide external respiratory compression (iron
lungs)
• Death may result in 75% of patients, usually due
to respiratory infections
Progressive Postpoliomyelitis Muscle Atrophy
• Occurs decades after paralytic polio in 20-80% of patients
• Not due to persistent poliovirus infection
• Affected people have deterioration of originally
affected muscles
• Syndrome thought to be due to loss of neurons in initially affected nerves
Crytococcosis
• Chronic to acute infection w/ C. neoformans
• Organism is an encapsulated yeast in culture at 25oC and
37oC and in tissues
• Has thick polysaccharide capsule that inhibits phagocytosis
• Known since 1894 to be able to infect humans but wasn't recognized as a major health threat until the 1980s with the onset of the AIDS pandemic
• Lung is 1o site of infection; but has tendency for systemic spread to CNS & meninges
• C. neoformans is the leading cause of fungal meningitis
▫ Important esp. in patients w/ AIDS and transplant recipients
Cryptococcal Meningitis
• Increased risk in patients with deficiencies in cell- mediated immunity (AIDS is highest risk group, CD4 < 100)
• Clinical presentation:
▫ Insidious onset of headache +/- fever.
▫ Meningismus (having the signs and symptoms of meningitis without objective findings, such as finding the etiologic agent) is less common
• Often more acute in non-AIDS patients (they have an intact immune system that responds to the infection)
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