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Neuro I > Microbiology-Viral Meningitis > Flashcards

Microbiology-Viral Meningitis Flashcards

1
Q

What types are viruses are particularly prone to going viremic and causing meningitis?

A

Systemic paramyxoviruses (respiratory tract -> blood), enteroviruses (gains access through the mouth -> gut -> blood), arboviruses (direct injection into blood from arthropod).

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2
Q

What are major viruses that gain access to neurons, spread to the brain and cause encephalitis?

A

Herpes virus and rabies virus

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3
Q

What does neuronal viral spread typically lead to?

A

Encephalitis (neurons are being killed off)

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4
Q

What does viremia typically lead to?

A

Meningitis

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5
Q

What virus type is the most common cause of meningitis across all age groups?

A

Enteroviruses (85-95%)

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6
Q

What acute CNS problems can happen in patients who are infected with measles and were never vaccinated?

A

Acute disseminated encephalomyelitis (ADEM)

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7
Q

What slow progressing CNS problems can happen in people who are immunocompromised?

A

Measles inclusion body encephalitis (MIBE)

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8
Q

What very slow progressing CNS problems can happen in people who had measles as a kid that don’t present until adulthood?

A

Subacute sclerosing panencephalitis (SSPE)

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9
Q

How do you differentiate between viral meningitis and encephalitis?

A

Meningitis: nuchal rigidity & photophobia. Encephalitis: alterations in consciousness, seizures, paralysis and changes in vision or sensation.

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10
Q

What agents of viral encephalitis are specialized neuron killers?

A

Herpes (hemorrhagic necrosis and neuronophagia), Poliovirus (motor neuron destruction) and Rabies virus

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11
Q

How do you differentiate viral from bacterial meningitis?

A

Spinal tap and CSF analysis in the lab. You can also look for IgG antibodies in the CSF specific for the infecting agent.

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12
Q

Why is poliovirus so infectious? What are its viral characteristics?

A

It is a picornavirus: non-enveloped, 5,3 and 2 fold axis of symmetry, isocahedral structure, +ssRNA (VERY INFECTIOUS) that will produce a long polyprotein precursor

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13
Q

What enteroviruss cause meningitis and encephalitis?

A

Polio, coxsackie and echo viruses. These all have the brain and meninges as their target tissues.

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14
Q

How many serotypes are there of poliovirus? What are the different polio vaccines?

A

3 serotypes. Salk = killed vaccine (all 3 serotypes). Sabin = oral attenuated vaccine (all 3 serotypes, increased amount of secretory IgA).

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15
Q

How is poliovirus spread?

A

Fecal oral route, particularly in contaminated water

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16
Q

What determines if poliovirus will cause paralysis or be eliminated without the host even knowing?

A

How quickly antibody can be made before viremia occurs and the virus gains access to the CNS

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17
Q

Why are parents who have not been vaccinated against polio at risk for paralysis when their child has been given the Sabin vaccine?

A

Reversion: serotype three mutates fairly easily and can infect the immunodeficient parent while changing diapers.

18
Q

Why would Sabin be preferred to Salk when vaccinating kids against polio?

A

Sabin only requires one dose

19
Q

How can labs determine whether the poliovirus in a caretaker is related to the vaccine strain or is a wild-type virus?

A

Determine the nucleic acid sequence of the virus

20
Q

What arboviruses are associated with encephalitis? Where do these come from?

A

*

21
Q

What are the clinical symptoms of arbovirus infection?

A

Fever, rash, aches and chills. Progression to encephalitis is indicated by changes in mental status (seizures, optic neuritis, ataxia etc.)

22
Q

What is the main way to prevent arbovirus spread? What puts you at highest risk for severe CNS infection?

A

Vector control. Advanced age puts you at highest risk for severe infection.

23
Q

A 50 year old male comes to see you complaining of fever, rash, aches and chills. He also had a seizure this morning. He works at the zoo. What portion of the zoo is this patient most likely to work in if serology reveals West Nile Virus?

A

Birds

24
Q

A 50 year old male comes to see you complaining of fever, rash, aches and chills. He also had a seizure this morning. He works on a farm. What animals is he most likely to work with if he is diagnosed with Japanese encephalitis?

A

Pigs. Pigs have standing water that attracts mosquitos and then mosquitos give us the virus. Birds can also be a reservoir.

25
Q

What are the different types of Toga viruses? Which are more prevalent?

A

Western Equine Encephalitis (prevalent), Eastern EE (rare, but most fatal) and Venezuelan EE (prevalent and weaponized).

26
Q

What are the different types of Bunyaviruses? How are these spread?

A

California encephlitis, La Crosse. They are spread by the Aedes mosquito.

27
Q

What is the most important cause of pediatric arbovirus encephalitis in the US?

A

La Crosse

28
Q

What types of viral encephalitis peak during the summer?

A

Enteroviruses, tick-borne and mosquito-borne viruses

29
Q

A 21 year old man comes to see you in the ED with a sudden onset fever, headache, and severe low back pain. He just came back from SE Asia 3 days ago. Physical exam reveals a faint maculopapular rash and conjunctivitis. How was the causal virus most likely transmitted?

A

Insect (possible JE, Dengue or Chikungunya)

30
Q

What are the viral characteristics of the virus shown below?

A

This is a bullet-shaped rhabdovirus (possibly Rabies). -ssRNA, enveloped.

31
Q

What are risks for rabies in the US?

A

Animal saliva (raccoons, skunks), bat feces and organ donation from a previously infected host that never manifested symptoms.

32
Q

A patient comes to see you with a fever and headache that started yesterday. His throat hurts really bad and he is delirious. History reveals being bitten by a raccoon 19 years ago. Peripheral nerve biopsy is shown below. How will this virus progress through his nervous system if it goes untreated?

A

This patient has rabies, note the Negri cytoplasmic inclusion body. Rabies is taken up by peripheral nerves at the site of infection. It is transported via retrograde axoplasmic flow to the CNS if left untreated.

33
Q

A bunch of boys were out feeding a dog, but the dog wouldn’t eat any of their food and bit one of them and ran away. How would you want to treat these boys?

A

HRIG (passive human antibody) + vaccinate before symptoms begin and they will not develop rabies.

34
Q

What is a key clue for meningitis or encephalitis if you think a patient might have mumps?

A

Parotid gland swelling

35
Q

What paramyxoviruses can cause encephalitis or meningitis?

A

Measles and mumps

36
Q

What type of viral meningitis may present with a maculopapular rash? What do you know about the progression of this infection if you see this rash?

A

Measles. The skin is the last of all the organs to get infected, so you know everything else has been hit by measles.

37
Q

What physical exam finding will you see in measles just prior to skin manifestations?

A

Koplik’s spots on the inside of the cheeks.

38
Q

How might you see herpes virus infection on CT or MR?

A

HSV encephalitis will show decreased density and loss of sulci

39
Q

What viruses can cause congenital viral meningitis? What would you look for on CT scan of a pregnant woman with possible CMV encephalitis?

A

HSV-2 (during delivery) and CMV (most frequent cause of congenital viral infection). With CMV you may see CNS calcifications.

40
Q

What drugs do you give to a pregnant woman with herpes to prevent microcephaly in the neonate? How do these drugs work?

A

Acyclovir or Ganciclovir. They work by causing early chain termination during viral replication.

41
Q

What types of viral encephalitis are patients with HIV at particular risk for?

A

PML (progressive multifocal leukoencephalopathy) which causes widespread demyelination.

42
Q

A 75 year old woman presents with a fever, focal seizures and muscular weakness on one side of her body. MRI reveals hemorrhagic lesions in the inferior medial portion of her temporal lobe. What antiviral treatment is recommended?

A

Acyclovir is used to treat this possible herpes infection.

Neuro I (52 decks)

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