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Microbio Viruses > GI Viral Infection > Flashcards

GI Viral Infection Flashcards

1
Q

What AB is used for bacterial meningitis?

A

Ceftriaxone

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2
Q

What family of viruses often causes aseptic meningitis?

What ocular signs are present?

A

Picornaviridae (enteroviruses)

Ocular nerve swelling and peripapular swelling (region right around optic nerve head)

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3
Q

Pathogenesis of viruses that DO cause diarrhea

A

Slight viremia but not systemic signs
Does NOT replicate in blood
Cause very little / no cytopathology in gut
Diarrhea caused by toxins

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4
Q

Pathogenesis of viruses that do NOT cause diarrhea

A

Enteroviruses
Disseminated infections
Cause significant cytopathology

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5
Q

4 main enteroviruses

Other non GI virus in picornaviridae family

A

Polio, cocksackievirus, echovirus, enterovirus

Rhinovirus

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6
Q

What does echovirus stand for?

A

Enteric cytopathic human orphan

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7
Q

What vaccines are available for picornaviridae?

A

Polio and Hep A

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8
Q

Hardy characteristics of enteroviruses

A

High titers w/ lots shed in feces

Hardy: stable at pH 3.0, can survive some ethanol / lysol. Organic matter in feces protects against inactivation

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9
Q

Susceptibilities of enteroviruses

A

Sensitive to formaldehyde.

Inactivated by 50 deg C.

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10
Q

Structure of enteroviruses

A

Small, non-enveloped RNA viruses

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11
Q

Do enteroviruses cause local or disseminated infections?

A

Disseminated

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12
Q

Main sxs of enteroviruses

A

Mild self-limiting illness w/ rash, colds, aseptic meningitis, pericarditis / myocarditis, paralysis, and hepatitis

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13
Q

Which enterovirus causes myocariditis?

A

Coxsackievirus

Leading cause of heart transplants and heart failure

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14
Q 
Poliovirus
Spread
Seasonal peak
Incubation period
Sxs
Pathogenesis of paralysis
Cause of death
Treatment
Vaccines
A
  • Spread via fecal-oral. Enters body through Peyer’s patches and M cells in gut.
  • Peaks in late summer due to contaminated swimming pools.
  • 2 week incubation period
  • Most infections are mild and self-limiting. May cause aseptic meningitis.
  • Invades CNS in 1-2% of infections. Replicates in motor neurons in anterior horn, brain stem, and motor cortex.
  • Surviving pxs usually regain some motor function. Post-polio syndrome occurs later in life.
  • Death often occurs due to suffocation
  • No antivirals. Supportive care.
  • Salk Vaccine: formalin inactivated virus. 3 serotypes. Recommended.
  • Sabin Vaccine: live attenuated virus. 3 serotypes. May revert to virulence (most common w/ type 3 strain) so not used anymore.
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15
Q 
Hepatitis A virus
Classification
Incubation period
Sxs
Age effects
Vaccine
A
  • Part of picornaviridae family but not an enterovirus
  • Long incubation period (avg 1 month)
  • Abdominal pain, fatigue, increased liver enzymes, dark urine, jaundice, nausea, vomiting
  • Children less than 6 y/o are generally asymptomatic. Adults are generally symptomatic.
  • Vaccine: inactivated whole virus (HAVRIX or VAQTA). Approved for pxs 12 months old +
  • Recommended for people at high risk of exposure: international travelsers, men who have sex w/ men, using illegial drugs, working at sewage plant, chronic liver disease, healthcare workers.
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16
Q 
General characteristics of viruses that cause diarrhea
Mechanism of spread
Incubation period
Sxs
Pathology of diarrhea
Site of replication
Therapy
Time course
A
  • Spread via oral-fecal. Large amounts shed in GI tract. Shedding can last weeks after sxs stop. Resistant to low pH.
  • Incubation period 1-3 days
  • Abrupt onset of vomiting, diarrhea, and GI cramps. May also cause headache, myalgia, and low grade fever.
  • Diarrhea is usually watery (except for coronavirus)
  • Very little intestinal inflammation / cell death. Some shortening of microvilli may cause maladsorption. Toxins.
  • Viruses only replicate in enterocytes.
  • No antivirals. Only vaccine for rotavirus. Tx w/ supportive care (hydration is most important). Do NOT use anti-peristaltics.
  • Usually recover in 1-2 days.
17
Q 
Rotavirus
Seasonal peak
Population
Pathogenesis of diarrhea
Diagnosis
Therapy
Vaccine
Precautions against vaccine
A
  • Peaks in winter. AKA Winter Diarrhea.
  • Acute gastroenteritis in kids less than 2 y/o. Rare in adults due to presence of Ab (90% of people older than 4 y/o are seropositive). SINGLE MOST IMPORTANT CAUSE OF DIARRHEA IN KIDS LESS THAN 3 y/o, especially in unvaccinated children.
  • Toxin similar to cholera. NS4 protein activates adenylate cyclase.
  • Mild fever may occur.
  • Diagnosis is made on the basis of age, seasonality, and sxs. ELISA is available.
  • No specific therapies. Antiemetics may be used, but NOT anti-peristaltics.
  • Vaccine contains 5 reassortment rotaviruses. Attenuated live virus. Vaccine administered at 2, 4, and 6 months. Minimum age 6 weeks. Do not start after 12 weeks.
  • Precautions – immunosuppresion, recent receipt of blood (may contain Abs to virus), acute gastroenteritis, pre-existing chronic GI disease, infants w/ history of INTUSSESCEPTION (intestine telescopes on self)
18
Q 
Astrovirus
Incidence
Incubation period
Transmission
Sxs
Peak
Pathogenesis of diarrhea
Diagnosis
Tx
A
  • Causes 20-30% of diarrheal infections in US.
  • 10-70 hr incubation period
  • May also be spread by vomit.
  • Acute gastroenteritis in kids.
  • Fever is NOT common.
  • Peak incidence in winter.
  • Toxin: capsid alters actin cytoskeleton opening cell-cell junctions
  • Diagnosis based on sxs and age. ELISA.
  • No therapy.
19
Q 
Norovirus
Incidence
Incubation period
Leading cause of what?
Sxs
Transmission
Peak
Diagnosis
Tx
A
  • Causes 20-30% of infections in US.
  • 12-60 hr incubation period
  • Leading cause of hospitalization due to diarrhea in US. LEADING CAUSE OF DIARRHEA IN ADULTS.
  • Acute gastroenteritis in kids and adults. Diarrhea is more common in adults. Vomiting is more common in kids.
  • Possible airborne transmission as well as fecal-oral.
  • No seasonal variation. Often seen as outbreaks in schools, ships, etc.
  • Diagnosis made based on age and sxs. PCR is available.
  • No treatments.
20
Q 
Adenovirus
Incidence
Incubation period
Subtypes
Population
Peak
Diagnosis
Tx
A
  • 5-15% of infections in US.
  • Short incubation period 2-4 days.
  • Diff subtype causes respiratory infections.
  • Mainly infects infants / kids
  • No seasonal incidence. Usually sporadic outbreaks.
  • Diagnosis made based on sxs. ELISA.
  • No treatment.
21
Q 
Coronavirus
Incidence
Associated sxs
Pathogenesis of diarrhea
Population
Peak
Diagnosis
Tx
A
  • 10% of infections in US.
  • Diarrhea may be associated w/ respiratory coronavirus as well (SARS CoV, MERS CoV).
  • May cause blood / mucus in stool, indicating more cellular invasion / cytopathology compared to other viruses.
  • Most frequent in kids

Microbio Viruses (9 decks)

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