GI Viral Infection Flashcards
(21 cards)
What AB is used for bacterial meningitis?
Ceftriaxone
What family of viruses often causes aseptic meningitis?
What ocular signs are present?
Picornaviridae (enteroviruses)
Ocular nerve swelling and peripapular swelling (region right around optic nerve head)
Pathogenesis of viruses that DO cause diarrhea
Slight viremia but not systemic signs
Does NOT replicate in blood
Cause very little / no cytopathology in gut
Diarrhea caused by toxins
Pathogenesis of viruses that do NOT cause diarrhea
Enteroviruses
Disseminated infections
Cause significant cytopathology
4 main enteroviruses
Other non GI virus in picornaviridae family
Polio, cocksackievirus, echovirus, enterovirus
Rhinovirus
What does echovirus stand for?
Enteric cytopathic human orphan
What vaccines are available for picornaviridae?
Polio and Hep A
Hardy characteristics of enteroviruses
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
Susceptibilities of enteroviruses
Sensitive to formaldehyde.
Inactivated by 50 deg C.
Structure of enteroviruses
Small, non-enveloped RNA viruses
Do enteroviruses cause local or disseminated infections?
Disseminated
Main sxs of enteroviruses
Mild self-limiting illness w/ rash, colds, aseptic meningitis, pericarditis / myocarditis, paralysis, and hepatitis
Which enterovirus causes myocariditis?
Coxsackievirus
Leading cause of heart transplants and heart failure
Poliovirus Spread Seasonal peak Incubation period Sxs Pathogenesis of paralysis Cause of death Treatment Vaccines
- 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.
Hepatitis A virus Classification Incubation period Sxs Age effects Vaccine
- 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.
General characteristics of viruses that cause diarrhea Mechanism of spread Incubation period Sxs Pathology of diarrhea Site of replication Therapy Time course
- 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.
Rotavirus Seasonal peak Population Pathogenesis of diarrhea Diagnosis Therapy Vaccine Precautions against vaccine
- 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)
Astrovirus Incidence Incubation period Transmission Sxs Peak Pathogenesis of diarrhea Diagnosis Tx
- 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.
Norovirus Incidence Incubation period Leading cause of what? Sxs Transmission Peak Diagnosis Tx
- 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.
Adenovirus Incidence Incubation period Subtypes Population Peak Diagnosis Tx
- 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.
Coronavirus Incidence Associated sxs Pathogenesis of diarrhea Population Peak Diagnosis Tx
- 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
