Enteric Viruses 1 and 2 Flashcards
Virology of reoviruses
- Double protein capsid
- dsRNA
- Segmented genome
- Environmentally rugged - fecal oral transmission
What are the human-infecting reoviruses and what do they cause?
- Orthoreoviruses - cause mild GI Syx
- Rotaviruses - Significant gastroenteritis
Cause of death associated with rotaviruses?
Death due to dehydration
Pathogenesis of rotavirus?
- Primarily infects the cells of the small intestinal villi
- Impaired villus function leads to impaired hydrolysis of carbs
- Rotavirus nonstructural protein 4 - “Enterotoxin” that interferes w/ Na transport pumps, profuse watery diarrhea
- Virus shed in stool
What demographic are typically infected by rotavirus?
Children b/w 4 and 24 months
What are the signs of rotavirus infection?
- Dehydration - may be unremarkable
- Hx of exposure to other children
- N/V/F
Labs used for Rotavirus Dx?
Available but rarely used
Tx and Px for rotavirus?
Largely supportive Tx w/ rehydration: No soda, soup, milk, free water
Use Pedialyte
Px: Wash hands
Do not use antiemetics or antidiarrheal medications
Norovirus virology?
- (+)ssRNA in the Caliciviridae family
- Norwalk virus is prototype
- Fecal oral
- Highly contagious
- Cruise ships and summer camps
Typical Syx of Norovirus?
- Low fever
- Anorexia, N/V - PROFUSE
- Abdominal cramps
- Watery diarrhea
Difference b/w rotaviruses and noroviruses?
- Nausea more common in noroviruses
- Dehydration more likely in rotaviruses
Similarities b/w rotaviruses and noroviruses?
- Diarrhea
- Fecal oral
- Self-limited
Enterovirus virology?
- Small naked icosahedral
- (+)ssRNA
- Environmentally rugged
- Primary replication in the gut spread to regional lymph node
- Possible dual tropism resulting in rare CNS manifestations
What are the enteroviruses?
- Polioviruses
- Coxsackie A
- Coxsackie B
- Echoviruses
What is different b/w rota/noroviruses and enteroviruses?
- Rota/noros stay in gut and enteros have possible secondary replication outside the gut
- Enteroviruses can rarely invade CNS
Similarities b/w rota, noro, and enteroviruses?
- All replicate in gut
- have RNA genomes
- Fecal Oral
What immunity is protective against Polio?
IgA and IgG
Vaccines for Polio?
- Inactivated - dead, Salk vaccine; Used in first world
- Attenuated - weakened, Sabin vaccine, oral polio; Virus weakened and causes attenuated polio
Polioviruse pathogenesis?
- Fecal oral enteric infection
- uses CD155 receptor to enter and infect epithelial lymphoid cells
- CD155 on gray matter in CNS cells
- Can enter CNS and cause problems via lytic virus replication and immune response
What is post polio muscle atrophy?
Following acute polio attack, some of the neurons are killed off. If some of the cell bodies remain, remodeling and reinervation occurs. Later on, the nerves burn out with Syx of muscle weakness again.
Syx of polio infection on exam?
Nonparalytic or paralytic poliomyelitis
What tests are performed on exam?
- Lumbar puncture
- Virus recovery
- MRI - inflammation of anterior horns
Polio Tx?
No specific Tx exists; Supportive care and possible positive pressure ventilation
What is postpolio syndrome?
New Hx of decreased muscle weakness/atrophy due to dysfunction in surviving motor neurons
What conditions does Coxsackie A cause?
- Herpangina
- Hand-Foot-Mouth Disease
- Acute Hemorrhagic Conjunctivitis
Herpangina pathogenesis?
- Acute febrile
- Small vesicular/ulcerative lesions on posterior oropharyngeal structures
- Summer
- Self-limiting
Labwork for herpangina?
Typically not required
Tx for Herpangina?
Supportive Tx - NO aspirin for kids
Hand foot mouth disease pathogenesis?
- Fecal-oral route/contact w/ skin lesions/oral secretions
- Syx follow invasion of mucous membranes
- Widespread apoptosis = characteristic lesions
Lab tests for HFM disease?
Usually unnecessary
Tx of HFM disease?
- Supportive
- Ensure adequate fluid intake
Pathogenesis of acute hemorrhagic conjunctivitis?
- Coxsackie virus A24
- Rapid onset of painful conjunctivitis
What should be avoided when treating acute hemorrhagic conjunctivitis?
Tx w/ topical steroids should be avoided!
What is the major complication associated with Coxsackie B infection?
Myocarditis
Describe pathogenesis of Coxsackie B virus
- Myocarditis - pump failure
- INflammation - edema and congestive HF
- Infants/pregnant at higher risk
Mild presentation of Coxsackie B? Severe?
- Mild - few/no Syx
- Severe - acute cardiac decompensation
What are findings on the Hx that may lead you to viral myocarditis Dx?
- Recent, nonspecific, flulike illness, gastrointestinal Syx
What labs should be performed if viral myocarditis is suspected?
- CBC - determine presence of anemia
- Sedimentation rate and C-reactive protein - markers of inflamm
- Creatine kinase-MB isozyme and Troponin I: Markers of myocardial damage
Best test to evaluate myocardial function?
Echocardiography
Utility of endomyocardial biopsy for viral myocarditis? Risks?
- Establishes Dx and classifies disease stage
- Safe and effective in older children
- Risk for very sick and infants
Viral myocarditis Tx?
- Admit to hospital if only mild signs of respiratory distress or congestive heart failure -rapid progression may occur
- Bed rest necessary
Medications for viral myocarditis?
- Immunosuppresives controversial
- Pleconaril being tested
Disease caused by coxackievirus B resulting in sudden occurrence of lancinating chest pain, fever, malaise and headache?
Pleurodynia
Target of coxsackievirus B in Pleurodynia?
Striated muscle in the chest causing lancinating chest pain
Exam findings of Pleurodynia?
- Headache fever malaise
- N/V/D and abd. pain in children
- Herpangina
- Pleural friction rub on stethoscoope exam
Findings on CXR for pleurodynia?
Typically normal
Patient most susceptible to Pleurodynia?
Newborn
Tx for pleurodynia?
No specfic Tx; Supportive care and follow up
What is aseptic meningitis?
Inflammation of the leptomeninges
What must be done when considering aseptic meningitis in DDx?
Rule out infection by bacteria or fungi: untreated outcomes are severe
What are the findings of aseptic meningitis on exam?
- Adults: Fever, meningismus, irritability, photophobia
- Neck stiffness, headache
Typical exam findings of a pediatric patient with aseptic meningitis?
- Less obvious Syx of fever, cold hands/feet, refusing food, fretful, blank stare, stiff neck
Specific infection signs of enteroviruses?
- Pharyngitis
- Pleurodynia
- Gastroenteritis
Common signs of measles and enterovirus infection?
Maculopapular rash
Signs of infection of Coxsackie A?
Herpangina
What test differentiates viral from bacterial meningitis?
CSF Tests
Tx for viral meningitis?
Mostly supportive care: Rest, hydration, antipyretics, pain and anti-inflammatory medications
What is the plan of action to treat infants with meningitis?
Broad-spectrum ABs and acyclovir
