Viruses Flashcards
Where do enteric viruses primarily replicate?
distal ileum
What enteric infections are agammaglobulinemia patients prone to?
chronic EV infections of CNS
Typical EV incubation period? Exception?
- 3-6 days
- acute hemorrhagic conjunctivitis = 1-3 days
Who gets asymptomatic EV infections?
50% - usually older kids and adults
MOst common EV clinical manifestation?
non-specific febrile illness
Which EV causes herpangina and stomatitis/anterior mouth lesions?
Coxsackie A strains and Cox A16 (HFMD)
What is pleurodynia?
- Bornholm disease = resp EV manifestation
- fever, sharp episodic pain in chest/upper abdomen
- young adults
- Cox B3, B5
How common are GI Sx in EV infections?
- 1/3 patients
- vomiting and diarrhea are common but are rarely severe
What 2 virus types can commonly cause hemorrhagic conjunctivitis?
EV and adenoviruses
CV manifestations of EV infections?
- pericarditis, myocarditis, or both
- young adults/adolescents
- Cox B5, Echo 6
- commonly arrhythmias, usually recover completely but may be linked to chronic cardiomyopathy
Viral exanthems are common with EV infections. Who gets them?
expression inversely related to age
What is the most common neurologic manifestation of EV infections?
- aseptic meningitis –> EV accounts for 80-92% of AM cases
Who gets aseptic EV meningitis? When?
- summer and fall
- <1 year but also older children
Course and prognosis of aseptic meningitis?
- 7-14 days presenting with fever/irritability or fever/headache (photophob, NV, rash, pharyngitis)
- <70% have nuchal rigidity
- excellent prognosis
What is the most profound of serious EV disease? Mimics?
- severe neonatal infection
- may mimic bacterial sepsis, disseminated/CNS HSV infection
How and who gets severe neonatal EV infection?
- perinatal from mother with EV infection in week before delivery (late infection so no maternal AB yet)
- <10 days (immune deficient)
Common viral cause of gastroenteritis in children worldwide?
Rotaviruses (decreasing due to vaccination, especially in US)
Morphology of rotaviruses?
- reoviridae
- segmented, non-enveloped, dsRNA
- 2 shell nucleocapsid containing structural proteins
What ages get most severe RV GI disease?
3-24 months, milder disease throughout life
Contagious and shedding of RV illnesses?
- highly contagious
- high viral concentrations in stool - shedding begins a few days BEFORE illness and can persist for 3+ weeks
Pathophysiology of RV infections?
- attach to villus epi cells (enterocytes) in small intestine
- replications leads to dec absorption of salt/water and failure to process/absorb complex sugars –> inc osmotic load in gut lumen
What is a toxin associated with RV?
non-structural protein 4 = enterotoxin (acts on epi receptor to potentiate Cl- secretion = secretory diarrhea)
Course of RV GI?
- incubation 1-3 days
- lasts 3-8 days (longer in IC)
- fever and vomiting followed 24-48 hours by diarrhea (dehydration)
Which 2 caliciviruses are associated with disease in humans?
- norovirus
- sapovirus
What is most common cause of outbreaks of gastroenteritis in closed populations?
norovirus
Who do sapoviruses commonly occur in?
children with sporadic diarrhea
Morphology of caliciviruses?
- non-enveloped ssRNA
- diverse genetically and antigenically
- classified into genogroups and genotypes
Most common cause of foodborne illness and foodborne disease outbreaks in US?
norovirus
When do calicivirus infections occur?
cold months
Course of calicivirus infections?
- older = more vomiting
- V and D; usually don’t have fever and lasts 1-4 days
- incubation 12-48 hours
Shedding of calicivirus?
- viral excretion peaks 4 days after exposure and may persist for 3 weeks (worse in IC)
Adenovirus morphology?
- dsDNA, non-enveloped
- NO seasonality
- many manifestations, mild to severe
What does adenovirus gastroenteritis look like in children?
- 4-17% of diarrhea in children <4
- incubation 3-10 days
- diarrhea tends to be more protracted (8-12 days) and severe than other EV diarrheas + vomiting, low-grade fever
Astrovirus morphology?
- non-enveloped ssRNA
Who gets astroviruses? Presentation?
- children >4, late winter/early spring
- mild diarrhea lasting 5-6 days + V, fever, ab pain
- outbreaks can occur in closed populations
Where is inflammation primarily observed in acute hepatitis? What is seen?
- portal triad
- intracellular cholestasis
- piecemeal necrosis with Councilman apoptotic bodies
- ballooning degeneration
What percent of fulminant hep cases are caused by viral hep?
12%
What two HV’s commonly lead to chronic hep?
- HCV = most common
- HBV = younger age at infection is assoc w/ inc risk of chronicity
What HV is assoc with a carrier state?
HBV
IP and general presentation of HAV?
- 3-6 weeks
- benign, self-limited; flu-like syndrome with RUQ pain with mild-severe icteric phase
How is HAV primarily transmitted?
- fecal-oral in contaminated water/shellfish/food
How is HAV detected?
- IgM anti-HAV = acute (inc assoc with peak of Sx)
- IgG (total anti-HAV) = convalescent
5 manifestations of HBV?
- Sx or asym acute hep
- fulminant hep
- chronic hep w/ cirrhosis and HCC progression
- carrier state
What HBV patients usually progress to chronic disease?
those infected early in life (90% progression) vs. only 5% infected as adults
3 ways to transmit HBV?
- parenteral
- intimate (STD)
- perinatal (endemic)
1/3 unknown
IP of HBV? Icteric phase marked by?
- 6-16 weeks
- inc LFT’s, dark urine
What causes ground glass appearance in HBV?
- cytoplasm packed with spheres and tubules of HBsAg
When is HBsAg detected in acute disease?
- appears before onset
- peaks during overt disease then declines to undetectable levels in 3-6 months?
When is HBsAg detected in chronic disease?
- increases during acute infection
- remains persistently elevated
When does anti-HBs appear in acute disease?
- does not rise until acute infection is over
- usually not detectable for weeks-months after HBsAg has disappeared
- may persist for life
When does HBeAg appear?
- soon after HBsAg
- signifies active viral replication
- persistence indicates continued rep, infectivity and probably progression to chronic disease
What does the appearance of anti-HBe mean?
implies that acute infection has peaked and is waning
Pattern of IgM anti-HBc appearance?
- becomes detectable shortly before onset of symptoms
- concurrent with elev LFT’s
- IgM replaced by IgG over months (seen as inc total anti-HBc)
How is HCV transmitted?
- parenteral (IVDA most common RF)
- possible sexual
- 23% unknown
Three outcomes of HCV infection?
- acute with recovery = 15%
- fulminant rare
- chronic = 85%
Complications in patients with chronic HCV?
- 80% stable disease
- 20% cirrhosis and possible HCC
What makes HCV chronic progression more rapid?
EtOH, toxins
Which HCV genotype is most prevalent in US? Why is this a problem?
- HCV type 1
- most difficult to treat
IP of HCV? What marks chronic disease?
- 6-8 weeks
- asymp periods alt with periods of active disease
Serologic pattern in chronic HCV?
- initial symptomatic infection marked by elev LFT’s, HCV RNA (PCR)
- takes months for anti-HCV to develop
- chronic disease has active periods with elev LFT’s and HCV RNA
What is limiting and unique about HDV?
dependent upon HBV to assist in replication and packaging into infective virions
Primary form of transmission of HDV?
parenteral
What determines disease presentation of HDV?
- when infection is acquired relative to HBV
- co-infection = both
- superinfection = HBV then D
Manifestation of D/B co-infection?
- acute or fulminant hep
- 95% recover (rare progression to chronic disease)
Manifestation of B-D superinfection?
- new acute/fulminant infection
- 7-10% die from fulminant
- 10-15% recover from acute hep
- 80% go on to have chronic HBV and HDV infections
Which zoonotic virus is associated with fecal-oral water transmission?
HEV
IP and typical presentation of HEV?
- 2-9 weeks
- flu-like syndrome and icteric phase
- usually self-limited
What is associated with high HEV mortality?
- pregnancy
- 15% of patients gets fulminant hep
Which LFT is elevated more in viral hep?
AST > ALT
What 4 serologies are included in acute panel?
- HBsAg
- IgM HBc
- HAV IgM
- HCV EIA (PCR if +)
What 3 hepatitis etiologies should always be at the top of your DDx?
viral
drug-induced
toxic (occ, hobby)
Max neut band %?
10%
What type of anemia is Fe deficiency? MCH/MCV?
- microcytic, hypochromic
- low
What type of anemia is folate deficiency? MCV?
- megaloblastic
- high
Upper normal limits of ALT, AST, alk phos?
- 40, 40, 120
Quick and dirty assessment of lab hepatic vs. biliary disease?
look at ratios between patient values and upper normal limits
How do AST and ALT elevations compare in EtOH disease?
AST:ALT = 2:1
What 3 viruses are blood borne pathogen concerns?
HIV, HBV, HCV