Hepatitis

Question 1

Hepatitis A

Answer 1

Picornaviridae 
-Small, +ssRNA
-naked (non env)
-Replicates in the cytoplasm 
−Low infectious dose 
−Humans are the main reservoir
−One serotype
-Fecal-oral
-no chronic carrier state
-short incubation period
-risk: Crowded living conditions
−Common in families and institutions, summer camps, day care centers, neonatal intensive care units & among military troops
-Pathogenesis: Replication in the GI tract-->infect the liver where it replicates-->transported to the intestines via bile-->sheds in feces (infectious) & there’s a *transient viremia; damage to liver due to CTL response
Disease
−Low viremia
−No carrier state
−No chronic infection
−No link to hepatocellular carcinoma
−Incubation period: 3-4 weeks
−Duration of symptoms including fever, jaundice & elevated ALT: 2-4 weeks
−

Question 2

Hepatitis B

Answer 2

Hepadnaviridae
-Small, partially dsDNA
-enveloped
−Replicates in the *nucleus
−Uses reverse transcription inside the nucleocapsid
−Only one serotype with immunity due to antibodies to HBs (called anti-HBs or HBsAb)
−Four subtypes (adr, adw, ayr, ayw) and *eight genotypes (A-H)
−Reservoir: Humans only
-Blood, sex, perinatal, percutaneous
-chronic carrier state
-long incubation period (70-100 days)
-risk: PWID; birth from HBsAg+ mother; MSM
Disease
Acute infection
−Symptoms are dependent on age at infection: 30%–50% of persons aged ≥5 years have initial signs and symptoms; children under 5 years old are usually asymptomatic
−Incubation period: 90 days on average
−More severe than HAV
−May cause serum sickness-like rash & arthritis (due to antibodies)
−Only 1% of acute infections result in fulminate hepatitis
Chronic infection
−Defined as having detectable HBsAg for at least six months
−Extrahepatic manifestations occur in up to 20% of HBV-infected individuals and may involve the gastrointestinal, renal & nervous systems
Diagnosis (chart!)
−Determine HBV status by measuring HBsAg, anti-HBc (IgM & total) & anti-HBs (total)
-tx: Interferon-α & various nucleos(t)ide analogs
-prev: Vaccine & Ig

Question 3

Hepatitis C

Answer 3

Flaviviridae
-Small, +ssRNA
-enveloped
−Replicates in the cytoplasm
-Blood, sex, perinatal, percutaneous
−Reservoir: Humans only
-chronic carrier state
-long incubation period (42-49 days)
-highest prevalence in Egypt
−Six genotypes (and over 50 subtypes)
−Most common genotypes in U.S. are 1, 2, & 3
−Quasispecies within an infected patient to allow for escaping the immune system
-risk: PWID
Pathogenesis
−Quasispecies interfere with effective humoral & cell-mediated immune responses
−HCV masquerading as a lipoprotein during assembly & secretion can evade immune system
−Chronic (ineffective) inflammation leads to CTL-mediated liver injury, hepatocellular carcinoma (HCC), end-stage liver disease (ESLD)
Diagnosis
−Serology for HCV antibodies (IgM/IgG) via enzyme immunoassay (EIA) or enhanced chemiluminescence immunoassay (CIA) to detect antibodies to **core, NS3, NS4 & NS5 proteins
−Confirmatory test using HCV RNA test via RT-PCR, transcription mediated amplification (TMA) or branched DNA testing (bDNA)
-tx: Ribavirin, interferon, protease or polymerase inhibitor
-can be in *sustained virology response (undetectable)
-prev: Bloodscreening; safe sex; safe IDU
-No vaccine & no Ig

Question 4

Hepatitis D

Answer 4

Deltavirus
-Small, -ssRNA
-enveloped
−Replicates in the nucleus using a *ribozyme
−a satellite virus (requires HBV co-infection)
-can cause *co-infx or *superinfx
-Blood, percutaneous
-risk: PWID
Diagnosis
−For HBsAg-positive patients, **detection of anti-HD is the first step
-tx: treat HBV vaccine
-prev: HBV vaccine (prevents co-infx of HBV & HDV, cannot prevent HDV superinfx)

Question 5

Hepatitis E

Answer 5

Hepeviridae
-Small, +ssRNA
-naked (non env)
−Replicates in the cytoplasm
−One serotype but four genotypes;
-Humans are the reservoir for genotype 1 & 2
-Genotypes 3 & 4 can be zoonotic (*pigs, primates, cows, rats)
-Fecal-oral
-no chronic carrier state
-short incubation period
-risk: Travelers
Disease manifestations
−Incubation period: ~2-8 weeks
−Duration of symptoms: ~2 weeks
−Acute infection similar to HAV, except for:
-Slightly higher mortality rate (up to ~4%)
-Greater risk for fulminant hepatitis & death for pregnancy women, especially 3rd trimester with mortality rate at ~20-27%
-Chronic infection possible in immunosuppressed patients
-tx: Supportive & proper nutrition. liver transplant if severe
-prev: Hygiene; safe water. *No vaccine in U.S. *immune globulins are not protective