Download HEPATITIS: Etiology, Differential and Transmission

HEPATITIS: Etiology, Differential and Transmission
Etiologies
1. Infections: a) targeting liver: Hep A, B, C, D, E, F, G viruses
b) liver not 1 target: CMV, HSV, EBV, Coxackieviruses, Yellow fever,
Ebola, Marburg, Toxoplasma, Q Fever
 The non-hepatitis infectious agents may cause elevations in serum
aminotransferase and less commonly in serum bilirubin levels
2. Drugs: many drugs and certain anesthetic agents (e.g. INH, halothane)
3. Alcohol - usually the serum aminotransferase levels are not as markedly elevated in
alcoholic hepatitis
4. Others: gallstones, tumors, genetic
Clinical Features
Acute Viral Hepatitis
- Non-specific: anorexia, abdominal pain, nausea, vomiting, weight loss, fatigue
- Fever, pruritis, dark urine, light stools, jaundice, hepatomegaly, splenomegaly
Chronic Hepatitis
- Non-specific: fatigue, RUQ pain, weight loss
- jaundice, ascites
Laboratory Features
high serum bilirubin, high liver enzymes (AST, ALT, LDH, GGT),
low albumin, high PT and PTT
Viruses
Hep A
- fecal-oral transmission (may transmit through blood and secretions)
- Only 1 serotype
- 2 – 7 weeks incubation (avg. 4 wks)
- Fecal shedding of the virus occurs during the incubation period and usually ceases a few
days after symptoms begin  infectivity often has already ceased when diagnosed
- Most infections are subclinical or unrecognized
- no chronic carrier state; lifelong immunity
- low mortality
- Diagnosis: IgM, IgG
- Vaccine: yes; killed virus
- No Tx
Hep B
- Transmission: blood (high), semen, vaginal secretion, saliva (moderate), vertical
transmission (usually during delivery) BUT doesn’t X placenta
- 2-5 month incubation
- Insidious onset of symptoms. Tends to cause a more severe disease than Hep A.
Asymptomatic infections occur frequently.
- Most likely of the viruses to have symptoms
- Chronic carriers: approximately 5% of infected individuals fail to eliminate the virus
completely and become persistently infected. Opp stats for kids. (if don’t clear virus
within one month will likely not be able to in future)
- See most symptoms after 5 years
- Very low rate of acute cases, 1%
Dx:
- no culture
- HBsAg – person has virus and is infectious; virus is replicating; can be chronic state;
don’t know when person got it
- Anti HBs - immunity to HBV; not found in chronic carriers
- Anti HBc - IgG; not a neutralizing Ab
- indicates past or active infection
both in immune and carrier
If IgM indicates a recent infection
- HBeAg – shows virus is replicating in liver, highly infectious, more likely to be chronic
- Anti HBe - good prognostic indicator; less infectious  means will eventually clear
virus
- HBV DNA – for monitoring
Prevention
-vaccine: injection of HBsAg, therefore will only have Anti HBs and not HBc; can tell that it
was a vaccine and not prior infection
-recombinant, from yeast
- 5% don’t produce Abs after vaccine
-HBIG – post-exposure prophylaxis; health care workers, infants of infected mothers (screen
all pregnant women)
Tx
Acute – supportive/none
Chronic – interferon and lamivudine (3TC) for some patients
Hep C
Dx
Tx
-
transmission: blood, vertical, sexual contact
1.5 – 2 months incubation
6 types
Causes a milder form of acute hepatitis than does hepatitis B (mild acute illness)
Low case fatality rate
But 80% individuals develop chronic infection, following exposure.
Most commonly don’t have symptoms  progression of disease is slow
look for anti HCV; no IgM test  does NOT mean have immunity
monitor by HCV RNA (no culture test)
interferon and Ribavirin
liver transplant
-both B and C increase risk of hepatocellular carcinoma
Risk of infection by needle stick:
HBV > HCV > HIV
Severity of disease
HBV > HCV > HAV
Incubation:
A and E: a few weeks
B and C: a few moths (C is shorter)
Hep D
- RNA virus with Hep B surface Ag
- Replicates only in presence of HBV
- Not endemic in Asia
- Co-infection: mild; low prevalence of chronic carriers
- Super-infection: severe disease; high chronic carriers
- Dx: HDV IgM; if high titers ongoing chronic infection
- HDV RNA
Hep E
- similar to Hep A; fecal-oral transmission
- not like Hep A in that: there’s no vaccine, infection of pregnant W will cause mortality in
10-20% (gen. Pop. 1%)