Hepatitis A and E
Hep A virus, or "HAV", causes a relatively benign, self-limiting disease.
HEPATITIS A VIRUS
--originally named "infectious hepatitis"
--does not cause chronic hepatitis or a carrier state
--rarely causes fulminant liver failure: fatality rate is about 0.1%
--outcome more severe if infx is superimposed on chronic Hep B, C, or alcohol damage
--INCUBATION period: 2-6 weeks
--TRANSmission: fecal-oral, highly contagious
--occurs all over the world, more with poor hygiene/sanitation
--populations where it is endemic may have anti-HAV antibodies by age 10
--TESTING: no antigen test is available, so antibody testing is the standard
--IgM antibodies appear in blood at onset of symptoms 99% of the time, usually 3-4 weeks after exposure, and just before liver enzymes elevate
--IgG antibodies appear weeks-months later, and may persist for years or for life, conferring lifelong immunity to Hep A Virus.
--so if a person tests + for the IgM and - for the IgG, it's an acute infection, possibly contagious, and reportable here in Oregon
--if a person tests - for the IgM and + for the IgG, the antibodies are from a previous infection (since there is no chronic state for hep A), and the person is not contagious
--if someone tests + for both IgM and IgG, they may have had a previous infection and had a reinfection
--Sx: mild or asymptomatic, fever, nausea, vomiting
--HAV accounts for 25% of clinically evident acute hep worldwide
--270,000 new cases/year in the US
--LABS: ALT may go as high as 1000
--TX: get IgG to boost resistance
--VACCINE: available for travelers, a big needle in the bum last I heard, confers immunity for a limited time period. (I got it prior to going to Chile in 1992 and am no longer immune as of 2006).
HEPATITIS E VIRUS
--non-enveloped, positive-sense, single-stranded RNA virus
--causes 1% of the acute hepatitis cases in US
--Trans: fecal-oral
--S/Sx resolve over approx 6 wks
--exception: infx in pregnant woman can lead to fulminant hepatic necrosis
--fatality rate in pregnant woman 20% in third trimester
--Locations: N. Africa, Egypt, Mexico, India, Burma, Russia
--testing is indicated after travel to these locations
--serological markers for Hep A, B, C, EBV, and CMV are ABSENT
--not recognized as unique disease agent in humans until 1980
