Term
| which of the hep viruses are endemic in the US? |
|
Definition
| A-C. E is not endemic in the US. |
|
|
Term
| what are viruses other than hepatitis which can also cause jaundice? |
|
Definition
|
|
Term
|
Definition
| non-A, non-B hepatitis virus - which is still used as a catch-all for unclassified hep viruses even though C has since been discovered |
|
|
Term
| which hep virus is responsible for the most acute cases reported? |
|
Definition
| hep B, though acute hep C cases are difficult to dx |
|
|
Term
| does hep A cause a chronic infection? |
|
Definition
|
|
Term
| which hep virus is responsible for the most chronic cases reported? |
|
Definition
|
|
Term
| how have the rates of different hep infections changed since development of vaccines? |
|
Definition
| hep A has decreased 92% since 1995. hep B has decreased 82% since 1990. hep C decreased through the 90s, but plateaued in 2003. |
|
|
Term
| what kind of virus is hep A? |
|
Definition
| picornavirus (little - same family as rhinovirus), naked, icosahedral, RNA |
|
|
Term
| what kind of virus is hep B? |
|
Definition
| hepadnavirus, enveloped, icosahedral, DNA |
|
|
Term
| what kind of virus is hep C? |
|
Definition
| flavivirus, enveloped RNA |
|
|
Term
| what kind of virus is hep D? |
|
Definition
| deltavirus, subviral agent - can't exist on its own, needs hep B for its envelope |
|
|
Term
| what kind of virus is hep E? |
|
Definition
| calcivirus-like, naked, icosahedral, RNA (same family as norovirus and similar to hep A) |
|
|
Term
| what kind of virus is hep G? |
|
Definition
| flavivirus, enveloped RNA (similar to hep C) |
|
|
Term
| how many serotypes are there for hep A virus? how does this affect pt's immunity? |
|
Definition
| there is only one hep A serotype worldwide, so if a pt gets an acute infection they are immune thereafter. |
|
|
Term
| what kinds of infection can hep A cause? |
|
Definition
| acute, either symptomatic or asymptomatic (makes it hard to control spread). hep A does not cause chronic infections. |
|
|
Term
| what genotypes of hep E are associated with human illness? |
|
Definition
| 1 causes most cases and is endemic in N africa and asia. 3 is endemic in the US (15-30% are positive for IgG antibodies to HEV). 4 is seen in E asia. 3&4 are zoonotic. |
|
|
Term
| where was hep E first recognized? |
|
Definition
| india, associated with fecally contaminated drinking water |
|
|
Term
| what are the 3 forms of hep B? |
|
Definition
| small spherical: an empty envelope which will bind antibody and take it out of solution, but is noninfectious. long filamentous: same as small spherical. large spherical: the dane particle, which is infectious and lesser numbers of. |
|
|
Term
| what kind of genetic material does hep B have? |
|
Definition
| dsDNA - and hep B has its own DNA polymerase |
|
|
Term
| what is crucial to developing immunity to hep B? |
|
Definition
| developing antibody to HBsAg, which when accomplished clears the virus (all 3 forms) and prevents re-infection. |
|
|
Term
| if someone is chronically infected with hep B, can they make antibody against it? |
|
Definition
| no - which is why it is difficult to tell the difference between a chronic infection and the end of an acute infection |
|
|
Term
| what are the 2 kinds of hep B core antigen? do they generate the same or different Ab response? |
|
Definition
| HBc (core protein) and HBe (alt form of HBc which is secreted, if this is high with low Ab - that blood is very infectious). these generate 2 different antibody responses. |
|
|
Term
| why does hep D only exist with hep B? |
|
Definition
| hep D is a subviral particle that needs hep B's surface antigen to form an envelope - allowing it to spread from cell to cell |
|
|
Term
| what are the 2 scenarios for hep D infection? |
|
Definition
1) co-infection with hep B
2) superinfection of a chronic carrier of hep B |
|
|
Term
| what characterizes hep C and G? |
|
Definition
| both hep C and G are flaviviruses (related to yellow fever, but not mosquito-borne). hep G may not cause hepatitis and severity of G/C co-infections similar to hep C alone |
|
|
Term
| how does co-infection of HIV and hep C affect a pt? hep G? |
|
Definition
| HIV makes hep C worse, but it is unclear if it alters the progression of AIDS. hep G appears to slow HIV disease progression. |
|
|
Term
| why was hep C the leading cause of serum acquired hepatitis prior to 1992? |
|
Definition
| 1992 is when hep C blood screening was developed. it was first IDed in 1989. |
|
|
Term
| how many genotypes are there of hep C? which is most common in the US? hardest to treat? |
|
Definition
| 6, and genotype 1 of hep C is the most common in the US as well as least responsive to antiviral therapy |
|
|
Term
| what is a virulence factor for hep C related to its genetics? |
|
Definition
| hep C is a RNA virus, and its polymerase makes a lot of mistakes, which generates quasispecies - which are harder for the immune system to attack |
|
|
Term
| what characterizes an acute hep C infection? |
|
Definition
| often asymptomatic, most often diagnosed only by elevated LFTs |
|
|
Term
| what % of hep C infections become chronic? |
|
Definition
|
|
Term
| how is hep A transmitted? |
|
Definition
| fecal-oral, iv drug use, contacts |
|
|
Term
| how is hep B transmitted? |
|
Definition
| sexually, iv drug use, blood |
|
|
Term
| how is hep C transmitted? |
|
Definition
| iv drug use, blood, sexual |
|
|
Term
| how is hep D transmitted? |
|
Definition
|
|
Term
| how is hep E transmitted? |
|
Definition
|
|
Term
| how is hep G transmitted? |
|
Definition
|
|
Term
| what characterizes both hep A and E as naked icosahedral viruses? |
|
Definition
| they are enteric viruses that can survive pH, drying out and are resistant to bile salts - making fecal-oral transmission ideal |
|
|
Term
| what are risk factors for hep A infection? |
|
Definition
| sexual, IV drug use, household contact, international travel, homosexual intercourse, and food/waterborne outbreak (low risk in US). however, 50% of risk factors are unknown. |
|
|
Term
| why do hep A outbreaks uncommon usually involve travelers in the US? |
|
Definition
| b/c hep A is not endemic in the US due to the vaccine and most of the population is not exposed. in areas where the vaccine is not distributed, early childhood is the peak age of infection. |
|
|
Term
| are hep E outbreaks seen in the US? |
|
Definition
| not really, and if there are they are related to travel outside the US |
|
|
Term
| what were common routes of transmission for hep A in the US before the vaccine? |
|
Definition
| transmission through asymptomatic children and goods brought in from mexico |
|
|
Term
| what are risk factors for hep B infection? |
|
Definition
| hep B is efficiently transmitted through blood, but b/c blood donors are screened it's a low risk factor. the biggest risk factor for hep B is multiple sex partners. |
|
|
Term
| what are concentrations of hep B in various body fluids? |
|
Definition
| blood: high. moderate: semen/saliva/vaginal fluid. low/nondetectable: breast milk, feces, sweat, tears, urine |
|
|
Term
| what are risk factors for hep C infection? |
|
Definition
| IVDA is the biggest, followed by multiple sex partners (less than hep B), and contact blood w/blood is low due to screening procedures. |
|
|
Term
| what are risk factors for hep D infection? |
|
Definition
| IVDA, multiple transfusions. not sexually at this point. |
|
|
Term
| what characterizes acute hepatitis? what is the clinical definition? |
|
Definition
| acute hepatitis can be asymptomatic or pts may present with: fever/jaundice/nausea/abdominal discomfort/dark urine for 1-3 weeks. clinical definition: discrete onset of symptoms/jaundice or elevated ALTs (& must be lab confirmed) |
|
|
Term
| what are indicators of liver damage? |
|
Definition
| increased ALTs, bilirubin, and alkaline transferase |
|
|
Term
| how often does fulminant hepatitis (liver failure) occur with acute hepatitis? |
|
Definition
|
|
Term
| what are the incubation period ranges for the hep viruses? |
|
Definition
| hep A & E: shorter, 2-8 wks. hep B/C/D: longer 6wks-6 mos |
|
|
Term
| what are the clinical features of a hep A infection? |
|
Definition
| acute. often *asymptomatic in young kids (can still shed high titers of viruse). *jaundice presence goes up with age of infection (14+ yrs = 70-80%). incubation period range: 15-50 days. complications: fulminant hep, cholestatic hep (prolonged w/jaundice), and relapsing hep (after several wks) - *all rare. chronic illness does not occur. |
|
|
Term
| what are the clinical features of a hep E infection? |
|
Definition
| acute. similar to hep A. incubation period: avg 40 days. more severe in pregnant women, illness severity increases w/age. no chronic sequelae. |
|
|
Term
| what is the definition of a chronic hep infection? |
|
Definition
| viral antigen detectable for > 6 mos |
|
|
Term
| what are the risks associated with chronic hep? |
|
Definition
| risk for cirrhosis and hepatocellular CA are increased |
|
|
Term
| what determines if hep B goes chronic? |
|
Definition
|
|
Term
| how likely is it that hep C will go chronic? |
|
Definition
|
|
Term
| how likely is it that hep D will go chronic? |
|
Definition
| hep D is more likely to go chronic when it superinfects vs coinfects w/hep B |
|
|
Term
| what are the clinical features of a hep B infection? incubation period, symptoms, acute, chronic infection rate? |
|
Definition
| incubation period: 60-90 days. symptoms: more likely when older. acute fatality rate: low. chronic infection rate: only 2-10% after 5 yrs old (& mortality from this is 15-25%). (*infection at birth is not likely to be symptomatic but is likely to be chronic*) |
|
|
Term
| what are the stages of chronic hep B? |
|
Definition
| *immune tolerant: high levels of antigen, low levels of antibody, asymptomatic (ALTs normal, normal or minimal liver inflammation). *immune active: high levels of antigen, symptomatic (elevated ALTs, liver inflammation). *inactive chronic carrier: rising levels of antibody, declining levels of antigen, less symptomatic (normal ALT levels, some inflammation, no/minimal fibrosis) |
|
|
Term
| what are the clinical features of a hep C infection? incubation period, mortality rate, acute, chronic infection rate, cirrhosis rate? |
|
Definition
| incubation: 6-7 wks avg. acute: mild, 20% jaundice rate. mortality rate: 3%. chronic infection rate 60-85%. |
|
|
Term
| what is the outcome following hep C infection % breakdown? |
|
Definition
| 10-30% clear virus, 60-80% seroconvert, but infection persists, and 1-4% have no seroconversion |
|
|
Term
| what are the clinical features of a hep D infection? how does coinfection vs superinfection with hep B affect this? |
|
Definition
| if hep D *coinfects with hep B: severe acute disease w/low risk of chronic infection. if hep D *superinfects w/hep B: chronic hep D infection usually develops w/a high risk of severe chronic liver disease. |
|
|
Term
| what is the progression of events in a hep A infection? |
|
Definition
| viremia/viral shedding in stool occurs early, followed by an increase in ALT which is concurrent with the appearance of clinical illness and rising IgM levels. as clinical illness, ALT and IgM levels drop, IgG levels rise. |
|
|
Term
| how is a hep A infection diagnosed? |
|
Definition
| commercial ELISA for IgM (indicates acute infection - IgG just indicates a past infection), and increased LFTs (not specific) |
|
|
Term
| what is the progression of events in a hep E infection? |
|
Definition
| essentially the same as hep A. virus sheds before the appearance of symptoms, symptoms occur when LFTs rise and antibody response is the same |
|
|
Term
|
Definition
| no approved serological test in the US, can look for IgM in lab |
|
|
Term
| what is the typical serological course of an acute hep B infection? |
|
Definition
| during the acute phase, HBsAg is produced in high amounts. slightly after, IgM anti-HBc starts to be produced (defines acute phase). then IgG anti-HBc production starts, IgM anti-HBc production drops and IgM anti-HBs production starts. there is a lag between when HBsAg shows up and when IgM anti-HBs starts (indicates resolution) and therefore around 32 wks it is temporarily unclear if the disease will continue as chronic or not. |
|
|
Term
| what is the typical serological course of a chronic hep B infection? |
|
Definition
| similar to the initial stage of the acute infection, but IgM anti-HBs is never produced and HBsAg continues to persist. IgM anti-HBc is also not produced, even though IgG anti-HBc may exist - b/c in that case, the IgG is not in response to the current infection. there can be anti-HBe at this point as well, which in the absence of IgM anti-HBs indicates an inactive carrier state. |
|
|
Term
| what does a positive serological test in a hep B pt for HBsAg mean? |
|
Definition
| either an acute or chronic infection |
|
|
Term
| what does a positive serological test in a hep B pt for anti-HBs mean? |
|
Definition
| immunity either due to past cleared infection or vaccination |
|
|
Term
| what does a positive serological test in a hep B pt for HBeAg mean? |
|
Definition
| high infectivity - a lot of virus is replicating |
|
|
Term
| what does a positive serological test in a hep B pt for anti-HBe mean? |
|
Definition
| there is an antibody response being generated - but this on its own does not mean the virus is/will be cleared |
|
|
Term
| what does a positive serological test in a hep B pt for IgM anti-HBc mean? |
|
Definition
|
|
Term
| *why does IgM anti-HBs not appear until HBsAg has disappeared? |
|
Definition
| b/c hep B has 3 forms, including 2 "dummy" forms which do not replicate - but soak up extra Ab. therefore once the Ab starts to finally get ahead, the Ag is completely bound. |
|
|
Term
| if a pt has an immunity to hep be through vaccination, why will they not have anti-HBc Ab? |
|
Definition
| b/c this is not included in the vaccine, just anti-HBs |
|
|
Term
| how can you tell the difference between a hep B acute and chronic pt? |
|
Definition
| the acutely infected pt will have IgM anti-HBc, but the chronically infected pt will not (b/c this drops to allow the start of IgM anti-HBs in the resolution of an acute infection) |
|
|
Term
| what is the typical serological course for hep B and D co-infection? |
|
Definition
| HBsAg and hep D RNA will be detectable in the acute phase. IgM anti-HDV Ab production starts and as IgM anti-HBs starts to be produced, hep B clears and with it hep D |
|
|
Term
| what is the typical serological course for hep B and D super infection (chronic hep B pt is infected with hep D)? |
|
Definition
| HBsAg is already present, and its levels do not change. at the point of superinfection, hep D RNA will be detectable and symptoms will worsen (higher ALT/jaundice). anti-HDV Ab will be produced, however hep D RNA will now be detectable until the hep B infection is cleared. |
|
|
Term
| what are the diagnostic tests for hep D? |
|
Definition
| only available: IgG anti-HDV, which will be present in both co-infection and superinfection situations along with IgM, however both will decrease in co-infection resolution while IgG levels will stay relatively high in a superinfection. |
|
|
Term
| what is the serologic pattern of an acute hep C infection with recovery? |
|
Definition
| hep C RNA levels will rise, symptoms (LFTs/jaundice - if present) will increase then both will decrease with the steady rise of anti-HCV Ab until resolution (more rare) |
|
|
Term
| what is the pattern of an acute hep C infection with progression to chronic infection? |
|
Definition
| hep C RNA levels will rise, symptoms (LFTs/jaundice - if present) will increase then both will decrease with the steady rise of anti-HCV Ab - *however hep RNA and symptoms will not completely disappear, rather they flucutate. therefore, remember that if you don’t detect hep C RNA and you do detect antibody, have to do repeat tests to make sure you are not in one of the fluctuation periods. (more common) |
|
|
Term
| what are diagnostic tests for hep C? |
|
Definition
| *EIA to detect anti-HCV Ab (cannot distinguish acute/chronic/resolved). *RIBA (recombinant strip immunoblot assay), tests for anti-HCV Ab and confirms EIA. *serum ALT levels (7x higher in acute, less in chronic). *RT-PCR, but detection of HCV RNA is intermittent - so a single negative test is inconclusive. |
|
|
Term
| are there vaccines to hep A and B? |
|
Definition
|
|
Term
| what can be used for postexposure prophylaxis for hep A and B? |
|
Definition
| there are anti-hep A and B Ig preps available |
|
|
Term
|
Definition
| an inactivated hep A and recombinant hep B combination recommended for 18 yrs +, travel to endemic areas, pts with liver disease or pts w/risk factors. |
|
|
Term
|
Definition
| a combination of DTaP, hep B, and inactivated polio vaccine - good for kids |
|
|
Term
| what is the recommendation for hep A vaccine? |
|
Definition
| for all kids 12-13 mos or those w/increased risk |
|
|
Term
| what are the recommendations for hep B vaccine? |
|
Definition
|
|
Term
| what are settings associated with hep risk factors? |
|
Definition
| HIV testing/tx facilities, correctional facilities |
|
|
