Diebel: Viral Hepatitis Flashcards Preview

GI- Week 6 > Diebel: Viral Hepatitis > Flashcards

Flashcards in Diebel: Viral Hepatitis Deck (76):
1

What are the major causes of viral hepatitis?

Hepatitis A Virus (HAV)
Hepatitis B Virus (HBV)
Hepatitis C Virus (HCV)
Hepatitis D Virus (HDV)
Hepatitis E Virus (HEV)

Hepatitis G Virus (HGV)

Yellow Fever Virus (YFV)

2

What forms of hepatitis cause ONLY acute infections?

HAV
HEV

3

What forms of hepatitis cause acute and chronic infections?

HBV
HCV
HDV

4

HGV

RNA virus
Icosahedral Nucleocapsid
Enveloped
SS (+) Nonsegmented Genome (Class IV)
Flaviviridae
Pegvirus

5

Hepatitis G virus (GBV-C) in the same family of viruses as...

HCV
YFV

6

What is the infection pattern for GBV-C? Distribution?

Hepatotropic

Global

7

How big is the genome of Hepatitis G?

~9,400 nucleotides and encodes for a single large polyprotein.

8

How is GBV-C transmitted?

Exposure to contaminated blood products is the route of transmission in humans.

multiple blood transfusions, IV drug users at risk

9

Individuals w/ GBV-C are likely to be co-infected w/ ...

HBV
HCV

or both viruses.

10

What is the significance of Hep G?

May infect lymphocytes and may be an important co-infection that can dictate the course of HIV infections

11

How do you dx HGV?

Identified in infected individuals by the detection of the genome by RNA detection methods like RT-PCR

12

HAV

picornaviridae
no envelope
(+) ssRNA, Group IV

13

HBV

hepadnaviridae
enveloped
Partially dsDNA, Group VII

14

HCV

flaviviridae
enveloped
(+) ssRNA, Group IV

15

HDV

Deltavirus
enveloped
(-) ssRNA, Group V

16

HEV

Calciviridae
nonenveloped
(+) ssRNA, Group IV

17

What hepatitis viruses have fecal oral transmission?

HAV
HEV

18

What hepatitis viruses can be transmitted through blood or sexual contact?

HBV
HCV
HDV

19

What hepatitis viruses ahve a short incubation period (2-8 wks)?

HSV
HEV

20

What viruses have a long incubation period (2-24 wks)?

HBV
HCV
HDV

21

What viruses can cause acute infection?

all of them

22

What viruses cause a chronic infection?

HBV
HCV
HDV
HEV

23

HAV
Dx?
Therapy?
Vaccine?

Anti-HAV IgM, IgG (prior infection)

Supportive care, pooled immune globulins

yes

24

HBV
Dx?
Therapy?
Vaccine?

Multiple serological markers

a-interferon, lamivudine, hepatitis B immune globulin

Yes

25

HCV
Dx?
Therapy?
Vaccine?

Anti-HCV antibody, RT-PCR
a-interferon, ribavirin, boceprevir, telaprevir
No (viral antigens vary over the course of an infection)

26

HDV
Dx?
Therapy?
Vaccine?

Anti-HDV delta-antigen IgM
Same as HBV
No (vaccination against HBV is effective)

27

HEV
Dx?
Therapy?
Vaccine?

Anti-HEV IgM, IgG, ruling out HAV infection
None
No

28

What viruses only cause acute hepatitis?

HAV
HEV

29

Describe the structure of the HAV.

small, naked virus with a (+) ssRNA genome ~7,500 nucleotides long.

30

What is the VPg protein?

VPg protein is covalently attached to the 5’ end and the genome contains a polyA tail

31

What is unique about the capsid structure of HAV?

one of the most stable of all picornaviruses and is stable at pH 1, resistant to destruction by many solvents and detergents and desiccation.

32

How can HAV be inactivated?

chlorine treatment of drinking water
formalin treatment
UV radiation

33

How is HAV transmitted?

fecal oral

34

How does HAV infect cells?

Infects cells expressing the HAV cell receptor 1 glycoprotein (HAVCR-1).
(Found on liver cells and T cells)>
Virus replicates in large quantities in the liver and is shed in the stool approximately 10 days before the onset of jaundice.

35

What leads to the pathogenesis and disease associated w/ an HAV infection?

immune response to virally infected liver cells

36

What percent of acute hepatits cases are caused by HAV?

40%

37

How does HAV spread in the populatio?

spreads rapidly b/c most ppl are contagious 10-14 d prior to onset of sxs

90% of all children and 25 to 50% of infected adults have asymptomatic, productive infections.

38

A pt presents w/ fever, fatigue, nausea, loss of appetite, abdominal pain, dark urine and jaundice.

Dx?

HAV

Symptoms occur 15 to 50 days post-exposure and intensify for 4 to 6 days.

Complete recovery 99% of the time

39

How do you dx an acute HAV?

Acute infection shown by ELISA of anti-HAV IgM

40

What is given to contacts of a HAV infected individual?

Prophylaxis with immune globulin serum.

41

Who is the killed HAV vaccine given to?

Given to children and adults at high risk for infection.

Travelers to endemic regions.

Administered to children 2 years of age and to adults in conjunction with the HBV vaccine.

42

How does HEV compare to HAV?

Sxs and transmission are almost identical to HAV.

Symptoms of disease occur slightly later than seen with HAV and the disease is slightly more severe with an overall mortality rate of around 1 to 2%.

43

Who is HEV particularly dangerous for?

Disease is particularly dangerous for pregnant women with a mortality rate of ~20%

44

What may be responsible for the more severe disease outcome of HEV?

immunological and hormonal factors

the maternal immune system is altered. T cells are reduced up to the 20th week of gestation. This has been speculated to lead to an increased susceptibility to viral infections such as hepatitis, rubella, herpes, and HPV.

Levels of HCG are up and have a suppressive effect on cell-mediated immunity.

Liver damage is still through immunological mediated injury… ?

45

How do you dx HEV?
Tx?

Presence of anti-HEV antibody or HEV RNA.

No treatment available

46

How are HAV and HEV transmitted?


Transmitted via the fecal to oral route.
Ingestion of contaminated food and water can cause infection.
HAV in shellfish from sewage-contaminated water.
Viruses can be transmitted by food handlers, day-care workers, and children

47

What are RF for HAV and HEV?

overcrowded unsanitary cities

48

Who is at risk for HAV/HEV?

Children – mild disease, major source of the spread of HAV
Adults – abrupt-onset hepatitis
Pregnant women – high mortality rate with HEV infections

49

how is the spread of HAV and HEV controlled?

good hygiene
HAV passive antibody protection for contacts
HAV vaccine

50

What hepatitis viruses cause acute and chronic hepatitis infections?

HBV, HDV, and HCV

51

What is the infectious virion of HBV?

Dane particle

52

What is the route of infection for HBV?

Bloodborne pathogen
Infects liver cells expressing the transferrin receptor, asialoglycoprotein receptor, and the human liver annexin V protein using the HBV HBsAg viral protein.

Virus causes acute or chronic, symptomatic or asymptomatic diseases. The individual’s immune response to the initial infection dictates the outcome of the disease.

53

How does HBV spread w/in the body?

The major source is in the blood but it can also be found in semen, saliva, milk, vaginal and menstrual secretions, and amniotic fluid

54

WHen are sxs associated w/ HBV observed?

The virus starts to replicate in the liver within 3 days of exposure. Symptoms of infection may take up to 45 days

55

What characterizes the clinical syndrome of HBV?

long incubation period
insidious onset

56

How do you prophylactically tx HBV? Who is it given to?

Prophylaxis with immune globulin serum.
--Given to newborns of HBsAg mothers to ameliorate disease.
--Given to individuals within a week of exposure to prevent disease

57

How do you tx a chronic HBV infection?

Lamivudine (HIV RT inhibitor)--targets the viral pol, taken for 1 year

Adefovir, dipivoxil, and famciclovir – nucleoside analogues. Taken for 1 year.

Pegylated interferon-a can also be taken. Taken for at least 4 months

58

HBV vaccination is recommended for what groups?

infants
children
people in high risk groups

59

What groups are at high risk for HBV?

People from endemic regions
Babies of mothers with chronic HBV
IV drug users
People with multiple sex partners
People needing multiple blood transfusions
Health care personnel

60

What is the route of infection fo HDV?

Bloodborne

61

HDV can only affect what cells....

cell that are already infected w/ HBV (requires HBsAg for packaging)>

rapid, severe progression of infection in individuals who are already HBV carriers

62

What virus is responsible for causing 40% of fluminant hepatitis infections?

HDV

63

How do you dx HDV?

detecting the RNA genome (RT-PCR), the delta antigen, or anti-HDV antibodies (ELISA)

64

How do you tx HDV?

No specific treatment for HDV.

Treating and preventing HBV infections also works to clear and prevent HDV infections

65

What percent of all HCV infections become chronic infections? What do chronic infections lead to?

70-80% of all infections become chronic infections

Chronic infections lead to degenerative liver disease

Cirrhosis or hepatocellular carcinoma, liver failure

66

How is HCV transmitted?

blood-borne pathogen transmitted through recreational drug use, needle sharing, blood transfusions prior to 1992

67

How long does it take before HCV sxs appear?

10-20 yrs post infection

68

How does HCV infect liver cells?

Infects liver cells expressing CD81 surface receptor (also seen on B lymphocytes)>
Uses the lipoprotein receptor to facilitate uptake into hepatocytes>
HCV proteins inhibit cellular apoptosis and interferon-a>
promotes persistent infection.

69

Where is HCV most prevalent?

southern Italy, Spain, central Europe, Japan, and parts of the Middle East

70

How do you dx HCV?

ELISA recognition of the anti-HCV antibody or detection of the RNA genome.

Genome detection, quantitation, and genotyping by RT-PCR are the gold standard for confirming the diagnosis of HCV and for planning the correct course of treatment against the infection.

71

How do you tx HCV?

Recombinant interferon-a or pegylated interferon-a
ribavirin
boceprevir
telaprevir.

72

How is yellow fever spread?

Aedes mosquito

73

How does YFV cause infection?

cytolytic virus that destroys cells it infects>
systemic disease>
IR to infection is both humoral and cellular and can destroy tissues

74

A pt presents w/ a severe systemic disease, flu-like syndrome, hemorrhagic fever, shock and loss of liver/kidney/heart function.

Dx?

YFV

75

How do you dx YFV?

IF, RT-PCR, ELISA
Direct isolation of virus

76

How do you tx YFV?

Supportive care
vector control measures
vaccination (Yellow Fever Virus live-attenuated vaccine).