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IMED2001 UWA > Chronic Viral Infections > Flashcards

Chronic Viral Infections Flashcards

1
Q

What are the major bloodborne viruses in context of clinical occupational exposure?

A

HIV

HepB V

HepC V

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2
Q

What are the types of hepatitis viruses?

A

A, B, C, D, E

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3
Q

How are hep B, C, and D transmitted? What else do they have in common?

A

Through needles and intercourse. They are all enveloped viruses

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4
Q

How are hep A and E transmitted?

A

They are transmitted via faecal-oral route and don’t have envelopes

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5
Q

What family is hepB a part of?

A

Hepadnaviridae

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6
Q

How is hep B transmitted?

A

Survives on various surfaces and is resistant to disinfectants. It is transmitted via blood-borne transmission. (Needle stick, IV drug injection, organ transplant, blood product transfusion, sexual and vertical transmission)

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7
Q

What does HBV do?

A

HBV infection accounts for ~50% of cirrhosis, end-stage liver disease and hepatocellular carnicoma.

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8
Q

Where is HBV commonly seen?

A

In areas of high endemicity, children get it from their mothers at birth.

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9
Q

Which body fluids are most high in concentration of HBV and which are lowest?

A

Highest: Blood, serum, wound exudates

Moderate: Semen, vaginal fluid, saliva

Low: Urine, faeces, sweat, tears, breast milk

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10
Q

What are the symptoms of HBV infection?

A

Most infections are asymptomatic but age of infection determines symptom likelihood.

Later acquisition leads to symptomatic infection (fever, abdominal pain, jaundice)

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11
Q

What percentage of 1 - 5 year olds infected with HBV develop symptoms?

A

5 - 10%

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12
Q

What percentage of adolscents and adults with HBV develop symptoms?

A

33 - 50%

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13
Q

Why are younger individuals more prone to HBV infection?

A

More developed immune system in adults

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14
Q

Who should be screened for hepB infections?

A

Patients with abnormal ALT (abnormal liver function)

Patients engaging in high-risk sexual behaviour

Injection drug users

People from areas of high endemicity

Immunocompromised patients

Dialysis patients

Transplant recipients

Sexual partners of known HBV carriers

Occupational exposure

Pregnant women

Indiviuals infected with HCV or HIV

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15
Q

What are the types of chronic Hep B disease?

A

Chronic persistent Hepatitis (asymptomatic)

Chronic active hepatitis (symptomatic exacerbations of hepatitis)

Cirrhosis of liver

Hepatocellular Carcinoma

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16
Q

Why is liver damage a consequence of some HBV infections?

A

Due to HBV-specific CD8+ T cell response

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17
Q

What percentage of people with chronic HBV infection develop cirrhosis?

A

30% approx and of these people 6% develop liver cancer and 23% liver failure within 5 years

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18
Q

What percentage of people with HBV develop liver cancer?

A

5 - 10%

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19
Q

What percentage of people with HBV develop Liver failure?

A

23%

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20
Q

Who most commonly get chronic HBV?

A

– Injecting drug users

– Men who have sex with men

– Correctional facility inmates

– Immigrants from endemic regions

– Aboriginal and Torres Strait Islander
peoples

21
Q

What are the subtypes of HBV and can they all be prevented by a single vaccine?

A

HBV/A - H

Yes they are all prevented by the same vaccine

22
Q

What is the difference between chronic and acute HBV infection in terms of antibody titre?

A

In acute infection

23
Q

What serological tests are used for HBV?

A

HBsAg (If positive indicates infection and if it lasts for more than 6 months the infection is considered chronic)

Anti-HBs (anti HBV surface antigen antibodies indicates recovery and/or immunity to HBV)

HBeAg (Active HBV protein which indicates replication)

Anti-HBe (antibody to anti-HBe indicates recovery)

Anti-HBc (Ab)

24
Q

How do nucleosides inhibit HBV from pathogenicity?

A

They inhibit reproduction.

25
Q

What does lamivudine do to reproduction of the viruses’ nucleic acids?

A

It inhibits HBV DNA synthesis by inhibiting reverse transcriptase preventing release of virion.

26
Q

What kind of virus is hepC?

A

(+) ssRNA, enveloped

27
Q

What family is hepC?

A

Flaviviridae

28
Q

What genus is hepC?

A

Hepacivirus

29
Q

What are the types of envelope coding genes of hepC?

A

E1 and E2 which are highly variable making it easy to evade host immune responses.

30
Q

How many genotypes of hepC are there and how are they named?

A

6 named genotype 1 - 6

31
Q

How is HCV transmitted?

A

Sharing of contaminated needles

Sexual contact

Birth from infected mother

Needlestick injury

Transplant

Healthcare setting

32
Q

What percentage of hepC is chronic and persistent?

A

70% with similar spectrum to HBV

33
Q

What limits studies of hepC?

A

Lack of a good culture system

34
Q

What percentage of people infected with HCV are asymptomatic?

A

80%

35
Q

What happens after acute infection with hepC?

A

Spontaneous resolution in 15 - 40% of cases.

Chronic infection in 60 - 85% of cases

36
Q

What happens after chronic infection with HCV?

A

5 - 20% after 25 years develop cirrhosis and the rest are stable

37
Q

What happens to people with cirrhosis from HCV?

A

It either slowly progresses to liver failure or decompensation liver cancer (Decompensation HCC)

38
Q

What are the symptoms of hepC?

A

Fever, fatigue, decrease in apetite, abdominal pain, vomiting, joint pain, jaundice

39
Q

How is hepC treated?

A

Interferon (chronic hepatitis)

Ribovarin (new treatment)

Combination of both.

40
Q

What 3 parameters are looked at for treating hepC?

A

High levels of aminotransferase

HepC RNA

Evidence of liver damage

41
Q

Is ribovarin+interferon treatment effective against all hepC genotypes?

A

Yes

42
Q

What stages of the HCV lifecycle are targetted by drugs?

A

RNA replicase drugs are inhibited.

Protease inhibition which prevents proteolytic processing by viral protease

43
Q

What stages of HIV infection are targetted by drugs?

A

Fusion inhibitors

Co-receptor antagonists

Reverse transcriptase inhibition

Integrase inhibitors

Protease inhibitors

44
Q

What to remember regarding lifecycle and drugs:

A

No need to memorize the entire lifecycle but remember the stage of the lifecycle targetted by the drugs.

45
Q

Why is serological testing so important with chronic viral infections?

A

It allows us to know who has the disease and to prevent transmission

46
Q

What is the relationship between HBV and HDV?

A

HDV is the satellite virus of HBV meaning its envelope is the same as HBV. Meaning HDV can only infect someone who already has a HBV infection

47
Q

What kind of disease can HDV result in?

A

Either completely asymptomatic or fulminant hepatitis

48
Q

What happens when both HBV and HDV are contracted simultaneously?

A

Coinfection results in severe acute disease with low risk of chronic infection

49
Q

What happens when a chronic HBV carrier is infected with HDV?

A

Patients develop chronic HDV infection and this has a high risk of severe chronic liver disease and may result in acute hepatitis.

IMED2001 UWA (44 decks)

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