Hepatitis Viruses

Question 1

Which hepatitis types are waterborne?

Answer 1

HAV and HEV are spread via contaminated food and water, oral-faecal transmission

HEV is spread via undercooked animal meats

Question 2

Which hepatitis types are bloodborne?

Answer 2

HBV, HCV, HDV

Question 3

How does HAV spread?

Answer 3

Contaminated water, shellfish and seafood
Can survive outside the body for months, boiling or cooking kills the virus but freezing does not, so can spread through raw foods

Question 4

How do you diagnose HAV infection?

Answer 4

IgM serology test

Question 5

HAV symptoms?

Answer 5

Tiredness, muscle ache
Nausea, vomiting
Abdominal pain/discomfort, esp right upper abdomen
Loss of appetite
Mild fever
Dark urine
Jaundice (yellowish sclera)

Question 6

How many serotypes does HAV have?

Answer 6

1, vaccine/infection results in lifelong immunity

Question 7

Significant exposure to HAV?

Answer 7

Give vaccine within 2 weeks of exposure, consisting of 2 doses 6 months apart

Question 8

HEV acute vs chronic?

Answer 8

Causes acute hepatitis with high mortality in pregnant women
Can become chronic in immunosuppressed patients

Question 9

How many genotypes does HEV have?

Answer 9

4 major genotypes

1 and 2 in developing countries with poor sanitation, spreading via oral-faecal transmission or contaminated water supplies, causing frequent sporadic infection

3 and 4 are more in developed countries via zoonotic spread, often in immunosuppressed middle aged and elderly males, often causing chronic infection

Question 10

What is the difference between genotype and serotype?

Answer 10

Genotype is sequencing of viral genome to find differences in genetic sequences for differentiation between strains

Serotype is what manifests on the surface of the virus, characterized by what antibodies are produced when inoculating animal test subjects

Question 11

How does HEV spread?

Answer 11

Undercooked meats and shellfish, oral-faecal, contaminated water supplies, zoonotic

Relatively heat resistant and therefore can survive on lightly cooked food

Question 12

HBV differences from HAV?

Answer 12

Has envelope with HBsAg, therefore more resistant to moderate heating, freezing, low pH and ether

HBV genome consists of partially dsDNA with a reverse transcriptase

Question 13

Why can HBsAg be found in the blood with active HBV infection?

Answer 13

During replication HBV commonly produces excess antigens, released into the blood circulation in the form of spherical structures without DNA

These antigens can be detected via surface antigen tests to diagnose infection

Question 14

Pathogenesis of HBV infection

Answer 14

Compared to HAV and HEV, has a long incubation period of 3-6 months. Acute disease is seen in 25% of patients, with infection in childhood more likely to lead to chronic disease

Can either resolve or develop into chronic disease, where inflammation is caused by cell-mediated lysis of the infected cells, resulting in fulminant hepatitis, primary hepatocellular carcinoma and liver cirrhosis

Question 15

How is HBV spread?

Answer 15

Bodily secretions like blood or genital secretions, sexual, parenteral, perinatal

High risk groups:
Regions of high endemicity
Babies of infected mothers
Injecting drug users
Multiple sex partners
Hemophiliacs
Healthcare personnel performing invasive procedures
Hemodialysis patients
Blood and organ recipients

Question 16

Symptoms of acute HBV infection

Answer 16

Fever, rash, arthritis, jaundice, dark urine, malaise, anorexia, nausea, right upper quadrant pain, itching

4 stages:
Incubation (3-6 months) –> Preicteric –> Icteric (jaundice stage) –> Convalescent (recovery) period

Question 17

Serologic markers for HBV infection

Answer 17

HBsAg - acute infection/carrier (for testing and screening)
ALT, AST - acute infection/carrier (for testing)
Anti-HBc IgM - recent acute infection (for testing)
Anti-HBs antibody - immune (for screening)
Anti-HBc total - evidence of past infection (for screening)
HBeAg - higher infectivity
HBV DNA - higher infectivity

Question 18

How to treat HBV?

Answer 18

Antivirals targeting the polymerase to limit disease progression: adefovir, entecavir, tenofovir

Immunization at birth, healthcare workers

Immunoglobulin prophylaxis for babies born to HBsAg positive mothers or needlestick injuries

Question 19

What is HDV?

Answer 19

A helper virus, co-infection with HBV, can only replicate in cells also infected by HBV, making hepatitis worse and causing some fulminant hepatitis infections

Question 20

How is HCV transmitted?

Answer 20

Infected blood, sexual intercourse, esp risk groups like injecting drug users, organ transplant recipients, hemodialysis patients, hemophiliacs

6 genotypes

Question 21

Pathogenesis of HCV

Answer 21

Incubation period of 2-26 weeks, average of 7 weeks

Mostly asymptomatic, but high rate of progression to chronic liver disease, liver failure and liver cancer

Question 22

What is HGV?

Answer 22

Found with coinfection with HIV, HBV, HCV, but doesnt cause hepatitis