Hepatitis lecture

Question 1

Hepatitis A (HAV)

Answer 1

– Typical enterovirus, RNA non enveloped virus.
– Virus primarily replicates in the intestine, mouth and
throat.
– After primary infection, virus spreads through blood reaching the liver.
– Virus are present on feces 2 weeks before the symptoms start.
– Acute type infection, virus does not persist in the host.

Question 2

Hepatitis A (HAV) Transmission

Answer 2

Fecal – Oral route (water and food contaminated with virus)

Question 3

Hepatitis A (HAV) epidemiology

Answer 3

– Children are the most frequently affected

– Rarely transmitted by blood

Question 4

Hepatitis A (HAV) Mechanism of Disease

Answer 4

– Virus replicates within Liver cells (Hepatocytes)
– Immune response clears infected cells.
– No chronic infection with HAV.

Question 5

Hepatitis A (HAV) Symptoms of Hepatitis

Answer 5

Symptoms of Hepatitis are similar independent of virus type.
– Fever, lack of appetite, nausea, vomiting and jaundice. dark urine, pale feces
– Infection resolves itself in 2-4 weeks.
– No chronic hepatitis or predisposition to cancer
happens with HAV.
– Most infections are asymptomatic.

Question 6

Hepatitis A prevention & treatment

Answer 6

1) Treatment
– No antiviral drug is available
2) Prevention
– Vaccine – Formaldehyde killed Virus
 * Indication for travelers, children 2-18yo, anal-oral sex.
 * Proper hygiene and sewage disposal.

Question 7

Hepatitis B (HBV) Important features

Answer 7

– DNA double strand enveloped virus
– Produces a persistent infection of liver cells.
– Humans are the only host, no animal reservoir.

Question 8

Hepatitis B (HBV) cycle

Answer 8

– DNA – RNA – Protein

– RNA - Reverse transcriptase– DNA – New viral particles

Question 9

Hepatitis B Transmission and epidemiology

Answer 9

– Blood, sexual intercourse, during birth

– Enveloped Viruses more sensitive to environment than non enveloped viruses.

Question 10

Hepatitis B (HBV) Transmission and epidemiology

Answer 10

– 300 million people are infected – 75% are Asians.
– Vaccination has reduced the rates of liver cancer.
– 5% of infected individuals become chronic carriers – Chronic carriers have virus in the blood for more than 6 months.
– High risk of liver cancer in carriers.
– 90% of the neonate infected become chronic carriers.

Question 11

Hepatitis B (HBV) Mechanism of Disease

Answer 11

– Immune response trying to eliminate infected cells.
– Replication of virus in the liver.
– Some Chronic carriers clear the infection, some will develop cirrhosis, liver failure or cancer.

Question 12

Hepatitis B (HBV) Treatment & Prevention

Answer 12

1) Treatment
– Alpha interferon
– Inhibitors of reverse transcriptase
– Inhibitors of viral DNA transcriptase
2) Prevention 
– Vaccine
  * Health professionals, transfusions, dialysis, frequent STDs, IV drug users.
  * All blood transfusions should be screened and no one with history of hepatitis should donate blood.

Question 13

Hepatitis C (HCV) Important features

Answer 13

– Single strand RNA enveloped virus.

– Hyper-variable genome

Question 14

Hepatitis C (HCV) Cycle

Answer 14

Uncertain- can not grow in culture.

Question 15

Hepatitis C (HCV) Transmission

Answer 15

1) BLOOD
2) Sexual transmission (inefficient modes)
3) Mother-child happens but are inefficient modes.
– HCV is the most prevalent blood borne pathogen in US
4 million Americans are infected (1-2% population)

Question 16

Hepatitis C (HCV) Mechanism of Disease

Answer 16

– Immune system attacks infected cells.
– Alcoholism accelerates the disease – additional injury to liver cells.
– 75% of the infected individuals will become chronic carriers (more than 1 year producing virus)
– 10% of the carriers develop cirrhosis and cancer.
– HCV is the most common indication for liver transplant.

Question 17

Hepatitis C (HCV) Treatment & Prevention

Answer 17

1) Treatment
– Alpha interferon injections and reverse transcriptase inhibitors
– Eliminate consumption of alcoholic beverages
2) Prevention
– There is no vaccine
– Blood contact – IV drug users.

Question 18

Hepatitis D (HDV) Important features

Answer 18

– RNA enveloped virus

– Defective Virus – HDV only infects individuals already infected with HBV.

Question 19

Hepatitis D (HDV) Transmission and Epidemiology

Answer 19

Same of HBV

Question 20

Hepatitis D (HDV) Treatment and prevention

Answer 20

No specific treatment for HDV, prevention of HBV also prevents HDV

Question 21

Hepatitis E (HEV) Important features

Answer 21

– RNA non enveloped virus

– Major cause of enteric transmitted hepatitis in Asia, Africa, India, Mexico. Rare in US.

Question 22

Hepatitis E (HEV) Transmission and epidemiology

Answer 22

Same of HAV
Transmission:
Fecal – Oral route (water and food contaminated with virus)
Epidemiology:
– Children are the most frequently affected
– Rarely transmitted by blood

Question 23

Hepatitis E (HEV) Treatment and prevention

Answer 23

Vaccine, avoid contamination of water and food with virus in the feces.