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Flashcards in Hepatitis lecture Deck (23):
1

Hepatitis A (HAV)

– 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.

2

Hepatitis A (HAV) Transmission

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

3

Hepatitis A (HAV) epidemiology

– Children are the most frequently affected
– Rarely transmitted by blood

4

Hepatitis A (HAV) Mechanism of Disease

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

5

Hepatitis A (HAV) Symptoms of Hepatitis

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.

6

Hepatitis A prevention & treatment

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.

7

Hepatitis B (HBV) Important features

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

8

Hepatitis B (HBV) cycle

– DNA – RNA – Protein
– RNA - Reverse transcriptase– DNA – New viral particles

9

Hepatitis B Transmission and epidemiology

– Blood, sexual intercourse, during birth
– Enveloped Viruses more sensitive to environment than non enveloped viruses.

10

Hepatitis B (HBV) Transmission and epidemiology

– 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.

11

Hepatitis B (HBV) Mechanism of Disease

– 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.

12

Hepatitis B (HBV) Treatment & Prevention

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.

13

Hepatitis C (HCV) Important features

– Single strand RNA enveloped virus.
– Hyper-variable genome

14

Hepatitis C (HCV) Cycle

Uncertain- can not grow in culture.

15

Hepatitis C (HCV) Transmission

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)

16

Hepatitis C (HCV) Mechanism of Disease

– 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.

17

Hepatitis C (HCV) Treatment & Prevention

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.

18

Hepatitis D (HDV) Important features

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

19

Hepatitis D (HDV) Transmission and Epidemiology

Same of HBV

20

Hepatitis D (HDV) Treatment and prevention

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

21

Hepatitis E (HEV) Important features

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

22

Hepatitis E (HEV) Transmission and epidemiology

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

23

Hepatitis E (HEV) Treatment and prevention

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