hepatitis virus a & b

HEPATITIS VIRUS A & B

Presented By:Dora Amoako

Gerardo Castro

Background

• 6 viruses in the Hepatitis alphabets A-E and G• Target Organ is liver• Similar Symptoms• Different mode of replication, transmission,

course and sequence of disease helps determine specific virus.

Introduction Hepatitis A virus(HAV)

• Sometimes known as Infectious Hepatitis• Picornavirus ( + sense, ss RNA)• Oral-fecal route

Hepatitis B

• Previously known as Serum Hepatitis• Hepadnavirus (double stranded DNA

genome)• Spread by blood or needles, by sexual

contact, perinatally

StructureHepatitis A

• 27nm• Naked Icosahedral

• VPg protein attached to 5’ end, polyadenosine attached to 3’ end.

StructureHepatitis B• Enveloped • DNA virus • 42nm in diameter

• HBSAg (L,M and S glycoproteins)

Pathogenesis

• HAV=IngestedbloodLiver(hepatocytes)• Jaundice• Extra-hepatic symptoms Unusual• Fatigue• Loss of appetite

Pathogenesis HBV

• Also replicates in hepatocytes• Acute chronic symptomatic or asymptomatic

disease• Jaundice• Abdominal pain• Dark urine• fever

Case Study-Patient A• A 55-year-old man (patient A) was admitted to the hospital

with fatigue, nausea, and abdominal discomfort. He had a slight fever, his urine was dark yellow, and his abdomen was distended and tender. He had returned from a trip to Thailand within the previous month.

Case Study-Patient B

• A 28-year-old woman (patient B) was admitted to the hospital complaining of vomiting, abdominal discomfort, nausea, anorexia, dark urine, and jaundice. She admitted that she was a former heroin addict and that she had shared needles. In addition, she was 3 months pregnant.

Clinical/ Epidemiological clues

Patient A Patient B

FatigueNauseaAbdominal DiscomfortSlight feverDark yellow urineDistended Abdomen and tenderTrip to Thailand

VomitingNauseaAbdominal DiscomfortAnorexiaDark UrineJaundiceFormer Heroin Addict, shared needles3 months pregnant

Laboratory tests helpful in distinguishing between HAV &HBV

• Patient A: Most effective diagnosis method is an Enzyme-Linked ImmunoSorbent Assay (ELISA) or a radioimmunoassay for anti-HAV IgM.

Cont’d

• Patient B: Look for presence of HBsAg and HBeAg and a lack of antibodies for these antigens diagnosed through ELISA or radioimmunoassay.

Most likely means of viral acquisition in each case

• Patient A: Fecal-Oral Route: Contaminated water or seafood acquired while on vacation in Thailand.

• Patient B: Sharing contaminated needles.

Personal and public health precautions they could have taken in each case

• Patient A: Personal- Washing hands thoroughly, not eating seafood, especially clam, from contaminated water sources. Public health measures are ensuring sewage is properly treated and require food service workers to always wash hands.

Cont’d

• Patient B-Not sharing needles, abstaining from drug use. Avoiding unprotected sexual activities, especially with carriers of HBV. Public health measures that can be implemented include education on drug use, needle use, safer sex.

Which of the patients was susceptible to chronic disease?

• Patient B: Up to 10% of patients infected with HBV will develop a chronic disease. Chronic disease effects include liver scaring, cirrhosis, liver failure, and primary hepatocellular carcinoma.

How can HAV, HBV disease be prevented and treated?

• HAV-Avoiding contaminated food/water(fully cooked food)

• Washing hands for food preparers, and those that take care of others.

• Chlorine treatment of drinking water.• VaccineHAV-Treatment:• Prophylaxis with Immune Serum Globulin

HBV prevention

• Screening donated blood• Avoiding unprotected sexual contact• Avoiding drug use and the sharing of needles • Hepatitis B Immune Globulin• Vaccine

Cont’d

Lamivudine

References• http://www.ncbi.nlm.nih.gov/books/NBK7864/• http://www.nlm.nih.gov/cgi/mesh/2011/MB_cgi?

field=uid&term=D004797