Hepatitis
This section will cover the major viral pathogens causing hepatitis, focusing on Hepatitis A Virus (HAV), Hepatitis B Virus (HBV), and Hepatitis C Virus (HCV). We will discuss their etiology, epidemiology, transmission, disease states, and key differences
Hepatitis A Virus (HAV)
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Etiology
- Classification: A member of the Picornaviridae family
- Non-Enveloped RNA Virus: HAV is a single-stranded RNA virus
- One Serotype: There is only one serotype of HAV
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Epidemiology
- Global Distribution: Found worldwide, but more common in areas with poor sanitation and hygiene
- Seasonality: Can occur year-round, but outbreaks are more common in the fall and winter
- Age Groups: Can affect all age groups, but children are often asymptomatic
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Transmission
- Fecal-Oral Route: Primarily spread through the fecal-oral route via contaminated food, water, or surfaces
- Close Contact: Can also be spread through close personal contact with an infected individual
- Outbreaks: Common in settings with poor sanitation, such as restaurants, daycare centers, and schools
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Disease States
- Acute Hepatitis: Characterized by fever, fatigue, nausea, vomiting, abdominal pain, jaundice (yellowing of the skin and eyes), dark urine, and pale stools
- Symptoms: Typically begin 2-6 weeks after exposure and last for several weeks to months
- Chronic Infection: HAV does not cause chronic infection
- Severity: Usually self-limiting and resolves without specific treatment
- Complications: Rarely causes liver failure or death
Hepatitis B Virus (HBV)
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Etiology
- Classification: A member of the Hepadnaviridae family
- DNA Virus: HBV is a partially double-stranded DNA virus
- Multiple Genotypes: There are multiple genotypes of HBV (A-J), which vary geographically
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Epidemiology
- Global Distribution: Found worldwide, with higher prevalence in certain regions, such as Asia and Africa
- Chronic Infection: Approximately 257 million people worldwide are living with chronic HBV infection
- Age Groups: Can affect all age groups, but chronic infection is more common in infants and young children
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Transmission
- Bloodborne: Spread through contact with infected blood or body fluids
- Sexual Contact: A common route of transmission
- Mother to Child: Can be transmitted from mother to child during childbirth (perinatal transmission)
- Injection Drug Use: Sharing needles or syringes
- Healthcare Settings: Unsafe injection practices, blood transfusions, and medical procedures
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Disease States
- Acute Hepatitis: Similar symptoms to HAV, including fever, fatigue, nausea, vomiting, abdominal pain, jaundice, dark urine, and pale stools
- Chronic Hepatitis: Long-term infection that can lead to cirrhosis (scarring of the liver), liver failure, and hepatocellular carcinoma (liver cancer)
- Asymptomatic Carriers: Some individuals with chronic HBV infection are asymptomatic carriers, meaning they do not have symptoms but can still transmit the virus
- Severity: Chronic HBV infection can range from mild to severe
- Complications: Cirrhosis, liver failure, hepatocellular carcinoma, and death
Hepatitis C Virus (HCV)
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Etiology
- Classification: A member of the Flaviviridae family
- RNA Virus: HCV is a single-stranded RNA virus
- Multiple Genotypes: There are multiple genotypes of HCV (1-7), which vary in their response to treatment
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Epidemiology
- Global Distribution: Found worldwide, with higher prevalence in certain regions
- Chronic Infection: Approximately 71 million people worldwide are living with chronic HCV infection
- Age Groups: Can affect all age groups, but chronic infection is more common in adults
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Transmission
- Bloodborne: Primarily spread through contact with infected blood
- Injection Drug Use: Sharing needles or syringes is the most common route of transmission in many countries
- Blood Transfusions: Before routine screening of blood products, blood transfusions were a significant source of transmission
- Healthcare Settings: Unsafe injection practices and medical procedures
- Sexual Contact: Less common than HBV, but can occur
- Mother to Child: Can be transmitted from mother to child during childbirth (perinatal transmission), but less common than HBV
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Disease States
- Acute Hepatitis: Often asymptomatic or mild symptoms, such as fatigue and jaundice
- Chronic Hepatitis: Long-term infection that can lead to cirrhosis, liver failure, and hepatocellular carcinoma
- Asymptomatic Carriers: Many individuals with chronic HCV infection are asymptomatic for years or decades
- Extrahepatic Manifestations: HCV can also cause other health problems, such as fatigue, joint pain, skin problems, and kidney disease
- Severity: Chronic HCV infection can range from mild to severe
- Complications: Cirrhosis, liver failure, hepatocellular carcinoma, and death
Key Terms
- Etiology: The cause or origin of a disease or condition
- Epidemiology: The study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems
- Transmission: The way a disease is spread from one person or source to another
- Hepatitis: Inflammation of the liver
- Hepatitis A Virus (HAV): A virus that causes acute hepatitis, transmitted through the fecal-oral route
- Hepatitis B Virus (HBV): A virus that can cause acute and chronic hepatitis, transmitted through blood and body fluids
- Hepatitis C Virus (HCV): A virus that can cause acute and chronic hepatitis, transmitted primarily through blood
- Jaundice: Yellowing of the skin and eyes
- Cirrhosis: Scarring of the liver
- Hepatocellular Carcinoma: Liver cancer
- Serological Tests: Blood tests that detect viral antigens or antibodies
- Molecular Tests: Tests that detect viral RNA or DNA
- Viral Load: The quantity of virus present in a specific amount of a patient’s blood
- Liver Function Tests (LFTs): Blood tests that measure liver enzymes
- Direct-Acting Antivirals (DAAs): Medications that target specific steps in the HCV life cycle
- Sustained Virologic Response (SVR): Eradication of the virus from the body
- Fecal-Oral Route: Transmission of pathogens through contact with fecal matter and then ingestion
- Bloodborne: Transmission of pathogens through contact with infected blood or body fluids
- Asymptomatic Carrier: An individual who is infected with a virus but does not show symptoms