13. Viral Hepatitis Flashcards
What is Hepatitis? what are the 5 diverse viruses? How they transmit?
Hepatitis: inflammation of the liver
Hepatitis A virus (HAV) and hepatitis E virus (HEV) are transmitted via the fecal-oral route
Hepatitis B virus (HBV), hepatitis C virus (HCV) and hepatitis delta (D) virus are transmitted via exposure to infected blood/body fluids or perinatally
HAV: Transmission
Person-to-person through the fecal-oral route (ingestion of something that has become contaminated with the feces of an infected person)
Often results from close personal contact with an infected household member or sex partner
Can also occur with uncooked foods or inadequately cooked foods, or cooked foods handled by an infected food worker
Can lead to common-source outbreaks and sporadic cases
Water-borne outbreaks occur infrequently in developed countries with well-maintained sanitation and water supplies
No insect vector or animal reservoir
HAV: Incubation period
28 days (range 15-50 day
HAV: symptoms
Inverse relationship between symptoms and age of patient
Most infants and children < 6 years old (70%) are asymptomatic
Most adults and adolescents (70%) do develop symptoms
Symptoms typically begin abruptly and include: fever, loss of appetite, nausea, vomiting, abdominal pain, jaundice
Symptoms last less than 2 months, but some individuals experience relapses for up to 6 months
Once infected with HAV, individual has life time protection
HAV: diagnosis, treatment
Diagnosis: Detection of immunoglobulin M (IgM) serum antibodies
Treatment: No specific treatment; will resolve on its own in several weeks
HAV: pop at risk
- International travelers, esp. to developing countries
- People who live with or have sex with an infected person
- Day care children and employees, during outbreaks
- Men who have sex with men
- Users of illicit drugs
HAV: prevention
Vaccination
- Best method of prevention in the U.S.
- Licensed in the U.S. for persons 12 months of age and older; 2 dose series
- 2006 – Advisory Committee on Immunization Practices (ACIP) universally recommended HAV vaccine for children; receive at 12 month well-child check
Good hygiene
- Handwashing after toileting, changing diapers, preparing foods
- In developing countries, improved environmental sanitation to prevent fecal contamination of food and water is the most important preventive measure
HBV: transmission
- Percutaneous (puncture through the skin) blood exposure
- Increased risk among IVDU who share equipment
- Other methods: acupuncture, tattooing, body piercings, sharing razors
- Developing countries – medical injections
- Sexual intercourse: Increased risk among those with high number of sexual partners
- Perinatal
HBV: Incubation Period
90 days (range 60-150 days)
HBV: symptoms (acute and chronic)
Acute infection
- Severity ranges from asymptomatic/mild to (rarely) fulminant (severe and sudden in onset) hepatitis;
- Like HAV, the presence of symptoms is age dependent; most children <5 years are asymptomatic
- 30-50% of persons ≥ 5 years have signs and symptoms
- Disease is more severe among adults >60 years
- When present, signs and symptoms include: fever, loss of appetite, nausea, vomiting, abdominal pain, jaundice
- Symptoms last for several weeks, but can persist for 6 months
HBV: symptoms (acute and chronic)
Chronic HBV
- Some individuals do not recover and progress to chronic disease
- Risk of chronic infection decreases with increasing age: 90% of infants and 25-50% of children aged 1 – 5 years will remain chronically infected; by contrast 5% of adults will develop chronic disease
- Individuals with chronic HBV develop a spectrum of disease from normal liver to cirrhosis (severe damage to liver) or liver cancer
- Individuals infected as infants/children have a higher risk of significant chronic liver disease
HBV: diagnosis, treatment
Diagnosis
Confirmed via serologic testing
HBV serology is complex and involves testing a number of markers (antigens and antibodies) to distinguish between the following categories:
- Susceptible
- Immune due to natural infection
- Immune due to HBV vaccination
- Acutely infected
- Chronically infected
Treatment
- Acute infection – No specific treatment
- Chronic infection
- Several antiviral medications licensed in the U.S.
- Treatment cannot eradicate the virus, but can suppress the virus & help prevent the onset/progression of liver damage
- Due to treatment cost, toxicity & development of resistance, treatment targeted to those with moderate/severe liver inflammation
HBV: Worldwide Epidemiology
varies greatly worldwide
- Highly endemic - 8%+ of population infected with chronic HBV
- 45% of the global population (China, Southeast Asia, sub-Saharan Africa)
- Most infections occur in perinatal or childhood period: results in chronic carriage
- Liver cancer is very common; often most frequent cancer in adult men
- Intermediate – 2-8% of population infected with chronic HBV
- 43% of global population
- Mixed patterns of infant, childhood and adult transmission
- Low - <2% population infected with chronic HBV
- 12% of global population (North America, Western Europe, Australia, parts of South America)
- Most infections occur among high-risk adult populations
HBV: pop at risk
- infants born to infected mothers
- Sex partners of infected persons
- Sexually active persons who are not in a longterm, mutually monogamous relationship
- Injection drug users
- Household contacts of persons with chronic HBV infection
- Health care and public safety workers at risk for occupational exposure to blood or bloodcontaminated body fluids
- Hemodialysis patients
- Travelers to countries with intermediate and high prevalence rates of HBV
HBV: prevention
- Vaccine
Individual requires 3 (or more) doses to induce a protective immune response
Not known whether vaccine confers lifelong immunity, but data supports at least 15 years of protection
Currently ACIP recommends universal vaccination for all children starting at birth, and all children <19 years who have not been vaccinated previously
Also recommended for at-risk adults
HCV: transmission
- Percutaneous (puncture through the skin) blood exposure: risk with a single needle stick is 1 – 3%
- Injection drug use: most common means of transmission in U.S
- Healthcare worker associated needle stick
- Receipt of donated blood/blood products: rare in U.S. due to blood screening
- Perinatal transmission
- Sexual intercourse: an inefficient means; NOT very common
HCV: incubation period
Average is 4-12 weeks (range 2 – 24 weeks)
HCV: symptoms (acute and chronic)
Acute HCV
- Most acute HCV infections are asymptomatic
- 20-30% of infected will experience fatigue, abdominal pain, poor appetite or jaundice
Chronic HCV
- Following acute infection, 60-85% of individuals will remain persistently infected
- Most individuals are asymptomatic or have mild symptoms that aren’t recognized as HCV
- Many develop chronic liver disease (mild to severe) which can progress slowly without signs/symptoms for decades
- 2-25% develop life-threatening cirrhosis and/or liver cancer
- Deaths in the US due to HCV have been increasing steadily
HCV: diagnosis, treatment
Diagnosis
- Detection of antibodies via enzyme immunoassay
- Detection of HCV RNA: newer assays can provide both presence (qualitative) and amount (quantitative) information; Can be utilized to assess treatment response
Treatment
- HCV treatment regimens are available
- Goal of treatment is elimination of infection (cure)
- Newer treatments have resulted in cure rate of 70%
HCV: prevention
No vaccine available
Prevention accomplished by efforts to prevent exposure, e.g. blood screening, needle exchange programs, improvements in medical procedures that involve percutaneous exposures
CDC & U.S. Preventative Services Task Force recommend
- One-time hepatitis C testing for everyone born 1945-1965
- Regular testing for others at high risk (e.g. IVDUs)
HCV: Worldwide Epidemiology
Several highly endemic regions for HCV have been identified. E.g. Egypt – HCV prevalence rates range from 10%-30% - thought to be due to national campaign to treat schistosomiasis
In developed countries, HCV prevalence is <3%
However, high rates have been reported in some urban areas
More Americans die as a result of HCV than from 60 other infectious diseases reported to the CDC
- Have seen a significant rise in cases since 2010
- 2/3 of cases related to injection drug use
- Remaining cases due to sexual/household contact, occupational exposures, transfusions/other medical procedures
