ð é«åžçç
ð äžé éé»
- Virus: ssRNA Picornaviridae (Hepatovirus genus)
- Transmission: fecal-oral primarily; contaminated food/water; person-to-person; rare blood
- Reservoir: humans only
- Incubation: 15-50 days (mean 28)
- Clinical:
- Mild URI-like prodrome (1-2 wk): fever, malaise, anorexia, nausea, abdominal pain
- Icteric phase: jaundice, hepatomegaly, dark urine, light stool, pruritus (2-4 wk)
- Never chronic â key feature distinguishing HAV from HBV/HCV
- Severe: fulminant hepatic failure (1-2% adults â much higher in older)
- Cholestatic variant â prolonged jaundice + itching
- Relapsing variant â recurrent symptoms over months
- Mortality: ~ 0.3% overall; up to 2-3% in ⥠50 yr; fulminant rare but possible
- Diagnosis:
- IgM anti-HAV = acute infection
- IgG anti-HAV = past infection or vaccination (immunity)
- PCR (research / outbreak surveillance)
- Liver enzymes elevated (AST/ALT often 1000+)
- Treatment: supportive only; liver transplant for fulminant
- Prevention:
- Vaccine (inactivated): 2-dose series 6-12 mo apart
- Universal childhood vaccination in many countries (USA 2006, Taiwan)
- Pre-exposure prophylaxis: high-risk travelers, MSM, IDU, food handlers
- Post-exposure prophylaxis: vaccine ± immunoglobulin within 14 days
- 2017-2024 USA outbreaks: homeless + IDU + MSM clusters in CA, KY, TN, MI; reactivation of HAV transmission in urban settings; vaccination campaigns
1ïžâ£ Virology
- ssRNA picornavirus
- Hepatovirus genus
- Single serotype (despite genotype variation)
- Capsid VP1-VP4
- Acid + heat stable (survives stomach + persists environment)
Pathogenesis
- Ingestion â gut absorption â portal blood â hepatocytes
- Replication in hepatocytes
- Cytopathic + immune-mediated hepatocellular damage
- Viral shedding in bile + feces (begins 1-2 wk before symptoms; peak just before icterus; declines after)
- IgM rise â IgG seroconversion
- Lifelong immunity after natural infection or vaccination
2ïžâ£ Epidemiology
Global Distribution
- High endemicity: low-income countries (universal childhood acquisition)
- Intermediate: middle-income, transitioning
- Low: developed countries (now adolescent + adult susceptibility increasing)
Transmission Routes
- Fecal-oral primary
- Food: contaminated water, shellfish (filter-feeders concentrate virus), produce (irrigated with contaminated water)
- Person-to-person: close contact (households, daycare)
- Sexual: MSM (anal-oral)
- Blood: rare (transient viremia; not chronic carrier state)
- Vertical: rare
Risk Groups
- International travelers to endemic
- MSM
- IDU
- Homeless (recent USA outbreaks)
- Food handlers (transmission)
- Childcare workers
- Chronic liver disease (severe disease if infected)
2017-2024 USA Outbreaks
- CA 2017+ homeless + IDU outbreak (San Diego)
- KY, TN, MI, FL clusters since 2018
- 40,000+ cases since 2016
- Hospitalization rate ~ 60%
- Deaths reported
- Drivers: housing instability, drug use, vaccination gaps, sanitation in homeless settings
- Public Health response: mass vaccination, sanitation, harm reduction
3ïžâ£ Clinical
Incubation (15-50 d)
- Asymptomatic during incubation
- Shedding begins 1-2 wk before symptoms
Prodromal Phase (1-2 wk)
- Fever
- Malaise, fatigue
- Anorexia
- Nausea, vomiting
- RUQ pain
- Mild URI-like
- Aversion to smoke / tobacco (classic clue)
Icteric Phase (2-4 wk)
- Jaundice + pruritus
- Dark urine (bilirubin) + clay-colored stool
- Hepatomegaly + tender
- Splenomegaly (10-20%)
- Symptoms paradoxically improve as bilirubin rises
- Liver enzymes peak (AST/ALT > 1000 common)
Recovery Phase
- 4-8 wk total disease duration usually
- Complete recovery in most
- Lifelong immunity
4ïžâ£ Diagnosis
Serology
- IgM anti-HAV â acute infection (positive at symptom onset, persists 3-6 months)
- IgG anti-HAV â past infection or vaccination (lifelong)
Liver Enzymes
- AST/ALT 1000-5000 typical (very high)
- Bilirubin variable
- ALP mildly elevated (cholestatic variant higher)
- PT/INR â assess severity (prolonged = severe/fulminant)
- Albumin (severe)
- Glucose (severe â hypoglycemia)
Imaging
- Not routinely needed
- Ultrasound for differentiation (rule out obstruction)
Other Tests
- HBV serology (concurrent test)
- HCV serology
- HEV serology (acute hepatitis differential)
- Differential: drug-induced, autoimmune, HSV (rare hepatitis), CMV, EBV mononucleosis, leptospirosis, malaria
5ïžâ£ Treatment
Supportive
- Hydration, rest, antiemetic, antipruritic
- Avoid hepatotoxic medications (acetaminophen safe in low doses if liver function OK)
- Avoid alcohol
- Adequate nutrition
Hospitalization
- Severe symptoms
- Inability to maintain hydration
- Coagulopathy (INR > 1.5)
- Mental status changes
- Pregnancy 3rd trimester
- Older + comorbid
Fulminant
- ICU
- Mannitol for cerebral edema
- N-acetylcysteine (some evidence)
- Liver transplant if Kingâs College criteria met
- Coagulopathy management
6ïžâ£ Prevention
Vaccine
- Inactivated (HAVRIX, VAQTA)
- 2-dose series 6-12 mo apart
- > 95% efficacy seroconversion
- Lifelong immunity expected (long-term Ab data 25+ yr)
Recommendations (ACIP 2024)
- Universal childhood vaccination 12-23 mo (USA 2006)
- Catch-up children + adolescents through 18 yr if not vaccinated
- Adults at risk:
- International travelers (endemic regions)
- MSM
- IDU
- Chronic liver disease (HBV, HCV, cirrhosis)
- Healthcare workers (some exposures)
- Childcare / institutional
- Food handlers (where required)
- Pregnancy: safe if needed (inactivated)
- Outbreak vaccination: homeless populations, IDU, MSM in outbreak settings
Twinrix (HAV + HBV Combination)
- Used for travel + high-risk
- 3-dose series
Post-Exposure Prophylaxis (PEP)
- Within 14 days of exposure
- Vaccine if previously unvaccinated:
- Healthy 1-40 yr: vaccine alone
- + Immunoglobulin if < 12 mo, > 40 yr, immunocompromise, chronic liver disease
- Household + sexual + daycare + childcare close contacts
Sanitation + Hygiene
- Handwashing
- Safe food + water (high-risk travelers)
- Avoid raw / undercooked shellfish (filter-feeders)
- Cook shellfish thoroughly (heat inactivates HAV)
- Donât eat from street food (where uncertain)