Hepatitis A SATHIYASILAN. G IQBAL HAKIM GROUP 21 B
Hepatitis inflammation of the liver n Caused by : drugs n toxins n alcohol n viral infections (A, B, C, D, E) n other infections (parasites, bacteria) n physical damage n
Taxonomy n n n Family – Picornoviridae Genus – Hepatovirus Species – Hepatitis A virus (HAV) Electron micrograph of hepatitis A virions.
Healthy Liver Cirrhosis Liver
Hepatitis Terms n Acute Hepatitis: Short-term hepatitis. n n Body’s immune system clears the virus from the body within 6 months Chronic Hepatitis: Long-term hepatitis. n Infection lasts longer than 6 months because the body’s immune system cannot clear the virus from the body
Morphology n n n Non-enveloped. Contains a single-stranded RNA packaged in a protein shell. There is only one type.
Cultural Properties n n n Difficult to grow in cell culture. Primary marmoset cell culture and also in vivo in chimpanzees and marmosets. Not cytolytic, released by exocytosis.
Resistance n n n Capsid is more stable than enteroviruses to acid and others. Resistant to inactivation by heat at 60 celsius for 1 hour, ether & acid at p. H 1. Inactivated by Cl, formalin, peracetic acid, beta-propiolactone & UV radiation. Not affected by nonionic detergents. Prolonged storage at 4 celsius or colder, but destroyed by boiling for 1 minute.
Symptoms Nausea n Loss of appetite n Vomiting n Fatigue n Fever n Dark urine n Pale stool n Jaundice n Stomach pain n Side pain n A person may have all, some or none of these
Incubation period 30 days on average (range 15 -50 days) n infectious latter half of incubation period while asymptomatic through 1 week after having jaundice. n
Pathogenesis n n n Following ingestion, HAV enters the bloodstream through the epithelium of the oropharynx or intestine. The blood carries the virus to its target, the liver, where it lives and multiplies within hepatocytes and Kupffer cells (i. e. , liver macrophages). There is no apparent virus-mediated cytotoxicity, and liver pathology is likely immune-mediated.
n n n Virions are secreted into the bile and released in stool. HAV is excreted in large quantities approximately 11 days prior to appearance of symptoms or anti-HAV Ig. M antibodies in the blood. The incubation period is 15 -50 days, and mortality is less than 0. 5%.
Transmission n Close personal contact (e. g. , household contact, sex contact, child day care centers) n Contaminated food, water (e. g. , infected food handlers, raw shellfish) n Blood exposure (rare) (e. g. , injecting drug use, transfusion)
Laboratory Diagnosis n Acute infection is diagnosed by the detection of HAV-Ig. M in serum , serological method by ELISA or radioimmunoassay. n Past Infection i. e. immunity is determined by the detection of HAV-Ig. G. n Cell culture – difficult and take up to 4 weeks, not routinely performed.
Epidemiology n n HAV is found in the feces of infected persons and those who are at higher risk include travelers to developing countries where there is a higher incidence rate, and those having sexual contact or drug use with infected persons. HAV outbreaks still occur in and caused by poor hand hygiene among infected, sometimes symptomatic restaurant employees failing to wash their hands after toilet breaks.
Immunity n n Interferon limits viral replication. Natural killer cells & cytotoxic T cells required to lyse infected cells. Antibody, complement & antibody dependent cellular toxicity. Antibody against reinfection is lifelong.
Prevention Shot of immune globulin up to 2 weeks after exposure n Good hand washing n Cook food well n Good diaper hygiene n Only drink clean water n VACCINE!!! n
Prophylaxis n n Killed & live vaccine administered for immunization against HAV infection. Prophylaxis with immune serum globulin given before or early in the incubation period.
Sources n n www. wikipedia. org Medical Microbiology, A Guide To Microbial Infections : Pathogenesis, Immunity, Laboratory Diagnosis & Control 16 th edition by Churchill Livingstone
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