Hepatitis A Virus : Characteristics, Clinical Features

Viral Characteristics Of HAV

This nonenveloped RNA virus belongs to the hepatoviral genus in the picornavirus family and is the most prevalent cause of acute hepatitis in children and viral hepatitis globally. It can withstand heat, acid, and ether, requiring particular neutralization techniques.

The virus spreads by the faecal-oral route; it can be killed by appropriate chlorination, autoclaving, and boiling contaminated water for longer than a minute. In developing nations, tainted water is a common source; in industrialized nations, food is the usual means of transmission. 

 The virus reaches the liver through the portal vein in the intestine of a youngster who consumes contaminated food or water, causing inflammation. Bile secretion allows the virus particles from the liver to enter the intestine. The development of this technique takes roughly seven days. 

The incubation period has a mean duration of three weeks and a range of 15 to 45 days. Late in the incubation stage, the patients start to exude the virus, which peaks right before symptoms appear. Two weeks after the onset of jaundice, it goes away.  The virus is more persistent in newborns' feces; It is contagious for two weeks prior to and one week following the start of jaundice. 

Clinical Features Of HAV Infection

 Acute febrile sickness caused by HIV is characterized by anorexia, vomiting, jaundice, and a prodromal period of fever with or without chills. Following 7 to 14 days of illness, people heal on their own. It can be akin to gastroenteritis in infants, characterized by loose, watery feces, vomiting, and fever. A checkup may detect minor splenomegaly, local lymphadenopathy, or hepatomegaly. 

Immune complexes, GI ulcers, and self-limited hypoplastic bone marrow are more common in adolescent adults than in children. Adults with concomitant conditions, such as immunosuppression, liver disease, transplantation, long-term corticosteroid usage, and transplantation, are most likely to have these. Cryoglobulinemia, leukocytoclastic vasculitis, nephritis, and arthritis are all caused by immune complexes. 

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Diagnosis of HAV

The ALT level increases starting in the second week following infection and peaks 1.5 months following HAV infection. Thereafter, there is a steady decline back to baseline hepatitis. Two to two and a half weeks after the commencement, a virus excretes in the stool, and symptoms of jaundice persist for seven to fourteen days. IgG anti-HAV often lasts a lifetime, whereas IgM anti-HAV first develops and after six months, its titres tend to decrease off quickly. 

Since the presence of an IgM anti-HAV antibody implies an active or acute infection, radioimmunoassay is the chosen method of investigation. It is visible as soon as symptoms start and can be found up to four or six months following infection. Because IgG is a lifelong result of previous infection or vaccination, it is not a reliable indicator of an ongoing infection. However, within eight weeks of commencement, new IgG from fresh exposure manifests. It offers protection for life. 

Liver function tests indicate the presence of the infection but do not prove it. Increased levels of alkaline phosphatase, gamma-glutamate transferase, 5'-nucleotidase, AST, ALT, and bilirubin . The only use of blood PCR for HAV detection is in research. 

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Biochemical profile of patients with HAV infection.

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Complications Of HAV

Rarely, complications arise in immunocompromised elderly patients or those with underlying liver disorders. When HAV infection is present, chronicity is rare. Less than 0.5 percent of cases result in acute liver failure; however, in endemic areas, it is prevalent in about 40 percent of patients; prolonged cholestatic syndrome can happen; it manifests as waxes and wanes and can lead to pruritis and fat malabsorption. It gets resolved on its own. 

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Treatment and Prevention

Treatment, either supportive or symptomatic, is required if the patient has chronic cholestasis. Vaccination, post-exposure prophylaxis, appropriate faecal material disposal, and hand hygiene are among the preventive measures. 

Vaccination: There are two kinds of vaccines: Inactivated/killed and live attenuated. The live attenuated vaccination is given in one dose during the 12th month of pregnancy. Two doses are required for inactivated vaccines: one at the 12th month and another at the 18th or 19th month. 

The national immunization schedule does not include the HIV vaccination. Prophylaxis following exposure. Following exposure, vaccination against the virus with the HIV vaccine is possible.
90% protection against severe or symptomatic HAV infection is provided by the vaccine if it is administered within 10 days of exposure from an unvaccinated individual. 

Hope you found this blog helpful for your NEET SS Pediatrics Infections preparation. For more informative and interesting posts like these, keep reading PrepLadder’s blogs.