Handwritten Lecture on symptoms and treatment for Hepatitis A Virus (HAV) for medical students studying for USMLE Step 1, USMLE Step 2, and USMLE Step 3 review.
During your USMLE review, it is helpful to watch this video and then attempt questions in the Kaplan QBank or UWorld QBank.
MICROBIOLOGY 00:00
PATHOPHYSIOLOGY 00:54
EPIDEMIOLOGY 04:35
SIGNS AND SYMPTOMS 07:35
INVESTIGATION 10:47
TREATMENT 13:51
VACCINATION 14:59
POST-EXPOSURE PROPHYLAXIS 17:45
MICROBIOLOGY
The Hepatitis A Virus (HAV) has an icosahedral pattern. The hepatitis A virus (HAV) is a naked virus, around 27 nm. Its has single stranded positive sense RNA virus, and at the 5' end there is a protein called of VPg, which is necessary for replication. The Hepatitis A Virus (HAV) part of the Picornavirus family and the genus Hepatovirus.
PATHOPHYSIOLOGY
The Hepatitis A Virus (HAV) is transmitted through fecal-oral route. Once the hepatitis A virus is in the small intestine, many will feel GI symptoms such as nausea, vomiting, abdominal pain, and fever, which lasts 2 to 3 weeks. During this time period, the individual is infectious.
EPIDEMIOLOGY
On a worldwide scale, the prevalence of hepatitis A virus is much greater in the third world countries. This is primarily because of issues related to sanitation regulations with food handling and distribution. Therefore, these factors have play a large role in the spread of hepatitis A virus in these first world country.
The overall United States of rate of hepatitis A virus is low. However, in 2013 there was a hepatitis outbreak relation related to Turkish pomegranates, it returned to its baseline under 0.5/100,000 in 2014 and 2015. After 2016 there has been a sharp increase in the number of cases of Hepatitis A virus went from a baseline of 0.5/100,000 in 2015 to almost 4/100,000 in 2018. This is largely been attributed to the increased homelessness, IV drug use and MSM.
SYMPTOMS
The hepatitis A virus is it has a long incubation period up to 28 days. Like we discussed before, these symptoms are nausea, vomiting, abdominal pain, fever, typical GI symptoms. Approximately, 40 to 70% of patients who move on to the liver symptoms, jaundice pruritus, also rash, arthralgias and hepatospenomegaly on physical exam or imaging. Fortunately, hepatitis A virus is not chronic, like Hepatitis B or Hepatitis C. But 10% of patients may experience relapse. However, all patients typically have a lifelong immunity as long as they have an intact immune system.
There are some rare complications to be aware of. First, you can get fulminant hepatic failure. This occurs in less than 1% of patients, but when it does occur it's associated with a very high mortality.This is particularly common in patients with liver disease, and patients were old and 50 years old. There are a number of cases of autoimmune hepatitis after exposure to hepatitis A. Rarely patient can have Leukocytoclastic vasculitis, cryoglobulinemia, myocarditis, optic neuritis and transverse myelitis.
INVESTIGATIONS
Patients with hepatitis A virus have an elevated ALT & AST, greater than 1000. There is an associated increase in bilirubin, but it's typically less than 10, so greater than that kind of is rare in in a hepatitis A virus setting.
ALP is always also increase, but again, it doesn't typically go above 400.
At a certain time you will get increase in inflammatory markers and this goes back to the pathophysiology. INR is increased only if there is fulminant liver failure.
The diagnostic test is IgM hepatitis A virus antibody. It stays elevated and then reduces approximately 3 months later. IgG is not helpful for diagnosis, but it does tell you the prevalence.
TREATMENT
Treatment for hepatitis A virus is a largely supportive. The best advice is to avoid hepatoxic medication. If they develop fulminant hepatic failure, then they require urgent liver transplant.
VACCINATION FOR HEPATITIS A
Currently, there is an effective hepatitis A virus vaccine available. It is an inactivated vaccine that requires two doses, 6 to12 months apart.
Indications
1 to 18 years old, Liver disease, Outbreaks, Homeless, IVDU & MSM
Travelers
Two doses of the vaccine if age less than 40 years old. Vaccine and an Ig, if over the age of 40, immunosuppressed, chronic disease, liver disease. Remember, you should administer the vaccine and Ig in two different arms.
POST EXPOSURE PROPHYLAXIS
At risk for HAV are households, sexual contacts, people who share needles IVDU, and food handlers during an outbreak.
If vaccinated, they typically don't need any treatment because they already have a vaccine, except HIV patients who require a dose of Ig.
For unvaccinated, they should receive a single dose of the hepatitis A vaccine or Ig within 2 weeks of exposure. For those older than 40, or weak immune system, chronic disease, liver disease. You're going to have to vaccinate completely and give and Ig.