Hepatitis B serology question - USMLE Forums
USMLE Forums Logo
USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
Home
USMLE Articles
USMLE News
USMLE Polls
USMLE Books
USMLE Apps
Go Back   USMLE Forums > USMLE Step 2 CK Forum

USMLE Step 2 CK Forum USMLE Step 2 CK Discussion Forum: Let's talk about anything related to USMLE Step 2 CK exam


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 02-24-2013
USMLE Forums Scout
 
Steps History: Step 1 Only
Posts: 33
Threads: 7
Thanked 23 Times in 11 Posts
Reputation: 33
Default Hepatitis B serology question

A 22 y/o man used illicit IV drugs briefly 1 year ago. He is asymptomatic and has no history of viral hepatitis. Serum ALT and bilirubin concentrations are normal. Serologic studies show:
Hepatitis B surface antigen (HBsAg) positive
Hepatitis B core antibody (HBcAb) positive
Hepatitis B e antigen (HBeAg) negative
Antibody to surface antigen (Anti-HBs) negative
Antibody to e antigen (Anti-HBe) positive

Which of the following statements best describes the current condition?
a-He is in the incubation period, is highly infectious, is likely to develop acute hepatitis B.
b-He is in the incubation period, is minimally infetious, and is likely to develop acute hepatitis B.
c-He is a chronic carrier of hepatitis B and is highly infectious.
d-He was infected previously with hepatitis B. has recovered and is immune to hepatitis B.



Answer given is A

My concern: If e Ag is Negative and e Ab is positive, is it considered highly infectious

High Infectivity depends on which marker
Reply With Quote Quick reply to this message



  #2  
Old 02-24-2013
USMLE Forums Master
 
Steps History: 1+CK+CS
Posts: 1,867
Threads: 149
Thanked 2,085 Times in 1,046 Posts
Reputation: 2105
Default

There is a small period when the above scenario is possible (Weeks 20-24 post infection) and the patient is still infective since HBsAg is positive.

You can read here for more discussion on this topic and here , here, & here for Hepatitis in general.

Quote:
Both HBsAg (surface)& HBeAg (inner core) are part of the same virus.
So, it makes sense that both indicate infectivity.
However, it takes some time for HBeAg to appear in the serum (and, therefore, detectable by the test). During this period (HBsAg + & HBeAg -) the patient can still transmit the infection. Test for HBsAg does not tell you the quantity of the virus just the presence of it.

However, appearance of HBeAg means that patient is actively producing a lot of virus. The more quantity means more chances of transmission. Therefore, there is a very high risk of infection in the presence of HBeAg (HBsAg + & HBeAg +) as compared to HBsAg + & HBeAg - since there is a lot more of the virus to infect per unit volume (HBeAg+ = High Infectivity).

There cannot be a scenerio where HBsAg - & HBeAg + since the virus has to be alive and well to make HBeAg.
__________________
A man doesn't know what he knows until he knows what he doesn't know.
“What is man? He's just a collection of chemicals with delusions of grandeur.”
Reply With Quote Quick reply to this message
  #3  
Old 02-24-2013
koolkiller88's Avatar
USMLE Forums Master
 
Steps History: Step 1 Only
Posts: 864
Threads: 62
Thanked 370 Times in 224 Posts
Reputation: 380
Default Nice explanation

Quote:
Originally Posted by Novobiocin View Post
There is a small period when the above scenario is possible (Weeks 20-24 post infection) and the patient is still infective since HBsAg is positive.

You can read here for more discussion on this topic and here , here, & here for Hepatitis in general.
I got your point here but still confused regarding question.
This patient have no history of viral hep
As you said this condition can develop in 20-24 wks post infection. How this patient is in incubation period? Is he developing acute infection again? (as he already have anti-HBeAg +)
__________________
One day i will infect these microbes and they will search for "Anti-MEbiotic"....
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Quick reply to this message
  #4  
Old 02-24-2013
USMLE Forums Scout
 
Steps History: Step 1 Only
Posts: 33
Threads: 7
Thanked 23 Times in 11 Posts
Reputation: 33
Default Incubation period???

THANKS novobiocin and koolkiller

I would like to clarify/understand the following issues


1. Patient is HBeAg negative and Anti HBe Ab positive, but HBsAg positive: can the infection still be considered highly infectious or only infectious/minimally infectious

2. How do you define/justify the incubation period when AntiHBe Ab is negative



THANKS AGAIN TO ALL YOU GUYS
Reply With Quote Quick reply to this message
  #5  
Old 02-25-2013
USMLE Forums Master
 
Steps History: 1+CK+CS
Posts: 1,867
Threads: 149
Thanked 2,085 Times in 1,046 Posts
Reputation: 2105
Default

Patient is infectious as long as they are HbsAg positive.

It is possible that he got an acute infection (but there is nothing in the history to suggest that?) and his immune system cleared the HBeAg and produced HbeAb. So it is possible that he is in incubation period but I doubt that he is highly infectious since he has HBeAb.

Quote:
In acute cases of hepatitis B, when the body’s immune
system quickly responds and eradicates the viral infection,
the “e” antigen appears only briefly. It disappears as viral
replication declines in the liver as the immune system
launches “e” antibodies to combat this antigen
But I must say that this question is all messed up. Where is it from and did they provide any explanation?
__________________
A man doesn't know what he knows until he knows what he doesn't know.
“What is man? He's just a collection of chemicals with delusions of grandeur.”

Last edited by Novobiocin; 02-25-2013 at 09:32 AM.
Reply With Quote Quick reply to this message



Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the USMLE Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Medical School
Choose "---" if you don't want to tell. AMG for US & Canadian medical schools. IMG for all other medical schools.
USMLE Steps History
What steps finished! Example: 1+CK+CS+3 = Passed Step 1, Step 2 CK, Step 2 CS, and Step 3.

Choose "---" if you don't want to tell.

Favorite USMLE Books
What USMLE books you really think are useful. Leave blank if you don't want to tell.
Location
Where you live. Leave blank if you don't want to tell.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
hepatitis B infection question in UW svmle USMLE Step 3 Forum 1 12-19-2012 03:28 AM
Hepatitis B Serology Question tyagee USMLE Step 2 CK Forum 17 10-07-2012 04:47 PM
Hepatitis B Serology; Very High Yield for the exam koolkiller88 USMLE Step 1 Bits & Pieces 3 09-27-2012 10:22 AM
Hepatitis serology! 1TA2B USMLE Step 2 CK Forum 5 06-17-2011 04:21 PM
Hepatitis Profile Question Yallah USMLE Step 1 Forum 3 06-25-2010 07:16 PM

RSS Feed
Find Us on Facebook
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

USMLE® & other trade marks belong to their respective owners, read full disclaimer
USMLE Forums created under Creative Commons 3.0 License. (2009-2014)