Category Archives: virology

“Over the top testing….Hepatitis A”

The Science of Microbiology, virology, , ,

Over the next few weeks I will do a few articles on micro-organisms where I believe “overtesting” to occur and where there is ample scope to reduce the amount of tests without missing diagnoses.

The first of these tests I would like to look at is Hepatitis A.

There are a few reasons why Hepatitis A is over-tested which I will describe as follows:

  • Hepatitis A is essentially a non-endemic disease in NZ, and is becoming so in many other developed countries. Occasionally there are clusters associated with a known imported case, but rarely in a non-traveller without a contact history. Requestors are not always aware of this.
  • Hepatitis A almost always causes an acute illness with significant derangement of Liver Function Tests (LFTs) with the liver enzymes ALT and AST>100). Yet many times Hepatitis A is requested for the investigation of chronic mild derangement of LFTs.
  • Hepatitis A is often requested as part of a “Hepatitis Screen” which may comprise a panel of Hepatitis A, B & C, even though they usually have completely different clinical presentations.

So what is the solution:

Firstly I am not a big fan of “Hepatitis Screens” and I think requestors should be made to request these tests individually.

Secondly, I would support rejection of the request for Hepatitis A in countries of low endemicity unless one of the following apply:

  • The patient has a travel history.
  • The patient has significant derangement of LFTs. (ALT or AST >100)

I think such measures (if not already used) applied in countries with low endemicity for Hepatitis A would see their testing volume for this test decrease by at least 2/3, and probably more, without adversely affecting the sensitivity of the test. On the contrary, the specificity of the test should increase due to the relatively higher prevalence of disease in the tested cohort.

In the era where health budgets are getting tighter, we need to start thinking seriously about how to test smarter…..Hepatitis A is a great place to start.

Michael

“Predicting the Unpredictable”

virology

Even though it is the middle of the summer here in the Southern Hemisphere, it is time to start thinking about the forthcoming Influenza season.

I usually try and predict how “severe” each season is going to be, based on past seasons and what is happening on the other side of the world. However I am wrong as often as I am right. Of some comfort is the fact that people with much more Influenza expertise than me have similar success rates when trying to predict Influenza seasons. It is a little bit like trying to predict the stockmarket. Equally difficult to predict is which individuals are going to suffer from Influenza and which ones are going to get very sick.

However what we can predict is the following:

1) Influenza has the capability of causing severe illness and occasionally death.

2) The Influenza vaccine will give good coverage against most of the circulating Influenza strains.

For the reasons above I happily take my Influenza vaccine thankyou very much. Life is too short to suffer or die from what is a largely preventable illness most of the time.

Michael

Over the next two to three weeks I will be focusing on building up the “resource” part of this website, with powerpoints, tutorials and MCQs etc. To create time for this I will reduce the daily posts to 3-4/week. Any feedback is much appreciated!

“The Price of Progress”

The Science of Microbiology, virology

The treatment of Hepatitis C infection is undergoing a revolution at present.

Traditional treatments using pegylated Interferon injections and ribavirin are poorly tolerated, often requiring almost a year of treatment and with only a 40-50% success rate overall in eradicating the virus.

In a few years time, treatments using Direct Acting Antivirals(DAAs) will be available that will be taken orally for three months, and with greater than 90% success rate. Interferon treatment for Hepatitis C will almost certainly be a thing of the past. The first of these DAA drugs (Telepravir and Bocepravir) are already on the market in some places but are likely to be superseded by newer and better tolerated DAA drugs in the not too distant future.

However these new treatments will not come cheaply. A treatment course for one patient will run into tens of thousands of dollars. Added to this is the fact that the real benefits of treatment are often not seen for decades. By eradicating Hepatitis C infection from a patient, the risk of subsequent liver cirrhosis and carcinoma is reduced in the future.

It will be interesting to see how keen governments and health institutions are to fund the new treatments, given the long term vison that is required.

A good proportion of patients with Hepatitis C have a history of injecting drug use. It is hoped that this will not further compromise their chances of being treated with the new drugs.

Potentially an active case finding and treatment programme using the new treatments could virtually eradicate Hepatitis C within 20 years. I cannot see that happening though….

Michael