Babesia microti diagnosis methods

       As stated in the previous post Babesia microti can sometimes be difficult to screen for.  In the past the only reliable method for screening for Babesia microti was through microscopic examinations of blood smears.  However, this form of testing is extremely limited because it can only detect down to the genus level based on morphological features (Teal et. al, 2011).  This means that Babesia microti cannot be distinguished from other Babesia species.  Another common problem with using microscopic examinations of blood smears is that Babesia microti is often confused with plasmodium in the trophozoite stage (Teal et. al, 2011). 

            This article developed a new method to testing for Babesia microti.  The new method uses a real time PCR assay that targets 1 8S rRNA gene of Babesia microti.  This test is preformed on the DNA that has been extracted from whole blood samples (Teal et. al, 2011).  This method of testing has many benefits compared to the old standard of testing.  First, real time PCR is 100% effective in distinguishing species in the genus Babesia.  In addition to this it also distinguishes between Babesia microti and Plasmodium species that it is commonly confused with (Teal et. al, 2011).  Real time PCR can detect very low parasitemia.  When using microscopic examinations of blood smears its possible to make an incorrect diagnosis if the parasitemia is too low (Teal et. al, 2011).  Using the new PCR assay this will no longer be a problem. 

            It is essential to use sensitive and accurate testing.  Incidents of Babesia microti have had a high increase over the past ten years.  Many times Babesia microti infections will clear over time and will remain asymptomatic in healthy individuals (Teal et. al, 2011).  One of the difficulties with diagnosis through microscopic observations of blood smears is that asymptomatic hosts would not be tested because they showed no symptoms.  This results in asymptomatic carries donating contaminated blood for transfusions.  Usually the recipients of blood transfusions are immune compromised and are more vulnerable to the parasite.  Infections of Babesia microti can become more severe when the host is also infected with Lyme disease (Teal et. al, 2011).  This is a common occurrence because Ixodid ticks transmit both parasites.  Using real time PCR allows for a rapid and accurate test so people donating blood can now be easily screened.  

            The reason I choose this article was because in my previous post I discussed difficulties with diagnosing Babesia microti infections.  I wanted to provide a more in depth look at the problems that occur with the current methods of diagnosis and what methods were likely to be used in the future.  The real time PCR analysis has been developed with in the past year and is not yet a common clinical testing method.  However, due to the success seen in this article I would anticipate it would start to become more common. 

Teal, A. E. Habura, A. Ennis, J. Keithly, J.S. Antenucci S.M. 2011. A new real-time PCR assay for improved detection of the parasite Babesia microti. Journal of Clinical Microbiology. 50: 903-908