Question

Dear Doctor, I read that everyone with hiv should get a toxo screen,so I did it. I had a toxo Igg from Quest Labs.The value reported was 1.54. Can you tell me what this means? (My id doc didn't know).Thank you, Luke

Answer

There are 2 issues here. One is that different labs have different cut-off values for positive and negative tests, depending on the technology used. You need to look carefully at the printed report from Quest-- often this info is buried in the 'small print', but you should be able to find out whether they consider a result of 1.54 to be positive or negative. If it's not on the report, then call their Customer Service line and ask them for that information.

That said, the second issue comes into play, which is: what does a positive test mean? Happily, it turns out that all that a positive test means is that you've been exposed to and infected by toxoplasmosis sometime in the past. Before we had good HIV drugs, there was a possibility that the toxo could "reactivate" and cause disease when your immune system had sustained significant damage for HIV. Now that it is possible for HIV disease to be well controlled, the possibility that you will go on to develop toxo is pretty remote, especially since there are preventive medicines that can be used even if your immune system is badly damaged.