Hello and welcome to HCM,
Presence of positive ELISA
and Western blot test for Ig M indicates an active infection. In any infection, Ig M are the first immunoglobulins
which become positive followed by Ig G. Positive Ig G indicates a past infection.
However, you have not mentioned the causative organism for which the test is done.
I can only guess that the test was performed for some bacterial infection for which doxycyclin was given.
Thanks and take care.
Dr Shailja P Wahal