IL2 and Pythiosis: The mechanism behind P. insidiosum antigen (PIA) immunotherapy in human pythiosis includes a switching from the host’s T helper-2 (Th2) to T helper-1 (Th1) mediated immune response in the host; the Th1 response producing higher levels of interferon-γ (IFN-γ) and interleukin 2 (IL-2) [10,12,13].