Immunohistochemical analysis of the location of AMCase secreting macrophages in the infected brain shows them in close proximity with tissues cysts (Figures 3A-C) . As a proportion of macrophages and microglia in the brain, alternatively activated cells are in the minority and it was not possible to find such cells in the naïve brain. However, cysts are easily identifiable with a highly spherical distinct morphology, can stain non-specifically and specifically with antibodies and individual bradyzoites within the cyst are visible by DAPI staining. Examination of chitinase localization in the infected brain revealed distinct cytoplasmic staining of several cells, nearly all of which were within 75 mm of a cyst (Fig. 3A) . Although there were cells that were AMCase positive yet did not stain positively for macrophage/microglial markers, there were clearly several macrophages in close association with cysts that displayed chitinase activity polarized to the cyst wall ( Figure S5 , arrows). AmCase activity was also observed in macrophages surrounding cysts that seemed to be in the process of lysing or cysts that had been lysed (Figures 3B,C and Video S1). The examples provided show the destruction of the spherical cyst (Video S1) and escaping parasites visualized using anti-Toxoplasma antibodies. Directly at the point of rupture there are AMCase expressing macrophages (Figures 3B). Taken together, these data suggest that the induction of chitinase activity in macrophages occurs in close proximity with the cyst wall and that this distinct population of macrophages is responsible for attacking the long-term chronic cyst stage of Toxoplasma via chitinase activity.