STAT4 and parasitic infectious disease: As expected, inoculation of either STAT-1−/− or STAT-4−/− mice with WT parasites resulted in high levels of parasitemia and death of 100% of the mice between 15-23 days post-infection (for STAT-1−/−) (Fig. 4a) or 21–62 days for STAT-4−/− mice (Fig. 4b).