IL-21 transcripts are detectable following cutaneous leishmaniasis caused by Leishmania panamensis, Leishmania major, and Leishmania braziliensis infections as well as in humans and mice infected with Leishmania donovani, the causative agent of visceral leishmaniasis (Espitia et al., 2010; Bollig et al., 2012; Costa et al., 2015; Kong et al., 2017; Khatonier et al., 2018). The gene discussed is IL21; the disease is visceral leishmaniasis.