Gametocytosis and sporogony in Plasmodium chabaudi chabaudi . a, Parasitaemia and gametocytaemia of BALB/c and C57BL/6 mice infected with P. c. chabaudi AS by ip injection of 105 pE (n = six per group; data are presented as mean with SEM). Transmission efficiency to Anopheles stephensi is highlighted under the graph: low efficiency (red line) versus high efficiency (green line). b-c, Number of oocysts in the midguts of An. stephensi on day 8 (b) and sporozoites isolated from the salivary glands of infected An. stephensi on day 14 (c) post-infection with P. c. chabaudi AS (Pcc AS) or P. c. chabaudi CB (Pcc CB) (n = 820; data are presented as median with range). The number of sporozoites in the salivary glands of An. stephensi infected with Pcc CB is significantly increased, as compared to those infected with Pcc AS (*p = 0.0222 (Mann–Whitney test)). C57BL/6 mice with a gametocyte density of ≥0.1% of total erythrocytes were utilized on day 14 post-infection at a ratio of ≥1 mouse to 100 mosquitoes.