It is a parasitic protozoan found in chimpanzees in Central Africa.

[1] The parasite is named in honour of the malariologist William E.

[2] Both P. billcollinsi and P. billbrayi were suggested based on mtDNA and nuclear gene sequences, in addition to having been obtained from chimpanzee samples.

[4] Analysis made on 1,261 samples revealed that at least six Plasmodium species circulate in great apes in Gabon, with P. billcollinsi being found faecal samples from 791 chimpanzees.

[5] Along with P. reichenowi, P. billbrayi and P. gaboni, P. billcollinsi infects with malaria to only chimpanzees.