Out of three currently available methods of performing experimental human malaria infections (blood stage infection, mosquito bites and sporozoite infection), experimental injection directly by needle and syringe using aseptic, purified, cryopreserved sporozoites is, in principle, the most accurate and practical way of dosing sporozoites for challenge studies. Recently, Sanaria Inc have been able to overcome the technical issues associated with the production of aseptic, purified, cryopreserved Plasmodium falciparum sporozoites. As a result, an Investigational New Drug application (IND) was submitted to the U.S. Food and Drug Administration in February 2009, and a Phase 1 clinical trial with experimental challenge of volunteers was initiated in April 2009. Another trial sponsored by Sanaria to find the dose of aseptic, purified, cryopreserved sporozoites that should be used for experimental human malaria infections is currently ongoing with collaboration with the Radboud University Nijmegen Medical Center, The Netherlands.