Advanced quantitative microscopy for plasmodium falciparum diagnosis during PfSPZ challenge and other controlled human malaria infection studies: Results of an African training workshop

Sanaria has developed aseptic, purified, cryopreserved infectious Plasmodium falciparum (Pf) sporozoites (SPZ) called PfSPZ Challenge as a tool for Controlled Human Malaria Infections (CHMI) to study protective efficacy of anti-malarial drugs and vaccines, to allow refinement of the method of administration of the highly protective PfSPZ Vaccine, and to study innate and acquired immunity to Pf. A critical component of the CHMI studies with PfSPZ Challenge is the diagnosis of malaria parasites in the blood. Diagnosis needs to be highly sensitive in order to detect parasites before the onset of major clinical symptoms, and needs to be highly specific in order to prevent misdiagnosis (i.e. false positive results), which could alter the outcome of the study. False positive results must be avoided in PfSPZ studies where misdiagnosis after vaccination would have potential safety implications and where misdiagnosis after CHMI would alter the estimates of protective efficacy. The European and Developing Countries Clinical Trials Partnership has funded a 7 country African consortium of institutions working with PfSPZ Challenge to optimize CHMI studies in Africa. Technical staff from across the network were hosted by the Ifakara Health Institute in Bagamoyo, Tanzania, for a 1 week course to develop expert level technical expertise in Advanced Quantitative Microscopy for rapid, sensitive, and specific diagnosis of Pf. Here we describe the results of the intensive training sessions and the subsequent establishment of a quantitative thick smear microscopy certification center at KEMRI, Nairobi, Kenya.T.