Optimization of Controlled Human Malarial Infection by Injection of P. Falciparum Sporozoites in Non-Immune Adults

Inclusion Criteria: * Healthy adults aged 18 to 45 years * Able and willing (in the Investigator's opinion) to comply with all study requirements * Women only: must agree to practice continuous effective contraception for the duration of the study (such as hormonal contraceptives, condom or intrauterine device (IUD)). * Agreement to refrain from blood donation in Spain during the course of the study and thereafter * Agree not to participate in another study with an investigational product during the course of this study * Written informed consent to undergo CHMI * Reachable (24/7) by mobile phone during the whole study period * Willingness to take a curative anti-malarial regimen * Agreement to stay overnight for observation during the period of intensive follow-up post-challenge if required * Answer all questions on the informed consent quiz correctly * A body mass index \< 35 Exclusion Criteria: * History of P. falciparum malaria * Travel to malaria endemic region before the participation in the study with positive P. falciparum serology at screening. * Use of systemic antibiotics with known antimalarial activity within 30 days of study enrolment (e.g. trimethoprim-sulfamethoxazole, doxycycline, tetracycline, clindamycin, erythromycin, fluoroquinolones, or azithromycin) * Is using and intends to continuing using a medication known to cause drug reactions with chloroquine or Malarone®, such as cimetidine, metoclopramide, antacids or kaolin (antacids and kaolin can be administered at least 4 hours from intake of chloroquine) * Receipt of an investigational product in the 30 days preceding enrolment, or planned receipt during the study period * Prior receipt of an investigational malaria vaccine * Any confirmed or suspected immunosuppressive or immunodeficient state, including HIV infection, asplenia, recurrent, severe infections and chronic (more than 14 days) immunosuppressant medication within the past 6 months (inhaled and topical steroids are allowed) * Use of immunoglobulins or blood products within 3 months prior to enrolment * Presence of sickle cell anemia, sickle cell trait, thalassemia or thalassemia trait * Pregnancy, lactation or intention to become pregnant during the study * A history of allergic disease or reactions likely to be exacerbated by malaria * Contraindications or known allergy to the first-line anti-malarial medications: chloroquine, atovaquone/proguanil and artemether/lumefantrine. * History of cancer (except successfully treated and cured basal cell carcinoma of the skin and cervical carcinoma in situ) * History of serious psychiatric condition that may affect participation in the study * Any other serious chronic illness requiring hospital specialist supervision * Suspected or known current alcohol abuse as defined by an alcohol intake of greater than 30g (men) or 20g (women) per day * Suspected or known injecting drug abuse in the 5 years preceding enrolment * Seropositive for hepatitis B surface antigen (HBsAg) * Seropositive for hepatitis C virus (antibodies to HCV) * An estimated, ten year risk of fatal cardiovascular disease of ≥5%, as estimated by the Systematic Coronary Risk Evaluation (SCORE) system \[42\] * Abnormal electrocardiogram on screening: pathologic Q wave and significant ST-T wave changes, left ventricular hypertrophy, non-sinus rhythm except isolated premature atrial contractions, right or left bundle branch block, advanced A-V heart block (secondary or tertiary) * Volunteers unable to be closely followed for social, geographic or psychological reasons * Any clinically significant abnormal finding on biochemistry or haematology blood tests, urinalysis or clinical examination * Any other significant disease, disorder or finding which, in the opinion of the Investigator, may significantly increase the risk to the volunteer because of participation in the study, affect the ability of the volunteer to participate in the study or impair interpretation of the study data