Patient description: A group of 14 humanitarian service workers is preparing a trip to the Amazon Rainforest region in Brazil. All the members of the group have traveled on multiple occasions and have up-to-date vaccine certificates. Malaria Chemoprophylaxis is indicated but three of the women are in different stages of pregnancy.

Clinical trial eligibility criteria: eligible ages (years): 18.0-35.0,  Malaria In order to be eligible to participate in this study, a subject must meet all of the following Subject is aged ≥ 18 and ≤ 35 years and in good health Subject has adequate understanding of the procedures of the study and agrees to abide strictly thereby Subject is able to communicate well with the investigator, is available to attend all study visits, lives in proximity to the trial centre (<10 km) or (if >10km) is willing to stay in a hotel close to the trial centre during part of the study (day 5 post-infection until three days post-treatment). Furthermore the subject will remain within the Netherlands during the challenge period, not travel to a malaria-endemic area during the study period, and is reachable (24/7) by mobile telephone throughout the entire study period Subject agrees to inform his/her general practitioner about participation in the study and to sign a request to release by the General Practitioner (GP) any relevant medical information concerning possible contra-indications for participation in the study Subject agrees to refrain from blood donation to Sanquin or for other purposes throughout the study period and for a defined period thereafter according to current Sanquin guidelines For female subjects: subject agrees to use adequate contraception and not to breastfeed for the duration of study Subject has signed informed consent Subject agrees to refrain from intensive physical exercise (disproportionate to the subjects usual daily activity or exercise routine) for ten days following each immunization and during the malaria challenge period  A potential subject who meets any of the following will be excluded from participation in this study Any history, or evidence at screening, of clinically significant symptoms, physical signs or abnormal laboratory values suggestive of systemic conditions, such as cardiovascular, pulmonary, renal, hepatic, neurological, dermatological, endocrine, malignant, haematological, infectious, immunodeficient, psychiatric and other disorders, which could compromise the health of the volunteer during the study or interfere with the interpretation of the study results. These but are not limited to, any of the following 1 Body weight <50 kg or Body Mass Index (BMI) <18.0 or >30.0 kg/m2 at screening 2 A heightened risk of cardiovascular disease, as determined by: an estimated ten year risk of fatal cardiovascular disease of ≥5% at screening, as determined by the Systematic Coronary Risk Evaluation (SCORE); history, or evidence at screening, of clinically significant arrhythmia's, prolonged QT-interval or other clinically relevant ECG abnormalities; or a positive family history of cardiac events in 1st or 2nd degree relatives <50 years old 3 A medical history of functional asplenia, sickle cell trait/disease, thalassaemia trait/disease or G6PD deficiency 4 History of epilepsy in the period of five years prior to study onset, even if no longer on medication 5 Positive Human Immunodeficiency Virus (HIV), Hepatitis B Virus (HBV) or Hepatitis C Virus (HCV) screening tests 6 Chronic use of i) immunosuppressive drugs, ii) antibiotics, iii) or other immune modifying drugs within three months prior to study onset (inhaled and topical corticosteroids and oral anti-histamines exempted) or expected use of such during the study period 7 History of malignancy of any organ system (other than localized basal cell carcinoma of the skin), treated or untreated, within the past 5 years 8 Any history of treatment for severe psychiatric disease by a psychiatrist in the past year