A Study of a New Leishmania Vaccine Candidate ChAd63-KH

Inclusion Criteria: * Adults The volunteer must be: * Aged 18 to 50 years on the day of screening * Females must be unmarried, single, or widowed * Willing and able to give written informed consent Adolescents * Aged 12 to 17 years on the day of screening * Female adolescents must be unmarried * Written informed consent must be obtained from a parent All Participants * Uncomplicated PKDL of \> 6 month's duration * Available for the duration of the study * In otherwise good health as determined by medical history, physical examination, results of screening tests and the clinical judgment of a medically qualified Clinical Investigator * Negative for malaria on blood smear * Judged, in the opinion of a medically qualified Clinical Investigator, to be able and likely to comply with all study requirements as set out in the protocol * Willing to undergo screening for HIV, Hepatitis B and Hepatitis C * For females only, willing to undergo urinary pregnancy tests on the day of screening, on the day of vaccination (prior to vaccination) and 7 and 42 days after vaccination. Exclusion Criteria: The volunteer may not enter the study if any of the following apply: * Has mucosal or conjunctival PKDL * Has had treatment for PKDL within 21 days * Is negative for antibodies in the RK39 strip test * Receipt of a live attenuated vaccine within 60 days or other vaccine within 14 days of screening * Administration of immunoglobulins and/or any blood products within the three months preceding the planned administration of the vaccine candidate * History of allergic disease or reactions likely to be exacerbated by any component of the vaccine or a history of severe or multiple allergies to drugs or pharmaceutical agents * Any history of severe local or general reaction to vaccination as defined as * Local: extensive, indurated redness and swelling involving most of the antero-lateral thigh or the major circumference of the arm, not resolving within 72 hours * General: fever ≥ 39.5°C within 48 hours, anaphylaxis, bronchospasm, laryngeal oedema, collapse, convulsions or encephalopathy within 48 hours * Females - pregnancy, less than 12 weeks postpartum, lactating or willingness/intention to become pregnant during the study and for 3 months following vaccination. * Seropositive for hepatitis B surface antigen (HBsAg) or Hepatitis C (antibodies to HCV) * Any clinically significant abnormal finding on screening biochemistry or haematology blood tests or urinalysis * 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 * Tuberculosis, leprosy, or malnutrition * Any other significant disease, disorder or finding, which, in the opinion of a medically qualified Clinical Investigator, may either put the volunteer at risk because of participation in the study, or may influence the result of the study, or the volunteer's ability to participate in the study * Unlikely to comply with the study protocol