The purpose of this study is to determine if Azithromycin in combination with chloroquine is superior to chloroquine alone in eradicating P. falciparum asexual parasitemia in asymptomatic, semi-immune adults in Western Kenya.

The trial was terminated prematurely 9 November 2004 due to the inability to recruit the planned number of subjects. There were no safety or efficacy concerns regarding the study in the decision to terminate the trial.

Inclusion Criteria:

• Healthy adult: male or female
• Asymptomatic mono-infection with P. falciparum parasitemia with a parasite density of 1000 - 30,000 parasites/μL
• Age 18 years to 60 years
• Willingness to sign and ability to understand consent form
• Willingness and ability to return for scheduled follow up visits

Exclusion Criteria:

• Mixed malaria infection by Giemsa smear
• History of allergy to or hypersensitivity to chloroquine, Azithromycin or other macrolides (e.g. erythromycin, clarithromycin)
• Any of the following: a.) Antimalarial therapy administered in the past 4 weeks, including quinine therapy or an artemisinin derivative; or b.) An antibacterial with known antimalarial activity (including, erythromycin, doxycycline, clindamycin, cotrimoxazole) within one week prior to enrollment into the study
• Fever, history of fever in past 48 hours, or signs/symptoms of malaria (including acute or subacute headache, nausea, or vomiting)
• Inability to swallow oral medication
• Laboratory evidence or history of significant cardiovascular, liver, hematologic or renal functional abnormality
• Any situation which could prevent the patient from returning to follow up visits
• Pregnancy or breast feeding
• Any other concurrent illness that may confound the result
• Any other condition or circumstance that in the opinion of the Investigator may pose a threat to the study participant or study