INTESTINAL PARASITE INFECTIONS AFTER EXTENDED USE OF CHLOROQUINE OR PRIMAQUINE FOR MALARIA PREVENTION

Comparative results of baseline and endpoint screening for intestinal parasites are reported from Javanese men enrolled in a yearlong, place bo-controlled malaria prophylaxis trial in Irian Jaya. The objective w as to detect nontarget qualitative changes that may have resulted from prolonged chloroquine (300 mg base weekly) or primaquine (0.5 mg base /kg daily) prophylaxis. Fresh fecal specimens were examined (blinded t rial) for parasites and ova using a modified Kato-Katz thick smear met hod. More than 88% (94/106) of the baseline population was infected by 1 or more parasite species of which hookworm and Blastocystis hominis were dominant. Paired comparison between baseline and endpoint reveal ed no significant changes within the primaquine or chloroquine groups with regard to the variety of species found, the mean number of specie s or ova/subject, the relative proportion of infections caused by thes e species, or the occurrence of parasite-free, single, and multiple in fections. Relative to placebo, there was a significantly greater propo rtion of infections by Entamoeba histolytical/ dispar and a lower mean hookworm egg count in the chloroquine group. The endpoint proportion of new or increased infections in the primaquine group was significant ly lower than that of the chloroquine group but comparable to that of the placebo. Despite the dosage employed, the frequency and duration o f use, and excretion primarily through the bowels as the active parent compound, primaquine appeared to have little or no significant effect against a variety of common intestinal parasites. These largely negat ive results lend support for the safety and acceptability of primaquin e as a daily malaria prophylactic in a population frequently at risk o f intestinal helminth infections.