Azithromycin in the treatment of Plasmodium falciparum gametocytes. Preliminary observation.

Background: Treatment of malaria represents a problem as antimalarial drugs are relatively few, and because of the increasing widespread resistance of Plasmodium falciparum to most of these drugs. A partial efficacy of azithromycin against Pl. falciparum hepatic stage and against trophozoytes in the erythrocytic stages of the disease has been demonstrated. No data concerning the activity against gametocytes are available, and primaquine stands as the only therapy against Pl. falciparum gametocytes. Primaquine causes haemolysis in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency, so primaquine therapy is usually avoided. A better tolerated therapy against gametocytes would be useful to reduce malaria transmission. We present the results of a study concerning the efficacy of azithromycin in the treatment of P. falciparum gametocytes.

Methods: A prospective study was performed: 4 patients with Pl. falciparum gametocytes (3 children, 1 adult) were treated with azithromycin for concomitant bacterial infections; in the meantime two children with gametocytes were taken as control. Azithromycin was administered as recommended.

Results: Gametocytes were detectable in children thick blood smears after 8, 5 and 6 days respectively after the beginning of azithromycin therapy, while they were undetectable in the adult thick blood smear 5 days after the beginning of the therapy. The gametocytes spontaneously disappeared in the two controls 4 to 6 days after the beginning of observation.

Conclusions: These data suggest that azithromycin seems ineffective against Pl. falciparum gametocytes. Further studies are needed in order to determine whether azithromycin treated gametocytes are infective to mosquitoes or not, and to confirm this first observation.