The effect of antimalarial chloroquine therapy and prophylaxis on concurrent infection with Onchocerca volvulus in Ecuador

Abstract

The effect of chloroquine phosphate on Onchocerca volvulus in vivo was studied in Ecuadorians undergoing treatment for malaria. All persons with a diagnosis of acute malaria and treated with 2500 mg of chloroquine over 3 d showed a 100% reduction of dermal O. volvulus microfilariae 7 d after treatment. However, 28 d after treatment the microfilarial densities returned to their pre-treatment levels and at 35 d they had increased to 121.6% of their pre-treatment values. Treatment did not appear to have any effect on the adult O. volvulus examined histologically in extirpated nodules. Patients treated for acute malaria and subsequently kept on a prophylactic regimen of 500 mg chloroquine weekly showed a reduction of 56.7% from pre-treatment microfilarial density after 27 weeks. Patients who underwent nodulectomy as well as treatment for acute malaria and were given 500 mg of chloroquine prophylactically for 27 weeks showed a reduction in dermal microfilarial density of 93.6%. Symptoms of onchocerciasis were reduced in the latter group of patients, with the elimination of all acute dermatological changes within 6 weeks. Ocular examination of these surgically and chemotherapeutically treated individuals revealed reductions of 94.9% of microfilariae in the anterior chamber, 95.9% of live microfilariae in the cornea, and 95.1% of dead microfilariae in the cornea. There was a reduction of 69.8% in corneal fluffy opacities. No alteration in the visual acuity or in visible lesions in the posterior segment was recorded. The results suggest that a complex interaction between chloroquine and O. volvulus takes place in vivo, which can be beneficial to the patient over a long period.(ABSTRACT TRUNCATED AT 250 WORDS)

Macrofilaricidal effects of chloroquine on adult Onchocerca volvulus by local infiltration of palpable onchocercal nodules

“…This is in contrast to the results observed when chloroquine was taken orally 5 , where no pathomorphological changes in extirpated nodules were noted. No pathological changes were seen in nodules infiltrated with saline, indicating that the signs of toxicity, degradation and intra-uterine microfilarial degeneration seen in this study were probably due to chloroquine infiltration.…”

“…Clinical studies show that ingestion of oral choloroquine, though it has a suppressive effect on dermal microfilarial numbers, and though there is a rapid accumulation of chloroquine in the tissues of adult O. volvulus 10 , does not appear to have any demonstrable effect on adult worms 5 . However, nothing is known concerning the status of the adult worm when bathed in high concentrations of chloroquine in situ by infiltration of nodules with the drug.…”

Heterogeneity in the in vitro susceptibility of Loa loa microfilariae to drugs commonly used in parasitological infections

“…Among the agents used for comparison here, the anti-malarials ATS, CQ, AQ and QN have all been found inactive against L. loa mf in humans [ 48 ]. Except CQ, whose in vivo microfilaricidal activity has been proven against O. volvulus [ 49 ], agents that are known to be active against filariae and that were also active in our present studies are MQ [ 25 ] and imatinib, an anti-cancer compound recently added to the list of active filaricidal drugs [ 17 , 18 , 50 ]. PZQ, an anti-schistosomal drug, was also tested but was inactive in this system.…”

A Controlled Trial to Assess the Effect of Quinine, Chloroquine, Amodiaquine, and Artesunate on Loa loa Microfilaremia

“…36 Despite this finding, no macrofilaricidal effect was observed after oral chloroquine treatment, 13 and adult O. volvulus were killed only when the drug was injected into the nodule.…”