Purpose : Ophthalmomyiasis is an infection of the external eye caused by the larvae of the Diptera Oestrus ovis. This pathogen is the most frequent cause of ocular myiasis, particularly in countries with tropical or mild climates, where sheep farming is common. Currently, there are no commercially available drugs to treat this condition in humans and mechanical removal of the larvae is the only effective therapy. The purpose of this study was to investigate the in vitro efficacy of povidone-iodine 0.6%, ivermectin 1%, and propylene glycol, alone and in combinations, against L1 larvae of O. ovis. Methods : Specimens of L1 larvae of O. ovis, collected by the nasal boot of sheep slaughtered, were put into a single Petri dish with 1 ml of each study drug and examined by light microscopy to assess their viability. We defined time of death the period from the first contact of the larvae with the drug to the observation of total immobility (Fig 1). Negative control samples were run in parallel by suspending the larvae in saline solution. Results : 893 L1 larvae were consecutively tested. The average time of death was 96, 46, 44, 11, 6 and 10 minutes for saline solution, povidone iodine 0.6%, ivermectin 1% suspension, propylene glycol, ivermectin 1% solution in propylene glycol, and the association ivermectin 1% solution in propylene glycol + povidone iodine 0.6% respectively (Fig 2). Ivermectin 1% suspension and povidone iodine 0.6% were found to be significantly more effective than saline solution, but no statistical difference was found between these drugs. Propylene glycol, the ivermectin solvent, showed an efficacy statistically superior to ivermectin 1% suspension and povidone-iodine 0.6% (p< 0.001). Ivermectin 1% solution in propylene glycol and the association ivermectin 1% solution + povidone iodine 0.6% were found to be significantly more effective than propylene glycol alone (p=0.0422). Furthemore, ivermectin 1% suspension was found to be more effective than the association ivermectin 1% solution + povidone iodine 0.6% (p< 0.001). Ivermectin 1% solution in propylene glycol showed the fastest killing effect on L1 larvae (p< 0.001). Conclusions : Our results suggest that ivermectin 1% and propylene glycolcould be potential candidates for topical treatment of ophthalmomyiasis caused by L1 larvae of O. ovis.
Development of new topical preparations for external ophthalmomyiasis treatment
Ermete Giancipoli;
2019-01-01
Abstract
Purpose : Ophthalmomyiasis is an infection of the external eye caused by the larvae of the Diptera Oestrus ovis. This pathogen is the most frequent cause of ocular myiasis, particularly in countries with tropical or mild climates, where sheep farming is common. Currently, there are no commercially available drugs to treat this condition in humans and mechanical removal of the larvae is the only effective therapy. The purpose of this study was to investigate the in vitro efficacy of povidone-iodine 0.6%, ivermectin 1%, and propylene glycol, alone and in combinations, against L1 larvae of O. ovis. Methods : Specimens of L1 larvae of O. ovis, collected by the nasal boot of sheep slaughtered, were put into a single Petri dish with 1 ml of each study drug and examined by light microscopy to assess their viability. We defined time of death the period from the first contact of the larvae with the drug to the observation of total immobility (Fig 1). Negative control samples were run in parallel by suspending the larvae in saline solution. Results : 893 L1 larvae were consecutively tested. The average time of death was 96, 46, 44, 11, 6 and 10 minutes for saline solution, povidone iodine 0.6%, ivermectin 1% suspension, propylene glycol, ivermectin 1% solution in propylene glycol, and the association ivermectin 1% solution in propylene glycol + povidone iodine 0.6% respectively (Fig 2). Ivermectin 1% suspension and povidone iodine 0.6% were found to be significantly more effective than saline solution, but no statistical difference was found between these drugs. Propylene glycol, the ivermectin solvent, showed an efficacy statistically superior to ivermectin 1% suspension and povidone-iodine 0.6% (p< 0.001). Ivermectin 1% solution in propylene glycol and the association ivermectin 1% solution + povidone iodine 0.6% were found to be significantly more effective than propylene glycol alone (p=0.0422). Furthemore, ivermectin 1% suspension was found to be more effective than the association ivermectin 1% solution + povidone iodine 0.6% (p< 0.001). Ivermectin 1% solution in propylene glycol showed the fastest killing effect on L1 larvae (p< 0.001). Conclusions : Our results suggest that ivermectin 1% and propylene glycolcould be potential candidates for topical treatment of ophthalmomyiasis caused by L1 larvae of O. ovis.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
