Efficacy of an oral formulation of afoxolaner and milbemycin oxime against Tunga penetrans in naturally infested dogs

Abstract Background The sand flea Tunga penetrans is one of the agents of tungiasis, an important parasitic skin disease affecting humans and their co-living mammalian animals. Tungiasis is mainly observed in disadvantaged rural and peripheral urban communities in Latin America and Sub-Saharan Africa. The dog is a major reservoir of Tunga fleas. Hematophagous adult female Tunga spp. embed and grow in their host’s epidermis and cause cutaneous inflammatory disorders. NexGard Spectra® (IVP) is an oral endectocide product for dogs combining the isoxazoline afoxolaner and the macrocyclic lactone milbemycin oxime. The objective of this study was to assess the efficacy of this product against canine tungiasis. Methods A blinded, negative-controlled field trial was conducted in a Brazilian community known to be highly endemic for tungiasis. Sixty-six (66) dogs naturally infested with live T. penetrans were randomly allocated to a treated group (44 dogs) and an untreated control group (22 dogs). In a first phase, dogs from the treated group were treated on Days 0, 30 and 60. Efficacy was evaluated on the basis of the macroscopical aspect of the parasitic skin lesions (Fortaleza classification), on Days 7, 14, 21, 30, 45, 60, 75 and 90. In a second phase, all dogs were treated on Day 90 and evaluated every two weeks until at least 30% of dogs were infested with live sand fleas. Results During the first phase, an efficacy (reduction of live sand fleas) of 92.4% was demonstrated on Day 7. From Day 14 and until Day 90, the efficacy of the IVP was 100%. In the second phase all dogs were free of live T. penetrans from Day 15 until Day 45 after treatment, 11% of dogs were re-infested at Day 60 post-treatment, and 40% were re-infested at Day 75 post-treatment. Conclusions NexGard Spectra® was demonstrated highly efficient against canine tungiasis. In addition to an obvious beneficial effect on the health and welfare of the treated dog, the use of this product may have a one-health benefit on human cases by controlling the main reservoir of sand fleas.