Efficacy of oral fluralaner (Bravecto) against Tunga penetrans in dogs: A negative control, randomized field study in an endemic community in Brazil

Abstract

The sand flea Tunga penetrans is one of the zoonotic agents of tungiasis, a parasitic skin disease of humans and animals. The dog is one of its main reservoirs. This negatively controlled, randomized, double-masked clinical trial evaluated the therapeutic and residual efficacy of fluralaner for treatment of dogs naturally infested with T. penetrans. Sixty-two dogs from an endemically affected community in Brazil were randomly assigned to either receive oral fluralaner (Bravecto chewable tablets) at a dose of 25 to 56 mg fluralaner/kg body weight, or no treatment (31 dogs per group). Dogs were clinically examined using a severity score for acute canine tungiasis (SCADT), parasitological examinations as defined by the Fortaleza classification, and pictures of lesions on days 0 (inclusion and treatment), 7 ± 2, 14 ± 2, 21 ± 2, 28 ± 2, 60 ± 7, 90 ± 7, 120 ± 7 and 150 ± 7. The percentage of parasite-free dogs after treatment was >90% between days 14 and 90 post-treatment with 100% efficacy on study days 21, 28 and 60. Sand flea counts on fluralaner treated dogs were significantly lower (p<0.025) than control dogs on all counts from day 7 to 120. The number of live sand fleas on treated dogs was reduced by > 90% on day 7, > 95% on days 14 and 90, and 100% from day 21 to 60, and with a significant difference between groups from day 7 to 120. From day 7 to day 120, mean SCADT scores were significantly reduced in treated dogs with a mean of 0.10 compared to 1.54 on day 120 in untreated dogs. Therefore, a single oral fluralaner administration is effective for treating and achieving long lasting (> 12 weeks) prevention for tungiasis in dogs.

Fig 1. Front paws of fluralaner treated and untreated dogs.

(A) Treated dog on day 0 showing multiple stage II (example in black arrow) and III (examples in red arrows) T. penetrans lesions. (B) Same dog day 7—no active lesions and visible parasite involution scars (stage V–examples in black arrows). (C) Same dog day 21—paw pad epithelium has regrown and pad is flea free (D) Untreated dog, on day 0 with multiple active flea lesions on the paw pads of the forelimbs (examples in black arrows). (E) Same untreated dog on day 7—numerous flea lesions in stages II (examples in black arrows) and III (examples in red arrows). (F) Same untreated dog—day 21, with flea active lesions II (example in black arrow) and III (example red arrow), indicating reinfestation. Notice that there are more lesions in Fig 1A, 1D, 1E and 1F than the arrows are showing. Source: author’s photographic collection.

Fig 2. Geometric means of log-transformed live flea counts per study group over time.

Fig 3. Mean severity score for acute dog tungiasis (SCADT) per study group over time.

Fig 4. Continued protection and improvement in paw clinical appearance in a fluralaner treated dog.

(A) Day 0—multiple stage II (examples marked by black arrows) and III (examples marked by red arrows) lesions caused by T. penetrans, located on the paw pads. (B) Day 28—no active sand flea lesions. (C) Day 60—paw pad epithelium regrowth and no new infestations. (D) Day 90 –normal paw pads. Notice that there are more lesions in Fig 4A than the arrows are showing.