Preventive efficacy of six monthly doses of NexGard® PLUS or Simparica Trio® against a macrocyclic lactone-resistant isolate (JYD-34) of Dirofilaria immitis and of a single dose of NexGard PLUS against a susceptible isolate.

IF 3 2区医学 Q1 PARASITOLOGY

Parasites & Vectors Pub Date : 2024-12-18 DOI:10.1186/s13071-024-06603-z

Joseph Prullage, Justin Frost, Utami DiCosty, Elizabeth Martin, Pascal Dumont, Stephen Yoon, Ricarda Süssenberger

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Abstract

Background: Two studies were conducted assessing the efficacy of NexGard® PLUS (NP) in preventing heartworm disease. Study 1 evaluated the efficacy of six monthly doses of NP or Simparica Trio® (ST) against a macrocyclic lactone-resistant isolate of heartworm, Dirofilaria immitis, and study 2 evaluated the efficacy of a single dose of NP against a susceptible isolate.

Methods: In two studies, dogs that were negative for heartworms by antigen test and modified Knott's test were used. In study 1, dogs were randomly allocated into three treatment groups (n = 6/group): negative control, NP per label instructions, and ST per label instructions. Dogs were inoculated with 50 third-stage D. immitis larvae (JYD-34 isolate) on day -30. NP and ST were administered orally on days 0, 30, 60, 90, 120, and 150. A necropsy was performed on day 180 for adult heartworm recovery. In study 2, dogs were randomly allocated into two treatment groups (n = 10/group): negative control and NP. Dogs were inoculated with 50 third-stage larvae (SC-20 isolate) on day -30. NP was administered orally once on day 0 to target the minimum moxidectin label dose. A necropsy was performed on day 120 for adult heartworm recovery.

Results: For study 1, all control dogs had adult heartworms at necropsy (geometric mean, 39.7; range, 28-48). Two of the NP-treated dogs had one live worm, and one of the ST-treated dogs had one live worm. Both treated groups were significantly different from the control group with an efficacy of 99.5% for NP and 99.8% for ST (P < 0.0001). There was no significant difference (P = 0.8797) between the groups treated with NP and ST. For study 2, all control dogs had adult heartworms (geometric mean, 34.5; range 26-43). None of the dogs treated with NP had live adult worms (efficacy of 100%, P < 0.0001).

Conclusions: The results of study 1 demonstrated that NexGard® PLUS and Simparica Trio® administered at the label dose provided comparable efficacy against a macrocyclic lactone-resistant isolate of D. immitis. The results of study 2 demonstrated that NexGard® PLUS administered once near the minimum label dose was 100% effective against a susceptible isolate.

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来源期刊

Parasites & Vectors 医学-寄生虫学

CiteScore

6.30

自引率

9.40%

发文量

433

审稿时长

1.4 months

期刊介绍： Parasites & Vectors is an open access, peer-reviewed online journal dealing with the biology of parasites, parasitic diseases, intermediate hosts, vectors and vector-borne pathogens. Manuscripts published in this journal will be available to all worldwide, with no barriers to access, immediately following acceptance. However, authors retain the copyright of their material and may use it, or distribute it, as they wish. Manuscripts on all aspects of the basic and applied biology of parasites, intermediate hosts, vectors and vector-borne pathogens will be considered. In addition to the traditional and well-established areas of science in these fields, we also aim to provide a vehicle for publication of the rapidly developing resources and technology in parasite, intermediate host and vector genomics and their impacts on biological research. We are able to publish large datasets and extensive results, frequently associated with genomic and post-genomic technologies, which are not readily accommodated in traditional journals. Manuscripts addressing broader issues, for example economics, social sciences and global climate change in relation to parasites, vectors and disease control, are also welcomed.