RESUMO
Dogs are the primary host for Dirofilaria repens, therefore it is mandatory to accurately diagnose the canine infection and to expand our current knowledge on parasite biology and the immune response of the infected host for a better prevention.Thus, the aim of the present study was to provide new insights from experimental infections of dogs with D. repens, focusing on the evaluation of: 1) the pre-patent period and 2) the antibody response against D. repens somatic antigens and against the Wolbachia endosymbiont. Briefly, on Day 0, twenty purpose-bred Beagle dogs were experimentally infected with 50 infective larvae (L3) of D. repens. Starting from Day 58 until the last day of the study (Day 281), blood samples were collected on a monthly basis for detection of antibodies against D. repens (Dr) and recombinant Wolbachia surface protein (rWSP) by non-commercial IgG-ELISAs. Additional samples were collected on Days 220, 245 and 281 for the detection of microfilariae (mff) using the modified Knott's test and biomolecular analysis, following two PCR protocols: Gioia et al. (2010; protocol A) and Rishniw et al. (2006- protocol B). The results were analysed by univariate statistical analyses using 2 × 2 contingency tables and K Cohen was calculated to assess the agreement among all the diagnostic techniques. Overall, the outcome of the study revealed that out of the 20 dogs experimentally infected with D. repens, 16 (80 %) were microfilaraemic, 17 (85 %) were positive at DNA detection in the blood, 18 (90 %) had D. repens antibodies and 16 (80 %) had Wolbachia antibodies on the last day of the study. The overall k agreement between Knott's and PCR protocol B was 0.442 (P = 0.0001) and increased throughout the study, reaching 0.828 (P = 0.0001) on Day 281. To the authors knowledge, this is only the second study reporting antibody response to D. repens somatic antigen in experimentally infected dogs. ELISA results showed that an antibody response develops before the onset of patency, and steadily increases with time. Results would suggest that the development of an immunological response to infection could lead to application in epidemiological studies, risk assessment and as an aid in the diagnostic approach in dogs, in particular for early infections without mff.
RESUMO
Dogs are the primary host for Dirofilaria repens, therefore it is mandatory to accurately diagnose the canine infection and to expand our current knowledge on parasite biology and the immune response of the infected host for a better prevention.Thus, the aim of the present study was to provide new insights from experimental infections of dogs with D. repens, focusing on the evaluation of: 1) the pre-patent period and 2) the antibody response against D. repens somatic antigens and against the Wolbachia endosymbiont. Briefly, on Day 0, twenty purpose-bred Beagle dogs were experimentally infected with 50 infective larvae (L3) of D. repens. Starting from Day 58 until the last day of the study (Day 281), blood samples were collected on a monthly basis for detection of antibodies against D. repens (Dr) and recombinant Wolbachia surface protein (rWSP) by non-commercial IgG-ELISAs. Additional samples were collected on Days 220, 245 and 281 for the detection of microfilariae (mff) using the modified Knott's test and biomolecular analysis, following two PCR protocols: Gioia et al. (2010; protocol A) and Rishniw et al. (2006- protocol B). The results were analysed by univariate statistical analyses using 2×2 contingency tables and K Cohen was calculated to assess the agreement among all the diagnostic techniques. Overall, the outcome of the study revealed that out of the 20 dogs experimentally infected with D. repens, 16 (80 %) were microfilaraemic, 17 (85 %) were positive at DNA detection in the blood, 18 (90 %) had D. repens antibodies and 16 (80 %) had Wolbachia antibodies on the last day of the study. The overall k agreement between Knott's and PCR protocol B was 0.442 (P=0.0001) and increased throughout the study, reaching 0.828 (P=0.0001) on Day 281. To the authors knowledge, this is only the second study reporting antibody response to D. repens somatic antigen in experimentally infected dogs. ELISA results showed that an antibody response develops before the onset of patency, and steadily increases with time. Results would suggest that the development of an immunological response to infection could lead to application in epidemiological studies, risk assessment and as an aid in the diagnostic approach in dogs, in particular for early infections without mff.
RESUMO
A fixed-combination chewable tablet incorporating afoxolaner plus milbemycin oxime (NexGard Spectra®, Merial) was tested in purpose-bred Beagle dogs for efficacy against adult Ancylostoma ceylanicum hookworms. Sixteen dogs were inoculated each by oral administration of approximately 500 infective larvae of A. ceylanicum. Seventeen days after inoculation, the dogs were weighed and allocated randomly to be treated with afoxolaner plus milbemycin oxime chewable tablets or to remain untreated. Commercial chewable tablets of different strength were combined to deliver doses as close as possible to the minimum effective dose of 2.5mg afoxolaner plus 0.5mg milbemycin oxime per kg body weight. Parasites were recovered and counted for determination of efficacy seven days after treatment. All eight dogs that had been left untreated were harboring adult A. ceylanicum (geometric mean, 317.8; range, 210-428) while only one and nine A. ceylanicum were recovered from two of the eight dogs treated with afoxolaner plus milbemycin oxime chewable tablets (geometric mean, 0.5; p<0.0001). Thus, 99.9% efficacy against induced infection of A. ceylanicum was obtained by the use of oral NexGard Spectra® at the minimum effective dose. Treatment with afoxolaner plus milbemycin oxime chewable tablets was well accepted and safe.
