Aelurostrongylus abstrusus Antibody Seroprevalence Reveals That Cats Are at Risk of Infection throughout Germany

Efficacy of Bravecto® Plus spot-on solution for cats (280 mg/ml fluralaner and 14 mg/ml moxidectin) in the prevention of feline Aelurostrongylus abstrusus infection evaluated in a multi-diagnostic approach

BACKGROUND

Aelurostrongylus abstrusus is one of the most important respiratory nematodes of felines. Infections may lead to respiratory clinical signs with varying severity or even death, emphasizing the need for preventive treatment of cats with outdoor access to circumvent patent infections.

METHODS

Therefore, the preventive efficacy of a spot-on formulation of 280 mg/ml fluralaner and 14 mg/ml moxidectin (Bravecto® Plus spot-on solution for cats, MSD) against A. abstrusus was evaluated in a negative controlled, randomized and partially blinded efficacy study with 28 purpose-bred cats in a non-terminal design. In three different treatment regimes, the minimum recommended dose of 40 mg fluralaner and 2.0 mg moxidectin/kg bodyweight (BW) was administered once at 12, 8 or 4 weeks (study group G1, G2 and G3, respectively) prior to experimental infection with 300 third-stage A. abstrusus larvae, while G4 served as placebo-treated control.

RESULTS

From 30 to 46 days post infection (dpi; SD 114 to 130), faeces were sampled to monitor first-stage larvae (L1) excretion for efficacy determination. Secondary efficacy criteria, including respiratory parameters, serological antibody levels and computed tomography (CT) findings, were assessed once before enrolment (SD -7 to -1) and before infection (SD 75 to 83). After infection, CT evaluation was performed once at 47-50 dpi (SD 131 to 134), and respiratory parameters and antibody levels were regularly assessed twice or once a week, respectively (1 up to 78 dpi, SD 85 up to 162). All animals in the control group excreted L1 by 33-37 dpi and remained positive throughout the study period from 41 to 46 dpi (SD 125 to 130). In the treatment groups, only one animal each of G1 and G2 excreted L1 at two consecutive days, and four cats of G1, two of G2 and three of G3 were positive on single occasions. While the geometric mean (GM) of the maximum number of excreted L1 per 5 g of faeces was 7380.89 in the control group (G4), GMs were significantly lower in the treatment groups with 1.63 in G1, 1.37 in G2 and 0.79 in G3. Thus, based on GMs, the reduction in excreted L1 exceeded 99.9% in all three treatment groups. Based on CT severity scores, all lungs of the animals of the control group showed severe pulmonary changes post infection, whereas lungs of the cats of the treatment groups were either unaltered (4 animals), mildly (11 animals), or moderately altered (5 animals). Moreover, seroconversion was observed in all cats of the control group, but not in those of the treatment groups.

CONCLUSIONS

The combination of diagnostic methods used in this non-terminal study yielded coherent and reliable results. A single administration of Bravecto® Plus spot-on solution for cats was well tolerated and effective in the prevention of aelurostrongylosis for at least 12 weeks.

Diagnostic challenges for Aelurostrongylus abstrusus infection in cats from endemic areas in Italy

BACKGROUND

The lungworm Aelurostrongylus abstrusus infects wild and domestic feline species worldwide and is considered a primary respiratory parasite of cats. Definitive diagnosis is based on the identification of first-stage larvae (L1s) released in faeces approximately 5 to 6 weeks after infection. More recently, serology has been shown to be a diagnostic alternative for A. abstrusus infection in cats. The present study aimed at evaluating the diagnostic performance of serological antibody detection compared to faecal examination for A. abstrusus infection in a population of cats with known infection status from endemic areas in Italy and to identify factors (larval scores, age, co-infections with other helminths) that may influence test sensitivity and specificity of serology.

METHODS

All cats resulting positive using the Baermann technique (n = 78) were tested with the A. abstrusus ELISA. An additional 90 serum samples from cats living in three geographical areas with infection prevalence > 10%, but that resulted negative on Baermann, were also tested.

RESULTS

Among 78 cats copromicroscopically positive for L1s of A. abstrusus (Group 1), 29 (37.2%) were seropositive in ELISA. Of the 90 cats from Group 2 (cats living in three geographical areas in Italy with A. abstrusus prevalence > than 10%, but negative on Baermann examination), 11 (12.2%) were positive on ELISA. The overall seroprevalence was 23.8%. There was no statistical difference either between average optical density (OD) values of cats excreting > 100 L1s vs. cats excreting < 100 L1s (0.84 vs. 0.66; P value = 0.3247) or comparing the OD values with age of infected cats. Few Baermann-negative cats positive for Toxocara cati or hookworms were seropositive, supporting lack of cross-reactivity to these nematodes.

CONCLUSIONS

Results from the present study suggest that relying solely on faecal examination may underestimate prevalence of A. abstrusus infection in cats and that field surveys based on antibody detection are useful for establishing true prevalence of infected and/or exposed animals.

Epidemiological Survey on Gastrointestinal and Pulmonary Parasites in Cats Around Toulouse (France)

Various feline parasites are potentially zoonotic thus establishing factors associated with parasitism is of animal and public health interest. The aim of this study was to determine the prevalence of endoparasites in client-owned cats, living in the area of Toulouse, France, over the period 2015 - 2017, and to investigate possible risk factors. A total of 498 faecal samples from cats of the University Animal Hospital of Ecole Nationale Vétérinaire de Toulouse were analysed, 448 from cats presented for consultation and 50 at post-mortem. Analysis was performed using a commercial flotation enrichment method with a hypersaturated sodium chloride solution and Baermann technique. Further examination of the gastrointestinal tract contents was conducted on necropsied cats. Overall, 11.6 % of cats were positive for endoparasites; 50 (11.2 %) consultation cases and 8 (16 %) post-mortem cases, with no significant difference in prevalence between the groups. Amongst infected cats, most were infected by a single species of parasite and 10.3 % (n=6) were infected with two or more. The most common parasite was Toxocara cati with a prevalence of 9.4 % (n=47). Other endoparasites encountered were: Cystoisospora sp 1.0 % (n=5), Aelurostrongylus abstrusus 1.0 % (n=5), Strongyloides sp 0.6 % (n=3), Dipylidium caninum 0.4 % (n=2), Aonchotheca putorii 0.2 % (n=1), Ancylostomatidae 0.2 % (n=1) and Toxascaris leonina 0.2 % (n=1). The examination of the gastronintestinal tract contents of the necropsied cats revealed Mesocestoides sp 0.4 % (n=2) and Tænia (Hydatigera) tæniaeformis sensu lato 0.2 % (n=1) which are seldomly diagnosed by flotation methods. In this study, increasing age and neutered status were statistically associated with reduced odds of infection by endoparasites (helminth and coccidian). Predictors of significantly increased risk included being male, intact, and not receiving regular anthelmintic treatment. The same risk factors were highlighted specifically for Toxocara cati infections, with rural location being an additional risk factor for infection.

Felid Parasitoses, New Insights and Open Perspectives

Felids are fascinating animals [...].