Case report: Severe and progressive bronchopneumonia by Aelurostrongylus abstrusus in an adopted stray cat from Portugal

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.

First Case of Clinical Cat Aelurostrongylosis in the Brazilian Amazon: Clinical and Molecular Insights

Aelurostrongylus abstrusus is the most important respiratory parasite infecting domestic cats worldwide. Nevertheless, most records and epizootiological data come from Europe, whilst poor and fragmentary information are available for other regions, including the Americas. The present article describes the first description of cat aelurostrongylosis from Amazonia, Brazil. Eighty-one cats, 13 from a shelter and 68 admitted at the Teaching and Research Unit in Veterinary Medicine (UV) at the Federal University of Acre (UFAC), Brazil, were included in the study. For all cats, three faecal samples from consecutive defecations were examined using the Baermann’s technique. Nematode first stage larvae (L1), retrieved in 2/81 (2.5%) samples, were microscopically identified as A. abstrusus and then subjected to a molecular assay able to identify the three most important species of metastrongyloids infecting felids. This test confirmed the A. abstrusus identity in one sample, while the second scored negative. The cat with confirmed aelurostrongylosis showed radiographic changes, i.e., an interstitial pattern, compatible with the infection. The other cat, which scored positive at the Baermann’s examination, was apparently healthy at the physical examination and showed no thoracic alterations. The occurrence of A. abstrusus in domestic cats from Brazilian Amazon is herein demonstrated for the first time. Clinical, epizootiological and molecular implications are discussed.

Efficacy of Bravecto® Plus spot-on solution for cats (280 mg/ml fluralaner and 14 mg/ml moxidectin) for the prevention of aelurostrongylosis in experimentally infected cats

Background

The feline lungworm Aelurostrongylus abstrusus affects the lower respiratory tract in cats worldwide. As infections may lead to chronic respiratory changes or even death, preventive treatment in cats with outdoor access is warranted.

Methods

The preventive efficacy of a spot-on solution (Bravecto® Plus spot-on solution for cats, MSD) against cat aelurostrongylosis was evaluated using three different preventive treatment regimes in a negative controlled, randomized and partially blinded laboratory efficacy study with 31 purposed-bred cats. The minimum recommended dose of 2.0 mg moxidectin + 40 mg fluralaner/kg bodyweight was applied once 12 (Group [G]1), 8 (G2) or 4 (G3) weeks before experimental infection with 300 third-stage larvae (L3) of A. abstrusus. Another group served as untreated control (G4). Individual faecal samples were analysed as of day 30 post infection (pi) to monitor larvae excretion. Necropsy was performed at days 47–50 pi. The lungs were examined macroscopically for pathological findings and (pre-)adult worms were counted to assess preventive efficacy.

Results

Beginning at day 32–40 pi, all cats of the control group were constantly shedding larvae of A. abstrusus, whereas only one animal of G1 excreted larvae at several consecutive days. In addition, two cats of G1 and G3 and three of G2 were positive on a single occasion. The geometric mean (GM) of the maximum number of excreted larvae was 7574.29 in the control group compared to 1.10 (G1), 1.19 (G2) and 0.53 (G3), resulting in a GM reduction of > 99.9% in all treatment groups. All lungs of the control animals showed severe or very severe alterations at necropsy, while in 94.44% of the treated cats lung pathology was rated as absent or mild. The GM number of (pre-)adult A. abstrusus retrieved from the lungs was 26.57 in the control group, 0.09 in G1 and 0.00 in G2 and G3. Thus, GM worm count reduction was 99.66% in G1 and 100% in G2 and G3.

Conclusions

A single application of Bravecto® Plus spot-on solution at a dose of 2.0 mg moxidectin + 40 mg fluralaner/kg bodyweight reliably prevents cat aelurostrongylosis for at least 12 weeks.

Controlled field study evaluating the clinical efficacy of a topical formulation containing emodepside and praziquantel in the treatment of natural cat aelurostrongylosis

BACKGROUND

Aelurostrongylus abstrusus is the most important nematode affecting the respiratory tract of cats in terms of prevalence and clinical relevance. The aim of this randomised controlled field study was to confirm the efficacy of the spot-on containing emodepside/praziquantel (Profender, Bayer Animal Health) in the treatment of aelurostrongylosis.

METHODS

Seventeen cats with aelurostrongylosis and presenting with clinical and/or radiographic signs were included in the study. Eight cats received two biweekly doses of emodepside/praziquantel, while nine cats were allocated to a control group and received a rescue treatment at the end of the study. Clinical response was the primary outcome, while the secondary end point was the reduction of larval shedding in faeces.

RESULTS

Two weeks after the first application, the cats showed a significant, though partial, recovery of clinical signs with complete clinical and parasitological resolution. The resolution of inflammatory leucogram and a significant reduction of radiographic lesions were observed two weeks after the second treatment. Red blood cells and albumin values significantly increased after eight weeks from the second application, together with the complete regression of radiographic patterns.

CONCLUSION

Two applications of this spot-on solution two weeks apart assured complete cessation of larval shedding and led to a complete clinical, clinicopathological and radiographic recovery.

First molecular identification of Aelurostrongylus abstrusus in a cat presenting severe respiratory disease from Israel

Feline lung worm infection is increasingly reported in recent years, and recognized as a cause for respiratory disease in cats. Aelurostrongylus abstrusus is regarded as the most prevalent cause of such cases. Infective L3 larvae carried in gastropods and paratenic hosts infect felines, developing to adult worms that reside in the lungs' parenchyma and may cause verminous pneumonia. The L1 larvae hatch from eggs deposited in the lung, and are released to the environment by either feces or sputum. While the majority of epidemiological information regarding A. abstrusus originates in European countries, recent studies have shown that it is also found around the Mediterranean basin, as far east as Turkey and Cyprus. A local domestic cat from Israel showing signs of respiratory illness was diagnosed with aelurostrongylosis, confirmed by both morphological and molecular tools. Presence in Israel of this nematode was previously reported in 1949, with no further mentions since. ITS-2 sequence of the isolated larvae was highly similar to that of A. abstrusus from domestic cats from Italy. These findings show that distribution of A. abstrusus stretch to the eastern shores of the Mediterranean, and that this nematode should be considered as a cause for respiratory disease in cats in Israel and the surrounding countries.