Troglostrongylus brevior is the dominant lungworm infecting feral cats in Jerusalem.

Feline lungworms infect the respiratory tract of wild and domestic cats, causing infection often associated with clinical disease. Until recently, Aelurostrongylus abstrusus has been considered the most relevant species of lungworm, while Troglostrongylus brevior was considered of less significance. Fecal samples of feral cats from Jerusalem, Israel, collected over a year, were examined for first stage lungworm larvae (L1) using the Baermann method. Positive samples were morphologically identified, and their species identity was molecularly confirmed. Forty of 400 (10.0%) cats were lungworm-positive, of which 38/40 (95.0%) shed Troglostrongylus brevior and 6/40 (15.0%) shed Aelurostrongylus abstrusus. Four cats (10.0%) had mixed infections with both lungworm species. L1 shedding was associated with clinical respiratory signs in 11 (19.0%) T. brevior shedding cats of a total of 58 cats manifesting respiratory signs, while 23/342 (6.7%) cats without respiratory signs were L1-positive (p = 0.006). Non-respiratory clinical signs were also found to be more prevalent in L1 shedders (p = 0.012). A young kitten ≤ 4 weeks of age shed T. brevior L1 larvae. DNA sequences of both lungworm species using the ribosomal internal transcribed spacer 2 (ITS2) locus were > 99% similar to other sequences deposited in GenBank, suggesting that T. brevior and A. abstrusus ITS2 sequences are both highly conserved. In conclusion, L1 shedding in feral cats from Jerusalem were mostly caused by T. brevior with only a small proportion involving A. abstrusus, different from many studies from other geographical regions.