# Investigation of Respiratory Metastrongyloids and Other Endoparasites in Domestic Cats Living in the States of Rio de Janeiro and Rio Grande do Sul, Brazil

## TL;DR

This study found that cats in Brazil are infected with Aelurostrongylus abstrusus, a lung parasite, but not with Troglostrongylus brevior, highlighting the need for better diagnostic methods.

## Contribution

The study confirms the presence of Aelurostrongylus abstrusus in Brazilian cats and emphasizes the importance of molecular methods for accurate detection.

## Key findings

- Aelurostrongylus abstrusus was detected in cats from Rio de Janeiro and Rio Grande do Sul using PCR.
- Troglostrongylus brevior was not found in any of the examined cats.
- Molecular methods proved more effective than traditional fecal exams for detecting lungworms.

## Abstract

Aelurostrongylus abstrusus and Troglostrongylus brevior are major respiratory nematodes of cats. Adults of Aelurostrongylus abstrusus inhabit alveoli, alveolar ducts, and bronchioles, while adults of T. brevior live in the bronchi and bronchioles of cats. In Brazil, extensive and updated epizootiological data on the occurrence of aelurostrongylosis and troglostrongylosis in cats are still lacking. Furthermore T. brevior has never been reported in cats in South America. The present study evaluated and confirmed that cats living in two states in Brazil (Rio de Janeiro and Rio Grande do Sul) are at risk of simultaneous infection with A. abstrusus and intestinal parasites, while T. brevior was not detected. The results underline the usefulness of molecular biology, especially when parasites are not detected during faecal examination or when only a single stool sample is analysed.

The metastrongyloids Aelurostrongylus abstrusus and Troglostrongylus brevior, and the capillariid Capillaria aerophila, are major respiratory nematodes infecting cats. In recent decades these nematodes have been recorded in several areas of the world and have called for epizootiological studies to update knowledge on their distribution. While A. abstrusus is known to occur in some areas of Brazil, the presence of T. brevior remains uncertain, and feline infections with C. aerophila have never been reported. This study has investigated the occurrence of lungworms with or without other endoparasitoses in domestic cat populations of selected areas of Brazil. Individual faecal samples were collected from 537 cats, i.e., 521 in metropolitan area of Rio de Janeiro and 16 in Porto Alegre (Rio Grande do Sul). All samples were examined with Sheather’s flotation, and 521 of them also with the Baermann test. DNA was extracted from 425 Baermann sediments and molecularly examined for A. abstrusus and T. brevior. The most frequent parasites found at the copromicroscopy were Ancylostomatidae (n. 30, 5.8%), Toxocara cati (14, 2.7%), and Cystoisospora felis (n. 8; 1.5%). Larvae of A. abstrusus were identified by Baermann in 3 samples from Rio de Janeiro, while at PCRs, A. abstrusus DNA was amplified in 10 samples from Rio de Janeiro (n. 3), Seropédica (n. 3), Niterói (n. 3), and Porto Alegre (n. 1). The results indicate that A. abstrusus is enzootic in the investigated areas of Brazil and underline the usefulness of PCR when larvae are not detected by copromicroscopy or when only a single stool sample is analysed. Epizootiological implications, along with the absence of T. brevior in the examined cats and the presence of zoonotic endoparasites, are discussed.