Ectoparasites of opossum's (Didelphimorphia: Didelphidae) captured in an urban complex in the Northern Brazilian amazon: new hosts and research on hemotropic bacteria.

Ticks and mites are important ectoparasites that affect animal and human health, directly causing harm and acting as vectors of pathogens. This study investigated the ectoparasites of synanthropic didelphids marsupials in northern Amazonia, Brazil, and screened them for hemotropic bacteria. The study was carried out in October 2022 in the metropolitan region of Macapá, Amapá State, Brazil, in vegetation remnants characterized by terra firme rainforest, alluvial forest, and savanna. Sampling was conducted over 12 consecutive days using live traps (Tomahawk and Shanon) and pitfall traps for capturing small wild mammals. The ectoparasites were removed using tweezers. A fraction of the collected ectoparasites was separated for DNA extraction and subsequent PCR amplification, and an aliquot of the extracted DNA was used for pathogen molecular tests, including bacteria and protozoa. A total of 26 larvae of Amblyomma dissimile, 17 nymphs of Amblyomma humerale, and more than 20 larvae of Eutrombicula goeldii were analyzed. Molecular identification confirmed the identity of A. dissimile and A. humerale, with new host records for Didelphis imperfecta and Didelphis marsupialis, respectively. The 16 S rRNA gene amplified successfully for 38.5% of A. dissimile larvae and all A. humerale nymphs, while the 18 S rRNA gene failed for chiggers. Pathogen screening yielded negative results. These findings contribute to the knowledge of host-parasite interactions and highlight the need for further surveillance of potential zoonotic agents in ectoparasites from wildlife.