Nectomys squamipes sampling

Varella, Karina, Andrade-Silva, Beatriz Elise de, Costa-Neto, ocrates Fraga da, Cruz, Brena Aparecida de Oliveira, Junior, Arnaldo Maldonado & Gentile, Rosana, 2024, Helminth community of Nectomys squamipes naturally infected by Schistosoma mansoni in an endemic area in Brazil: A comparison of 22 years apart, International Journal for Parasitology: Parasites and Wildlife 24, pp. 100941-100941 : 100941-

2.2. Nectomys squamipes sampling and helminth recovery

Capture transects were established along streams, which are the natural habitat of N. squamipes . Adult specimens of N. squamipes were captured using Tomahawk® Live Traps (Hazelhurst, Wisconsin) model 201 (16” × 5” × 5″) baited with a mixture of peanut butter, banana, oats, and bacon. The trapping points were spaced 10 m apart. The animals were euthanized by exsanguination (full bleeding) under deep anesthesia by cardiac puncture. The anesthetic protocols included ketamine (100 mg /mL) combined with acepromazine (10 mg /mL) at a ratio of 9:1 (dose of 0.15 mL/ 100 g body weight). Rodents were captured under authorization of the Brazilian Government’ s Chico Mendes Institute for Biodiversity and Conservation (ICMBIO, license 13373). All procedures followed the guidelines for the capture, handling, and care of animals of the Ethical Committee on Animal Use of the Oswaldo Cruz Foundation (CEUA, license L-036/2018). Biosafety procedures and personal protective equipment, including biosafety level 3 respirators, were used during all procedures involving animal handling and biological sampling (Lemos & D’ Andrea, 2014).

Perfusion of the portal-hepatic system was performed with citrate saline (0–85% sodium chloride; 1–5% sodium citrate) according to Smithers and Terry (1965) to recover adult specimens of S. mansoni in the mesenteric and portal veins. The stomach, thoracic and abdominal cavities, and small and large intestines of the rodents were examined separately under a stereoscopic microscope for helminth collection. The helminths were washed in 0.85% saline solution to remove tissue debris and fixed in 70% ethanol solution for molecular analysis. The nematodes were cleared in lactophenol. The cestodes were stained in Carmine, Langeron, and dehydrated in an increasing alcohol series according to the method described by Amato (1985). The specimens were counted, sexed, and identified using a Zeiss Standard 20 light microscope (Zeiss, Jena, Germany). The species were identified using morphological keys based on adult helminth specimens according to Yamaguti (1961), Yorke and Maplestone (1969), Vicente et al. (1997), and Anderson (2000).