Infection by Trypanosoma spp. in Platydoras armatulus (Siluriformes, Doradidae), in Southwestern Amazon, Brazil

Trypanosoma is a hemoflagellate capable of infecting a wide variety of invertebrates and vertebrates, such as Neotropical freshwater fish. Thus, the present study described and morphologically compared Trypanosoma sp., found in Platydoras armatulus, Valenciennes, 1840, in southwestern Amazon. A sampling of fish specimens was carried out in a river located in Guajará, Amazonas, Brazil. Fish blood samples were collected through a cardiac puncture. Thus, smears were made for quantification, morphometric measurements, and morphotyping of trypanosomes found. Prevalence, mean abundance, and intensity of parasitism were estimated in the specimens of parasitized fish. Five fish specimens were collected, showing a 100% prevalence of parasites in the host. We found two Trypanosoma morphotypes, A and B, in which A had the highest infection intensity in host specimens. Thus, the present study showed the first report of Trypanosoma spp. in P. armatulus, besides the probability of two parasitic morphospecies in the blood of these fish specimens.

Trypanosomatids of four Loricariidae fish species in western Amazon rivers

The presence of trypanosomatids in fish is well known and can occur in many fish species worldwide. In this sense, this study aims to report the occurrence of Trypanosoma sp. in four species of the Loricariidae family in the western Amazon, as well as the morphology of these hemoparasites. The fish were collected in three sub-basins of the states of Acre and Amazonas, Brazil. Fish blood samples were collected by cardiac puncture, with smears made for quantification, morphometric measurements, and morphotyping of the trypanosomes found. We estimated the prevalence and parasitism density data. The morphometric variables of Trypanosoma sp. were subjected to analysis of variance. We found new reports of Trypanosoma distribution and occurrence in Loricariidae species for western Amazonia. The examined fish showed infection by more than one Trypanosoma spp. morphotype A has been identified infecting Loricariichthys anus, Sturisoma cf. robustum, and Loricaria cataphracta, morphotype B occurred in all fish species, and morphotypes C, D, and E occurred only in Loricaria sp. There was a significant difference between the morphotypes according to the morphometric parameters. Thus, this study significantly clarified the morphological variation, distribution, and diversity of Trypanosoma hosts.

Humane Use of Cardiac Puncture for Non-Terminal Phlebotomy of Wild-Caught and Released Peromyscus spp.

The cardiac puncture technique for obtaining relatively large volume (50–150 µL) blood samples from sedated rodents has been used in research for nearly a century. Historically, its use to phlebotomize and then release live rodents was more common. However, recently its use in a non-terminal capacity frequently imparts negative connotations in part because exsanguination of sedated animals via cardiac puncture is now an American Veterinary Medical Association-approved euthanasia technique. This association has resulted in ethical concerns by manuscript reviewers and in a few instances, outright refusal by some peer-reviewed journals to publish research that utilized the technique. To counter the perceived negative associations with its non-terminal use, we summarized nearly two decades (2001–2019) of capture and handling data throughout Connecticut, resulting in over 7000 cardiac punctures performed on nearly 5000 sedated, live-captured and released Peromyscus spp. We show that our total handling mortality rate (3.7%) was comparable, if not lower, than similar field studies that utilized other phlebotomy techniques. Many public health, integrated tick management, and vector-borne disease ecology studies require samples from individual wild-caught Peromyscus spp. over time to determine intervention efficacy and pathogen infection monitoring, and in such field studies, post-operative care is not an option. Proper execution of cardiac puncture does not increase susceptibility of individuals to predation upon release as can potential ocular abnormalities or infections that can occur as the result of use of other techniques. We posit that neither exsanguination nor resulting euthanasia are requirements of cardiac puncture and that its use is entirely appropriate for obtaining blood samples from live-captured and released Peromyscus spp. Properly performed cardiac puncture is an excellent technique to obtain blood samples from sedated, individual Peromyscus spp. on multiple appropriately-spaced occasions over single trapping seasons while keeping animal welfare a top priority.