A new subspecies of Trypanosoma cyclops found in the Australian terrestrial leech Chtonobdella bilineata
Research article published in Parasitology (2021)
Abstract
Previously, it was suggested that haemadipsid leeches represent an important vector of trypanosomes amongst native animals in Australia. Consequently, Chtonobdella bilineata leeches were investigated for the presence of trypanosome species by polymerase chain reaction (PCR), DNA sequencing and in vitro isolation. Phylogenetic analysis ensued to further define the populations present. PCR targeting the 28S rDNA demonstrated that over 95% of C. bilineata contained trypanosomes; diversity profiling by deep amplicon sequencing of 18S rDNA indicated the presence of four different clusters related to the Trypanosoma (Megatrypanum) theileri. Novy–MacNeal–Nicolle slopes with liquid overlay were used to isolate trypanosomes into culture that proved similar in morphology to Trypanosoma cyclops in that they contained a large numbers of acidocalcisomes. Phylogeny of 18S rDNA/GAPDH/ND5 DNA sequences from primary cultures and subclones showed the trypanosomes were monophyletic, with T. cyclops as a sister group. Blood-meal analysis of leeches showed that leeches primarily contained blood from swamp wallaby (Wallabia bicolour), human (Homo sapiens) or horse (Equus sp.). The leech C. bilineata is a host for at least five lineages of Trypanosoma sp. and these are monophyletic with T. cyclops; we propose Trypanosoma cyclops australiensis as a subspecies of T. cyclops based on genetic similarity and biogeography considerations.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Summary
Peer-reviewed clinical and outcomes research relevant to anticoagulation, leech therapy, and microsurgical flap management. Indexed in PubMed and verified against the NCBI record.
Why This Matters for Hirudotherapy
Using PCR, DNA sequencing, in vitro culture, and phylogenetic analysis, this study found that over 95% of the Australian terrestrial leech Chtonobdella bilineata carried trypanosomes, identified at least five Trypanosoma lineages monophyletic with T. cyclops, and proposed a new subspecies, T. cyclops australiensis, with blood-meal analysis showing feeding on swamp wallaby, human, and horse. The relevance to hirudotherapy is a reminder that leeches are blood-feeding vectors whose gut can host transmissible micro-organisms, reinforcing why medicinal leeching uses controlled, single-use Hirudo medicinalis from regulated sources rather than wild-collected leeches. This is a basic parasitology/vector-biology study of a non-medicinal terrestrial species in Australia, so it carries no direct clinical implication for therapeutic leeching and does not assess human infection risk from medical leeches.
Citation
A new subspecies of Trypanosoma cyclops found in the Australian terrestrial leech Chtonobdella bilineata.
Ellis et al. · Parasitology, 2021
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