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Introduction
Introduction
Trypanosoma is a unicellular parasite that can infect humans as well as many different species of wildlife (Nok, 2009).
Primary literature article: Meta-transcriptomic identification of Trypanosoma spp. in native wildlife species from Australia (Ortiz-Baez, A.S., Cousins, K., Eden, JS, 2020)
Taxonomy
Taxonomy
Kingdom: Excavata
Phylum: Protozoa
Class: Kinetoplastido
Order: Trypanosomatida
Family: Trypanosomatidae
Genus: Trypanosoma
Figure 1. Light microscopic image of T. nabiasi in rabbit blood. Image from The Laboratory Rabbit, Guinea Pig, Hamster, and Other Rodents (Pritt and Sedlacek)
Background
Background
Trypanosoma spp. are unicellular eukaryotic parasites (Ortiz-Baez et al., 2020)
Different species of Trypanosoma infect specific animals in different ways (Ortiz-Baez et al., 2020)
Generally, trypanosomes first attack an organism's immune system, then it moves on to the central nervous system if the animal's immune system cannot fight it off (Nok, 2009)
They can be found in the bloodstream or an intracellular environment of an infected organism (Nok, 2009)
Once the parasite has invaded the central nervous system, it can cause neurological diseases, coma, and death (Nok, 2009)
They are heterotrophic meaning they gain nutrients from their host, feeding on the blood or tissue (Nok, 2009)
Like other unicellular organisms, trypanosomes reproduce asexually through binary fission (Nok, 2009)
A trypanosoma's mode of entry to an organism varies depending on the animal and the species of trypanosoma; for example, T. brucei causes sickness in cattle while T. percae causes a different disease in fish (Nok, 2009)
Figure 2. Representation of the switch to different forms of parasites with different surface antigens. Image from https://www.sciencedirect.com/book/9780123694089/vaccines-for-biodefense-and-emerging-and-neglected-diseases
Concepts to Understand
Concepts to Understand
Metatranscriptomics: the analysis of metagenomic mRNA (metatranscriptome), which provides information about regulation and expression of complex microbial communities present in the environmental sample
Figure 3. "Tree depicting the evolutionary relationships among trypanosomes sampled...Branch tips are colored according to the host of sampling. Trypanosomes detected in fish and annelids are indicated by a star. Animal silhouettes represent the hosts that tested positive for trypanosome infection. Image from https://parasitesandvectors.biomedcentral.com/articles/10.1186/s13071-020-04325-6#citeas
Data Analysis
Data Analysis
A study was conducted to better understand the diversity of trypanosomes and their host-parasite associations, specifically in Australian wildlife (Ortiz-Baez et al., 2020)
This was done through an implementation of total RNA sequencing, or metranscriptomics, in trypanosome surveillance (Ortiz-Baez et al., 2020)
This method provided a methodological approach in understanding the "host species distribution of this important group of parasites" (Ortiz-Baez et al., 2020)
Trypanosomes in a variety of tissue were detected; Brain, lung, liver, skin, and gonads were included in this study (Ortiz-Baez et al., 2020)
The samples for this study were obtained from the Australian Registry for Wildlife Health (ARWH) and included healthy and diseased individuals (Ortiz-Baez et al., 2020)
The sample included four marsupials (koala, southern brown bandicoot, swamp wallaby, bare-nosed wombat), one bird (regent honeyeater), and one amphibian (eastern dwarf tree frog) (Ortiz-Baez et al., 2020)
Results
Results
At the end of the study, trypanosome sequences were detected in all six species. Each type of organism was infected differently by a different type of trypanosome. "Phylogenetic analysis indicated that the trypanosomes infecting marsupials were related to those previously detected in placental and marsupial mammals, while the trypanosome in the regent honeyeater grouped with avian trypanosomes," (Ortiz-Baez et al., 2020). This study also resulted in the first evidence of a trypanosome in the eastern dwarf tree frog that was distinct from those found in other amphibians.
Figure 4. Trypomastigote of T. brucei in the bloodstream. Image from American Society of Tropical Medicine and Hygiene/Zaiman “A Presentation of Pictorial Parasites.”
Conclusion
Conclusion
Since this was the first metatranscriptomic analysis of trypanosomes in native Australian wildlife, it helped in expanding the known genetic diversity of this parasite. It's been revealed that trypanosomes can infect a wide range of animals in many different ways. This study focused solely on the regions New South Wales and Tasmania, and from those places only, trypanosomes in multiple different vertebrate groups were identified, as well as a divergent species of trypanosoma in an amphibian species.
References
References
Ortiz-Baez, A.S., Cousins, K., Eden, JS. 2020. “Meta-transcriptomic identification of Trypanosoma spp. in native wildlife species from Australia”. Parasites and Vectors 13, 447 https://parasitesandvectors.biomedcentral.com/articles/10.1186/s13071-020-04325-6#Fig1
Andrew J. Nok. 2009. “Vaccines for Biodefense and Emerging and Neglected Diseases”. Academic Press 1255-1273
https://www.sciencedirect.com/topics/medicine-and-dentistry/trypanosoma
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