Objective Fish trypanosomiasis, caused by the blood parasite Trypanosoma spp., can infect both freshwater and marine fish around the world. With some sudden outbursts of fish trypanosomiasis in aquaculture recently, there are huge economic losses. This article aims to summarize all available information about fish trypanosomiasis in order to provide suggestions for controlling and preventing it.

Analysis This review highlights the recent progress on studying taxonomy, prevalence, pathogenesis, and control of trypanosome. Instead of old characters for classification, molecular systematics and multi-locus gene analyses are favored. Studies in epidemiology indicate that fish trypanosomiasis affect a diverse array of hosts, such as Cyprinidae, Percidae, and Cichlidae, with varying levels of parasitemia leading to anemia, injuries to various organs due to the kinds of parasite species. At the same time, specific symptoms include anemia and damage to several organs. Trypanosomiasis may cause immunological disorders or inflammation if these processes happen with something mis-regulated, while through expressing genes like TcaCRT calcium binding proteins (Calbindin), they avoid the use of complement to attack and thus survive the attack of host’s immune systems and make a difficult survival situation for the host when co-infected with other parasites. In diagnostics, conventional methods such as blood smears are being supplanted by more precise and sensitive molecular techniques, including polymerase chain reaction (PCR), fluorescent quantitation PCR (qPCR), loop-mediated isothermal amplification (LAMP), and multienzyme isothermal rapid amplification (MIRA)-colloidal gold rapid tests, which greatly improve detection capabilities. Even now, no effective medication and prevention approaches have been found yet. Some antimicrobial peptides can be used for controlling infection and creating new drugs for treating diseases because they are found in the bodies of mammal to enhance cellular immunity with effects like regulating iron levels and killing off parasites or bacteria (such as hepcidin).

Prospect To study the mechanism of parasitic agents, investigation of the genome and transcriptome can reveal molecular details that uncover the machinery enabling their survival and pathogenicity. This helps identify suitable targets to eliminate pathogens without side effects and supports the development of medical and diagnostic tools for better disease control. For example, target genes can be identified through knockout or knockdown using gene-editing methods such as CRISPR/Cas9, and then developed into low-toxic, effective drugs or vaccines.