Global distribution of zoonotic digenetic trematodes: a scoping review.

BACKGROUND: Digenetic trematodes, including blood flukes, intestinal flukes, liver flukes, lung flukes, and pancreatic flukes, are highly diverse and distributed widely. They affect at least 200 million people worldwide, so better understanding of their global distribution and prevalence are crucial for controlling and preventing human trematodiosis. Hence, this scoping review aims to conduct a comprehensive investigation on the spatio-temporal distribution and epidemiology of some important zoonotic digenetic trematodes. METHODS: We conducted a scoping review by searching PubMed, Web of Science, Google Scholar, China National Knowledge Infrastructure, and Wanfang databases for articles, reviews, and case reports of zoonotic digenetic trematodes, without any restrictions on the year of publication. We followed the inclusion and exclusion criteria to identify relevant studies. And relevant information of the identified studies were collected and summarized. RESULTS: We identified a total of 470 articles that met the inclusion criteria and were included in the review finally. Our analysis revealed the prevalence and global distribution of species in Schistosoma, Echinostoma, Isthmiophora, Echinochasmus, Paragonimus, Opisthorchiidae, Fasciolidae, Heterophyidae, and Eurytrema. Although some flukes are distributed worldwide, developing countries in Asia and Africa are still the most prevalent areas. Furthermore, there were some overlaps between the distribution of zoonotic digenetic trematodes from the same genus, and the prevalence of some zoonotic digenetic trematodes was not entirely consistent with their global distribution. The temporal disparities in zoonotic digenetic trematodes may attribute to the environmental changes. The gaps in our knowledge of the epidemiology and control of zoonotic digenetic trematodes indicate the need for large cohort studies in most countries. CONCLUSIONS: This review provides important insights into the prevalence and global distribution of some zoonotic digenetic trematodes, firstly reveals spatio-temporal disparities in these digenetic trematodes. Countries with higher prevalence rate could be potential sources of transmitting diseases to other areas and are threat for possible outbreaks in the future. Therefore, continued global efforts to control and prevent human trematodiosis, and more international collaborations are necessary in the future.

Taxonomic integrative and phylogenetic identification of the first recorded Triatoma rubrofasciata in Zhangzhou, Fujian Province and Maoming, Guangdong Province, China.

BACKGROUND: Most species of Triatominae live exclusively in Latin America. However, one species, Triatoma rubrofasciata, has been recorded in the Americas as well as in various port areas in Africa and Asia. An increasing number of T. rubrofasciata have been reported in southern China in recent years. However, the origin of this invasive insect vector in China remains unknown, therefore, accurate identification and phylogenetic analysis of the bugs are urgently needed. METHODS: A total of seven triatomine insect specimens were found and collected from Maoming City, Guangdong Province, China (GDMM) and Zhangzhou City, Fujian Province, China (FJZZ), respectively. The obtained insect vector specimens were observed under a dissecting microscope for morphological classification and then the genomic DNA was extracted, and the 16S ribosomal RNA (rRNA), 28S rRNA as well as cytochrome oxidase subunit I (COI) genes of the species were amplified and sequenced. Subsequently, molecular phylogenetic analyses based on multiple alignments of the above genes were conducted in order to identify the species and determine the phylogenetic origin approximation accurately. RESULTS: The triatomine insects collected from GDMM and FJZZ were identified as Triatoma rubrofasciata using morphological and genetic analyses. All of the Chinese T. rubrofasciata captured in FJZZ, GDMM and other localities in southern China, together with a Vietnamese and Brazilian strain, formed a new, cohesive clade. T. rubrofasciata in GDMM and FJZZ are likely derived from strains found in Vietnam or Brazil. CONCLUSIONS: To the best of our knowledge, this is the first record of the invasive insect T. rubrofasciata, which is likely derived from strains native to Vietnam or Brazil, in both Maoming City, Guangdong Province and Zhangzhou City, Fujian Province of China. A comparison of the DNA sequences of the 16 s rRNA, 28 s rRNA and COI genes confirmed the specific identification of T. rubrofasciata, and its potential origin in China is based on the phylogenetic analyses undertaken in this study. More targeted interventions and improved entomological surveillance are urgently needed to control the spread of this haematophagous insect in China.