Parasitological and histological aspects of Holochilus sciureus naturally infected by Schistosoma mansoni

Schistosomiasis Mansoni-Recruited Eosinophils: An Overview in the Granuloma Context

Eosinophils are remarkably recruited during schistosomiasis mansoni, one of the most common parasitic diseases worldwide. These cells actively migrate and accumulate at sites of granulomatous inflammation termed granulomas, the main pathological feature of this disease. Eosinophils colonize granulomas as a robust cell population and establish complex interactions with other immune cells and with the granuloma microenvironment. Eosinophils are the most abundant cells in granulomas induced by Schistosoma mansoni infection, but their functions during this disease remain unclear and even controversial. Here, we explore the current information on eosinophils as components of Schistosoma mansoni granulomas in both humans and natural and experimental models and their potential significance as central cells triggered by this infection.

New challenges for the control of human schistosomiasis: The possible impact of wild rodents in Schistosoma mansoni transmission

Schistosomiasis is a neglected parasitic disease caused by digenean trematodes from the genus Schistosoma that affects millions of people worldwide. Despite efforts to control its transmission, this disease remains active within several endemic regions of Africa, Asia, and the Americas. In addition to the deficits in sanitation and educational structure, another major obstacle hindering the eradication of schistosomiasis is the ability of Schistosoma spp. to naturally infect multiple vertebrate hosts, particularly wild rodents. Due to climate change and other anthropogenic disturbances, contact between humans and wild animals has increased, and this has contributed to more frequent interactions between Schistosoma species that typically infect different hosts. This new transmission dynamic involving Schistosoma spp., humans, wild rodents, and livestock could potentially increase the frequency of Schistosoma hybridization and the establishment of new genotypes and strains. Although it is not currently possible to precisely measure how this biological phenomenon affects the epidemiology and morbidity of schistosomiasis, we speculate that these Schistosoma variants may negatively impact control strategies, treatment regimens, and disease burden in humans. In the present study, we discuss the natural infections of wild rodents with Schistosoma spp., the role of these animals as Schistosoma spp. reservoirs, and how they may select hybrids and strains of Schistosoma mansoni. We also discuss measures required to shed light on the actual role of the wild rodents Nectomys squamipes and Holochilus sciureus in the transmission and morbidity of schistosomiasis in Brazil.

First mitochondrial genome of the Amazonian marsh rat Holochilus sciureus Wagner 1842 (Rodentia, Cricetidae, Sigmodontinae)

The Amazonian marsh rat, Holochilus sciureus, is a member of the subfamily Sigmodontinae, the second-largest subfamily of muroid rodents, with 410 species and ca. 84 genera in 12 tribes. This semiaquatic rodent is distributed in South America and is of great economic and epidemiological importance. In this study, we obtained the first mitochondrial genome of the genus Holochilus obtained from a tissue sample associated with a museum voucher specimen. The generated mitogenome sequence of H. sciureus is 16,358 bp length. It comprises a control region and a conserved set of 37 genes encoding for 2 rRNA genes, 22 tRNA genes and 13 protein-coding genes. We conducted a phylogenetic analysis that included H. sciureus and the only five other published mitochondrial genomes of this poorly studied subfamily of rodents.