Microsporidia in Rodents—<i>Mus musculus</i>, <i>Rattus norvegicus,</i> and <i>Rattus rattus</i>—A Public Health Concern in the Canary Islands, Spain

Rodents are recognized as reservoirs of a wide range of pathogens, including microsporidia. The presence of microsporidia in the environment of mainland Spain and its islands has become increasingly known, as the number of studies has multiplied over time. The present study was conducted to determine the occurrence and diversity of microsporidia in three rodent species (<i>Mus musculus</i>, <i>Rattus norvegicus</i>, and <i>Rattus rattus</i>) in the Canary Islands, Spain. Ninety-three fecal samples were obtained from wild rodents on La Gomera and Gran Canaria Islands. Each sample was tested using Weber’s modified trichrome staining and immunofluorescence antibody tests (IFATs) against the <i>Encephalitozoon</i> genus and <i>Enterocytozoon bieneusi</i>. The microscopy-positive samples were subsequently analyzed using a nested polymerase chain reaction (PCR) followed by Sanger sequencing. The staining technique showed 38.7% (36/93) positivity, whereas the IFATs for <i>Encephalitozoon</i> spp. and <i>Ent. bieneusi</i> revealed 3.2% (3/93) and 6.5% (6/93) positivity, respectively. Finally, the nested PCR and nucleotide sequence analysis confirmed a 9.7% (9/93) occurrence of <i>Ent. bieneusi</i> and 17.2% occurrence (16/93) of different undetermined microsporidia species, whereas no <i>Encephalitozoon</i> spp. were detected. Seven different <i>Ent. bieneusi</i> genotypes were detected as follows: three known (AAE1, D, and SBM1) and four novel (GRE1, GRE2, LGE1, and LGE2), all of which belonged to Group 1. The results demonstrate, for the first time, that microsporidia are present in the rodent populations of the Canary Islands. Further studies are needed to determine the impact of the presence of microsporidia in rodents on the zoonotic transmission of these parasites.