Enterocytozoon bieneusi (Microsporidia): evidence of transmission between sympatric wild boars (Sus scrofa ferus) and Iberian pigs (Sus scrofa domesticus) in Southern Spain

Authors: DASHTI, ALEJANDRO - Instituto De Salud Carlos Iii; RIVERO-JUAREZ, ANTONIO - University Of Cordova (UCO), Spain; Santin-Duran, Monica; LOPEZ-LOPEZ, PEDRO - University Of Cordova (UCO), Spain; CABALLERO-GOMEZ, JAVIER - University Of Cordova (UCO), Spain; FRIAS-CASAS, MARIO - University Of Cordova (UCO), Spain; KOSTER, PAMELA - Instituto De Salud Carlos Iii; BAILO, BEGOÑA - Instituto De Salud Carlos Iii; CALERO-BERNAL, RAFAEL - Complutense University Of Madrid (UCM); BRIZ, VERONICA - Instituto De Salud Carlos Iii; CARMENA, DAVID - Instituto De Salud Carlos Iii

Submitted to: Transboundary and Emerging Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/28/2020
Publication Date: 6/5/2020
Citation: Dashti, A., Rivero-Juarez, A., Santin, M., Lopez-Lopez, P., Caballero-Gomez, J., Frias-Casas, M., Koster, P., Bailo, B., Calero-Bernal, R., Briz, V., Carmena, D. 2020. Enterocytozoon bieneusi (Microsporidia): evidence of transmission between sympatric wild boars (Sus scrofa ferus) and Iberian pigs (Sus scrofa domesticus) in Southern Spain. Transboundary and Emerging Diseases. 67(6):2869-2880. https://doi.org/10.1111/tbed.13658.
DOI: https://doi.org/10.1111/tbed.13658

Interpretive Summary: Microsporidia are parasites that infect numerous hosts ranging from protist to mammals. Enterocytozoon bieneusi is the most prevalent species infecting humans worldwide. It has been frequently reported in multiple animal hosts, including wild and domestic, raising concerns of zoonotic transmission. Epidemiological information on the presence and molecular diversity of E. bieneusi in livestock and wildlife is limited. Therefore, the occurrence of this microsporidia was investigated in sympatric, extensively reared Iberian pigs (n = 186) and free ranging wild boars (n = 142) in the province of Córdoba, Southern Spain. Forty-two Iberian pigs (22.6%) and three wild boars (2.1%) were found E. bieneusi-positive by molecular methods. In Iberian pigs, occurrence of E. bieneusi was significantly higher in sows than in fattening pigs (31.6% vs. 11.4%). Molecular characterization identified five genotypes in Iberian pigs, four previously reported (EbpA, PigEb4, O, Pig HN-II) and a novel genotype (named PigSpEb1), while only two genotypes were identified in wild boars, EbpA and novel genotype PigSpEb1. All five genotypes identified belong to Group 1 suggesting zoonotic potential. This study constitutes the first report on the occurrence and molecular characterization of E. bieneusi in Iberian pigs and wild boars. The identification of two genotypes with zoonotic potential in sympatric Iberian pigs and wild boars suggests that E. bieneusi can be potentially transmitted between those two hosts, but also implies that they may act as natural sources of microsporidia infection to other hosts including humans. This information should be useful to other scientists, veterinarians and public health agencies.

Technical Abstract: Microsporidia is a phylum of obligate emergent intracellular protist-like fungi parasites that infect a broad range of hosts including vertebrates and invertebrates. Enterocytozoon bieneusi is the most common cause of microsporidiosis in humans, affecting primarily immunosuppressed patients but also reported in immunocompetent individuals. Epidemiological information on the presence and molecular diversity of E. bieneusi in livestock and wildlife in Spain is limited. Therefore, the occurrence of this microsporidia was investigated in sympatric, extensively reared Iberian pigs (n = 186) and free ranging wild boars (n = 142) in the province of Córdoba, Southern Spain. Forty-two Iberian pigs (22.6%) and three wild boars (2.1%) were found E. bieneusi-positive by PCR. In Iberian pigs, occurrence of E. bieneusi was significantly higher in sows than in fattening pigs (31.6% vs. 11.4%; p = 0.001). Five genotypes were identified in Iberian pigs, four previously reported (EbpA, PigEb4, O, Pig HN-II) and a novel genotype (named PigSpEb1), while only two genotypes were identified in wild boars, EbpA and novel genotype PigSpEb1. All five genotypes identified belong to Group 1 suggesting zoonotic potential. This study constitutes the first report on the occurrence and molecular characterization of E. bieneusi in Iberian pigs and wild boars. The identification of two genotypes with zoonotic potential in sympatric Iberian pigs and wild boars suggests that E. bieneusi can be potentially transmitted between those two hosts, but also implies that they may act as natural sources of microsporidia infection to other hosts including humans.