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Carmona Gasca CA, Martínez González S, Castillo Sánchez LO, Rodríguez Reyes EA, Cárdenas Marrufo MF, Vado Solís I, Castañeda Miranda G, López Huitrado LP, de la Peña-Moctezuma A. The Presence of a Virulent Clone of Leptospira interrogans Serovar Canicola in Confirmed Cases of Asymptomatic Dog Carriers in Mexico. Microorganisms 2024; 12:674. [PMID: 38674618 PMCID: PMC11052047 DOI: 10.3390/microorganisms12040674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 03/06/2024] [Accepted: 03/11/2024] [Indexed: 04/28/2024] Open
Abstract
Leptospirosis is a neglected zoonotic disease that commonly affects cattle, pigs, horses, and dogs in many countries. Infection in dogs is usually subclinical, but acute cases of leptospirosis may occur along with systemic failure, which may become fatal. After recovery from an acute infection, dogs may become asymptomatic carriers and shed pathogenic leptospires through urine for long periods of time. Here, a study of ten different cases of leptospirosis is presented, showing the relevance of dogs as asymptomatic carriers of pathogenic Leptospira. The diagnosis was confirmed via isolation and further serological and genetic identification. Four Leptospira isolates (LOCaS28, 31, 34, and 46) were obtained from the kidneys and urine samples of 58 dogs destined for destruction (6.89%) at a Canine Control Center in Mexico City. No spirochetes were observed in the urine samples of those Leptospira-positive dogs examined under dark-field microscopy, and no clinical signs of disease were observed either. Six additional isolates were obtained: two came from asymptomatic carrier dogs (CEL60 and UADY22); another isolate came from an asymptomatic dog that was a pack companion of a clinically ill dog with fatal leptospirosis (AGFA24); and finally, three isolates were taken from dogs that died of leptospirosis (LOCaS59, Citlalli, and Nayar1). Nine out of the ten isolates were identified as being from the serogroup Canicola via cross-absorption MAT using reference strains and specific antisera, and their identity was genetically confirmed as Canicola ST34 via multi-locus sequencing typing (MLST). In contrast, the isolate Nayar1 was identified as serovar Copenhageni ST2. Interestingly, the asymptomatic dogs from which Leptospira isolates were recovered consistently showed high antibody titers in the microscopic agglutination test (MAT), revealing values of at least 1:3200 against serogroup Canicola and lower titer values against other serogroups. Isolates showed different virulence levels in the hamster model. Taken as a whole, all these findings confirmed that dogs may act as asymptomatic carriers of pathogenic leptospires and possibly spread them out to the environment, thus representing an active public health risk. The results also showed that the Canicola ST34 clone is the most prevalent Leptospira serovar in dogs in Mexico, and finally that the old-fashioned MAT is a good alternative for the detection of presumptive Leptospira asymptomatic carrier dogs.
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Affiliation(s)
- Carlos Alfredo Carmona Gasca
- Functional Biology Laboratory, Academic Unit for Veterinary Medicine and Zootechnics, Autonomous University of Nayarit, Tepic 63155, Mexico; (S.M.G.)
| | - Sergio Martínez González
- Functional Biology Laboratory, Academic Unit for Veterinary Medicine and Zootechnics, Autonomous University of Nayarit, Tepic 63155, Mexico; (S.M.G.)
| | - Luz Olivia Castillo Sánchez
- Functional Biology Laboratory, Academic Unit for Veterinary Medicine and Zootechnics, Autonomous University of Nayarit, Tepic 63155, Mexico; (S.M.G.)
- Leptospira and Leptospirosis Research Group, Teaching, Research and Extension Center for Animal Husbandry in the Plateau, School of Veterinary Medicine and Zootechnics, National Autonomous University of Mexico, Tequisquiapan 76795, Mexico
| | | | | | - Ignacio Vado Solís
- School of Medicine, Autonomous University of Yucatan, Merida 97000, Mexico; (M.F.C.M.)
| | - Giselle Castañeda Miranda
- Leptospira and Leptospirosis Research Group, Teaching, Research and Extension Center for Animal Husbandry in the Plateau, School of Veterinary Medicine and Zootechnics, National Autonomous University of Mexico, Tequisquiapan 76795, Mexico
| | | | - Alejandro de la Peña-Moctezuma
- Leptospira and Leptospirosis Research Group, Teaching, Research and Extension Center for Animal Husbandry in the Plateau, School of Veterinary Medicine and Zootechnics, National Autonomous University of Mexico, Tequisquiapan 76795, Mexico
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