PATHOGENICLEPTOSPIRASEROVARS IN FREE-LIVING SEA LIONS IN THE GULF OF CALIFORNIA AND ALONG THE BAJA CALIFORNIA COAST OF MEXICO

Abstract

The California sea lion ( Zalophus californianus ), a permanent inhabitant of the Gulf of California in Mexico, is susceptible to pathogenic Leptospira spp. infection, which can result in hepatic and renal damage and may lead to renal failure and death. During summer 2013, we used the microscopic agglutination test (MAT) to investigate the prevalence of anti-Leptospira antibodies in blood of clinically healthy sea lion pups from seven rookery islands on the Pacific Coast of Baja California (Pacific Ocean) and in the Gulf of California. We also used PCR to examine blood for Leptospira DNA. Isolation of Leptospira in liquid media was unsuccessful. We found higher antibody prevalence in sea lions from the rookery islands in the gulf than in those from the Pacific Coast. Antibodies against 11 serovars were identified in the Gulf of California population; the most frequent reactions were against serovars Bataviae (90%), Pyrogenes (86%), Wolffi (86%), Celledoni (71%), and Pomona (65%). In the Pacific Ocean population, MAT was positive against eight serovars, where Wolffi (88%), Pomona (75%), and Bataviae (70%) were the most frequent. Serum samples agglutinated with more than one Leptospira serovar. The maximum titer was 3,200. Each island had a different serology profile, and islands combined showed a distinct profile for each region. We detected pathogenic Leptospira DNA in 63% of blood samples, but we found no saprophytic Leptospira. Positive PCR results were obtained in blood samples with high and low MAT titers. Together, these two methods enhance the diagnosis and interpretation of sea lion leptospirosis. Our results may be related to human activities or the presence of other reservoirs with which sea lions interact, and they may also be related to sea lion stranding.

Detection of pathogenicLeptospiraspecies associated with phyllostomid bats (Mammalia: Chiroptera) from Veracruz, Mexico

“…Although leptospirosis is a human and veterinary problem in Mexico, especially in states with tropic climate such as Tabasco and Veracruz with a human incidence that fluctuates between 4.39 and 11.74 cases per 100,000 inhabitants (Sánchez‐Montes, Espinosa‐Martínez, Ríos‐Muñoz, Berzunza‐Cruz, & Becker, ) and a seroprevalence in cattle that varies from 60% to 80% in Veracruz (Zárate‐Martínez, Rosete‐Fernández, Ríos‐Utrera, Barradas‐Piña, & Olazarán‐Jenkins, ), few studies have been carried out in order to identify wild hosts involved in the transmission of this pathogenic spirochaetes, all of them concentrated in terrestrial (Cantu et al., ; Espinosa‐Martínez et al., ; López‐Pérez et al., ; Méndez et al., ; Montiel‐Arteaga, Atilano, Ayanegui, Ceballos, & Suzán, ; Ruiz‐Pina, Puc‐Franco, Flores‐Abuxapqui, Vado‐Solis, & Cardenas‐Marrufo, ; Vado‐Solís et al., ) or marine mammals (Acevedo‐Whitehouse et al., ; Aragón‐Martínez, Olivera‐Gómez, & Jiménez‐Domínguez, ; Avalos‐Téllez et al., ; Godínez et al., ; Ziehl‐Quirós, García‐Aguilar, & Mellink, ), with a lack of knowledge regarding bats as potential reservoirs of these bacteria. To identify the role of bats as carriers of pathogenic leptospires, we detected and evaluated the diversity of Leptospira using molecular techniques in samples of kidneys from several bat species of Veracruz, Mexico.…”

Effect of environmental variables on the number of births at California sea lion (Zalophus californianus) rookeries throughout the Gulf of California, Mexico

“…Our study suggests that over the short term (2009–2016), the reproductive success of California sea lions in the central region is related to prey availability; however, the historical trend indicates that this species’ population dynamics are the result of more factors operating together, such as mortality owing to entanglement, illegal catches and disease (Acevedo‐Whitehouse et al, 2003; Ávalos‐Téllez et al, 2016; Gallo‐Reynoso, 2019). There is an urgent need to propose new (or significantly modify current) management strategies to protect and encourage the recovery of these colonies.…”

“…At the San Pedro Nolasco breeding colony in the GoC, a high mortality of California sea lions owing to shark fishing was registered (1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000); the animals were used as bait and the use of fishing nets increased the likelihood that sea lions also would become entangled (Zavala-González & Mellink, 1997;Gallo-Reynoso, 2019). Our study suggests that over the short term (2009-2016), the reproductive success of California sea lions in the central region is related to prey availability; however, the historical trend indicates that this species' population dynamics are the result of more factors operating together, such as mortality owing to entanglement, illegal catches and disease (Acevedo-Whitehouse et al, 2003;Avalos-Téllez et al, 2016;Gallo-Reynoso, 2019). There is an urgent need to propose new (or significantly modify current) management strategies to protect and encourage the recovery of these colonies.…”

Detecting signals of chronic shedding to explain pathogen persistence:Leptospira interrogansinCalifornia sea lions

“…Currently available data on Leptospira diagnostics in the Baja population show different serologic response profiles (potentially indicating a different infecting strain) and demographic infection patterns (including evidence of infection in pups) that do not resemble patterns seen in our study population (Avalos‐Téllez et al . ). Further research is needed to identify the infecting strain in the Mexican population and to investigate possible connectivity or epidemiological interactions between these populations, to determine whether spatial coupling may contribute to pathogen persistence in this system.…”