Seroprevalence of leptospirosis in Korean municipal zoo animals

Pinnipeds carriers of pathogenic Leptospira: New data based on molecular characterization

Leptospirosis is a bacterial disease caused by the infection of pathogenic strains of the genus Leptospira, endemic in tropical and subtropical regions. Although well documented in terrestrial animals and humans, little information is available on its distribution and impact on marine animals. Despite clinical manifestations that may occur, the occurrence of carriers was suggested in some species. Nevertheless, there are few studies regarding the infection by Leptospira sp. in marine mammals. In this context, and considering the One Health approach, the present aimed to investigate pinnipeds' role as Leptospira sp. carriers. Kidneys of 47 pinnipeds of two species, Arctocephalus australis (n = 40) and Arctocephalus tropicalis (n = 7) were collected. DNA was extracted and the diagnosis was performed through LipL32-PCR and genetic characterization based on secY gene sequencing. Phylogenetic analysis and haplotype networks were constructed. Pathogenic Leptospira sp. DNA was detected in 31.9% (15/47) of the tested pinnipeds. It was possible to amplify and sequence eight strains (6 for A. australis, 2 for A. tropicalis), all identified as L. interrogans, with high similarity with sequences from Icterohaemorrhagiae serogroup. Phylogenetic analysis revealed sequences from the present study grouped in species-specific unique clusters, but very close to others from humans, wild animals, and domestic animals. We demonstrate that pinnipeds could act as carriers, and play an important role in leptospirosis dynamics.

A multipronged approach for the detection of leptospirosis in captive sloth bears (Melursus ursinus) in Agra and Bannerghatta sloth bear rescue centers in India

Leptospirosis is an exacerbating factor responsible for the drastic decline of sloth bear population in India. In this study, a multipronged approach based on antigen detection using Polymerase Chain Reaction (PCR) employing G1/G2 and LigBF/LigBR primers, antibody detection using Microscopic Agglutination Test (MAT) and recombinant LigBCon1-5 antigen based Latex Agglutination Test (rLigBCon1-5 LAT), serum biochemistry using hepatic (serum glutamate oxalo acetic transaminase (SGOT) and serum glutamate pyruvic transaminase (SGPT) and renal biomarkers (blood urea nitrogen (BUN) and Creatinine) and gross/histopathological evidence in liver and kidneys were employed to investigate leptospirosis in captive sloth bears. A total of 133 serum samples collected from Agra (n=113) and Bannerghatta (n=20) sloth bear rescue centers were screened using MAT and rLigBCon1-5 LAT. A total of 87 and 78 sera tested positive by MAT and LAT respectively. Pyrogenes was the leading serovar obtained using MAT followed by Icterohaemorrhagiae, Javanica, Grippotyphosa, Canicola and Tarassovi. The relative sensitivity, specificity and accuracy of rLigBCon1-5 LAT in comparison to MAT were 89.66%, 100% and 93.23% respectively. PCR performed on hepatic and renal tissues showed amplicon of 285 and 219 base pairs for G1/G2 and LigBF/LigBR primers respectively. Gross evidence (icteric liver, severely engorged hepatic sinusoids, congested kidneys with necrotic white spots on sub capsular surface), histopathology (severe hepatic degeneration and tubulointerstitial nephritis) and elevated hepatic/renal biomarkers were suggestive of leptospirosis. This study suggests that rLigBCon1-5 LAT can be employed as a pen-side test for detecting leptospirosis in sloth bears.

Leptospirosis in the republic of Korea: historical perspectives, current status and future challenges

Leptospirosis is an important public health problem in the Republic of Korea (ROK), occurring sporadically or in outbreaks during the autumn season. Wild rodents, Apodemus agrarius, have been mainly involved in human leptospirosis. The majority of carrier animals are infected with Leptospira interrogans serovar lai. The characteristic pulmonary involvement or hemorrhage may increase the clinical severity or result in fatal outcomes, and these aspects continue to be a threat to people in endemic areas. While the disease incidence has been relatively low in recent years, there have been newer findings of livestock (zoo animals and racing horses) and rats (Rattus norvegicus) captured in urban environments as potential animal carriers. Many avenues of research are still open to define current changes in ecology, epidemiology, and the disease burden in both humans and animals in the ROK, together with global warming and climate change issues. In addition, national policy regarding the weighted wildlife monitoring system and the enhanced disease surveillance program is required to facilitate better monitoring and understanding of this disease.

Seroprevalence of Leptospira spp. in clinically healthy racing horses in Korea

Leptospirosis is a zoonotic disease of global importance, and has a worldwide distribution. The present study aimed to determine leptospiral seroprevalence in clinically healthy racing horses from all three racecourses in Korea. Serum samples from 1,226 racing horses were examined using a microscopic agglutination test to detect the presence of antibodies against 18 Leptospira serovars. Of the tested samples, 307 (25.0%) were found to be positive. The distribution of seroprevalence differed significantly by racecourse (P=0.004); the Jeju course had the highest incidence (31.1%), followed by the Seoul (25.2%) and Busan (19.5%) racecourses. Seasonal variation in seropositivity was also apparent (P=0.000), being lower in spring (13.0%) and winter (12.5%), and higher in summer (36.7%) and autumn (34.7%). No significant age- or gender-related difference in seroprevalence was noted in this study (P>0.05). Seroprevalence was higher (P=0.006) among ponies than among thoroughbreds. Sejroe was the most frequently detected serovar (n=236), followed by Bratislava (n=35), Ballum (n=16), Autumnalis (n=10), and Canicola (n=10). The majority of serum titers were relatively low; most values ranged from 1:100 (n=217) to 1:200 (n=69). These results suggest that the Sejroe serovar may be maintained in the racing horse population in Korea.