Detection of New Leptospira Genotypes Infecting Symptomatic Dogs: Is a New Vaccine Formulation Needed?

Abstract

Leptospirosis in dogs has been largely described worldwide, and epidemiological studies have been mainly based on serological data. This study aims to detect and genotype leptospires affecting symptomatic dogs in Northeast Italy between 2013 and 2019. Overall, 1631 dogs were tested using real-time PCR, and leptospires from 193 dogs were subjected to Multilocus Sequence Typing and a Multiple Loci Variable-number Tandem Repeat Analysis. Leptospires were successfully isolated from 15 symptomatic dogs. Six distinct Sequence Types (STs) were found for 135 leptospires, with 3 STs characterizing Leptospira interrogans (ST17, ST198 and ST24), 2 STs characterizing Leptospira kirschneri (ST117 and ST289) and 1 ST characterizing Leptospira borgpetersenii (ST155), revealing the circulation of the serogroups Icterohaemorrhagiae, Australis, Sejroe and Pomona. The Multiple Loci Variable-number Tandem Repeat Analysis of 17 samples did not result in any additional discrimination. Genotypes were compared with those of strains present in the historical internal database, and possible transmission chains were identified from rat, mouse, hedgehog and pig. This work highlights the importance of molecular methods in revealing and identifying circulating Leptospira strains, and it also encourages the evaluation of the ability of commercially available vaccines to reduce the disease burden among dogs.

Environmental Exposure of Wild Carnivores to Zoonotic Pathogens: Leptospira Infection in the First Free Living Wolf (Canis lupus Linnaeus, 1758) Found Dead in the Friuli Venezia Giulia Region

“…Serovar Mozdok was previously detected in domestic pigs ( Sus scrofa ), cattle, and dogs [ 4 , 11 , 13 , 14 ] while L. interrogans , serogroup Pomona, serovar Pomona was evidenced by MAT in wild boars ( Sus scrofa ) [ 15 ]. In the same study, L. kirschneri was also reported in a wild boar [ 13 ].…”

“…It must be highlighted that serogroup Pomona is not currently included in commercial vaccines available in Italy; furthermore, Pomona infection in dogs has also been suggested of having a worse outcome compared to other serogroups [ 23 ]. Serovar Mozdok ST117 has been previously identified from dogs of the neighboring Veneto region, sometimes leading to a lethal outcome [ 4 ]. Gross pathological changes of this wolf were in accordance with similar findings in affected dogs [ 21 ], however, we did not find any description of pathological modifications due to Leptospira infection in the wolf in literature, although natural infection was reported [ 1 ].…”

“…The Friuli Venezia Giulia region and northern Italy is an endemic area for leptospirosis. Despite widespread vaccination of dogs ( Canis lupus familiaris ), Leptospira serovars are regularly responsible for the disease and death of dogs each year [ 4 , 5 ]. The current regional wildlife surveillance plan includes leptospirosis within priority diseases of wild carnivores and its monitoring is being carried out by means of passive surveillance.…”

Leptospira Infections in Domestic and Wild Animals

“…Genotypes were compared with those of strains present in the historical internal database, and possible transmission chains were identified from rat, mouse, hedgehog, and pig. The work highlights the importance of molecular methods in revealing and identifying circulating Leptospira strains, and it also encourages the evaluation of the ability of commercially available vaccines to reduce the disease burden among dogs [23].…”

Molecular and Serological Characterization of Pathogenic Leptospira Spp. Isolated From Symptomatic Dogs in a Highly Endemic Area, Brazil

“…The PCR technique, on the other hand, has been successfully used to con rm infection at the early stages of the disease (8,9), showing to be also a useful tool to identify infecting species by further DNA sequencing of PCR amplicons (10). Yet, PCR may not provide reliable results during the convalescent phase of the disease (5) and its use as a single diagnostic strategy is also limited.…”