Risk factors related to seropositivity for Leptospira spp. in horses in the Serra Catarinense region

Abstract

Leptospirosis is a zoonotic infectious disease caused by the bacterium Leptospira spp. The consequences of infection in horses are unclear, and the serogroups involved vary depending on the region. This study aimed to evaluate the seropositivity of unvaccinated horses in the Serra Catarinense region and the possible risk factors associated with the infection. We used 207 horses from 26 properties, with no clinical history of infection and unvaccinated for leptospirosis. We submitted serum samples to the microscopic agglutination serum (SAM) to obtain the main reference serogroups. We considered animals with titre ≥100 as infected. The results of the serology revealed seropositivity in 45.4% (94/207) of the animals studied. The most frequent antibodies reportedwere those against the serogroups Australis 16.9% (35/207), Ichterhaemorrhagiae 14.4% (30/207), and Grippotyphosa 5.31% (11/207). Among the primary risk factors associated with the infection we reported extensive rearing system (OR = 1.27; P<0.05) and the presence of other animal species such as cattle (OR = 3.85; P<0.01) and capybaras (OR = 2.07; P=0.06). The findings presented in this study showed that leptospirosis is endemic in horses in the Serra Catarinense region, and revealed the need for emergency surveillance and control measures specific to this important zoonosis.

Seroprevalence of Leptospira in Racehorses and Broodmares in New Zealand

“…In contrast, once in training, racehorses typically have less than 12 h access to pasture per day and experience a more “intensive” management system [ 24 , 40 ]. Our findings are in agreement with those from Switzerland [ 33 ] and Brazil [ 30 ], reporting an increased risk of exposure to Leptospira for horses spending more time at pasture and for horses in extensive rearing systems.…”

“…A quarter of the horses in the cohort tested positive to at least one serovar, which is the same as the seroprevalence rates reported in Korea (25%) [ 28 ] and slightly lower than a study in Australia (29%) [ 29 ]. Studies in Brazil, Italy, and North America have reported higher rates of 45%, 67%, and 77% of horses testing positive to at least one serovar, respectively [ 30 , 31 , 32 ]. Direct comparisons of seroprevalence across geographic regions may be difficult due to variations in the positive titre cut-off used between studies and differences in endemic serovars across regions.…”

“…Pomona is reported to be the most common serovar causing clinical disease, such as ERU and abortions, in North America [34,35]. The most common serovars in horses in North America, Brazil, and Italy are Australis and Bratislava [30][31][32]36]. Neither of these serovars are considered endemic in New Zealand [3].…”

Occurrence of Leptospira spp. and factors associated with the infection in horses from a military contingent in the Rio Grande do Sul State, Brazil

“…The observed seroprevalence varied widely in previous research conducted in southern Brazil. In the state of Santa Catarina, Silva et al (2020) and Farias et al (2020) found 45.9% (273/595) and 45.4% (94/207) of horses were positive for anti-Leptospira antibodies. And in the state of Paraná, the seroprevalence of 75.8% (47/62) (Finger et al, 2014) were detected, while in RS, studies involving cart horses reported seroprevalences of 60% (75/125) in the city of Porto Alegre (Lasta et al, 2013) and 89.9% (107/119) in Pelotas (Dewes, 2017).…”

“…Both categories sometimes shared pastures with cattle and had contact with rodents and wild animals. Farias et al (2020) pointed out that the presence of different animal species occupying the same spaces suggests the environment as a determining factor in the infection epizootiology and variability of circulating serovars. The presence of rodents was also reported in the feed deposit of mares.…”