Risk factors of Leptospira infection in Mediterranean periurban micromammals

Abstract

SummaryUrbanization of natural areas can change abiotic factors, providing artificial sources of humidity in summer and decreasing variation of temperatures in winter. Our study aimed at document risk factors of infection in mammal reservoirs of pathogenic Leptospira in the human/wildlife interface of a large metropolitan area. We hypothesize that survival of Leptospira and thus their prevalence in animal reservoirs should be higher in residential areas than in natural habitats, especially after the hot, dry Mediterranean summers. We established the prevalence of Leptospira spp. and identified the serovars in 353 urine samples from micromammals (chiefly the wood mouse Apodemus sylvaticus, n = 266) using direct immunofluorescence and PCR. Animals were captured in spring and autumn, 2011-2012, in two natural parks and two adjacent residential areas in periurban Barcelona (NE Spain). Overall observed prevalence of infection was 11%, ranking between 8% and 13% in the better represented host species. We observed marked differences between seasons; the probability of finding a micromammal infected in spring was three times greater than in autumn (almost four times for wood mouse). Prevalence was not related with type of habitat, micromammal relative abundance or sex of the animal. Three Leptospira species were confirmed: Leptospira interrogans (47% of cases), Leptospira borgpetersenii (41%) and Leptospira kirschneri (12%). The serovars most commonly detected were those typically hosted by rodents, and serovars Ballum and Icterohemorrhagiae were the only ones found in autumn. People living in periurban Barcelona and those visiting the natural areas of the metropolitan area face hazard of infection with rodent-borne Leptospira, especially during spring.

Leptospira Detection in Cats in Spain by Serology and Molecular Techniques

“…To our knowledge, this is the first study in Spain to confirm by MAT, the seropositivity against serovars Bataviae, Bratislava, Cynopteri, Grippotyphosa, Pomona, Proechimys, and Rachmati in cats, suggesting the possible presence of serovars from serogroups Australis, Autumnalis, Bataviae, Cynopteri, Grippotyphosa, and Pomona among cats in the country. In the metropolitan area of Barcelona, Spain, the presence of members of serogroups Australis, Bataviae, and Grippotyphosa (also detected in our study in cats) has been detected in small mammals [40], so it may be possible for serovars to circulate between animal species. Another factor to consider is the increased contact between cats and animal reservoirs of leptospires, due to shifts in the dynamics and colonization of cities.…”

Isolation of pathogenic Leptospira strains from naturally infected cattle in Uruguay reveals high serovar diversity, and uncovers a relevant risk for human leptospirosis

“…Infected bovines also constitute an active reservoir for the spread of the zoonotic disease, especially for humans in direct contact with infected animals including veterinarians, abattoir and farm workers, hunters, as well as scientists handling laboratory animals or during fieldwork [ 3 , 4 ]. Domestic and wild animals are important reservoirs in rural areas, unlike urban settings where rats play a major dissemination role [ 5 , 6 ]. Human infection with Leptospira spp.…”

What evidence exists on the impact of specific ecosystem components and functions on infectious diseases? A systematic map

“…Derne et al [116] tested the dilution effect hypothesis on the prevalence in human beings at a global scale. The other studies all tested the effect of wild hosts-related exposures on the infection in wild hosts, but these exposures were very heterogeneous: proximity with fruit bats [117], composition of rat population [118], density of small mammals [119], and density of rodents [120]. As such any synthesis was not attempted.…”

“…Group 22 (density of cervids): Four studies were excluded from the synthesis as they were attributed a medium/low validity [120,133,138,139]. The three studies that tested the effect of deer density on the human incidence of Lyme disease found a positive correlation, but variable in time and in space.…”