Leptospirainfection and shedding in cats in Thailand

Abstract

In Thailand, leptospirosis is considered an emerging disease in humans and animals. Many species can shed pathogenic Leptospira, including domestic cats (felis catus), which might be able to pose a risk to humans. There are no studies on Leptospira infections in cats in Thailand, but in other countries, it was demonstrated that cats can shed pathogenic Leptospira with high prevalences. The aims of this study were to evaluate whether outdoor cats in Thailand shed pathogenic Leptospira in their urine, and to determine antibody prevalence and risk factors associated with Leptospira infection. Two hundred and sixty outdoor cats were prospectively recruited. Urine samples were tested by real‐time PCR targeting the lipL32 gene of pathogenic Leptospira. Urine was additionally cultured for 6 months in Ellinghausen‐McCullough‐Johnson‐Harris medium to grow Leptospira. Antibodies against 24 serovars (Anhoa, Australis, Autumnalis, Ballum, Bataviae, Bratislava, Broomi, Canicola, Celledoni, Copenhageni, Coxi, Cynopteri, Djasiman, Grippotyphosa, Haemolytica, Icterohaemorrhagiae, Khorat, Paidja, Patoc, Pomona, Pyrogenes, Rachmati, Saxkoebing, Sejroe) belonging to 16 serogroups were determined using microscopic agglutination tests. Risk factors were analysed by Fisher's exact test. Urine samples of 2/260 cats (0.8%; 95% confidence interval (CI): 0.1%–2.8%) were PCR‐positive, but none of the 260 urine samples were culture positive. Leptospira antibodies were detected in 14/260 cats (5.4%; 95% CI: 3.0%–8.6%) with titers ranging from 1:20 to 1:160 (serovars: Anhoa, Autumnalis, Celledoni, Copenhageni, Djasiman, Icterohaemorrhagiae, Patoc). Cats aged ≥4 years were significantly more often infected with Leptospira than younger cats. No other significant risk factors were found. In conclusion, outdoor cats in Thailand can shed DNA and, possibly, viable, pathogenic Leptospira in their urine, although at a much lower prevalence than expected when compared to countries with similar climate. Thus, cats can be a potential source of infection for people. Further studies are needed to determine the role of cats in transmitting this zoonotic disease in Thailand.

Leptospira Detection in Cats in Spain by Serology and Molecular Techniques

“…The prevalence of urinary shedding from leptospiral DNA in the present research is consistent with that reported in previous studies in cats [6,7,14,15,18,19]. Our results also match with those obtained by Sprißler et al, 2018 (0.8%) [14] and Gomard et al, 2019 (0.6%) [8].…”

“…A plausible explanation for this could be that either the animals had an acute infection with increasing antibody titers at the moment of sampling and no shedding of Leptospira DNA had occurred yet, or most likely that they were chronic carriers with falling or steady antibody titers and non-continuous Leptospira shedding in the urine. Similar findings have been previously described [14,15,18,20].…”

“…Seroprevalence against Leptospira observed in our study (4.1% positive 95% CI: 2.1-7.18%), fell within the previous intervals described worldwide, 4% to 33.3% [14,16,17,37]. Environmental factors such as outdoor habits, presence of farm animals that may shed leptospires in the neighborhood, prey habits, or even the season of the year (resulting in different levels of exposure to pathogenic leptospires), can explain the broad ranges of antibody prevalence reported in the literature.…”

“…Except for two cats from Cáceres (titer 1:320), antibody titers of the animals in our study were not ≥1:100. Adler, 2014 [23], reported that infected animals may have MAT titers below 1:100; which is supported by epidemiological studies in cats [13,14,16,39]. Seropositive animals in our study demonstrate previous evidence of contact with Leptospira.…”

“…Clinical presentation of the disease is rare and usually mild in cats [9][10][11][12]. Several studies in different geographical areas have demonstrated that cats have contact with Leptospira since they develop specific antibodies ranging from 4% to 33.3%, with no clear association to clinical disease [13][14][15][16][17]. Urinary shedding of Leptospira DNA has also been documented in cats, with a prevalence ranging up to 67.8% depending on various factors including the geographical area, the presence in the area of farm animals infected with leptospires, and prey habits [7,14,15,[18][19][20][21].…”