Cats shedding pathogenic Leptospira spp.-An underestimated zoonotic risk?

Shedding of DNA of pathogenic Leptospira spp. has been documented in naturally infected cats in several countries, but urinary shedding of infectious Leptospira spp. has only recently been proven. The climate in Southern Chile is temperate rainy with high annual precipitations which represents ideal preconditions for survival of Leptospira spp., especially during spring and summer. The aims of this study were to investigate shedding of pathogenic Leptospira spp. in outdoor cats in Southern Chile, to perform molecular characterization of isolates growing in culture, and to assess potential risk factors associated with shedding. Urine samples of 231 outdoor cats from rural and urban areas in southern Chile were collected. Urine samples were investigated for pathogenic Leptospira spp. by 4 techniques: qPCR targeting the lipL32 gene, immunomagnetic separation (IMS)-coupled qPCR (IMS-qPCR), direct culture and IMS-coupled culture. Positive urine cultures were additionally confirmed by PCR. Multilocus sequence typing (MLST) was used to molecularly characterize isolates obtained from positive cultures. Overall, 36 urine samples (15.6%, 95% confidence interval (CI) 11.4-20.9) showed positive results. Eighteen (7.8%, 95% CI 4.9-12.1), 30 (13%, 95% CI 9.2-18), 3 (1.3%, 0.3-3.9) and 4 cats (1.7%; 95% CI 0.5-4.5) were positive in qPCR, IMS-qPCR, conventional culture, and IMS-coupled culture, respectively. MLST results of 7 culture-positive cats revealed sequences that could be assigned to sequence type 17 (6 cats) and sequence type 27 (1 cat) corresponding to L. interrogans (Pathogenic Leptospira Subgroup 1). Shedding of pathogenic Leptospira spp. by cats might be an underestimated source of infection for other species including humans. The present study is the first one reporting growth of leptospires from feline urine in culture in naturally infected cats in South-America and characterisation of culture-derived isolates. So far, very few cases of successful attempts to culture leptospires from naturally infected cats are described worldwide.

Leptospira infection and shedding in cats in Thailand.

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.