Leptospirosis in rodents from an arid environment

Area of Science:

• Veterinary Microbiology
• Zoonotic Disease Epidemiology
• Rodent-borne Pathogen Surveillance

Background:

• Leptospirosis is a significant zoonotic disease with rodents as a primary reservoir.
• Understanding Leptospira prevalence in different rodent populations is crucial for public health and animal health.
• Previous studies have highlighted the role of rodents in the transmission cycle of Leptospira.

Purpose of the Study:

• To investigate the prevalence and distribution of Leptospira in rodents from diverse habitats in Arizona.
• To identify specific Leptospira serovars circulating in rodent populations.
• To assess the diagnostic utility of serological methods versus direct isolation for detecting leptospiral infection in rodents.

Main Methods:

• Rodents (n=358) were trapped from six distinct locations in Arizona, encompassing dairies, swine operations, and areas with limited domestic animal access.
• Kidney tissues were examined for Leptospira using silver staining, and bacterial isolation was attempted.
• Serological testing was performed to detect antibodies against various Leptospira serovars.

Main Results:

• Leptospira interrogans serovar ballum was isolated from three house mice (Mus musculus) captured at dairy premises.
• Leptospira organisms were detected in kidney sections of 10.4% of the examined rodents.
• Microscopic kidney lesions were observed in nearly 60% of rodents, with 59% of those showing positive Leptospira detection also exhibiting these lesions.
• High serological titers (≥1:160) were observed for multiple serovars, including autumnalis, ballum, bratislava, canicola, grippotyphosa, hardjo, icterohaemorrhagiae, and pomona.

Conclusions:

• House mice on Arizona dairies can harbor Leptospira interrogans serovar ballum.
• The presence of Leptospira correlates with renal microscopic lesions in rodents.
• The effectiveness of serological data for diagnosing leptospiral infection in these rodent populations was inconclusive due to low isolation rates.