Rodent leptospirosis in Colorado

Area of Science:

• Veterinary Medicine
• Infectious Diseases
• Wildlife Ecology

Background:

• Leptospirosis is a zoonotic disease caused by pathogenic Leptospira bacteria.
• Rodents are known reservoirs for various Leptospira serotypes.
• Understanding leptospirosis in wildlife populations is crucial for public health and ecological management.

Purpose of the Study:

• To investigate the prevalence and serotypes of Leptospira in brown rats, muskrats, and mice in southeastern Larimer County, Colorado.
• To determine the infection rates and identify specific Leptospira serotypes circulating in these rodent populations.

Main Methods:

• Isolation of Leptospira from rodent kidney tissues.
• Serological testing (e.g., microscopic agglutination test) to detect antibodies against Leptospira serotypes.
• Histological examination of kidney tissues for the presence of leptospires.

Main Results:

• Leptospira serotype icterohaemorrhagiae was isolated from 9.8% (14/143) of feral brown rats (Rattus norvegicus).
• Serological evidence of L. icterohaemorrhagiae infection was found in 66.4% of brown rats.
• Serological evidence of L. serotype ballum infection was detected in 3/17 muskrats (Ondatra zibethicus).
• Leptospires were observed in kidney tissue of 2/61 feral mice (Mus musculus), but no isolations or serology were performed on mice.

Conclusions:

• Brown rats in southeastern Larimer County, Colorado, are significant hosts for Leptospira serotype icterohaemorrhagiae.
• The study highlights the potential role of brown rats, muskrats, and mice as reservoirs for leptospirosis in this region.
• Further research is recommended to fully assess leptospiral infection in mice populations.