Detection of Neorickettsia risticii from various freshwater snail species collected from a district irrigation canal in Nevada County, California.

The research article focuses on establishing the role of an irrigation canal in Nevada County, California as key in spreading the infection of Neorickettsia risticii, which causes equine neorickettsiosis. Through testing snails and horse feces they found a homology between the snail and horse isolates of N. risticii, suggesting the canal is the likely source of the infection.

Research Objectives and Methodology

• The main goal of the research was to investigate if the irrigation canal in Nevada County, California was the source of Neorickettsia risticii infection, which is responsible for equine neorickettsiosis (EN).
• The researchers gathered a total of 568 freshwater snails from different species along with feces from three horses that were already infected with EN.
• The collected samples were submitted to real-time PCR testing to detect the presence of N. risticii.

Results and Findings

• Among the freshwater snails collected for the study, four tested positive for N. risticii through PCR.
• The snail species found positive included species of Juga, Planorbella subcrenata (Rough Rams-horn), and Physella virgata (Protean Physa).
• Further, a phylogenetic analysis was done to evaluate the homology between the N. risticii isolates from different snails and horses.
• It showed a 99.8-100% homology between the snail and horse isolates of N. risticii. This indicated that the N. risticii found in different species were virtually identical.

Conclusions

• From the results of the study, it can be concluded that the irrigation canal in Nevada County, California serves as the pathway for the spread of N. risticii, leading to EN in horses.
• This study is the first to report the infection with N. risticii in Planorbella subcrenata.
• The findings of this study suggest a need for further exploration and potential mitigation plans to address the spread of N. risticii, thus preventing future EN outbreaks.