Effect of season and geographic location in the United States on detection of potential enteric pathogens or toxin genes in horses ≥6-mo-old

Abstract

We investigated the effects of season and geographic location on detection of nucleic acids of potential enteric pathogens (PEPs) or their toxins (PEP-Ts) in feces of horses ≥6-mo-old in the United States. Results of 3,343 equine diarrhea PCR panels submitted to Idexx Laboratories for horses >6-mo-old were reviewed. Submission months were grouped into 4 seasons, and states were grouped into 4 geographic regions. Logistic regression was performed to assess effects of season and region on detection rates of PEPs and PEP-Ts. Agresti–Coull CIs were determined. Detection rate of Salmonella enterica was higher in the South in summer compared to all other regions, and was also higher in the South in fall compared to the Midwest and Northeast. The Neorickettsia risticii detection rate was lower during summer in the West and higher in fall in the Midwest. Detection of Cryptosporidium spp. was lower during spring, summer, and winter in the West. Differences were not identified for detection rates of Clostridioides difficile, Clostridium perfringens, Lawsonia intracellularis, Rhodococcus equi, equine rotavirus, and equine coronavirus. Overall, our data support seasonal and regional differences in detection rates of S. enterica, N. risticii, and Cryptosporidium spp. in horses ≥6-mo-old in the United States.

Diagnostic approaches, aetiological agents and their associations with short‐term survival and laminitis in horses with acute diarrhoea admitted to referral institutions

“…12,14 Detection of DNA of N. risticii in faecal or blood samples is recommended for the diagnosis of Neorickettiosis (Potomac horse fever). 6 In our study, the level of agreement between blood and faecal PCR assays for detection of DNA of N. risticii was excellent. Although this finding could indicate that either sample can be submitted for DNA detection of N. risticii, a difference in the time and duration of molecular detection of N. risticii in blood versus faecal samples has been demonstrated in experimentally infected horses with blood samples testing positive earlier than faeces.…”

“…This is in agreement with previous reports. 6 Although the culture of five consecutive faecal samples remains the standard protocol for clinical diagnosis of equine salmonellosis, the submission of faecal samples serially collected for culture was highly variable among institutions.…”

“…1,3 The prevalence of sand accumulation and of each pathogen associated with acute diarrhoea in horses appears to vary by institution, season, geographical location, and population studied. [4][5][6][7][8][9] There is currently little information available regarding the differences in pathogen detection beyond single centre studies 4,5,[9][10][11][12] or multicentre studies from a single country. 7 A single study reported pathogen detection from diagnostic laboratories receiving specimens from a wider region without precise information on the health status of the horses.…”

Relationship between the Cycle Threshold Value (Ct) of a Salmonella spp. qPCR Performed on Feces and Clinical Signs and Outcome in Horses

“…Even in studies using PCR and targeting samples from horses with gastrointestinal problems, the reported Salmonella shedding rates vary greatly, between 2 to 68% [ 39 , 46 , 52 , 53 , 54 , 55 , 56 ]. The rate of positive samples obtained in this study is rather high compared with most of the previous studies using PCR.…”

Survival rates and factors associated with survival and laminitis of horses with acute diarrhoea admitted to referral institutions

“…in the summer and fall in the South of the USA and higher detection of N. risticii in the fall in the Midwest of the USA. 4,11,20,21 In contrast, acute larval cyathostomins, an important cause of acute diarrhoea in many European countries, 22,23 usually develop in late winter to early spring and could explain the numerically high percentage of cases seen in winter. 22,24,25 The age and breed distribution reported here was comparable to previous reports and is likely representative of the general population of the contributing institutions.…”