Assessment of seroprevalence and associated risk factors for anaplasmosis in North Carolina, USA, beef and dairy cattle

Objective: Our objective was to determine factors as-so ciated with seroprevalence of bovine anaplasmosis (BA) in North Carolina (NC), USA. Materials and Methods: Data were from 2005 to 2012 North Carolina Veterinary Diagnostic Laboratory System (NCVDLS) records of BA testing (n = 10,518) and from a 2013 and 2015 slaughter survey (n = 195). Results and Discussion: Estimated true period sero-prevalence of BA from NCVDLS was 9.83% (9.19-10.5%). Between May 2011 and March 2012, this estimate was 7.23% (5.25-9.59%) but was 3.92% (1.02-8.52%) from a slaughter survey at a comparable time of year. Cattle type, year, and season were associated with BA. In com-parison with dairy cattle, the odds of seropositivity for BA were 2.7 times greater in beef cattle. When compared with 2007, the odds of seropositivity for BA were 2.08, 2.69, 3.10, and 4.45 times greater, significantly, in 2005, 2009, 2011, and 2012, respectively. Compared with those from July to September, the odds of cattle being seroposi-tive for BA were approximately twice as great each from January to March and from October to December but 1.5 times as high from April to June. Positive BA results from NCVDLS, and slaughter survey data, are predominantly from counties located in the east central and west central parts of NC, respectively. Implications and Applications: The NCVDLS re-cords appear to overestimate seroprevalence of BA in NC compared with an active survey of animals and should be cautiously used for BA surveillance in NC. Prevention and control measures for BA in NC should be statewide and target these identified factors.

Automated summary

The objective of this study was to identify factors associated with the seroprevalence of bovine anaplasmosis (BA) in North Carolina, USA. Analyzing records from the North Carolina Veterinary Diagnostic Laboratory System (NCVDLS) and a slaughter survey, the estimated true seroprevalence of BA was 9.83%, with cattle type, year, and season being associated with BA. The NCVDLS records, compared to the active survey, may overestimate the seroprevalence of BA and should be used cautiously for surveillance in North Carolina.