Association of fecal shedding of mycobacteria with high ELISA-determined seroprevalence for paratuberculosis in beef herds.
OBJECTIVE
To evaluate the seroprevalence of paratuberculosis by use of 2 commercial ELISAs in association with prevalence of fecal shedding of mycobacteria within beef cattle herds.


METHODS
Cross-sectional field study.


METHODS
Six beef herds (affected herds; 522 cattle) with and 3 geographically matched herds (181 cattle) without high seroprevalence of paratuberculosis.


METHODS
Blood and fecal samples were collected from adult cattle and assessed for serum anti-Mycobacterium avium subsp paratuberculosis (MAP) antibodies with 2 commercial ELISA kits and submitted for bacterial culture for MAP and environmental bacteria (termed environmental mycobacteria) via a radiometric method, respectively. Species of mycobacterial isolates were identified, and sensitivities and specificities of the 2 ELISAs were compared.


RESULTS
Compared with comparison cattle, cattle from affected herds were 9.4 times as likely to have environmental mycobacteria isolated from feces. Among the 6 affected and 3 comparison herds, the proportions of cattle shedding environmental mycobacteria were 0.225 (range, 0.1 to 0.72) and 0.04 (range, 0 to 0.06), respectively. Although relative MAP- detection specificities (compared with bacterial culture of feces) were different between the 2 ELISAs, sensitivities were not. Nine environmental mycobacterial species were identified from participating herds. All affected herds apparently had > or = 1 bovid infected with MAP, although MAP was not isolated from any cattle in comparison herds.


CONCLUSIONS
In beef herds with persistently high rates of false- positive ELISA results, which may be associated with recovery of environmental myco- bacteria from feces, organism detection via bacterial culture of feces or PCR assay should direct paratuberculosis control measures.
Roussel
Allen J
AJ
Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA.
Fosgate
Geoffrey T
GT
Manning
Elizabeth J B
EJ
Collins
Michael T
MT
D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000662:veterinary*; D005189:False Positive Reactions; D005243:Feces / Q000382:microbiology*; D005260:Female; D008297:Male; D016927:Mycobacterium avium subsp. paratuberculosis / Q000276:immunology / Q000302:isolation & purification; D010283:Paratuberculosis / Q000175:diagnosis / Q000453:epidemiology*; D012680:Sensitivity and Specificity; D016036:Seroepidemiologic Studies
D000907:Antibodies, Bacterial