Risk factors associated with anthrax outbreak in animals in North Dakota, 2005: a retrospective case-control study.
OBJECTIVE
We identified the risk factors associated with the anthrax outbreak Of 2005 in animals in North Dakota.


METHODS
Medical records of the 2005 anthrax outbreak were obtained from the Veterinary Diagnostic Laboratory at North Dakota State University. Additional data were obtained from the North Dakota state veterinarian's office, and supplemental questionnaires were administered to producers. The data obtained included ecological and environmental factors, animal health factors, and management factors.


RESULTS
Anthrax occurred from July 1 to October 12, 2005. The cases were located in eastern North Dakota around the Red River Basin. Ransom, LaMoure, and Barnes counties reported most cases (71%). Species affected included cattle, bison, horses, sheep, elk, deer, pigs, and llamas. The predominant symptom was sudden death (38%) followed by bleeding from orifices (17%). Chi-square analysis indicated significant differences between case and control premises on the following variables: death reported on neighboring pasture, vaccination period, dry conditions, wet conditions, antibiotic use, multiple vaccination, and type of predator (coyote). Factors that significantly (p<0.05) predicted anthrax occurrences on the final logistic regression model were vaccination, use of antibiotics during an outbreak, and period of vaccine administration (before or during the outbreak).


CONCLUSIONS
The characteristics of the anthrax outbreak regarding time and place of occurrence, animals affected, clinical signs reported, and mortality rate were consistent with previous reports of natural anthrax outbreaks in animals. A number of factors that significantly predicted anthrax occurrence in animals in the 2005 outbreak in North Dakota were identified. This information is important in planning appropriate control and prevention measures for anthrax, including recommending the right vaccination and treatment regimens in managing future anthrax outbreaks.
Mongoh
Mafany Ndiva
MN
School of Natural Resources, College of Agriculture, North Dakota State University, Fargo, ND 58105-5406, USA.
Dyer
Neil W
NW
Stoltenow
Charles L
CL
Khaitsa
Margaret L
ML
D000820:Animal Diseases / Q000453:epidemiology* / Q000382:microbiology* / Q000517:prevention & control; D000818:Animals; D000881:Anthrax / Q000453:epidemiology* / Q000517:prevention & control / Q000662:veterinary*; D022122:Anthrax Vaccines / Q000008:administration & dosage; D000900:Anti-Bacterial Agents / Q000008:administration & dosage; D001408:Bacillus anthracis / Q000302:isolation & purification; D016009:Chi-Square Distribution; D004196:Disease Outbreaks / Q000517:prevention & control* / Q000662:veterinary*; D017753:Ecosystem; D040362:Geographic Information Systems; D006736:Horses; D009658:North Dakota / Q000453:epidemiology; D016133:Polymerase Chain Reaction; D011634:Public Health / Q000379:methods*; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012418:Ruminants; D018571:Sentinel Surveillance; D013552:Swine; D014730:Veterinary Medicine / Q000379:methods*
D022122:Anthrax Vaccines; D000900:Anti-Bacterial Agents