Source: UNIVERSITY OF TENNESSEE submitted to
A STUDY TO DETERMINE THE PREVALENCE AND ECONOMIC IMPACT OF ANAPLASMOSIS IN BEEF HERDS IN THE UNITED STATES
Sponsoring Institution
Cooperating Schools of Veterinary Medicine
Project Status
NEW
Funding Source
Reporting Frequency
Annual
Accession No.
0232569
Grant No.
(N/A)
Project No.
TENVWHITLOCK10118
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Sep 10, 2012
Project End Date
Sep 10, 2013
Grant Year
(N/A)
Project Director
Whitlock, B.
Recipient Organization
UNIVERSITY OF TENNESSEE
2621 MORGAN CIR
KNOXVILLE,TN 37996-4540
Performing Department
Large Animal Clinical Sciences
Non Technical Summary
Anaplasmosis, caused by the rickettsial hemoparasite Anaplasma marginale, is the most prevalent tickborne disease of cattle worldwide and a major obstacle to profitable beef production in the U.S. Recent information on the prevalence and economic impact of bovine anaplasmosis in the southern U.S. has not been reported. It is estimated that introduction of anaplasmosis into a previously naive herd can result in a 3.6 percent reduction in calf crop, a 30 percent increase in cull rate and a 30 percent mortality rate in clinically infected adult cattle. Therefore, it is critical for producers to screen for anaplasmosis prior to introducing cattle from an endemic to a non-endemic area provided they know the status of their own herds. The cost of a clinical case of anaplasmosis in the U.S. has been conservatively estimated to be over $400 per animal with the total cost to the beef industry estimated to be over $300 million per year. In the absence of effective vaccines, control of anaplasmosis in the U.S. is predicated on implementation of biosecurity practices and administration of low doses of tetracycline antimicrobials in feed or mineral supplements for several months. Both these control strategies require knowledge of the regional prevalence of anaplasmosis for implementation to be successful. Knowledge of the serological status of a herd and any new introductions is essential for disease control. The goal of this proposal is to determine the prevalence and economic impact of bovine anaplasmosis in the southern U.S. Our first objective is be to determine the between and within herd prevalence of anaplasmosis through direct sampling of cattle and retrospective evaluation of sample submissions to veterinary diagnostic laboratories in the region. Seroprevalence will be determined through the use of a new, more specific, competitive ELISA test that is in the final stages of USDA approval. The new test will be compared with results obtained using the existing cELISA test and a confirmatory RT-PCR test. The second objective is to determine the economic impact of anaplasmosis by surveying AABP membership in the southern U.S. to determine perceptions of the disease and current treatment and control strategies. These objectives will be achieved through the completion of 4 independent specific aims.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
31133991170100%
Knowledge Area
311 - Animal Diseases;

Subject Of Investigation
3399 - Beef cattle, general/other;

Field Of Science
1170 - Epidemiology;
Goals / Objectives
Anaplasmosis, caused by Anaplasma marginale, is associated with significant production losses, abortions and death in cattle. The goal of this proposal is to determine the prevalence and economic impact of bovine anaplasmosis in the southern U.S. so we can develop effective disease control strategies and prioritize future research efforts. The first objective of this study will be to determine the between and within herd prevalence of anaplasmosis through direct sampling of cattle and retrospective evaluation of sample submissions to veterinary diagnostic laboratories in the region. Seroprevalence will be determined through the use of a new, more specific, competitive ELISA test that is in the final stages of USDA approval. The second objective is to determine the economic impact of anaplasmosis by surveying AABP membership in the southern U.S. to determine prevalence of the disease in the southern U.S. as observed by practitioners and current treatment and control strategies used. These objectives will be achieved through the completion of 4 independent specific aims; (1) To determine the between herd seroprevalence of bovine anaplasmosis in cull cows from 10 of 14 southern states consigned to a slaughter plant in Augusta, GA and Rutledge, TN, (2) To determine the number of cases of anaplasmosis diagnosed in veterinary diagnostic laboratories in the southern U.S. over the past 10 years, (3) To survey veterinary practitioner observations of bovine anaplasmosis in the southern U.S., and describe current A. marginale diagnostic, treatment and control strategies implemented in the region, (4) To determine the within herd seroprevalence of bovine anaplasmosis in 6 herds identified as being infected with A. marginale in the southern U.S. The results from Aims 1-4 will enable us to estimate the economic impact of bovine anaplasmosis in the southern U.S. and assist veterinarians in determining appropriate regional diagnostic and control strategies.
Project Methods
We will track cattle back to the consigner to determine regional seroprevalence and ensure samples are not clustered within herd or region. From 165-200 samples from cows originating from 10 of 14 previously listed states will be analyzed using a novel competitive ELISA test currently undergoing USDA approval. Selected duplicate samples will be analyzed using the current cELISA test and a confirmatory RT-PCR assay to provide practitioners with up to date information regarding the most appropriate test to use for anaplasmosis diagnosis. To determine the number of cases of anaplasmosis diagnosed in veterinary diagnostic laboratories in the southern U.S. over the past 10 years, serology and necropsy submissions from 2001 to 2011 will be reviewed. These data will be compared with the seroprevalence information collected to determine if bovine practitioners are underdiagnosing anaplasmosis in this region. We will survey veterinary practitioner observations of bovine anaplasmosis in the southern U.S. and describe current A. marginale diagnostic, treatment and control strategies implemented in the region. A list of survey questions will be compiled to determine demographic information, presence of anaplasmosis in the practice area and the diagnostic, treatment and control strategies implemented by the practitioner. Practitioners will also be asked in the survey if they would be willing to select a herd previously confirmed with at least one case of anaplasmosis and take serological samples for analysis by the research team to determine within herd seroprevalence. Those who say yes will become the population from which practitioners and cattle herds will be selected to determine the within herd seroprevalence of bovine anaplasmosis in southern U.S. Blood samples will be collected and assayed from cows in 6 herds (50 to 150 cows) previously identified as being infected with A. marginale. The herds will be selected based upon the seroprevalence data, review of serology and necropsy submission at accredited diagnostic labs, and practitioner survey. Half the herds selected (3) will be in areas where there is a high regional seroprevalence and the remaining half (3) will be where there is a lower regional seroprevalence. Samples will be analyzed in duplicate using the current and an improved competitive ELISA test. This information is critical in determining if herds in areas of low seroprevalence have lower within-herd prevalence and the areas with high seroprevalence will have higher within herd prevalence. Moreover, this information will help in determining appropriate control strategies in anaplasmosis infected herds. Knowing within herd prevalence will enable us to estimate the number of beef cattle with anaplasmosis in the 14 state region. This will facilitate assessment of the economic significance of bovine anaplasmosis in the southern U.S. and prioritizing future research and educational efforts regarding anaplasmosis in the southern U.S.