Filter-Paper Blood Sampling for Detection of Pathogen Exposure and Pregnancy in Caribou


 
The main goal of this research was to assess the efficacy of filter-paper (FP) blood sampling for detecting pathogen exposure in caribou (Rangifer tarandus ssp.). FP sampling is a practical method that is well-suited to harsh environments and can be done by laypeople. FPs can be collected by hunters, biologists and others in the field, and this initial validation step sets the foundation for future widespread serosurveillance of infectious disease in caribou herds. Throughout International Polar Year (2007-2009), the CARMA network collected FP samples from circumpolar caribou herds for this ultimate purpose. FP samples will also be validated for progesterone (pregnancy) detection in caribou as this tool offers advantages in capture settings and other circumstances. 

 

Validation

 

- Pathogens: From July 2007 through August 2008, pairs of FP and serum samples were collected from individuals in three sample groups: 1) captive reindeer (Rangifer tarandus ssp.) vaccinated for five viral agents of domestic livestock to achieve known antibody-positive (seropositive) status for these agents; 2) an Alberta reindeer herd with known seropositive status for West Nile virus (WNV) and the parasite Neospora caninum; 3) a selected subset of wild caribou herd on Southampton Island, NU with known brucellosis prevalence. All these pathogens are potentially relevant to caribou in the context of climate change

 

- Progesterone: In March 2009, pairs of FP and serum samples were collected from 3 male reindeer and 7 female reindeer (some bred naturally in fall). Duplicate testing will be done at multiple time points up to 1 year, and with FPs subjected to different collection/storage regimes (freezing, room temp).

 

Hunter collecting blood on filter paper PCurry -smaller

 


Collection of blood on filter paper from the jugular vein of a hunter-killed caribou.

 

Filter paper collection Southampton PCurry -smaller

 


Filter paper blood samples from the Southampton Island herd. The samples were dried in racks overnight. (PCurry)

 

Results

 

Pathogens: For all eight pathogens initially investigated, serological testing (detection of antibodies in serum vs. filter paper [FP] samples) was done in duplicate at diagnostic laboratories. Serum and FP data were generated from competitive enzyme-linked immunoassay (c-ELISA) for Brucella, West Nile virus, Neospora caninum; from indirect-ELISA for Brucella, bovine herpesvirus-1, parainfluenza-3 virus, bovine respiratory syncytial virus; and from virus neutralization for bovine viral diarrhea virus types I and II. Quantities of data vary by pathogen. Initial analyses indicate that FP testing is valid (high sensitivity and specificity when FP is compared to serum as the gold standard) for the pathogens and tests noted. Testing continues in order to assess multiple time points (up to a year or longer of storage) and acquire larger sample sizes for some pathogens. A pilot study of collection/storage regimes suggests minimal difference between FP results after frozen storage vs dry storage. A more robust investigation of this is planned.

 

Progesterone: Initial results indicate that progesterone levels detected from Rangifer FPs are different from (higher than) the levels detected in matched serum samples; however, the difference is consistent. Sample size is small and testing is ongoing but results are promising. It appears reasonable that Rangifer-specific cut-offs could be established to identify animals as "pregnant - yes/no."

 

Applications

 

Once validated, filter-paper blood samples collected during International Polar Year and beyond will be used to establish baseline disease "profiles" for circumpolar caribou herds. The filter paper tool will permit widespread serosurveillance of infectious disease in caribou herds by biologists and communities (hunters) across northern regions. Validation for progesterone (pregnancy) detection will meet several needs of caribou biologists/researchers in capture settings and other situations, and could help provide valuable herd-health information.

 

Reports

 

"Expanding the Disease Surveillance Tool Box: Blood-on-Filter-Paper for Detecting Brucella Exposure in Caribou" by P Curry, B Elkin, M Campbell, K Nielsen, W Hutchins, C Ribble, and S Kutz- submitted to J Wildlife Diseases in October 2009

 

Contacts

 

Pat Curry
Graduate Student
Faculty of Veterinary Medicine
University of Calgary
3330 Hospital Dr NW
Calgary, AB, Canada  T2N 4N1
E: pscurry 'at' ucalgary.ca
Tel: 403-210-7862  

 

Susan Kutz
Associate Professor
Faculty of Veterinary Medicine
University of Calgary
3330 Hospital Dr NW
Calgary, AB, Canada  T2N 4N1
E: skutz 'at' ucalgary.ca
Tel: 403-210-7862

 

 

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