Development and validation of a chemiluminescent western blot assay for glanders (Burkholderia mallei) serodetection.

Glanders, caused by Burkholderia mallei, is a zoonotic disease of equids. Serologic testing for glanders is required by disease-free countries before international movement of equids. The World Organisation for Animal Health Terrestrial Manual recommends the complement fixation test (CFT) for clearance of individual animals for movement, but the CFT is prone to false-positive results. A colorimetric western blot (WB) assay was developed and validated to resolve false-positive CFT results; however, that assay is relatively time-consuming, and the interpretation is subjective. We present here a procedurally similar chemiluminescent WB assay that performs comparably to the validated colorimetric WB assay and offers noticeable benefits of decreased time-to-result and greater ease of interpretation.

Bayesian latent-class modelling of quarantine testing procedures for American Bison (Bison bison) in the Greater Yellowstone Area to determine Brucella abortus freedom.

OBJECTIVE: American bison (Bison bison) quarantine protocols were established to prevent transmission of brucellosis outside the Greater Yellowstone Area, while allowing for distribution of wild bison for conservation and cultural purposes. Quarantine standards require rigorous testing over 900 days which has led to the release of over 200 bison to Native American tribes. Standards were evaluated using 15 years of laboratory and management data to minimize the burden of testing and increase the number of brucellosis-free bison available for distribution. ANIMALS: All bison (n = 578) from Yellowstone National Park were corralled by the National Park Service and United States Department of Agriculture. PROCEDURES: A statistical and management evaluation of the bison quarantine program was performed. Bayesian latent-class modeling was used to predict the probability of nondetection of a seroreactor at various time points, as well as the probability of seroconversion by days in quarantine. RESULTS: At 300 days, 1 in 1,000 infected bison (0.0014 probability) would not be detected but could potentially seroconvert; the seroconversion model predicted 99.9% would seroconvert by day 294, and 12.8% of bison enrolled in quarantine would seroconvert over time. Using a 300-day quarantine period, it would take 30 years to potentially miss 1 seroreactor out of over 8,000 bison enrolled in the quarantine program. CLINICAL RELEVANCE: Reducing the quarantine program requirements from over 900 days to 300 days would allow management of quarantined bison in coordination with seasonal movement of bison herds and triple the number of brucellosis-free bison available for distribution.

Disease Progression and Serological Assay Performance in Heritage Breed Pigs following Brucella suis Experimental Challenge as a Model for Naturally Infected Feral Swine.

Invasive feral swine (Sus scrofa) are one of the most important wildlife species for disease surveillance in the United States, serving as a reservoir for various diseases of concern for the health of humans and domestic animals. Brucella suis, the causative agent of swine brucellosis, is one such pathogen carried and transmitted by feral swine. Serology assays are the preferred field diagnostic for B. suis infection, as whole blood can be readily collected and antibodies are highly stable. However, serological assays frequently have lower sensitivity and specificity, and few studies have validated serological assays for B. suis in feral swine. We conducted an experimental infection of Ossabaw Island Hogs (a breed re-domesticated from feral animals) as a disease-free proxy for feral swine to (1) improve understanding of bacterial dissemination and antibody response following B. suis infection and (2) evaluate potential changes in the performance of serological diagnostic assays over the course of infection. Animals were inoculated with B. suis and serially euthanized across a 16-week period, with samples collected at the time of euthanasia. The 8% card agglutination test performed best, whereas the fluorescence polarization assay demonstrated no capacity to differentiate true positive from true negative animals. From a disease surveillance perspective, using the 8% card agglutination test in parallel with either the buffered acidified plate antigen test or the Brucella abortus/suis complement fixation test provided the best performance with the highest probability of a positive assay result. Application of these combinations of diagnostic assays for B. suis surveillance among feral swine would improve understanding of spillover risks at the national level.

Entomological and sociobehavioral components of heartworm (Dirofilaria immitis) infection in two Florida communities with a high or low prevalence of dogs with heartworm infection.

OBJECTIVE To assess knowledge, attitudes, and practices regarding heartworms (Dirofilaria immitis) and mosquito vectors among residents (dog owners and non-dog owners) in 2 neighborhoods in Florida and to perform entomological surveys of mosquito species in these neighborhoods and identify mosquito species infected with heartworm. DESIGN Cross-sectional study. SAMPLE 2,572 mosquitoes and 96 residents of 2 northern Florida communities. PROCEDURES A 32-item questionnaire was orally administered to a convenience sample of community residents to collect information on their knowledge, attitudes, and practices regarding heartworms. Afterward, mosquito larvae were collected from the respondents' properties and adult mosquitoes were collected in both communities from surrounding wooded areas and residences of respondents. Mosquito species distribution and D immitis infection rates were determined. RESULTS Many residents (59% [57/96]) were unaware that mosquitoes transmit heartworms. Compared with non-dog owners, dog owners were significantly more likely to know about mosquito transmission, be concerned about heartworms, accurately estimate cost of treatment, and demonstrate willingness to pay for treatment. Most owners (71% [47/66]) administered heartworm preventives; those who did not cited lack of risk awareness, and cost was the least common reason. Of 28 mosquito species collected, Anopheles quadrimaculatus, Culex erraticus, Culex nigripalpus, Coquillettidia perturbans, Culiseta inornata, Aedes albopictus, and Aedes aegypti were positive for D immitis infection. CONCLUSIONS AND CLINICAL RELEVANCE Findings suggested that improved veterinary and public health messaging regarding the role of mosquitoes as vectors, higher cost of heartworm treatment versus prevention, and mosquito reduction and avoidance methods is needed.