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Highlights • We conducted retrospective testing of clinical samples submitted to veterinary diagnostic laboratories for porcine deltacoronavirus. • Over 2000 samples were tested over three separate years with 3 positive samples detected prior to the PDCoV outbreak detection in February 2014. • We surveyed 42 early infected swine farms to determine various farm level characteristics, descriptive estimates of biosecurity practices and disease status over time of each operation. • Clinical signs of PDCoV were reported to be similar to those of PEDv. The average number of animals on each operation exhibiting clinical signs (morbidity) and the average number of case fatalities was greatest for suckling and weaned pigs. • The survey included questions regarding biosecurity practices for visitors and operation employees; trucks, equipment and drivers; and feed sources. These questions attempted to identify a likely pathway of introduction of PDCoV onto the operations surveyed., Porcine deltacoronavirus (PDCoV) was first reported in the United States (US) in February 2014. This was the second novel swine enteric coronavirus detected in the US since May 2013. In this study, we conducted retrospective testing of samples submitted to three veterinary diagnostic laboratories where qualifying biological samples were derived from previously submitted diagnostic case submissions from US commercial swine farms with a clinical history of enteric disease or from cases that had been previously tested for transmissible gastroenteritis virus, PEDV, or rotavirus. Overall, 2286 banked samples were tested from 27 States. Samples were collected in 3 separate years and in 17 different months. Test results revealed 4 positive samples, 3 collected in August 2013 and 1 collected in October 2013. In addition, a case series including 42 operations in 10 States was conducted through administration of a survey. Survey data collected included information on characteristics of swine operations that had experienced PDCoV clinical signs. Special emphasis was placed on obtaining descriptive estimates of biosecurity practices and disease status over time of each operation. Clinical signs of PDCoV were reported to be similar to those of PEDV. The average number of animals on each operation exhibiting clinical signs (morbidity) and the average number of case fatalities was greatest for suckling and weaned pigs. Average operation-level weaned pig morbidity was greatest in the first week of the outbreak while average operation-level suckling pig case fatality was greatest in the second week of the outbreak. The survey included questions regarding biosecurity practices for visitors and operation employees; trucks, equipment and drivers; and feed sources. These questions attempted to identify a likely pathway of introduction of PDCoV onto the operations surveyed.

The reporting and monitoring of swine enteric coronavirus diseases (SECD), including porcine epidemic diarrhea virus and porcine delta coronavirus, in the United States have been challenging because of the initial absence of a regulatory framework and the emerging nature of these diseases. The National Animal Health Laboratory Network, the Emergency Management and Response System, and the Swine Health Monitoring Project were used to monitor the disease situation between May 2013 and March 2015. Important differences existed between and among them in terms of nature and extent of reporting. Here, we assess the implementation of these systems from different perspectives, including a description and comparison of collected data, disease metrics, usefulness, simplicity, flexibility, acceptability, representativeness, timeliness, and stability. This assessment demonstrates the limitations that the absence of premises identification imposes on certain animal health surveillance and response databases, and the importance of federally regulated frameworks in collecting accurate information in a timely manner. This study also demonstrates the value that the voluntary and producer-organized systems may have in monitoring emerging diseases. The results from all three data sources help to establish the baseline information on SECD epidemiological dynamics after almost 3 years of disease occurrence in the country.

The objectives of this study were to determine the distribution of Mycobacterium avium subspecies paratuberculosis (MAP) in the environment and assess the relationship between the culture status of MAP in the farm environment and herd infection status. The National Animal Health Monitoring System's Dairy 2002 study surveyed dairy operations in 21 states. One component of the study involved collection and culturing of environmental samples for MAP from areas on farms where manure accumulated from a majority of a herd's cows. Operations were selected for inclusion based on perceived risk factors for MAP infection identified in a previously administered questionnaire. Individual animal and environmental samples were collected and used to determine the efficiency of environmental sampling for determination of herd infection status. Individual animal fecal, serum, and milk samples were used to classify herds as infected or not infected based on the presence of at least one test-positive animal in the herd. A total of 483 environmental samples (approximately 5 per farm) were collected, and 218 (45.1%) were culture-positive for MAP. A similar percentage of environmental cultures collected from all designated areas were positive [parlor exits (52.3%), floors of holding pens (49.1%), common alleyways (48.8%), lagoons (47.4%), manure spreaders (42.3%), and manure pits (41.5%)]. Of the 98 operations tested with the environmental sample culture, 97 had individual serum ELISA results, 60 had individual fecal culture results, and 34 had individual milk ELISA results. Sixty-nine of the 98 operations (70.4%) had at least one environmental sample that was culture-positive. Of the 50 herds classified as infected by fecal culture, 38 (76.0%) were identified by environmental culture. Two of the 10 operations classified as not infected based on individual animal fecal culture were environmental culture-positive. Of the 80 operations classified as infected based on serum ELISA-positive results, 61 (76.3%) were identified as environmental-positive, whereas 20 of the 28 (71.4%) operations identified as infected based on milk ELISA were detected by environmental sampling. Environmental sample culturing is less costly than individual animal sampling, does not require animal restraint, and identified more than 70% of infected operations. Environmental sampling is another diagnostic tool that veterinarians and dairy producers can use to determine herd infection status for MAP.

Five laboratories participated in a study to evaluate sources of variation in results from an enzyme-linked immunosorbent assay (ELISA) for antibodies against Mycobacterium avium subsp. paratuberculosis. Each laboratory repeatedly tested duplicates of a negative, positive (P), and high-positive (HP) serum sample, which were supplied by the United States Department of Agriculture: Animal and Plant Health Inspection Service: Veterinary Services, National Veterinary Services Laboratories, Ames, IA, on all 96-well microtiter plates when routinely testing other samples for M. avium subsp. paratuberculosis antibodies. These 3 sera were aliquoted and sent to the 5 participating laboratories. This study focused on variation in test results because of assay reagents and laboratory techniques and did not account for biologic variability associated with the time course of infection in cattle. Overall, results from 868 microtiter plates were used in the study. For each sample a sample-to-positive (S/P) ratio was calculated according to the manufacturer's directions. The S/P ratio for the P sample ranged from 0.06 to 1.039 (mean = 0.466 and 0.484 for wells 1 and 2, respectively) and those for the HP sample ranged from 2.446 to 8.727 (mean = 4.027 and 3.980 for wells 1 and 2, respectively). The majority of the variation in S/P ratio for the P sample was attributed to kit lot (37.5%), followed by random (unexplained) error (27.0%), laboratory (18.3%), and kit lot by laboratory (11.9%). By eliminating plates in which the separation between negative and positive control ODs was less than 0.4, the proportion of variation attributed to laboratory was reduced markedly. These results confirm that there is variability in M. avium subsp. paratuberculosis ELISA results and that several sources contribute to the observed variability. The study gives a relative estimate of the contribution of various sources to the overall variability observed in the M. avium subsp. paratuberculosis ELISA results with kit lot being a primary contributor. Similar data for other ELISA tests for antibodies to M. avium subsp. paratuberculosis or other antigens also should be developed.

Objective—To report clinical and serologic findings in horses with oral vesicular lesions that were consistent with vesicular stomatitis (VS) but apparently were not associated with VS virus (VSV) infection. Design—Serial case study. Animals—8 horses. Procedure—Horses were quarantined after appearance of oral lesions typical of VS. Severity of clinical signs was scored every 2 to 5 days for 3 months. Serum samples were tested for antibodies by use of competitive ELISA (cELISA), capture ELISA for IgM, serum neutralization, and complement fixation (CF). Virus isolation was attempted from swab specimens of active lesions. Results—2 horses with oral vesicular lesions on day 1 had antibodies (cELISA and CF) against VSV; however, results of CF were negative by day 19. Five of the 6 remaining horses were seronegative but developed oral lesions by day 23. Virus isolation was unsuccessful for all horses. Conclusion and Clinical Relevance—Horses were quarantined for 75 days in compliance with state and federal regulations. However, evidence suggests that oral lesions were apparently not associated with VSV infection. The occurrence in livestock of a vesicular disease that is not caused by VSV could confound efforts to improve control of VS in the United States and could impact foreign trade.Vesicular stomatitis is of substantial economic and regulatory concern. (J Am Vet Med Assoc 2000;216:1399–1404)

Vesicular stomatitis is a viral disease primarily affecting horses and cattle when it occurs in the United States. Outbreaks in the southwestern United States occur sporadically, with initial cases typically occurring in Texas, New Mexico, or Arizona and subsequent cases occurring in a northward progression. The viruses causing vesicular stomatitis can be transmitted by direct contact of lesioned animals with other susceptible animals, but transmission is primarily through arthropod vectors. In 2012, an outbreak of vesicular stomatitis in the United States occurred that was caused by Vesicular stomatitis New Jersey virus serotype. Overall, 51 horses on 36 premises in 2 states were confirmed positive. Phylogenetic analysis of the virus indicated that it was most closely related to viruses detected in the state of Veracruz, Mexico, in 2000.

A competitive enzyme-linked immunosorbent assay (C-ELISA) for the detection of antibodies against vesicular stomatitis virus New Jersey (VSV-NJ) and vesicular stomatitis virus Indiana (VSV-IN) was compared with the serum neutralization test (SNT) using 1,106 serum samples obtained from dairy cattle on sentinel study farms in the Poa´s region of Costa Rica. Kappa coefficients between the C-ELISA and the SNT were 0.8871 (95% confidence interval [CI]: 0.8587–0.9155) and 0.6912 (95% CI: 0.6246–0.7577) for the VSV-NJ and VSV-IN tests, respectively. These results indicate good to excellent agreement between the 2 tests under these conditions. Ensayo inmunoabsorbente ligado a enzimas competitivo (C-ELISA) para la detección de anticuerpos contra El virus de la estomatitis vesicular de Nueva Jersey (VSV-NJ) y el virus de la estomatitis vesicular de Indiana (VSV-IN) se compararon con la prueba de seroneutralización (SNT) utilizando 1106 muestras de suero obtenidas de ganado lechero en granjas de estudio centinela en la región del Poa de Costa Rica. Los coeficientes Kappa entre el C-ELISA y el SNT fueron 0,8871 (95% intervalo de confianza [IC]: 0,8587–0,9155) y 0,6912 (IC 95 %: 0,6246–0,7577) para las pruebas VSV-NJ y VSV-IN, respectivamente. Estos resultados indican una concordancia de buena a excelente entre las 2 pruebas en estas condiciones. Universidad Nacional, Costa Rica Escuela de Medicina Veterinaria

Milk and serum samples from 35 dairy herds in 17 states were evaluated for cow- and herd-level Mycobacterium avium subspecies paratuberculosis (MAP) antibody test agreement. Evaluation of 6,349 samples suggested moderate agreement between milk and serum enzyme-linked immunosorbent assay (ELISA) results, with a kappa value of 0.50. Cow-level sensitivity (Se) for 18 dairy operations with 1,921 animals was evaluated relative to fecal culture results. At the cow level, the milk ELISA relative Se was not significantly different from that of the serum ELISA (21.2 and 23.5%, respectively). Logistic regression models revealed a positive association between lactation number and milk ELISA status. Non-Holstein cows were more likely to test milk ELISA positive than Holstein cows. Cows in the first 2 weeks of lactation and after week 45 of lactation were more likely to test milk ELISA positive than cows between 3 and 12 weeks of lactation. Milk production > 80% of herd average was negatively associated with testing milk ELISA positive. Animals in the West and Midwest regions were less likely than animals in the Southeast region to test ELISA positive by either test. Estimates for herd-level sensitivity for the milk and serum ELISA, relative to fecal culture results, ranged from 56 to 83%. At the cow and herd levels, milk ELISA performed equivalent to serum ELISA using fecal culture as a reference for MAP infection and has the advantage of decreased labor costs on farms that use Dairy Herd Improvement Association testing.

The use of sentinel chickens in establishing the negative status of commercial poultry flocks depopulated due to exotic Newcastle disease (END) is considered to be an economically beneficial process. However, the costs and benefits of using sentinel chickens in noncommercial operations are in question. The objective of this study was to use sentinel chickens to evaluate whether adequate cleaning and disinfection coupled with an appropriate time period without susceptible poultry species on the premises would eliminate END virus from a noncommercial poultry operation and preclude the need for placement of sentinels in previously infected operations before declaring them free of virus. Noncommercial poultry operations were selected from the 2002 to 2003 END outbreak database. Operations included in the study had one or more isolations of END virus (ENDV) from cloacal or oropharyngeal swabs of birds on the premises. A total of 546 birds were placed on 53 premises. All sentinel birds sampled after placements were negative by virus detection methods and serologic tests. Results of this study indicate that time and the application of appropriate cleaning and disinfection procedures will adequately mitigate the risk of viable virus persisting in noncommercial poultry operations. In the future, this information may eliminate the need for sentinel bird placement to ensure virus free status of premises before repopulation, thereby decreasing the costs of END eradication.

Objective—To determine effects on production and risk of removal related to Mycobacterium avium subsp paratuberculosis (MAP) infection at the individual animal level in dairy cattle. Design—Longitudinal study. Animals—7,879 dairy cows from 38 herds in 16 states. Procedure—A subset of dairy cattle operations that participated in the National Animal Health Monitoring System Dairy 2002 study was evaluated via a serum ELISA for antibodies against MAP and categorized according to ELISA score. Dairy Herd Improvement Association records were obtained to collect current and historical lactation data and removal (ie, culling) information. Production variables were evaluated on the basis of serum ELISA category. Results—Cows with strong positive results had mature equivalent (ME) 305-day milk production, ME 305-day maximum milk production, and total lifetime milk production that were significantly lower than cows in other categories. No differences were observed for ME 305-day fat and protein percentages, age, lactation, and lactation mean linear somatic cell count score between cows with strong positive results and those with negative results. After accounting for lactation number and relative herd-level milk production, cows with strong positive results were significantly more likely to have been removed by 1 year after testing. Conclusions and Clinical Relevance—Without management changes designed to reduce the farm-level prevalence of MAP infection, paratuberculosis will continue to reduce farm income by decreasing milk production and potentially increasing premature removal from the herd. (J Am Vet Med Assoc 2005;227:1975–1981)

Objective—To determine risk factors associated with hemorrhagic bowel syndrome (HBS) among dairy cattle in the United States and identify characteristics of HBS in individual cows.Design—Cross-sectional, population-based survey.Sample Population—A stratified random sample of 1,013 dairy operations with ≥ 30 cows located in 21 states.Procedure—Information on management and animal health-related topics was collected with a questionnaire.Results—HBS was estimated to have been observed on 9.1% of operations during the preceding 5 years and on 5.1% of operations during the preceding 12 months. Factors found in multivariable analysis to be associated with the occurrence of HBS during the preceding 12 months were large herd size, administration of bovine somatotropin, and routine use of milk urea nitrogen concentration to determine ration composition. Use of pasture as part of the lactating cow ration during the growing season was associated with decreased odds of HBS in operations with rolling herd average milk production ≤ 20,000 lb, whereas in operations with higher milk production, use of pasture was not associated with occurrence of HBS. For individual cows with signs consistent with HBS, the third lactation was the median of the parity distribution and the median time between parturition and the onset of clinical signs was 104 days.Conclusions and Clinical Relevance—Results suggest that management practices implemented to achieve high milk production may increase the risk of developing HBS in dairy cattle. Increased consumption of a high-energy diet seems to be the most plausible common pathway for all of the risk factors that have been described. (J Am Vet Med Assoc2005;226:1700–1706)

A multiplex single-tube reverse transcription—polymerase chain reaction (RT-PCR) has been developed for the detection and differentiation of vesicular stomatitis viruses (VSV), Indiana 1 and New Jersey, from insect samples. Using this assay, detection of either or both viruses in as little as 20 fg of total RNA from tissue culture was achieved, along with detection of vesicular stomatitis (VS) RNA from macerates containing 2 infected mosquitoes in pools of 10—30 noninfected mosquitoes. Vesicular stomatitis virus was detected by RT-PCR in all culture-positive samples, and detection as low as 4 plaque forming units per milliliter was achieved. Comparison between RT-PCR and tissue culture revealed that RT-PCR was able to detect VSV in a volume of insect macerate averaging almost 100 times less than that required for detection by tissue culture. The reported RT-PCR is a potential valuable tool for rapid and sensitive detection and differentiation of VS in insects because intense work associated with viral isolation, the cytotoxicity of insect extracts, and separate virus identification steps can be avoided. Potential application to detection and differentiation of VSV serotypes from vertebrate hosts is addressed.

Ground beef has been implicated in most outbreaks of Shiga-toxin-producing Escherichia coli O157 infections in humans.1–3 No outbreaks of infection with this organism have been linked to lamb; however, ruminants such as sheep may contribute to transmission of this organism to humans. Shiga-toxin-producing E. coli (STEC) have been reported to be more prevalent in sheep and goats than in cattle and have been isolated from several retail meats, including lamb.4,5 Sheep can be colonized by E. coli O157 experimentally and through natural exposure, and this serotype has been isolated from retail lamb in the United States.6–8 Here, we describe a pilot study conducted to determine the prevalence of E. coli O157 and other STEC serotypes in market lambs just prior to slaughter and to evaluate specific factors that may be associated with a higher or lower prevalence of E. coli O157 in lambs at slaughter. Lambs were sampled at a slaughter facility that processed lambs only located in the midwestern United States. All samples were collected over 3 days in October 1995. Sixty lambs were sampled from lots that exceeded 100 lambs; otherwise, 30 lambs were sampled per lot. Each lot was categorized by source (single farm flock vs. commercial feedlot), distance shipped, and elapsed time from farm to slaughter. Fecal samples were collected by rectal extraction of fecal pellets or, if feces were not in pellet form, by rectal swab with a cotton-tipped swab. For detection of E. coli O157, a single fecal pellet or fecal swab was placed in a culture tube containing 3 ml of tryptic soy brotha to which had been added 40 mg/ml vancomycinb and 50 ng/ml cefiximec (TSBcv). From every 10 lamb in order of sampling, a larger volume of feces was obtained with a gloved hand for culture of 10 g of feces (in addition to the pellet or swab cultures on the same lambs). The larger samples were placed into a polypropylene tube containing 20 ml of TSBcv to which was also added 2.5 mg/ml potassium tellurited (TSBcvt). From each of the same systematically selected lambs, a single fecal pellet was placed into a culture tube containing 10 ml of EC broth containing 20 mg/ml of novobiocind (ECBn). Samples in ECBn were used to determine the presence of STEC