Epidemiological Assessment of African Swine Fever Spread in the Dominican Republic.

Since African Swine Fever (ASF) was detected in the Dominican Republic in July 2021, it has negatively impacted the country's swine industry. Assessing the epidemiological situation is crucial to helping local authorities and industry stakeholders control the disease. Here, data on 155 reported outbreaks in the Dominican Republic from November 2022 to June 2023 were evaluated. Descriptive spatiotemporal analysis was performed to characterize disease distribution and spread, and between-herd R0 was calculated for the study period. The Knox test and a space-time permutation model were used to evaluate clustering. Data on clinical presentation, biosecurity measures, and suspected reasons for introduction were categorized and summarized. The majority (78%) of outbreaks occurred on backyard farms which generally had low biosecurity. Across farm types, the majority of pigs were still alive at the time of depopulation. Spatiotemporal findings and R0 estimates suggest an endemic pattern of disease geographically located centrally within the country. Clustering was detected even at small temporal and spatial distances due to outbreaks amongst neighboring backyard farms. These results provide critical information on the current state of the ASF epidemic in the Dominican Republic and will aid government officials and swine industry leaders in developing effective ASF control strategies.

Assessing the value of PCR assays in oral fluid samples for detecting African swine fever, classical swine fever, and foot-and-mouth disease in U.S. swine.

INTRODUCTION: Oral fluid sampling and testing offers a convenient, unobtrusive mechanism for evaluating the health status of swine, especially grower and finisher swine. This assessment evaluates the potential testing of oral fluid samples with real-time reverse-transcriptase polymerase chain reaction (rRT-PCR) to detect African swine fever, classical swine fever, or foot-and-mouth disease for surveillance during a disease outbreak and early detection in a disease-free setting. METHODS: We used a series of logical arguments, informed assumptions, and a range of parameter values from literature and industry practices to examine the cost and value of information provided by oral fluid sampling and rRT-PCR testing for the swine foreign animal disease surveillance objectives outlined above. RESULTS: Based on the evaluation, oral fluid testing demonstrated value for both settings evaluated. The greatest value was in an outbreak scenario, where using oral fluids would minimize disruption of animal and farm activities, reduce sample sizes by 23%-40%, and decrease resource requirements relative to current individual animal sampling plans. For an early detection system, sampling every 3 days met the designed prevalence detection threshold with 0.95 probability, but was quite costly. LIMITATIONS: Implementation of oral fluid testing for African swine fever, classical swine fever, or foot-and-mouth disease surveillance is not yet possible due to several limitations and information gaps. The gaps include validation of PCR diagnostic protocols and kits for African swine fever, classical swine fever, or foot-and-mouth disease on swine oral fluid samples; minimal information on test performance in a field setting; detection windows with low virulence strains of some foreign animal disease viruses; and the need for confirmatory testing protocol development.

Factors Associated with Highly Pathogenic Avian Influenza H5N2 Infection on Table-Egg Layer Farms in the Midwestern United States, 2015.

A case-control study was conducted among commercial table-egg layer and pullet operations in Iowa and Nebraska, United States, to investigate potential risk factors for infection with highly pathogenic avian influenza (HPAI) H5N2. A questionnaire was developed and administered to 28 case farms and 31 control farms. Data were collected at the farm and barn levels, enabling two separate analyses to be performed-the first a farm-level comparison of case farms vs. control farms, and the second a barn-level comparison between case barns on case farms and control barns on control farms. Multivariable logistic regression models were fit using a forward-selection procedure. Key risk factors identified were farm location in an existing control zone, rendering and garbage trucks coming near barns, dead-bird disposal located near barns, and visits by a company service person. Variables associated with a decreased risk of infection included visitors changing clothing, cleaning and disinfecting a hard-surface barn entryway, and ceiling/eaves ventilation in barns.

Analysis of the diagnostic accuracy of the gamma interferon assay for detection of bovine tuberculosis in U.S. herds.

The goal of this study was to evaluate the test sensitivity (SE) and specificity (SP) of the gamma interferon (G-IFN) assay used for the detection of bovine tuberculosis (bTB) in U.S. cattle herds. In addition, the study assessed the association between G-IFN test results and bTB status of cattle, and explored different cut off values for classification of test results in adult cattle using receiver operating characteristics (ROC) curve analysis. Test SE was estimated using a population of 87 confirmed infected cattle from 14 herds distributed in 6 states. Test SP was estimated using a population of 4123 cattle representing 3000 premises in 3 states. These animals were from bTB free areas, accredited bTB free herds, or herds that were historically bTB free based on the absence of lesions found at slaughter and historical records of negative tests performed for bTB surveillance. The distribution of G-IFN results and its association with bTB infection status was also explored in a group of 914 exposed cattle in which infection was not confirmed. The results showed that the SE of the G-IFN for a cut-off value ≥0.1 was 83.9% (76.1, 91.6). The SP of the G-IFN was 90.7% (95% CI: 89.8, 91.6), 97% (95% CI: 96.5, 97.5), and 98.6%(95% CI: 98.2, 98.9), for cut off values of 0.1, 0.3, and 0.5, respectively. For a cut off value ≥0.1, the likelihood ratio of a positive G-IFN test was 9.03 (95% CI: 7.90, 10.31), and the likelihood ratio of a negative G-IFN test was 0.18 (95% CI: 0.11, 0.29). The area under the ROC curve was 0.976 (95% CI: 0.97, 0.98), characteristic of a highly accurate test. ROC analysis also showed that lower cut-off values, such as 0.1, have high SE with suitable SP for use in parallel testing, while cut-off values ranging between 0.3 and 0.6 provide the high SP desired in series-testing protocols with lower SE values. Findings from this study indicated that the G-IFN performs with high accuracy in the field, yielding SE and SP estimates comparable to those reported in previous evaluations (Ryan et al., 2000; Ameni et al., 2000; de la Rua-Domenech et al., 2006; Gormley et al., 2006).

Characterization of Mycobacterium avium subspecies paratuberculosis disseminated infection in dairy cattle and its association with antemortem test results.

Mycobacterium avium subspecies paratuberculosis (MAP) disseminated infection in dairy cattle affects animal health and productivity and is also a potential public health concern. The study objectives were to characterize MAP disseminated infection in dairy cattle and to determine the role of antemortem tests in detecting cattle with disseminated infection. Forty culled dairy cows representing a variety of serum enzyme-linked immunosorbent assay (ELISA) results and body conditions were selected for the study. The physical condition of the cows was assessed via clinical examination prior to euthanasia and blood and feces were collected and tested by serum ELISA and fecal culture, respectively. Fifteen tissues were aseptically collected from each cow during necropsy and cultured for isolation of MAP. Disseminated infection was diagnosed when MAP was isolated in tissues other than the intestines or their associated lymph nodes (LNs) and was distinguished from infection found only in the gastrointestinal tissues and from absence of infection. Of the 40 cows in the study, 21 had MAP disseminated infection. Results showed that 57% (12/21) of cows with disseminated infection had average to heavy body condition and no diarrhea. Cows with disseminated infection had no to minimal gross pathologic evidence of infection in 37% (8/21) of cases. Only 76% (16/21) of cows with disseminated infection had positive historical ELISA results and only 62% (13/21) had a positive ELISA at slaughter. Thus, antemortem evidence of MAP infection was lacking in a high proportion of cows where MAP disseminated infection was confirmed.

La vacuna antiaftosa con adyuvante oleoso y su posible influencia en el diagnóstico de la tuberculosis en bovinos / Foot and mouth disease oil adjuvant vaccine and its possible role in the diagnosis of tuberculosis in cattle

Se investigó la posible influencia de la vacuna antiaftosa con adyuvante oleoso sobre la respuesta a la tuberculina PPD, y sobre el nivel de anticuerpos séricos anti-Micobacterium bovis determinado por un enzimoinmunoensayo (ELISA). Los resultados obtenidos en ambas pruebas diagnósticas de tuberculosis, antes y después de dos vacunaciones con vacuna antiaftosa con adyuvante oleoso no mostraron interferencia de esa vacuna sobre la especificidad de las respuestas tuberculínicas o de los niveles de anticurpos anti-M.bovis. Se analizó tambiém la presencia de anticuerpos anti-M.paratuberculosis por ELISA