Abstract
Rotaviruses (RV) are important causes of diarrhea in animals, especially in domestic animals. Of the 9 RV species, rotavirus A, B, and C (RVA, RVB, and RVC, respectively) had been established as important causes of diarrhea in pigs. The Minnesota Veterinary Diagnostic Laboratory receives swine stool samples from North America to determine the etiologic agents of disease. Between November 2009 and October 2011, 7,508 samples from pigs with diarrhea were submitted to determine if enteric pathogens, including RV, were present in the samples. All samples were tested for RVA, RVB, and RVC by real time RT-PCR. The majority of the samples (82%) were positive for RVA, RVB, and/or RVC. To better understand the risk factors associated with RV infections in swine diagnostic samples, three-level mixed-effects logistic regression models (3L-MLMs) were used to estimate associations among RV species, age, and geographical variability within the major swine production regions in North America. The conditional odds ratios (cORs) for RVA and RVB detection were lower for 1–3 day old pigs when compared to any other age group. However, the cOR of RVC detection in 1–3 day old pigs was significantly higher (p < 0.001) than pigs in the 4–20 days old and >55 day old age groups. Furthermore, pigs in the 21–55 day old age group had statistically higher cORs of RV co-detection compared to 1–3 day old pigs (p < 0.001). The 3L-MLMs indicated that RV status was more similar within states than among states or within each region. Our results indicated that 3L-MLMs are a powerful and adaptable tool to handle and analyze large-hierarchical datasets. In addition, our results indicated that, overall, swine RV epidemiology is complex, and RV species are associated with different age groups and vary by regions in North America.
Highlights
Rotaviruses (RVs) belong to the family Reoviridae and contain 11 segments of double stranded RNA [1, 2]
RVs are a major cause of diarrhea in pigs, and five (RVA-RVC, RVE, and RVH) out of the nine species have been found in swine [5]
While the pathogenesis of RVB was established in the 1980s, the revelation of RVB as an important enteric pathogen in pigs was only recently discovered in the United States of America (USA) [11, 12]
Summary
Rotaviruses (RVs) belong to the family Reoviridae and contain 11 segments of double stranded RNA (dsRNA) [1, 2]. RVs are a major cause of diarrhea in pigs, and five (RVA-RVC, RVE, and RVH) out of the nine species have been found in swine [5]. Sows infected with RVA were able to shed many different viral strains [7,8,9,10]. While the pathogenesis of RVB was established in the 1980s, the revelation of RVB as an important enteric pathogen in pigs was only recently discovered in the United States of America (USA) [11, 12]. RVC were first identified in swine and is an important cause of diarrhea in piglets in the USA [5, 13, 14]. Multiple RV infections can occur within a single swine herd [20], and clinical signs may vary between herds due to strain diversity and/or virulence [21]
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