Rotaviral enteritis is a common disease of the small intestine of pigs. Pigs of all ages are susceptible to infection; however, diarrheal disease usually occurs in nursing piglets and weaned pigs, with decreasing severity up to 6 weeks old.
Etiology and Pathogenesis of Rotaviral Enteritis in Pigs
Rotaviruses infect and destroy villous enterocytes throughout the small intestine. Lesions are segmental and are commonly observed from mid-jejunum through the ileum. Loss of villous epithelium results in villous atrophy, malabsorption, and osmotic diarrhea. Rotavirus groups A, B, and C are associated with diarrhea in piglets worldwide. They are easily transmitted by direct contact. Healthy carrier sows may shed rotavirus in their feces during the periparturient period, thereby exposing their litters to infection. Recently weaned pigs are commonly exposed to rotaviruses that persist in nursery facilities and in other carrier pigs during commingling.
Clinical Findings of Rotaviral Enteritis in Pigs
If neonatal pigs do not receive protective levels of maternal antibody, they are likely to develop profuse watery diarrhea in 12–48 hours. More commonly, rotaviral enteritis is endemic in a herd, and sows have varying levels of antibody in the colostrum and milk, which provide varying levels of passive protection to nursing pigs. Diarrhea often begins in pigs 5 days to 3 weeks old or immediately after weaning. The feces of nursing pigs are typically yellow or gray and pasty in the early stages, and they progress to gray and pasty after ~2 days. Diarrhea commonly persists for 2–5 days. Affected pigs become gaunt and rough-haired; however, mortality is usually low. Weaned pigs may have watery feces that contain poorly digested feed.
Lesions
The small intestine appears variably thin-walled, and the cecum and colon contain watery feces. Microscopically, there is segmental villous atrophy.
Diagnosis of Rotaviral Enteritis in Pigs
Detection of rotavirus by PCR assay
Histopathologic evaluation
Laboratory analysis of patient specimens is required for diagnosis of rotaviral enteritis. Confirmation is based on a combination of histologic demonstration of villous atrophy in the jejunum or ileum, PCR assay detection of rotavirus in feces (assays for groups A, B, and C are widely available), and immunodiagnostic procedures to demonstrate viral antigen in the intestinal mucosa. Direct examination of feces by electron microscopy may be helpful to identify rotaviral particles. Differential diagnoses commonly include coronaviral enteritis, Cystoisospora suis enteritis, and enteric colibacillosis.
Treatment and Control of Rotaviral Enteritis in Pigs
Supportive care
Increased lactogenic immunity
There is no specific treatment for rotaviral enteritis in pigs. Minimizing heat loss and providing adequate water to maintain hydration of the patient are helpful. Concurrent infection by enterotoxigenic Escherichia coli is common; therefore, antimicrobial treatment may reduce mortality. Providing affected weaned pigs with a warm, dry, draft-free environment and frequent limited feedings helps prevent starvation, secondary diseases, and permanent stunting. Vaccine for group A rotavirus appears beneficial when given to sows before farrowing. Vaccines for groups B and C have not been developed commercially because of difficulty in virus propagation. A serotyping scheme based on virus neutralization indicates a lack of cross-protection between isolates within groups. Intentional exposure of gilts and sows to feces from affected piglets, known as feedback, may be of benefit in increasing lactogenic immunity.
Key Points
Rotaviruses are ubiquitous in swine production environments.
Nursing and recently weaned pigs are commonly affected.
Infection results in malabsorptive diarrhea.
For More Information
Vlasova AN, et al. Porcine rotaviruses: epidemiology, immune responses, and control strategies. Viruses. 2017;9(3):48.
Shepherd FK, et al. Reoviruses (rotaviruses and reoviruses). In: Zimmerman JJ, et al, eds. Diseases of Swine. 11th ed. John Wiley and Sons, Inc; 2019: 715–723.
