Globally, avian rotaviruses (AvRVs) have been detected in many species of domesticated birds including chickens, turkeys, ducks, guinea fowl, pheasants, partridges, pigeons, and other avian species. AvRVs are one of several viruses that cause enteritis in birds. AvRV infections in chickens and turkeys are associated with subclinical to acute enteritis and diarrhea. Infections in poultry generally occur in birds ≤ 6 weeks old, with 1- to 2-week-old birds being most susceptible. Detection, by RT-PCR assay, of rotaviral RNA in the intestines or feces is the primary diagnostic test to confirm the presence of the virus in affected birds. No specific treatments are available. Good biosecurity is important to prevent the spread of and reinfection by AvRVs.
Etiology, Epidemiology, and Transmission of Rotavirus Infections of Poultry
The global prevalence of avian rotavirus (AvRV) has been estimated at 19–70% in turkey flocks and at 10–47% of chicken flocks. Four groups of rotavirus infect avian species and are designated as A (RVA), D (RVD), F (RVF), and G (RVG), based on genetic or serological characterization. RVD, RVF, and RVG are exclusive to avian species. RVA and RVD are the most prevalent, and interspecies transmission is known to occur within group A.
Broiler and turkey flocks often have simultaneous and sequential disease with different AvRV groups. Transmission occurs by horizontal infection via the fecal-oral route. AvRVs coinfect with other pathogens, most commonly avian astroviruses, but also with secondary bacterial pathogens.
Clinical Findings of Rotavirus Infections of Poultry
The following are the primary clinical signs of avian rotavirus infection:
listlessness
stunting
ingestion of litter
pasted vents
watery feces
wet litter
diarrhea
Other clinical signs include dehydration, anorexia, and weight loss with increased mortality rate. AvRVs also are associated with growth retardation in poultry. Carcasses are often dehydrated and stunted, and yellow, watery, scour fluid (diarrhea) with gas can be observed in the intestine and cecum. Prolific viral replication in the small intestinal villus epithelium disrupts the villus structure, causing enteritis and diarrhea by epithelial detachment, villus atrophy, and malabsorption.
Other gross lesions include whitish-transparent intestinal walls, enlarged gall bladder, and atrophy of the pancreas and bursa. Histopathological lesions include vacuolation of enterocytes with separation from the lamina propria and infiltration of inflammatory cells into the lamina propria. The mature villous absorptive epithelium in the distal third of the small intestine are the primary cells affected.
Diagnosis of Rotavirus Infections of Poultry
Detection of avian rotavirus RNA by RT-PCR assay
Electron microscopy
Laboratory diagnosis of avian rotavirus in the intestines, feces, or cloacal swabs can be confirmed by RT-PCR assay. Electron microscopy (EM) has historically been used to visualize virions in fecal floats; however, EM lacks sensitivity. Virions are approximately 70 nm in diameter with a wheel-like appearance; AvRV species can be determined with polyacrylamide gel electrophoresis (PAGE). Only group A (RVA) can be isolated in laboratory systems, whereas groups D, F, and G are uncultivable.
A multiplex real-time RT-PCR assay is available to detect and quantify RVA and RVD. PAGE can be used to analyze the segmented genome of rotavirus and is capable of distinguishing rotaviruses in the laboratory; however, this technique is not generally available in most diagnostic laboratories.
Prevention and Treatment of Rotavirus Infections of Poultry
Increased ventilation and fresh litter
Proper brooding temperature
Supportive care with electrolyte administration
Biosecurity measures
Avian rotavirus is resistant to inactivation by heat and many disinfectants, so measures to prevent its spread should focus on biosecurity and environmental management. No commercially available vaccine against AvRV exists. AvRV is extremely stable and resistant to some disinfectants yet sensitive to phenol and formaldehyde. Beneficial treatments during the acute phase of infection include administration of an oral electrolyte solution to maintain hydration, increasing housing temperature, improving ventilation, and adding fresh litter.
Antimicrobials may be used to treat secondary bacterial infections.
Zoonotic Risk of Rotavirus Infections of Poultry
Rotavirus is considered species-specific, although interspecies transmission and gene reassortment have been shown to occur. Although there are reports of transmission of RVA in mice, foxes, and calves, there is no evidence of zoonotic transmission.
Key Points
Avian rotavirus infections range from subclinical to acute with enteritis and diarrhea.
Infection occurs at ≤ 6 weeks old, with 1- to 2-week-old birds most susceptible.
Transmission occurs by horizontal infection via the fecal-oral route.
No commercial vaccine is available.
Good biosecurity is important to prevent spread of infection.
For More Information
Day JM. Rotavirus infections. In: Swayne DE, ed. Boulianne M, Logue CM, McDougald LR, Nair V, Suarez DL, associate eds. Diseases of Poultry. 14th ed. Wiley; 2020: 408-416.
Pfleiderer L, Vaillancourt JP. Other viral enteric infections. In: Brugere-Picoux J, Vaillancourt JP, Shivaprasad HL, Venne D, Bouzouaia M, eds. Manual of Poultry Diseases. French Association for the Advancement of Science; 2015:194-199.
