Mouse Rotavirus (EDIM - Epizootic Diarrhea of Infant Mice)

Prevalence
  • Highly contagious and common amongst both laboratory and wild mice.
 
Significance
  • Can alter results of studies with infant mice
  • Alter host physiology – increase susceptibility to pathological effects of co-pathogens
  • Modifies intestinal absorption and concentrations of intestinal enzymes
Disease
  • Non-enveloped, RNA virus
  • EDIM is a single strain of many viruses of group A rotaviruses isolated from mice
  • Mice of all ages susceptible – only mice younger than 14 days show clinical signs:
    • Diarrhea - watery, yellow stools 48 hours after infection that persist up to 1 week after
    • Steatorrhea with oily hair
    • Bowel flaccid and distended with fluid and gas
    • Obstipation due to faecal caking around anus
    • Severe stress-related thymic necrosis
  • Clinical signs of EDIM typically occur in naïve breeding populations – once enzootic within colony, disease no longer apparent, virus remains
  • Virus selectively infects terminally differentiated enterocytes of villi and surface mucosa of small and large intestine – malabsorptive effects accompanied by E. coli overgrowth
  • During first few days – fluid accumulation and dilation of small intestine
Transmission
  • Orofaecal route (shed copiously in faeces)
  • Direct contact with infected mice and contaminated bedding
  • Aerosol
  • Adult mice shed virus to susceptible young
Diagnosis
  • Presumptively - on basis of age, clinical signs, and lesions
  • Preferred – Serology for EDIM virus antibody useful for surveillance and retrospective confirmation (ELISA)
  • RNA can be detected by PCR
  • Antigen can be detected in faeces by ELISA
  • Electron microscopy of intestinal mucosa or faeces
Strains
  • Multiple strains have been identified
  • Rotavirus A group encompasses many viruses which has relative host specificity (interspecies infection can be shown experimentally with high doses of inocula)
Duration
  • Mice infected about 17 days of age – shed lower concentrations or virus
  • Virus shed in faeces for about 10 days post-infection - not known whether infection is persistent or whether low concentrations of virus continue to be shed
Durability
  • Readily destroyed by:
    • disinfectants - phenols, chlorine, and ethanol
    • treatment with calcium-chelating agents (e.g. EDTA)
  • Resistant to:
    • low pH - although virulence will decrease on prolonged exposure)
    • 5% chloroform, 20% ether or 0.1% sodium deoxycholate at 4°C for 60 mins
    • non-ionic detergents
    • high concentrations of proteolytic enzymes
Screening
  • Routine monitoring of colonies.
Prevention and Control
  • Rederivation through hysterectomy or embryo transfer
  • Filter top cages can be beneficial
  • Materials in contact with animals – autoclaved or cold sterilized
  • Environment chemically decontaminated – detergents and oxidizing agents
  • Eradication – cull colony and obtain replacement stocks from sources know to be disease free
 
Reading
  • Stephen W. Barthold, Stephen M. Griffey, & Dean H. Percy. Pathology of Laboratory Rodents and Rabbits (Fourth Edition), 2016
  • Infectious Diseases of Mice and Rats. National Research Council, 1991
  • Charles River Laboratories website, www.criver.com
  • University of Missouri, Research Animal Diagnostic Laboratory website, www.radil.missouri.edu
  • Mouse Rotavirus (Epizootic Diarrhea of Infant Mice or EDIM). Division of Animal Resources, University of Illinois, Urbana