Reoviridae
Summary
Reoviridae are non-enveloped viruses with a segmented, double-stranded RNA genome and a distinctive double protein capsid. The medically important members are rotavirus, the leading cause of severe paediatric gastroenteritis, and Colorado tick fever virus.
Detail
Reoviridae are unique among human pathogens as the double-stranded RNA viruses, and like influenza their segmented genome permits reassortment. Being non-enveloped, they resist detergents, drying, and the acidic and biliary environment of the gut, which suits faecal-oral transmission. Rotavirus has a wheel-like appearance on electron microscopy, from which it takes its name, and causes watery, non-bloody, osmotic diarrhoea by NSP4 enterotoxin and destruction of small bowel villous enterocytes, leading to dehydration in infants and young children. It is the commonest cause of severe childhood diarrhoea worldwide, and two live oral vaccines have markedly reduced hospitalization; both carry a small risk of intussusception and are contraindicated in infants with SCID or a history of intussusception. Colorado tick fever, transmitted by Dermacentor andersoni, causes a biphasic 'saddleback' fever with leukopenia in the Rocky Mountain region.
Sources
- Levinson Medical Microbiology and Immunology
- First Aid for the USMLE Step 1
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