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Streptococcus viridans

Streptococcus viridans - Gram-positive, coccoid prokaryote (dividing). Magnification 4000. S.viridans is a common bacterium that inhabitants the oropharynx (mouth & throat). It can also be found in the gut & urogenital tracts. It can cause human infections, including dental disease (tooth decay), endocarditis & abdominal abscesses. Courtesy of Dennis Kunkel.


Double-shelled intact Rotavirus particles visualized by transmission electron microscopy (TEM). This virus belongs to the Reoviridae family and can cause gastroenteritis typically among infants and young children. There are currently eight species of this virus (A, B, C, D, E, F, G and H) with Rotavirus A being most common and causes over 90% of rotavirus infections in humans. Transmission of the virus is by the faecal-oral route. Symptoms may include severe watery diarrhea, vomiting, fever, abdominal pain, loss of appetite and dehydration. Image courtesy of the Centers for Disease Control and Prevention (CDC / Dr. Erskine Palmer).

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