Rotaviruses. Coloured transmission electron micrograph (TEM) of a section through a cluster of rotaviruses. These viruses cause diarrhoea and gastroenteritis and are probably the most common viruses to infect humans and animals. Rotaviruses contain RNA (ribonucleic acid) genetic material within an outer protein coat or capsid. They get their name from their wheel-like structure. Typically they infect the intestines in children aged between 6 months and 3 years. The diarrhoea results in dehydration and the spread of the virus in the faeces. Negatively stained. Magnification: x80,000 at 35mm size.