Poliovirus causes poliomyelitis (polio), a highly infectious disease. It invades the nervous system and can cause total paralysis. The virus enters the body through the mouth and multiplies in the intestines. Initial symptoms are fever, fatigue, headache, vomiting, stiffness in the neck and pain in the limbs. Virus diameter: 24-30 nm. Colorization and graphic filters on transmission electron microscopy image (TEM).