What is the cause of polio

summary

Poliomyelitis is also called poliomyelitis. Its clinical manifestations are sore throat, fever and limb pain. Some patients may have flaccid paralysis. The occurrence of poliomyelitis has caused great harm to children and their families, making children lose their complete childhood. So, what's the cause of polio? Let's take a look.

What is the cause of polio

First, virus replication in the nervous system leads to pathological changes, the speed of replication is an important factor in determining its neurovirulence. The lesions were mainly located in the anterior horn of spinal cord, medullary substance, pons and midbrain, with Nissl degeneration of motor neurons at first, followed by nuclear changes, infiltration of peripheral polymorphonuclear cells and monocytes, and finally disappeared after being destroyed by neurophagocytic cells. However, not all the involved neurons were necrotic, and the damage was reversible. After 3-4 weeks of onset, the edema and inflammation subsided, and the function of nerve cells could gradually recover. High risk factors for paralysis include fatigue, strenuous exercise, intramuscular injection, tonsillectomy and genetic factors.

Second, the virus enters the body through the oropharynx of the host. Because of its acid resistance, it can survive in gastric juice, proliferate in intestinal epithelial cells and local lymphoid tissues, and excrete the virus outward. At this time, if the body has a strong immune response, the virus can be eliminated, which is a recessive infection; If the virus does not invade the nervous system, the body's immune system can clear the virus, and the patient does not have symptoms of the nervous system, it is a type of frustration; After a large number of virus proliferation, it can re infect human blood and form a second viremia. At this time, the virus can break through the blood-brain barrier and invade the central nervous system. Therefore, about 1% of the patients have typical clinical manifestations, of which mild patients have neurological symptoms without paralysis, and severe patients have paralysis, which is called paralysis type.

Third: poliovirus is an enterovirus belonging to the small ribonucleic acid virus family. The virus is spherical in shape, with a diameter of about 20-30nm. The nucleocapsid is a stereosymmetric 20hedron, with 60 shell particles and no envelope. According to the different antigens, they can be divided into type I, type II and type III. type I is easy to cause paralysis, and there is little cross immunity between each type. Poliovirus has strong resistance to external factors, but it can be inactivated by heating above 56 ℃, formaldehyde, 2% iodine tincture, mercuric chloride and various oxidants such as hydrogen peroxide, bleaching powder and potassium permanganate.

matters needing attention

We should pay attention to the cause of poliomyelitis. Found that children with polio should be treated as soon as possible to the hospital, choose a regular hospital for treatment.