What causes polio? Let you know the truth!

Polio is a disease that is more likely to be caused by infection. Not only will children suffer after contracting this disease, but parents should not worry about it. In order to better prevent the occurrence of this disease, the following is a detailed introduction to the causes of this disease:

1. Susceptible population

The disease is most common in children aged 1 to 5 years old, and infants under 4 months old rarely get sick. In recent years, children have generally taken vaccines. After the body is infected with polio virus, specific IgM appears first in the serum, and IgG and IgA appear 2 weeks later. Protective neutralizing antibodies can last a lifetime. After the illness, patients have long-lasting immunity to the same type of virus, and a secondary attack is rare.

2. Source of infection

Humans are the only source of infection for poliomyelitis. Patients can excrete polio from their nasopharyngeal secretions since the end of the incubation period. The fecal excretion period is from 10 days before the onset of the disease to 4 weeks after the onset of the disease, and in some cases up to 4 months. Asymptomatic virus carriers are the most important source of infection.

3. Mode of transmission

It is mainly transmitted through the fecal-oral route, and daily life contact is the main mode of transmission. Contaminated hands, food, supplies, clothing, and toys can all transmit the disease. In rare cases, it can be transmitted through airborne droplets.

4. Popular features

Found throughout the world, mostly in temperate zones. The epidemic is sporadic, with the highest incidence in summer and autumn. There is no significant difference in incidence between tropical and subtropical regions among the seasons. In the past, type I virus was the main prevalent type, with type III being the least prevalent. After large-scale vaccination, type I virus decreased, while types II and III increased relatively.

5. Pathogen knowledge

Poliovirus belongs to the Picornaviridae family and the Enterovirus genus. It is present in large quantities in the patient's spinal cord and brain, and can also be found in the nasopharynx, intestinal mucosa and lymph nodes. According to its antigenicity, it can be divided into three serotypes: I, II and III, and there is occasionally cross-immunity between types. The virus can be cultured in human embryonic kidney, human embryonic tumor, monkey kidney and Hela cells. It is cold-resistant and can preserve its vitality for up to 8 years at low temperatures (-70℃), survive for several months in water, feces and milk, and can be stored for several weeks in a 4℃ refrigerator. However, it is very sensitive to drying, so it is not suitable for preservation by freeze-drying. For heat resistance. It can be inactivated at 60℃ for 30 minutes, and can be quickly killed by boiling and ultraviolet radiation. It can withstand chemical disinfectants of normal concentrations, such as 70% alcohol and 5% tartaric acid soap solution. However, it is sensitive to potassium permanganate, hydrogen peroxide, bleaching powder, etc., which can be quickly inactivated.