Polio

Introduction to polio Polioyelitis (hereinafter referred to as polio), also known as polio, is an acute infectious disease caused by poliovirus. Clinical manifestations include fever, sore throat and limb pain, and some patients may experience flaccid paralysis. In the epidemic, there are many cases of concealed infections and innocent cases. The incidence of children is higher than that of adults. Before the general vaccine, especially infants and young children, it is also called Infantile paralysis. The main lesions are in the gray matter of the spinal cord. In severe cases, there may be sequelae. Since the widespread use of vaccines to prevent this disease in the late 1950s, the incidence has been greatly reduced. After the destruction of smallpox in the 1970s, polio has been designated as the next target to be eliminated at the end of the century. basic knowledge The proportion of illness: 0.005% Susceptible people: young children Mode of infection: fecal-oral infection Complications: pneumonia, atelectasis, pulmonary edema, hypertension

Causes of polio

Virus infection (50%)

Poliovirus from the mouth, pharynx or intestinal mucosa invade the human body, within a day can reach local lymphoid tissue, such as tonsil, lymphatic tissue of the pharyngeal wall, lymphatic tissue of the intestinal wall, etc., and discharge the virus to the local, if At this time, the human body produces a large amount of specific antibodies, which can control the virus to localized and form a recessive infection; otherwise, the virus further invades the bloodstream (first viremia) and reaches non-neural tissues such as the respiratory tract and intestine on the third day. Road, skin and mucous membranes, heart, kidney, liver, pancreas, adrenal gland, etc., especially in the whole body lymphoid tissue, and again into the blood circulation (second viremia) again from the 4th to the 7th, if this When the specific antibody in the blood circulation is enough to neutralize the virus, the disease develops to this point, forming a frustrating polio, only the upper respiratory tract and intestinal symptoms, without neurological disease, a small number of patients may be due to viral virulence Strong or bloody antibodies are not enough to neutralize, the virus can invade the central nervous system with blood flowing through the blood-brain barrier, severe cases can occur, and occasionally the virus can also The peripheral nerves transmit to the central nervous system, and the specific neutralizing antibodies do not easily reach the central nervous system and the intestines. Therefore, the cerebrospinal fluid and the fecal virus remain for a long time. Therefore, whether there is a specific antibody in the human blood circulation, the time of occurrence and the number of An important factor in determining whether a virus can invade the central nervous system.

Low immunity (20%)

A variety of factors can affect the outcome of the disease, such as cold, fatigue, local irritation, injury, surgery (such as vaccination, tonsillectomy, tooth extraction, etc.), as well as low immunity, may cause convulsions, Pregnant women are prone to convulsions if they are sick. Older and adult patients are more seriously ill, and there are more convulsions. Boys in children are more susceptible to severe illness than girls, and more common ailments.

Pathological changes

The most prominent pathological changes in polio are in the central nervous system (the virus has neurotropic toxicity). The lesions are characterized by scattered and multiple asymmetry, which may involve the brain, midbrain, medulla, cerebellum and spinal cord. The brain stem is second, especially the lesions of motor nerve cells are most prominent. The spinal cord has more lesions in the anterior horn of the cervical and lumbar segments. Therefore, the quadriplegia is common in the clinic, most of the brainstem center and the cerebral nerve motor nucleus All can be damaged, with reticular formation, vestibular nucleus and cerebellar nucleus lesions are more common, cerebral cortex is rarely lesions, even in the sports area, most of the lesions are mild, occasionally sympathetic ganglia and peripheral ganglion lesions, There are scattered inflammatory lesions on the pia mater, there is little arachnoid involvement, inflammatory changes in cerebrospinal fluid, and most of the neurological lesions in the innocent type are mild. After entering the human body, the poliovirus invades the lymph nodes of the pharynx and intestines. Tissues form a recessive infection; antibody-lower viruses enter the blood circulation, causing viremia. If the body lacks immunity, the virus invades through the blood-brain barrier. The central nervous system, which spreads along the nerve fibers, causes symptoms in the innocent period; if the motor neurons are severely damaged, it causes muscle spasms and causes symptoms in the flood season.

Polio prevention

The polio vaccine has a good immune response.

(1) Autoimmune

The earliest use of inactivated polio vaccine (Salk vaccine), the effect of protecting susceptible people after intramuscular injection is positive, and because it does not contain live vaccine, it is also very safe for immunodeficiency. In some countries, inactivated vaccine alone. It also achieves the remarkable effect of controlling and almost eliminating polio, but the immunity caused by inactivated vaccine is short-lived, requires repeated injections, does not cause local immunity, and the preparation price is expensive. However, in recent years, the preparation has been improved. In the second month, the fourth month, inoculation three times in the 12th to 18th months, 99% of the vaccinates can produce three types of antibodies for at least 5 years.

Live attenuated vaccine (Obin polio-virus vaccine, OPV) is currently used more frequently. This live vaccine virus has been passaged several times through tissue culture, has no or little toxicity to the human nervous system, and can be susceptible after oral administration. In the intestinal tissue, the homologous neutralizing antibody grows rapidly in the body, and at the same time, the secretory IgA can be produced, and the intestinal and pharyngeal immunity is also enhanced, the invading wild strain can be eliminated, and the spread in the crowd is cut off, and The live vaccine virus can be excreted from the body, and the infected person can obtain immunity indirectly, so the immune effect is better. It has been made into three types of sugar pill vaccine, which can be stored at 2 to 10 ° C for 5 months and stored at 20 ° C for 10 years. In the day, 30 °C is only kept for 2 days, so you should pay attention to cold storage (4 ~ 8 °C). The susceptible children from 2 months to 7 years old are the main vaccine recipients, but other age children and adults are also susceptible. Miao, large-scale vaccine should be carried out in winter and spring, divided into 2 or 3 times on an empty stomach, do not use hot water to send clothes, so as not to inactivate the virus in the vaccine, lose the effect, the sugar vaccine is divided into type 1 (red), type 2 (yellow), type 3 (green), type 2, type 3 mixed sugar pill (blue), and 1,2,3 mixed sugar pill vaccine (white), served from 2 months, divided into three oral doses, can be served in each order 1, 2, 3, 1 capsule, or each serving 1, 2, 3 mixed vaccine 1 capsule, the latter proved that the immune effect is good, the number of taking is small, not easy to miss, so China has gradually switched to a three-type mixed vaccine, each oral interval must be at least 4 to 6 weeks, the best Interval for 2 months, in case of possible mutual interference, for the strengthening of immunity can be repeated once a year for 2 to 3 years, 7 years before enrollment, and once every 2 weeks after oral administration, specific antibodies can be produced in vivo, 1~ After reaching a peak in February, it gradually weakened. After 3 years, half of the children's antibodies have decreased significantly.

Oral vaccine rarely causes adverse reactions, occasionally mild fever, diarrhea, active tuberculosis, severe rickets, chronic heart, liver, kidney disease, and acute fever, temporarily not suitable for vaccine, there are reports that the human intestinal tract After repeated passage, the vaccine virus strain can increase the neurovirulence of monkeys. In recent years, OPV countries have generally found cases of sputum confirmed by vaccine strain viruses, most of which occur in immunocompromised patients. Therefore, it is considered that live attenuated vaccines are banned from immunosuppression. Patients, whether they are congenital immunodeficiency, or because of medication, infection, tumor-induced secondary immunodeficiency are not available, should also avoid contact with OPV patients, it is also advocated that this patient should first use inactivated vaccine, and then Live attenuated vaccines have been strengthened, but most advocate the use of inactivated vaccines only.

(two) passive immunization

If the child has not been vaccinated, pregnant women, medical staff, immunocompromised, tonsillectomy and other local operations, if close contact with the patient, early injection of gamma globulin, pediatric dose of 0.2 ~ 0.5ml / kg, or placenta Globulin 6 ~ 9ml, once a day for 2 consecutive days, immunity can be maintained for 3 to 6 weeks.

(3) Isolating patients

At least 40 days from the onset of the disease, the first week should emphasize the isolation of the respiratory tract and the intestine. The excretion is blocked and disinfected with 20% bleaching powder. The utensils are soaked in 0.1% bleaching solution or boiled, or exposed to sunlight. For two days, the ground is disinfected with lime water. The contact person is soaked in 0.1% bleaching powder clear solution with hands or disinfected with 0.1% peracetic acid. The susceptible person who is in close contact should be inspected for 20 days.

(4) Doing daily hygiene

It is very important to do a good job in environmental sanitation, eliminate flies, and cultivate health habits. During the epidemic, children should go to many places in the crowd to avoid excessive fatigue and cold, postpone various preventive injections and urgently needed operations, so as not to cause depression. The type of infection becomes a sputum type.

Polio complications Complications pneumonitis atelectasis pulmonary edema hypertension

More common in patients with medullary respiratory paralysis, secondary to bronchitis, pneumonia, atelectasis, acute pulmonary edema and azotemia, hypertension, etc., about 1/4 of patients with acute electrocardiogram abnormalities, suggesting myocardial lesions, by virus Directly caused, or secondary to severe hypoxia, gastrointestinal paralysis can be complicated by acute gastric dilatation, gastric ulcer, intestinal paralysis, urinary retention and urinary tract infection, long-term severe paralysis, bedridden, bone atrophy and decalcification, Hypercalcemia and urinary tract stones.

Polio symptoms Common symptoms Gastrointestinal symptoms Flu-like symptoms Sore throat Meningitis Sensation Muscle soreness Reflexes disappear diarrhea Abdominal discomfort Constipation

During the epidemic season, if there is a susceptible person who comes into contact with the patient, sweating, irritability, hypersensitivity, sore throat, neck and back pain, rigidity, and paralysis reflex disappear, and the disease should be suspected. The prodromal period should be associated with general upper respiratory tract infection. Influenza, gastroenteritis, etc., pre-eclampsia patients should be differentiated from various viral encephalitis, purulent meningitis, tuberculous meningitis and epidemic encephalitis. The presence of flaccid paralysis contributes to the diagnosis. .

The incubation period is 3 to 35 days, usually 7 to 14 days. According to the severity of symptoms and presence or absence of phlegm, it can be divided into recessive infections, frustration, innocence and sputum.

(1) Recessive infection (asymptomatic type): 90 to 95% of all infected persons, asymptomatic after infection, virus reproduction only stays in the digestive tract, does not produce viremia, does not immerse into the central nervous system, but from Viruses can be isolated from the pharynx and feces, and specific neutralizing antibodies can be found in the body.

(B) the type of frustration (light): about 4 to 8%, the virus invades the whole body non-neural tissue, the clinical symptoms are lack of specificity, there may be 1 upper respiratory tract symptoms, such as different degrees of fever, pharyngeal discomfort, pharyngeal congestion and pharynx Posterior wall lymphoid tissue hyperplasia, tonsil enlargement, etc.; 2 gastrointestinal symptoms, nausea, vomiting, diarrhea or constipation, abdominal discomfort, etc.; 3 flu-like symptoms, joints, muscle soreness, etc., symptoms lasted for 1 to 3 days, self-recovery.

(3) Innocent type: poliovirus invades the central nervous system, and circulating nerve fibers are scattered throughout the body. This symptom can occur at the onset of the disease, but most patients may have asymptomatic symptoms or symptoms 1 to 6 days after the prodromal period. Lighten up and then enter this period.

(D) sputum type: about 1-2% of infected people, characterized by the clinical manifestations of innocent type, coupled with the gray matter of the anterior horn of the spinal cord, brain and cranial nerve lesions, leading to muscle spasm.

Polio examination

(a) hydrocephalus

More abnormal than before, the appearance is slightly turbid, the pressure is slightly increased, the number of cells is slightly increased (25 ~ 500 / mm3), the early stage is more neutrophils, then the mononuclear is the main, after the heat retreat quickly drops Normal, sugar can be slightly increased, chloride is mostly normal, protein is slightly increased, and lasts for a long time, a small number of patients with spinal fluid can always be normal.

(2) The surrounding blood

Most white blood cells are normal, and can be increased in early and secondary infections, mainly neutrophils, and acute erythrocyte sedimentation rate increases rapidly.

(3) Virus isolation or antigen detection

Within one week of onset, the virus can be isolated from the nasopharynx and feces, and the feces can be positive for 2 to 3 weeks. The early isolation of the virus from the blood or cerebrospinal fluid is of greater significance, generally using tissue culture separation methods, in recent years. The PCR method was used to detect intestinal viral RNA, which was sensitive to tissue culture.

(4) Serological examination

Type-specific immune antibody titers can reach a peak in the first week, especially the specific IgM rises faster than IgG. Neutralization test, complement binding assay and enzyme labeling can be used to detect specific antibodies, among which neutralization test More commonly, because of its long-lasting positive time, double serum titer 4 times and more than 4 times increase can be diagnosed, complement fixation test turned faster, such as negative and neutralization test positive, often suggesting previous infection; All of them are positive, suggesting a recent infection. Recently, immunofluorescence detection of antigens and specific IgM monoclonal antibodies have been used to facilitate early diagnosis.

Diagnostic identification of polio

The prodromal phase should be differentiated from general upper respiratory tract infection, influenza, gastroenteritis, etc. The pre-eclampsia patients should be differentiated from various viral encephalitis, purulent meningitis, tuberculous meningitis and epidemic encephalitis. The presence of flaccid paralysis contributes to the diagnosis and needs to be identified with the following diseases:

(1) Infectious multiple radiculitis or Guillain-Barre's syndrome

More common in older children, scattered disease, no fever or low fever, with mild symptoms of upper respiratory tract, gradually appear flaccid paralysis, ascending, symmetrical, often accompanied by sensory impairment, cerebrospinal fluid has increased protein and less cells Characteristics, recovery is faster and complete, with few sequelae.

(2) Familial periodicity

Less common, no heat, sudden convulsions, symmetry, rapid, can be spread throughout the body, blood potassium is low at the time of attack, rapid recovery after potassium supplementation, but recurrence, often family history.

(three) peripheral neuritis

Can be caused by diphtheria neuritis, intramuscular injection injury, lead poisoning, vitamin B1 deficiency, herpes zoster infection, etc., medical history, physical examination can be identified, cerebrospinal fluid no change.

(4) Other viral infections that cause contempt

Such as Coxsackie, Echo virus infection, etc., clinically difficult to identify, such as chest pain, rash and other typical symptoms, to help identify, the diagnosis depends on virus isolation and serological examination.

(5) Epidemic type B brain

Inflammation should be differentiated from the brain type of this disease. J-brain occurs mostly in summer and autumn, and the onset is urgent, often accompanied by mental disorder. The peripheral blood and cerebrospinal fluid are mainly neutrophils.

(6) False sex

Infants and young children due to injury, fractures, arthritis, vitamin C lack of subperiosteal hematoma, may have limited limb activity, should be carefully examined and identified.

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