What is Acute Poliomyelitis?
Acute poliomyelitis (epidemic infantile paralysis, Heine-Medina disease) is an acute infectious disease with localization of the pathological process in the anterior horns of the spinal cord.
The greatest number of diseases occur in children under the age of 5 years. Polio cases have also been reported in adults.
Polio has been known since ancient times (4th century BC), but the nature of this disease has long been unknown. In 1840, the German orthopedic doctor Jacob Heine described the clinical picture of polio, and the Swedish doctor Medin in 1887 established the contact of this infection and initiated the epidemiological study of the disease. In 1908, Landsteiner and Popper experimentally reproduced polio by introducing into the monkey’s body an emulsion of the spinal cord of a child who died of polio. Negative results of bacteriological studies have given reason to attribute the causative agent of this disease to filterable viruses. A turning point in the study of polio was receiving in 1949-1951. Anders, Waller and Robins culture of the virus outside the body on the tissues of the kidneys and testicles of monkeys, on the human embryo fibroblasts and on the placenta. This discovery made it possible to manufacture a vaccine against poliomyelitis, created the prerequisites for laboratory diagnosis of poliomyelitis and the development of methods for its active prevention.
Causes of Acute Poliomyelitis
Currently, three immunologically distinct types of acute polio virus have been studied:
- Type I – Brunnhilde virus (named after the monkey from which the virus was isolated);
- Type II virus Lansing (after the name of the city in the USA where this virus was isolated);
- Type III virus Leon (after the boy who died of polio from whom the virus was isolated).
Poliomyelitis virus is one of the smallest viruses from the group of enteroviruses (average diameter 17-27 microns). The virus is very resistant to environmental influences and retains pathogenic properties for a long time (in milk and dairy products for up to three months, in water for 114 days, in feces for 180 days). Within a few months, he endures low temperature, freezing and drying, but is sensitive to the effects of high temperature. The temperature of 55 ° C inactivates the virus for 6–8 minutes, the temperature of 75 ° C for 50 seconds. The virus is completely destroyed by chloramine, bleach, formalin, potassium permanganate, hydrogen peroxide and other disinfectants.
The bulk of the mass of polio virus is nucleoproteins. The purified virus contains 20-30% ribonucleic acid, which is associated with the main pathogenic properties of this pathogen.
The source of infection is a sick person or a virus carrier that releases viruses with gastrointestinal contents or with mucus from the nasopharynx and respiratory tract.
Transmission of infection is carried out by airborne droplets and fecal-oral route (through dirty hands, household items, food, water). The summer-autumn seasonality of poliomyelitis indirectly confirms the importance of flies in the spread of the disease. Prior to the use of mass vaccination, polio was a widespread disease and was observed in all countries of the world, especially in the USA, where special attention was paid to the study of this disease.
Major poliomyelitis epidemics were observed from 1949 to 1956. Due to active immunization in 1960-1962. there was such a sharp decrease in the incidence of poliomyelitis that we can talk about eliminating it as an epidemic disease. Only sporadic cases with mild and rapidly passing movement disorders are recorded.
Pathogenesis during Acute Poliomyelitis
The entrance gate of the infection is the alimentary canal and nasopharynx. In the lymphatic formations of the intestines and the posterior pharyngeal wall, the virus multiplies. From here it penetrates the bloodstream, where it circulates for 5-7 days. At the height of viremia, the virus appears in all organs and tissues. The virus enters the nervous tissue not only hematogenously, but also through the perineural fissures. It is in the nerve cells that the biological activity of the pathogen is manifested, in other tissues it dies.
In case of poliomyelitis, the pathological process is localized mainly in the motor neurons of the brain stem and anterior horns of the spinal cord. The introduction of the virus into the nerve cell is accompanied by pronounced changes in hemodynamics (paralytic vasodilatation, edema, multiple-pointed multiple hemorrhages) in the medulla and membranes. Perivascular cellular infiltration from neutrophils and glial cells is found. The main changes are expressed in the destruction of neurons in connection with the violation of intracellular protein synthesis by the invading virus. In the early stages of the disease in the cytoplasm of motoneurons, Nissl’s chromatophilic substance is detected, which is detected when the nervous tissue is stained with basic dyes. Then the core is destroyed; if the nucleoli of the cell are destroyed, the reparative processes in the neuron are impossible. The remains of decaying nerve elements are removed by macrophages into the bloodstream. The resulting nerve tissue defects are organized by the proliferative response of astrocytic glia. The formation of a glial scar ends by the end of the third month.
Despite the apparent neurotropic nature of the virus, pathological changes are found in all internal organs in the form of edema, point hemorrhages, small focal necrosis. This suggests that poliomyelitis is a common infectious disease with a predominant localization of the process in the central nervous system.
Symptoms of Acute Poliomyelitis
There are four forms of polio: asymptomatic, abortive, non-paralytic and paralytic.
Asymptomatic form of poliomyelitis, clinically unremarkable, is characterized by a temporary release of the virus. This form is extremely dangerous epidemiologically: virus carriers can be the source of the spread of the disease.
The abortive form occurs in the form of a short-term infectious disease with signs of lung damage to the upper respiratory tract or the alimentary canal, without signs of damage to the nervous system (visceral form of polio).
Non-paralytic, or meningeal, form characterized by lesions of the meninges or spinal roots. Clinically proceeds as serous meningitis or meningoradiculitis.
Polio serous meningitis begins acutely, with an increase in body temperature to 39-40 ° C. The temperature curve is bhourious. The first rise in body temperature lasts 1-3 days, accompanied by a minor headache, runny nose, cough, pharyngeal hyperemia or gastrointestinal disorders (constipation, diarrhea). Before the second rise in body temperature, the patient feels healthy for 2-3 days. The second rise in body temperature, which lasts 1-Zdnya, coincides with the appearance of meningeal symptoms. Headache is less pronounced than in meningitis of a different etiology, vomiting one or two times. Patients are sluggish, adynamic, drowsy.
In a colorless, transparent cerebrospinal fluid, pleocytosis of a mixed nature, lymphocytes and neutrophils are detected, and in the first days neutrophils predominate, and in 5-6 days lymphocytes predominate. The amount of protein is moderately increased, the pressure of cerebrospinal fluid is slightly increased.
The course of meningeal poliomyelitis is favorable, recovery without defects.
The paralytic form of poliomyelitis, actually poliomyelitis, occurs only in 2-3% of cases, but it is this form of the disease that has caused serious consequences in the form of gross movement disorders and has turned polio into a socially relevant problem.
In the paralytic form of polio, several forms are distinguished: spinal, bulbar, pontine, mixed (bulbo-pontine, bulbospinal, etc.), rare forms (encephalitic, atactic).
The incubation period lasts an average of 9-12 days and is characterized by mild non-specific signs of an infectious disease: subfebrile temperature, catarrhal symptoms of the upper respiratory tract or mild gastrointestinal disorders. Then the patient’s condition returns to normal, but after 2-3 days (latent period) symptoms of damage to the nervous system develop.
During the paralytic form of polio, four stages are distinguished: preparative, paralytic, restorative and residual.
A sudden increase in body temperature to 39–40 ° C is characteristic of the preparative stage. Body temperature decreases critically or gradually. Possible second rise in body temperature, which coincides with the penetration of the virus into the central nervous system. In this stage of the disease, catarrhal changes in the upper respiratory tract and gastrointestinal disorders are noted, which is often the cause of diagnostic errors. Neurological symptoms during this period manifest as hyperesthesia of the skin, general hyperhidrosis, signs of irritation of the roots and membranes of the brain, drowsiness, depressed mood is noted. The preparative stage lasts from several hours to 1-3 days.
It is followed by the paralytic stage. The appearance of paralysis usually coincides with an increase in temperature. Sometimes an increase in body temperature and the appearance of paralysis occur in the hours of a night’s sleep, and the patient discovers them in the morning (“morning paralysis”). Paralysis most often are multiple (para-, tri-, tetraplegia with spinal poliomyelitis).
When the bulbar form affects the muscles of the pharynx, larynx and soft palate, which leads to a violation of swallowing, aphonia, dysarthria. This is the most severe form of polio, which can be accompanied by impaired breathing and cardiac activity, often fatal.
In the pontine form of poliomyelitis, the nuclei of the facial nerve are most often affected, which leads to the development of facial paralysis.
Paralysis occurs in a peripheral type and is characterized by atony, areflexia and atrophy, which manifests itself already 7-10 days after the onset of paralysis.
The paralytic stage lasts for 7-10 days and, without a clear boundary, enters the recovery phase.
The recovery stage is characterized by the appearance of active movements in the paralyzed muscles. Characteristic asymmetry of paralysis. Restoration of motor function depends on the severity and ratio of organic and functional changes in the motor neurons of the brain and spinal cord and can occur over several years. The most intense motor function is restored in the first five months. The functions of the muscles are restored in some cases completely, in others – partially; the functions of the muscles that have lost more than 70% of the motoneurons that innervate them remain deeply disturbed.
The residual stage, or residual stage, is characterized by a diverse combination of paralysis and paresis of individual muscles, the presence of deformities and contractures of the limbs. The bones of the affected limbs are stunted, thinner, become porous. On the affected limbs marked vegetative disorders are noted: cyanosis, decrease in skin temperature, hyperhidrosis, etc.
Diagnosis of Acute Poliomyelitis
Cerebrospinal fluid with poliomyelitis is transparent, colorless, it flows under a slightly increased pressure. In the first 10 days of the disease, cell-protein dissociation is detected (pleocytosis up to 300-106 per liter, mostly lymphocytic). After 2-3 weeks, the cell-protein dissociation is replaced by a protein-cell. Glucose levels remain in the normal range. On the blood side of polio, there are no significant changes.
Treatment of Acute Poliomyelitis
Treatment for acute polio should be complex, taking into account the stage and form of the disease. Bed rest is prescribed, which is an important measure to prevent paralysis in this disease. Patients are placed for 2-3 weeks with strict observance of certain orthopedic recommendations aimed at preventing contractures and limb deformities.
In order to improve the immunobiological properties of the body, gamma globulin is administered intramuscularly to patients (1 ml / kg, but not more than 20 ml, only 3-5 injections).
Used serum from recovered parents and from adults in contact with sick children. According to the method of M. A. Khazanov, hemotherapy is performed: 5-30 ml of blood is taken from the father’s or mother’s veins and injected intramuscularly into the child (10-20 injections in total). Dehydration therapy is used to reduce the swelling of the nervous tissue. From the first days it is necessary to introduce thiamine chloride, ascorbic acid, cyanocobalamin. With bulbar forms, cardiac agents, respiratory analeptics, controlled breathing apparatus are used. With the cessation of the appearance of new paralysis, anticholinesterase drugs that stimulate myoneural and interneuronal conduction (Dibazol, Prozerin, Nivalin) are prescribed. With appropriate indications prescribed antibiotics, painkillers.
In the complex treatment of poliomyelitis, a large role is played by physiotherapeutic methods. After normalization of body temperature, stabilization of paralysis and improvement of the general condition, transverse diathermy is prescribed to the affected segments of the spinal cord, UHF, paraffin baths, wet wraps for 30-45 minutes. To restore the function of paralyzed muscles, massage, exercise therapy, electrical stimulation of the affected muscles is of great importance.
Sanatorium-resort treatment should be applied no earlier than 6 months and no later than 3-5 years after the disease (Evpatoria, Odessa, Anapa, Saki, etc.). Mud, sulfur, sea baths are used. In the residual period, orthopedic treatment is performed (conservative and operative).
Prevention of Acute Poliomyelitis
In acute poliomyelitis, two types of prophylaxis are used: sanitation and hygiene measures and active immunization.
Sanitation and hygiene measures carried out in the outbreaks of the disease are aimed at preventing the spread of the disease. These activities consist primarily of compulsory hospitalization of patients in special departments (for at least 40 days), and those suspected of having polio – in diagnostic departments. Disinfected dishes, clothing and objects that may be infected with the patient’s secretions, as well as the latrine, which the patient used. Children who have had close contact with patients with acute poliomyelitis are barred from visiting childcare facilities for a period of 15-20 days.
Active immunization against poliomyelitis began in 1953 using the vaccine offered by Salk. It was a vaccine from all three types of polio virus that were inactivated by formaldehyde. Since she did not give one hundred percent immunization against polio (even after three injections), Sabin offered a live vaccine made from attenuated viruses. In the Soviet Union, a great deal of work was done on the study of live vaccines by M. I. Chumakov and A. A. Smorodintsev, who confirmed the safety of the vaccine, the strength of the induced immunity, the greater cost-effectiveness of its production, and suggested an oral method for its use. Live vaccine is made in liquid form or in the form of candy, dragee, which children gladly take, which facilitates vaccination. Vaccinations are carried out three times with monovalent vaccines. The first dose of the vaccine is made at the end of winter (type I virus), the second dose (type III) is taken a month later, the third dose (type II) is taken another month. The second and third methods can be combined by applying divaccin (III and II types of virus). A year later, re-vaccination according to the same rules.