Polio is a viral infection that occurs with a predominant lesion of the central nervous system (gray matter of the spinal cord) and leads to the development of sluggish paresis and paralysis. Depending on the clinical form, the course can be either asymptomatic (with short-term fever, catarrhal phenomena, dyspepsia), or with pronounced meningeal symptoms, autonomic disorders, the development of peripheral paralysis, limb deformities, etc. The diagnosis is based on the isolation of the virus in biological fluids, the results of IFT and ELISA diagnostics. Treatment includes symptomatic therapy, vitamin therapy, physiotherapy, physical therapy and massage.
Polio (Heine-Medina disease, infantile spinal paralysis) is an enterovirus infection caused by polioviruses affecting the motor neurons of the anterior horns of the spinal cord, which leads to severe paralytic complications with disability of the patient. The greatest susceptibility to polio (60-80%) is observed in children under the age of 4 years, so the disease is studied mainly in pediatrics, pediatric neurology and pediatric orthopedics.
The last polio epidemic in Europe and North America was recorded in the middle of the last century. In 1988, WHO adopted a resolution proclaiming the task of eliminating polio in the world. Currently, in the countries where preventive vaccination against polio is carried out, the disease occurs in the form of isolated, sporadic cases. Afghanistan, Nigeria, Pakistan, Syria, and India are still endemic for polio.
The infection is caused by three antigenic types of poliovirus (I, II and III) belonging to the genus of enteroviruses, the picornavirus family. The greatest danger is the type I polio virus, which causes 85% of all cases of the paralytic form of the disease. Being stable in the external environment, the polio virus can persist in water for up to 100 days and in feces for up to 6 months; it tolerates drying and freezing well; it is not inactivated under the influence of digestive juices and antibiotics. The death of poliovirus occurs when heated and boiled, ultraviolet irradiation, treatment with disinfectants (bleach, chloramine, formalin).
The source of infection in polio can be both a sick person and an asymptomatic virus carrier that secretes a virus with nasopharyngeal mucus and feces. Transmission of the disease can be carried out by contact, airborne and fecal-oral routes. The susceptibility to polio virus in the population is 0.2–1%; the absolute majority of cases are children under 7 years of age. Seasonal peaks of morbidity occur in the summer-autumn period.
Vaccine-associated polio develops in children with severe congenital or acquired immunodeficiency (more often HIV infection) who received a live oral attenuated vaccine.
The conditions contributing to the spread of the polio virus are insufficient hygiene skills in children, poor sanitary and hygienic conditions, crowding of the population, lack of mass specific prevention.
The entrance gate for this virus in the body of the new host is the lymphoepithelial tissue of the mouth and nasopharynx, intestines, where the primary replication of the pathogen occurs and from where it enters the blood. In most cases, primary viremia lasts 5-7 days and when the immune system is activated, it ends with recovery. Only 1-5% of those infected develop secondary viremia with selective damage to the motor neurons of the anterior horns of the spinal cord and brain stem. The penetration of the polio virus into the nervous tissue occurs not only through the blood-brain barrier, but also by the perineural route.
When introduced into cells, the polio virus causes a violation of the synthesis of nucleic acids and protein, leading to dystrophic and destructive changes up to the complete death of a neuron. The destruction of 1/3-1/4 nerve cells leads to the development of paresis and complete paralysis, followed by muscle atrophy and contractures.
In clinical practice, there are forms of polio that occur without damage to the nervous system and with damage to the central nervous system. The first group includes inapparant and abortive (visceral) forms; the second – nonparalytic (meningeal) and paralytic forms of polio.
Depending on the level of damage to the nervous system, the paralytic form of polio can be expressed in the following variants:
- spinal, which is characterized by sluggish paralysis of the limbs, neck, diaphragm, trunk;
- bulbar, accompanied by speech disorders (dysarthria, dysphonia), swallowing, cardiac activity, breathing;
- pontinnom, occurring with complete or partial loss of facial expressions, lagophthalmos, drooping corner of the mouth on one half of the face;
- encephalitic with cerebral and focal symptoms;
- mixed (bulbospinal, pontospinal, bulbopontospinal).
A post-vaccination complication such as vaccine-associated paralytic polio is considered separately. The incidence of paralytic and nonparalytic forms of polio is 1:200.
During the paralytic forms of polio, incubation, preparation, paralytic, recovery and residual periods are distinguished.
The incubation period for various forms of polio is on average 8-12 days.
The inapparant form of polio is a carrier of the virus, which does not manifest itself clinically in any way and can only be detected by laboratory means.
Abortive (visceral) form of polio accounts for more than 80% of all cases of the disease. Clinical manifestations are nonspecific; common infectious symptoms prevail among them – fever, intoxication, headache, moderate catarrhal phenomena, abdominal pain, diarrhea. The disease ends in 3-7 days with complete recovery; there are no residual neurological symptoms.
The meningeal form of polio proceeds according to the type of benign serous meningitis. At the same time, two-wave fever, headaches, moderate meningeal symptoms (Brudzinsky, Kernig, rigidity of the occipital muscles) are noted. After 3-4 weeks, recovery occurs.
The paralytic form of polio has the most severe course and outcomes. In the preparation period, general infectious symptoms prevail: fever, dyspepsia, rhinitis, pharyngitis, tracheitis, etc. The second wave of fever is accompanied by meningeal phenomena, myalgia, pain in the spine and extremities, severe hyperesthesia, hyperhidrosis, confusion and convulsions.
Approximately on day 3-6, the disease enters a paralytic phase characterized by the sudden development of paresis and paralysis more often of the lower extremities with preserved sensitivity. Paralysis in polio is characterized by asymmetry, unevenness, and predominant damage to the proximal parts of the limbs. Paresis and paralysis of the upper extremities, face, and trunk muscles develop somewhat less frequently with polio. After 10-14 days, the first signs of muscular atrophy are observed. The defeat of the vital centers of the medulla oblongata can cause paralysis of the respiratory muscles and diaphragm and cause the death of a child from acute respiratory failure.
During the recovery period of polio, which lasts up to 1 year, there is a gradual activation of tendon reflexes, movements in individual muscle groups are restored. The mosaic nature of the lesion and the uneven recovery causes the development of atrophy and muscle contractures, the lag of the affected limb in growth, the formation of osteoporosis and bone atrophy.
In the residual period, residual phenomena of polio are noted – persistent flaccid paralysis, contractures, paralytic clubfoot, shortening and deformity of limbs, hallux valgus, kyphoscoliosis, etc.
The course of polio in children can be complicated by lung atelectasis, pneumonia, interstitial myocarditis, gastrointestinal bleeding, intestinal obstruction, etc.
Polio in a child may be suspected by a pediatrician or a pediatric neurologist based on anamnesis, epidemiological data, and diagnostically significant symptoms. In the preparation stage, the recognition of polio is difficult, and therefore the diagnosis of influenza, ARI, acute intestinal infection, serous meningitis of other etiology is mistakenly established.
The main role in the etiological diagnosis of polio is played by laboratory tests: isolation of the virus from nasopharyngeal mucus, feces; ELISA methods (IgM detection) and IFT (increase in the titer of virus-specific antibodies in paired sera). PCR is used to differentiate the types of polio virus.
During lumbar puncture, cerebrospinal fluid flows out under increased pressure; examination of cerebrospinal fluid in polio reveals its transparent, colorless nature, a moderate increase in protein and glucose concentrations. Electromyography confirms the lesion at the level of the anterior horns of the spinal cord.
Differential diagnosis of polio is carried out with myelitis, tick-borne encephalitis, botulism, polio-like diseases, serous meningitis, Guillain-Barre syndrome.
Manifest forms are treated inpatient. General measures include isolation of a sick child, bed rest, rest, a high-calorie diet. In the proper care of a polio patient, an important role is played by giving the limbs the correct (physiological) position, prevention of bedsores, chest massage. In case of dysphagia, nutrition is organized through a nasogastric probe; in case of violation of independent breathing, a ventilator is performed.
Since no specific treatment for polio has been developed, symptomatic and pathogenetic therapy is mainly carried out. B vitamins, ascorbic acid, painkillers and dehydrating drugs, neostigmine, respiratory analeptics, etc. are prescribed.
In the recovery period, the main role in the complex therapy of polio is assigned to rehabilitation measures: physical therapy, orthopedic massage, paraffin treatment, UHF, electromyostimulation, general therapeutic baths, spa treatment.
Polio treatment is carried out with the participation of a pediatric orthopedist. To prevent the development of contractures, the application of plaster bandages, splints, orthopedic splints, and wearing orthopedic shoes may be indicated. Orthopedic and surgical treatment of residual polio phenomena may include tenomyotomy and tendon-muscle plasty, tenodesis, arthrosis and arthrodesis of joints, resection and osteotomy of bones, surgical correction of scoliosis, etc.
Prognosis and prevention
Mild forms of polio (occurring without damage to the central nervous system and meningeal) pass without a trace. Severe paralytic forms can lead to permanent disability and death. Due to the long-term targeted vaccination of polio, the structure of the disease is dominated by mild inapparant and abortive forms of infection; paralytic forms occur only in unvaccinated individuals.
Polio prevention includes mandatory routine vaccination and revaccination of all children according to the national vaccination calendar. Children with suspected polio are subject to immediate isolation; disinfection is carried out in the room; contact persons are subject to monitoring and emergency immunization of vaccine.