Polio

Poliomyelitis (synonym: infantile spinal paralysis, disease Heine - Medina, children's infection paralysis) - an acute infectious disease characterized by a primary lesion of the nervous system.
Epidemiology. Polio is caused filterable virus that belongs to the group of intestinal neurotropic viruses. The spread of polio goes by type of intestinal infections; has the importance of airborne transmission. Source of polio are virus carriers-convalescents and patients with various forms of polio. Most often affects children aged 3-6 months. up to 5 years. The highest incidence is observed in late summer - early autumn. The patient becomes dangerous to others already in the end of the incubation period, but especially in the prodromal period (if any catarrhal phenomena of the upper respiratory tract). The virus is excreted into the environment with the mucous discharge throat and faeces. Once in the body, the virus through blood enters the nervous system that affects various departments, but much of motor cells of the anterior horns of the spinal cord and the kernel of the cranial nerves.

  • Clinic
  • The forecast. Nephrolithiasis form of polio flow of short-term and with a favorable outcome. Paralytic forms are still varying severity defects. However, in mild cases, with proper and long-term care can be achieved full recovery functions. The forecast is significantly reduced with the defeat of the respiratory centre and respiratory muscles.
    Differential diagnosis. In paralytic stage diagnosis is not difficult. Neparametricheskoi form and preparations stage paralytic form should be differentiated from influenza, gastrointestinal diseases, serous meningitis.

  • Treatment
  • Prevention. A polio patient or suspicious on this disease is subject to compulsory hospitalization. On each case of polio in the SES is sent map emergency notification. When polio by disinfection, as in acute intestinal infections. The selection of the patient (the feces, urine, sputum) in a separate dishes need pour disinfectant chlorine, carbolic acid and other Quarantine is for 20 days; children exposed to patients, introduce gamma globulin rate of 0,3-0,5 ml per 1 kg of weight.
    To produce active immunity applies live vaccine of Sabina weakened from different types of polio viruses (see Immunization). This vaccine is inserted through the mouth in the form of pills or drops. Re - vaccination is carried out through the year.

    Polio (poliomyelitis; from the Greek. polios grey + myelitis; synonym: disease Heine - Medina, children's infection paralysis, acute atrophic spinal infantile paralysis, acute epidemic front polio paralysis epidemic, epidemic infantile paralysis) - an acute viral disease of the Central nervous system, mainly in children of early age.

    Etiology
    The causative agent of poliomyelitis belongs to a filterable virus. Some strains of poliovirus (so dubbed as the polio virus) can cause in experimental conditions the disease not only in monkeys, but also in cotton rats and white mice.
    In the Soviet Union poliovirus was isolated and identified in 1945 (M. K. Voroshilov, M. P. Chumakov, A. P. Belyaev, I. A. Shutov).
    With the improvement of laboratory equipment selection this virus has become a common method of etiological diagnosis of the disease and the establishment of CSF in healthy persons.
    For the rapid development studies under the polio especially important were two discoveries. The first is the establishment in 1949 and 1951, in the USA and in the USSR existence of three independent antigenic types of poliovirus, practically does not create in the body against each other immunity, but for all other properties belonging to the same species of parasite. This fact had a great influence on the work on creation of preventive vaccines, as well as on the preparation of a full diagnostic immune sera.
    The second discovery: poliovirus can successfully isolate the crops susceptible tissue, not containing nerve cells, and quickly and accurately identify their purely vitro methods without resorting to the previously mandatory experiments on monkeys and rodents.
    It is established that the poliovirus cause the death of cells in culture (cytopathogenic effect) and stops acid metabolism cultures.
    Many laboratory scientists of several countries very quickly confirmed and developed this discovery, creating a modern highly diverse methods of laboratory examination of the sources of polio infection with the definition of antigenic types and titles of poliovirus types of antibody titers with the help of test-tube reactions.
    Thanks to the wide use of cultural methods of selection and serological identification of poliovirus from the contents of the intestine or nasal patients and suspected patients in healthy people showed that. in addition poliovirus, are regularly detected and representatives of a very large group of non-polio intestinal viruses, enteroviruses (see Enterovirus diseases, enteroviruses).
    Now it is accepted to include poliovirus in the group of enteroviruses, consisting of more than 60 representatives and, in turn, include enteroviruses in even more numerous taxonomic group of viruses of Picorna that have some characteristics in common. To a group of viruses of Picorna rank, except poliovirus, Coxsackie and ECHO viruses, rhinoviruses person, some new types of viruses person needing additional classification and similar enterovirus group of individual viruses isolated from the intestines of animals.
    Polioviruses are characterized by the following properties. The size of particles (virions)defined in the electronic microscope, or method of filtration through a graduated membrane filters are within 17-28 MMK. The form of particles - cubic-symmetric, icosahedral type; in the center of the virion is RNA molecule surrounded by a protein subunits, or capsomere. Clusters of virions in the cytoplasm affected susceptible cells can be in the form of crystals. RNA virus has infectious properties sensitive ribonuclease and resistant to desoksiribonukleaza, becomes red acridinium. Viral fusion is not suppressed 5-floradix-uridine. Exempt from protein antigens infectious RNA virus cannot be neutralized through viral anticorodal. Poliovirus is resistant to air and sodium deoxycholate, due to the absence of lipids. The poliovirus can withstand temperatures up to 50 degrees for 4 hours in the presence of 1 M MgCl2 or other salts with divalent cations. Polioviruses not tolerate desiccation, but quite well remain in a frozen state, or in 50% glycerin.


    In the laboratory strains of poliovirus can be propagated and maintained in the primary or in human cell cultures kidney monkeys or humans and some other transplantable tissue cultures with the intermediate storage of the virus in the frozen state. Reproduction of poliovirus in susceptible cells is accompanied cytopathogenic effect and reducing accumulation of acid in culture because of the death of a part of cells. The latter is registered in the so-called color of the sample by different indicators of acidity in infected and in the control cell cultures.
    The most important property of poliovirus - the ability to cause in humans and monkeys paralytic disease with a characteristic lesion of nervous cells of the anterior horns of the spinal cord. However, this property is different strains of poliovirus is very variable, and along with fully virulent there are strains with reduced neurovirulency.
    With the help of selection were obtained genetically homogeneous and stable populations, or options vysokointensivnykh strains of the three types of poliovirus, completely harmless to humans oral vaccination.
    Poliovirus type I is more epidemiological significance, as it most often caused epidemics of poliomyelitis. Poliovirus type III sometimes may also cause outbreaks of polio and some severe cases of the disease. Less often were isolated from patients poliovirus type II, although, judging by the frequency of detection of antibodies, II type poliovirus very widely circulated among the population, not causing the clinical symptoms of the infection. However, over the last 7-10 years in the literature has been reported quite large outbreaks of polio in Nicaragua, China and other countries, with the main role played poliovirus type II.
    In addition to the three types of poliovirus, with some reservations belong to the etiological agents of polio also enterovirus - Coxsackie virus VII of the type that, unlike all other Coxsackie virus (see)that can cause poliomyelitiso paralytic illness in humans, as in the experiment - the monkeys and cotton rats.
    Poliovirus belongs to strictly anthroponosis pathogens. It multiplies in the wall of the digestive tract, including the top pharyngeal ring, as well as in the brain after penetration into the Central nervous system It can be found in the intestinal content already in the incubation period (sometimes it is found in Kale 20 days before the beginning of the disease) and almost 100% of cases in the first two weeks of the disease followed the fall of the isolation rate of up to 5-6 weeks. You can often find poliovirus in Meyerovich plaques and tonsils. Intense emission of poliovirus possible with pharyngeal mucus 2-3 days before the first symptoms appear and in 3, less 10 days after illness onset.
    In blood poliovirus is short incubation period and very rarely detected after illness onset. Polio virus in the blood can be masked by antibodies, engaging with them in a convertible link. In the cerebrospinal fluid poliovirus was detected extremely rare. Non-polio enteroviruses, on the contrary, can often stand out from blood and spinal fluid.
    Cm. also Viruses.