[State of collective immunity against poliomyelitis in some regions of Russia].

AIM: Study the state of collective immunity against poliomyelitis in 7 regions of Russia in the last 3 years. MATERIALS AND METHODS: 2579 sera were studied for antibodies against poliomyelitis virus. Antibodies (AT) against 3 types of viruses were determined in neutralization reaction in RD cell culture, the state of collective immunity in the examined individuals was evaluated by the percent of individuals with AT against a type of poliovirus and geometric mean AT titer. The circulation of wild polioviruses was judged by the presence of strain specific AT against wild and vaccine viruses in the examined children (311 sera were studied). RESULTS: The indicators of collective immunity against poliomyelitis in both select examined regions and select age groups were generally high. The data obtained allow to make a conclusion that the quality of vaccine prophylaxis in the examined regions is good. Introduction of wild poliovirus type 1 from Tajikistan in 2010 caused disease in 7 residents of Russia whereas an epidemic that had affected more than 700 individuals emerged in Tajikistan. CONCLUSION: The studies carried out confirmed the necessity to continue qualitative poliomyelitis vaccine prophylaxis in the country despite the lack of circulation of wild polioviruses that can be introduced at any time.

[Possible method of eradication of poliomyelitis as an infection].

Problem of poliomyelitis eradication is examined in the review. After the eradication of wild poliovirus, vaccine poliomyelitis virus continues to circulate in the human population. In rare cases it can cause the development of the disease. The authors describe disadvantages of the use of oral and inactivated poliomyelitis vaccines and note that by using oral poliomyelitis vaccine and eradication only of wild poliovirus, eradication of poliomyelitis as an infection will not succeed. As one of the approaches to reach this goal the authors propose the use of various enterovirus interference. Use of live enterovirus vaccine is described and its advantages and disadvantages are examined.

[Use of the cultural variants of Coxsackie A viruses in virological practice].

Coxsackie A viruses belong to the enteroviruses, the isolation of which from infectious materials and further cultivation are possible only when laboratory animals are infected. The authors could adapt the strains of 17 of 23 serotypes of these viruses to RD cell culture. The strains of 8 serotypes were additionally adapted to Vero cell culture. The cultural variants of Coxsackle A viruses were used to prepare immune sera. The Bacterial and Viral Agents Enterprise, M. P. Chumakov Institute of Poliomyelitis and Virus Encephalitides, Russian Academy of Medical Sciences, has set up the production of bacterial and viral drugs based on the cultural variants of 5 Coxsackie A virus serotypes. The cultural variants of 14 Coxsackie A virus serotypes were used to carry out a virus neutralization test. Examination of more than 600 children from Moscow and the Moscow Region showed the wide circulation of individual Coxsackie A virus serotypes. It also demonstrated a drastic reduction in Coxsackie A-7 virus circulation in the past 50 years.

[Poliomyelitis eradication is a visible unsolved problem in the coming years].

The WHO global polio eradication initiative launched in 1988, by eradicating wild polio viruses, was to be completed in 2000. The initiative had not been implemented. Enormous work has resulted in a reduction in the number of poliomyelitis cases worldwide from 350,000 to 1,500-2,000 a year. However, the incidence of poliomyelitis does not and is unlikely to stop by the newly fix date--2013. The reason is that vaccine-derived polio viruses that are pathogenic in nature remain and long circulate in the earth. The circulation in human beings leads to the restoration of their neurovirulence and ability to induce severe paralytic diseases. In 1999 the WHO reported the global eradication of wild polio virus type 2 and therefore there should not be diseases caused by polio virus of this type. Nevertheless, the virus-induced diseases continue to emerge. About 300 cases of diseases induced by vaccine-derived poliovirus type 2 had been notified by July 2009. At present, there is no way to eradicate all polio viruses worldwide so the case in point may be only to stop their transmission or minimize morbidity with on-going vaccination.

[Herd immunity against poliomyelitis in children in the Moscow Region].

Herd immunity against poliomyelitis was studied in 1391 children and adolescents from 10 towns of the Moscow Region. It was ascertained that the values of herd immunity against poliomyelitis virus type 1 were high everywhere and those of herd immunity against poliomyelitis virus type 2 were high and very high in 9 towns and below the WHO minimum levels (80%). The values of herd immunity against poliomyelitis virus type 3; they were lower than the required minimum in 2 towns and very low in 2 other towns arouse alarm. The study of strain-specific antibodies to vaccine-derived and wild polioviruses has demonstrated that wild poliomyelitis viruses have not circulated in the areas of the examinees in the past decade.

[Immunity to poliomyelitis in adult population of Moscow region. Role of vaccine and wild polioviruses in its formation].

Assessment of immunity to poliomyelitis in adults from 8 towns of Moscow region was conducted. Low levels of population immunity against some serotypes of poliovirus in several towns have been found. At the same time, these levels were high and very high in other towns. Measurement of levels of strain-specific antibodies to vaccine and wild polioviruses demonstrated wide circulation of wild polioviruses during past decades which had significant influence on formation of immunity. Substantial number of non-immune adults represents favorable conditions for circulation of vaccine polioviruses after cessation of vaccination, which, in its turn, could result in reestablishment of their neurovirulent properties and subsequent reemergence of poliomyelitis.

[Collective poliomyelitis immunity in the adult population and its impact on eradication of this infection].

Collective poliomyelitis immunity was studied in 6339 donors from 19 towns and cities of Russia. Its stress substantially varied in different towns and cities. Studies of strain-specific antibodies to vaccine and wild viruses of poliomyelitis in donors from 4 towns established that the immune persons were more in the town where wild polioviruses had previously circulated than in those where the circulation of wild polioviruses had been limited and immunity resulted from vaccination. Circulation of vaccine viruses and reversion of their neurovirulent properties should be expected in the town where there are low collective poliomyelitis immunity rates. It is concluded that it is impossible to eradicate poliomyelitis as infection today; it is possible only to eliminate the disease if further vaccination of children is performed with live poliomyelitis vaccine.

[Serous meningitis].

During the second half of the 1950s serous meningitis and other enterovirus-induced diseases played one of the leading roles in human pathology in the world. Since the introduction of oral poliomyelitis vaccine (OPV) into wide medical practice from the beginning of the 1960s and during the subsequent decades the number of epidemics and the morbidity level in enterovirus-induced diseases sharply dropped. This was probably due to the interference of enteroviruses circulating in nature and vaccine polioviruses in the intestine of vaccinated children. At the beginning of the XXI century a tendency towards a growth in the morbidity of serous meningitis of enterovirus etiology was noted. This growth was probably due to a sharp decrease in the level of revaccinations of children with OPV. At the age of 2 to 14 years, most affected by enteroviruses, children were not vaccinated with OPV and they were thus left unprotected. The materials on the epidemiology of serous meningitis and recommendations on etiological diagnosis, as well as on the patients hospitalization and the vaccination of children with OPV as a nonspecific antiepidemic measures based on the phenomenon of virus interference are presented.

[Enteroviruses in the XX and XXI centuries].

The modern view of the role of enteroviruses in the eradication of poliomyelitis is presented. Enteroviruses were discovered in the XX century. In the 1950s they caused great epidemics of poliomyelitis and serous meningitis in many countries of the world. The introduction of oral poliomyelitis vaccine (OPV) into medical practice made it possible to eliminate the epidemics of poliomyelitis in a short time. Poliomyelitis morbidity was reduced to sporadic cases and in a number of regions disappeared. OPV produced non-specific influence also on the epidemics of serous meningitis, as well as on a case incidence. The eradication of poliomyelitis viruses and the cessation of immunization with OPV will not result in eradication of paralytic diseases. Paralytogenic viruses of 20 serotypes circulate in nature, and some of these viruses are capable of causing the outbreaks of severe paralytic diseases. The authors propose either to retain immunization with OVP as tour immunizations with monovaccine of type 2, or to create new live enterovirus vaccines on the basis of avirulent enterovirus strains.

[Strain-specific antibodies as an indicator of the circulation of wild poliomyelitis viruses and their role in the formation of collective immunity in the population]. / Shtammospetsificheskie antitela kak pokazatel' tsirkuliatsii dikikh virusov poliomielita v populiatsii i ikh roli v formirovanii kollektivnogo immuniteta u naseleniia.

Essential differences in the intensity of collective immunity to poliomyelitis in the donors of Moscow and Kaluga were established. To find out the nature of high characteristics of collective immunity to poliovirus, types 1 and 2, in the donors of Kaluga, strain-specific antibodies to wild and vaccine polioviruses were studied. In a considerable number of donors strain-specific antibodies to poliovirus, types 1 and 2, were detected. This made it possible to presume a sufficiently wide circulation of these viruses among the population of the city in the middle of the 20th century and, as a consequence, high level of collective immunity appeared. Strain-specific antibodies to poliovirus of type 3 were rarely detected. This made it possible to suggest that the circulation of viruses of this type among the population was limited. Immunity to viruses of this type was due only to immunization. For this reason the characteristics of collective immunity in the donors of Moscow and Kaluga coincided. The detection of strain-specific antibodies to poliomyelitis virus allowed to retrospectively form the opinion of the spread and time of the circulation of wild poliomyelitis viruses in the population.

[How poliomyelitis is to be eradicated completely]. / Kak zavershit' likvidatsiiu poliomielita.

In 1988 the World Health Assembly resolved to eradicate poliomyelitis globally by the year 2000. The work continues. The problem arose how to quit the system of mass immunization with oral poliovirus vaccine (OPV) without trouble and to achieve the disappearance of polioviruses worldwide. After the cessation of the OPV use a certain number of vaccine viruses may remain that will circulate among the ever growing number of nonimmune population. Live enterovirus vaccines prepared from nonpathogenic serotypes of ECHO virus are proposed for application to stop the circulation of vaccine poliovirus. These vaccines will make it possible to eliminate the remaining vaccine viruses from circulation and to complete the process of worldwide poliomyelitis eradication.

[State of collective immunity to poliomyelitis in Moscow donors]. / Sostoianie kollektivnogo immuniteta k poliomielitu u donorov Moskvy.

Immunity induced by immunization with oral poliomyelitis vaccine has long been considered to last for life, similarly to immunity developing after infection with wild poliomyelitis virus. Vaccine virus cannot circulate among the immune population for a long time. The vaccination of children against poliomyelitis, carried out in the course of many years, has made it possible to suggest that a considerable number of immune persons were present among the adult population. The examination of 1,030 Moscow donors has revealed that antibodies to poliomyelitis virus of types 1, 2 and 3 were detected in 47.3%, 45.5% and 76.4% of the examinees respectively, the values of the average geometric titers being low. It is known that passages of poliomyelitis vaccine virus through nonimmune persons may result in emergence of revertant viruses with increased neurovirulence. The nonimmune adult population, especially the mothers of vaccinated and revaccinated children, may serve as favorable environment for the circulation of vaccine viruses and the appearance of revertant viruses.

[Strain-specific antibodies to wild poliomyelitis viruses as an index of the circulation of these viruses in a surveyed territory]. / Shtammospetsficheskie antitela k dikim virusam poliomielita kak pokazatel' tsirkuliatsii étikh virusov na obsleduemoi territorii.

In response to vaccination or infection with wild poliovirus, some children can finely differentiate the virus structure and respond by forming strain-specific antibodies. The analysis of strain-specific antibodies indicates that in epidemically unfavorable regions strain-specific antibodies to wild poliovirus strains may prevail over those to vaccine poliovirus strains in children or occur with equal frequency. In epidemically favourable regions strain-specific antibodies to vaccine poliovirus strain significantly prevail in children or may be absent at all. The analysis of strain-specific antibodies makes it possible to retrospectively judge on the circulation of wild viruses in the surveyed region.

[Live enteroviral vaccines for the emergency nonspecific prevention of mass respiratory diseases during fall-winter epidemics of influenza and acute respiratory diseases]. / Zhivye énterovirusnye vaktsiny dlia ékstrennoi nespetsificheskoi profilaktiki massovykh respiratornykh zabolevanii vo vremia osenne-zimnikh épidemii grippa i ostrykh respiratornykh zabolevanii.

The results of the 3-year controlled trials of a new method of nonspecific urgent prophylaxis of influenza and acute respiratory diseases (ADR) by immunization of healthy adults with standard live enterovirus oral vaccines, introduced in 2-3 administrations at intervals of 7-10 days, at the initial stages of autumn and winter epidemics are presented. Observations, carried out in three republics, covered more than 150,000 persons immunized with enterovirus interferonogenic vaccines. A considerable decrease in morbidity rate among the vaccinees was achieved (on the average, by 3.2 times) in comparison to that among nonimmunized subjects. The method of nonspecific prophylaxis with live enterovirus interferonogenic vaccines is recommended during outbreaks of diseases induced simultaneously by several causative agents of influenza and ARD, as well as by pathogenic enterovirus strains.

[Characteristics of the genome of poliovirus type 3 isolated from patients with poliomyelitis in Moldavia]. / Kharakteristika genoma shtammov poliovirusa tipa 3, vydelennykh v Moldavii ot bol'nykh poliomielitom.

Twelve poliovirus isolates of serotype 3 from patients with paralytic poliomyelitis have been analyzed by oligonucleotide mapping of the viral genomes. All the studied strains were isolated from patients in different regions of the Moldavian SSR in 1982. The maps of all isolates are similar but they do not practically possess any large oligonucleotides characteristic of the vaccine strain of type 3 poliovirus. It is concluded that a wild neurovirulent strain of type 3 poliovirus, that circulated in 1982 in the Moldavian SSR was the cause of paralytic poliomyelitis cases. All the studied isolates are suggested to have been derived relatively recently from the common ancestor.

[Long-term observations of dynamics of collective immunity to poliomyelitis in vaccinated children]. / Dlitel'nye nabliudeniia za dinamikoi kollektivnogo immuniteta protiv poliomielita u privitykh detei.

Examinations of children in the Moscow region in 1972 revealed low values of the herd immunity to poliomyolitis. This was suggested to be due to improper organization of vaccination of children. The regional health authorities took special measures for better organization of vaccination. The examinations two years later, in 1974, showed nearly 90% of children between the ages of 1 and 6 years to have antibody to all three types of poliomyelitis virus. The geometric mean antibody titre increased. In children of 10--14 years the heard immunity values did not differ significantly from those found in 1972. It is concluded that proper vaccination gives sufficiently intensive immunity nearly in 90% of children. It was found that in children vaccinated 10--12 times the herd immunity persists without significant changes for 3 years after the last vaccine feeding; at 4 years, however, some values of the herd immunity, particularly to poliomyelitis virus type III, were significantly lower than the original values. It is suggested that it is likely to be expedient to revaccinate 4-grade schoolchildren and to reduce the total number of vaccine feedings during the first 4 years of life.

[Status of herd immunity to poliomyelitis in children in the Moscow region]. / Sostoianie kollektivnogo immuniteta k poliomielitu u detei v Moskovskoi oblasti

The paper presents the results of 3-year observations of the status of herd immunity to poliomyelitis in 7 towns of the Moscow region. In individual years antibody for poliomyelitis virus of 3 types was found in 63-74% of the examined children and from 2.7 to 7.5% of children were triple-negative. Insufficient levels of herd immunity to poliovirus types I and III were found. Some factors are analysed which could have some influence on the decline of herd immunity.