Modern epidemiology of hepatitis A in the north-western region of the Russian Federation.

The epidemiological features of hepatitis A virus (HAV) infection were studied in eleven territories located in the north-western region of the Russian Federation. The dynamics of HAV infection in Russia and in the region were evaluated during a 17-year period. The age-specific incidence was calculated and 229 305 patients with acute HAV were identified.

[Epidemiologic indices of cervical cancer morbidity in areas with various levels of industrial pollution].

While general cervical carcinoma morbidity is on the decline in most of the surveyed Russian Federation areas characterized by varying levels of industrial pollution, the heavily industrialized region of Salavat revealed a different tendency. Its level was 1.6 times (p<0.

[Characteristics of the manifest and latent components of the hepatitis A epidemic process in cities of Russia].

Seroepidemiological study of hepatitis A (HA) morbidity was carried out in three Russian cities, with different levels of HA morbidity. The study included the analysis of HA morbidity for 22 years, the determination of antibodies to HA virus (anti-HAV) in 2,958 healthy persons aged 0-12 months to 40 years and older. In one of the cities 7 isolates of HA virus were obtained from unrelated sources and the genotypes of the virus were determined.

[The theoretical bases of the epidemiology of viral hepatitis B].

In this article the development of the concepts concerning the sources of hepatitis B virus in the second half of the XXth century is analyzed and the importance of patients with manifest and latent forms of chronic infection as the main reservoir of the infective agent is substantiated. The scheme of the mechanisms and paths of the transmission of hepatitis B virus is proposed, the mechanism of transmission understood only as the natural ways of the spread of the infective agent which result from its evolutionary development and can be only slightly controlled at present. The study revealed that the present decrease of morbidity rate is greatly determined by measures of the social character, aimed at the elimination of the artificial paths of virus transmission.

[The morbidity and immunological structure of the population in viral hepatitis A at different phases in the development of multiyear epidemic cycles].

For the first time population immunity to virus hepatitis A has been studied during three different phases of prolonged morbidity cycles of this infection, and the results of this study have been compared with the data on morbidity in different age groups. Pronounced variability of the immunological structure of the population in different age groups, found to be related to the dynamics of hepatitis A morbidity, has been established. Fluctuations in immunity level are most pronounced among children aged 1-6 and 7-14 years, having the least proportion of seropositive persons.

[An epidemiological assessment of the chronic carriage of the hepatitis B virus surface antigen and other markers of this infection].

On the basis of prolonged (up to 10 years) observations of chronic HBsAg carriers (87 persons) slowly progressing chronic hepatitis B virus infection was detected in most of them (57.5%). In these persons up to 6 negative results of the analysis for the presence of HBsAg were periodically obtained, with the subsequent renewal of HBs-antigenemia.

[The effect of temperature and ionic strength on the electrophoretic motility of synthetic DNA fragments].

The following DNA fragments were studied: T5A5, U5G5, C5G5, RI (CCGAATTCGG), and RV (CCGATATCGG). The ligated decamers were run on 8% polyacrylamide gel. The PAGE anomaly was measured by the R-factor.

[Localization of melted regions in supercoiled DNA by means of chemical modification].

Diethyl pyrocarbonate was used as a probe in mapping early melting stages in supercoiled DNA. It was shown that in the process of early melting of pAO3 DNA two denatured regions (about 15 b.p.

[Viral infection markers in foci of chronic hepatitis B].

The intensity of detection and time course of the main markers of virus infection were studied in subjects who had contacts with patients in 74 foci with chronic active hepatitis, 52 with chronic persisting hepatitis and 41 with chronic hepatitis of unknown etiology. A high (up to 80.7%) frequency of detection of HBsAg, anti-HBs, anti-HBc was established in contact subjects which showed a trend of growth with the increase of the time of their contact with the source of infection.

[Methodological bases for the study and the patterns of the seasonality of viral hepatitis A].

On the basis of the study of the data on the incidence of viral hepatitis A in one of the districts of a big city for 20 years the authors come to the conclusion on the advisability of a comparative study of the monthly changes in the incidence of hepatitis A within individual uniform morbidity cycles covering the periods of many years and the use of average monthly data for many years for plotting the typical curve, as well as the use of the simplified for the calculation of the upper limit of annual morbidity. Similarities and differences in the monthly dynamics of morbidity in the years of high and low morbidity levels have been revealed, and the age group of the population (20-39 years) which ensures the continuity of the epidemic process all the year round has been determined. The factors contributing to the seasonal activation of the epidemic process start operating in June among schoolchildren aged 11-14 years, and later their operation spreads to other groups of the population.

[Monthly dynamics of the epidemic process in viral hepatitis B].

Monthly fluctuations in the number of registered cases of acute viral hepatitis B and HBsAg carriership have been studied. The study has revealed that, similarly to other infectious diseases, viral hepatitis is characterized by monthly fluctuations in the intensity of the epidemic process. Such fluctuations are characteristic of all known clinical forms of this infection; they are determined by the specific pathogenetic features of the process and by the ways of the transfer of the virus.

[Patients with chronic viral hepatitis as sources of infection].

Dynamic observation on 126 foci of infection formed by patients with manifest forms of chronic hepatitis B, 41 foci of chronic hepatitis of unknown etiology, and 37 foci formed by chronic "healthy" carriers was made. In the foci of type 1 the epidemic process developed intensively and was manifested mainly by HBsAg carriership in persons having had contacts with the patients. During the period of observation 43.

[Characteristics of the epidemic process manifested as chronic viral hepatitis].

The incidence rates of chronic viral hepatitis in Leningrad over the period of 1962-1984 were studied. The tendency towards a rise in total morbidity because of increased incidence of chronic hepatitis B was shown to appear in recent years. This increase in morbidity was mainly due to its rise among adult males and children, which led to the shift of morbidity to younger age groups.

[Use of highly sensitive methods of detecting hepatitis B virus markers for studying epidemic foci of hepatitis B].

Passive hemagglutination test (PHA) was found to detect HBsAg in the population living outside the hepatitis B virus foci 1.5-fold as frequently as counter immunoelectroosmophoresis technique, and anti-HBs by enzyme immunoassay 14-fold as frequently. As compared with normal population, the contacts in foci had 4-fold higher levels of HBsAg carrier state and twice as high rates of detection of anti-HBs.

[Epidemiological characteristics and the importance of carriers of the surface antigen of the hepatitis B virus (HBsAg)].

The occurrence of HBsAg carriership in Leningrad has been found to be 1.4% according to the results of countercurrent immunoelectroosmophoresis (CIEO) and 2.1% according to the results of the passive hemagglutination (PHA) test.

[Diagram of DNA states in water-salt-ethanol mixtures].

A detailed study of the behaviour of DNA in water-salt-ethanol mixtures has been carried out. We have made a diagram of DNA states in these mixtures and established the ranges of ethanol and salt concentrations corresponding to A and B conformations of DNA. We have also identified the ranges of strong DNA aggregation characterized by intense psi + and psi- CD spectra.