Multiyear and seasonal hepatitis A morbidity in different population age groups in certain areas

At the areas with high activity of hepatitis A (HA) epidemic process the duration of epidemic cycles was shown to differ, the intervals between the peaks of morbidity increasing in older age groups. The beginning of seasonal rises exceeding the average annual HA morbidity level in different age groups was found to depend on the activity of the epidemic process. At the areas with the highest activity of the epidemic process children aged 1-2 years were the first to be affected by the seasonal rise of HA. Stable direct correlation between HA morbidity levels at the beginning of seasonal rises and some markers indicative of unfavorable sanitary conditions (the size of the fly population, the purity of water samples deviating from the requirement of the Government Standard) during the preceding year was demonstrated.     

The structure of the population morbidity with specific intestinal infections in areas with different intensities in the development of the epidemic process and an evaluation of its manifestations]

The authors analyze the morbidity structure in five enteric infections (typhoid fever, dysentery caused by Shigella flexneri and Shigella sonnei, hepatitis A, and hepatitis E (non A, non B) with the fecal/oral mechanism of the agent transmission) in three towns of Turkmenia and in the town of Novomoskovsk, Tula Province. The incidence of S. sonnei dysentery was found higher in Novomoskovsk and that of the rest enteric infections under study in Turkmenia. The incidence of typhoid fever and hepatitis E was the highest among schoolchildren and adults, whereas preschool children suffered mostly from hepatitis A and S. sonnei dysentery. The authors discuss the specific features of the epidemic process manifestation in enteric infections.     

A trial of using immunoglobulins of known specificity for preventing hepatitis A in regions with high epidemic activity

The economic effectiveness of immunoglobulin prophylaxis (IGP), carried out among children aged 1-3 at the beginning of a seasonal rise in hepatitis A (HA) morbidity with high coefficients of protection (80-85%), was directly related to the activity of the epidemic process. Preparations with sufficiently high content of antibodies to HA virus sharply decreased the manifestation of this infection. The detection rate of the manifest forms of the infection among children covered by prophylactic measures in the foci of HA was considerably lower than among children who had not received the preparation. IGP exerted no essential influence on the dynamics of the formation of population immunity. A high share of children aged 3-4 years, seropositive to HA virus (up to 90%), validates the inadvisability of carrying out IGP in older groups of children.     

Morbidity and mortality in acute viral hepatitides in a hyperendemic region. The role of viral hepatitis E

Official annual statistical data on morbidity in acute viral hepatitides (AVH), including the number of lethal cases, for 1985-1995 were analyzed. Mortality rates per 100,000 of the population at the period of 11 years were calculated for different age groups, sex and the place of residence. 396 and 99 patients were examined for the presence of serological markers of hepatitides A, B and E, respectively, at the periods of epidemic rises in morbidity and satisfactory epidemic situation. In the course of 11 years AVH caused the death of 22,405 persons. In 1985-1987 the average mortality level (ML) reached 12.3-17.8 per 100,000 of the population (with morbidity being 1,200-1,400 and was essentially higher among the rural population in comparison with the urban population. During these years the highest ML, was registered among children aged 0-2 years (190-50 per 100,000) and, among adults, mainly among women aged 20-29 years (21.4-19.6 per 100,000). During the years when the epidemic of AVH was absent, ML among these groups was essentially lower: 40-20 among children aged 0-2 years and 4-5 among women aged 20-29 years. In 1987 in the Fergana Valley hepatitis E was detected in 72.2% of all examined patients, and in the southern areas of the country in 68.7%. A sharp rise on mortality among women of the productive age at the period of the epidemic rise of AVH morbidity in the endemic region indicated that this epidemic was linked with hepatitis E. High ML among young children may be indicative of a highly unfavorable course of hepatitis E in the group of infants, which had never been registered before. This newly established regularity may be used for the retrospective diagnostics of the outbreak of hepatitis E.     

Meningococcal infection in the Uzbek SSR

The epidemiological characteristics of meningococcal infection in Uzbekistan during the period of 8 years since its last epidemic rise in 1972 is presented. Differences in the intensity of the epidemic process among the urban and rural population due to a considerable isolation of most of the rural populated localities from the district centers and the low population density in the republic have been established. The seasonal distribution of the infection had a winter-spring character in urban areas and a spring character in rural areas. 63.4% of all cases were children under 14 years. In cities a high morbidity level among adolescents and young people was determined mainly by visitors from rural areas. A high epidemiological importance of healthy carriers, predominantly schoolchildren and young people was established. The immunological studies of humoral immunity in different groups of the population indicate that the process of immunization was more rapid in cities.     

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.     

Incidence of meningococcal infection in the RSFSR]

The authors present characteristics of meningococcus infection epidemic process in case of sporadic cases and under epidemic conditions (1965--1976). A scheme of epidemiological analysis suggested by the authors permitted to differentiate and to record the incidence of various clinical forms of meningococcus infection, to present data on the age, seasonal characteristics, focality, etc. Comparison of intensive morbidity indices for 10 years, both at the individual administration territories and in the Republic as a whole demonstrated morbidity level of 1.5--2.0 to be one of prognostic signs of the beginning epidemic. The main features differentiating the sporadic and epidemic morbidity periods were revealed. The presence of group diseases, a greater percentage of children among those who fell ill, and marked signs of seasonality and territorial difference characterized the period of rise caused by meningococcus of serological group A.     

The results of a serological study of viral hepatitis patients and healthy subjects under the conditions of a high-intensity epidemic process in hepatitis A

The activity of the involvement of preschool children of different ages in organized groups into the epidemic process of hepatitis A and the state of population immunity in elderly persons have been studied. Under the conditions of the intensive development of the epidemic process the active involvement of preschool children into this process as early as at the age of 1-2 years has been noted. At periods between epidemics the active circulation of the infective agent in the presence of decreased manifestations of the disease has been revealed.     

Problems of the epidemiology of viral hepatitis in Ryazan Province

The analysis of some features of the course of the epidemic process of viral hepatitis on the territory of the Ryazan region is presented. Periodic rises and falls in viral hepatitis morbidity, varying in their regularity (4-6 years), have been registered in the region. The general level and the seasonal distribution of viral hepatitis morbidity are determined by the morbidity rate among children, the increase in the proportion of children of senior school age being observed in recent years.     

The results of a seroepidemiologic study of Newcastle dysentery

Differences in the monthly distribution in the number of seropositive individuals among children and adults in years with different intensity of the epidemic process have been revealed. Immunity in cases of dysentery caused by S. newcastle reflects the yearly and seasonal activation of the epidemic process in this Shigella infection both in children and adults, the seroconversion characteristics observed in the year of a high morbidity level being a more objective criterion indicating the beginning of the activation of the epidemic process in dysentery caused by S. newcastle in comparison with the commonly registered morbidity level.     

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. The seasonal rises of morbidity in winter and spring were found to be characteristic of viral hepatitis.     

Retrospective epidemiologic diagnosis of viral non-A, non-B hepatitis with a fecal-oral mechanism of transmission of the causative agent

The possibility of the retrospective epidemiological diagnosis of viral hepatitis non A, non B with the fecal-oral mechanism of the transfer of infection in three cities of Central Asia on the basis of the analysis of the dynamics of registered hepatitis A morbidity is shown. With the irregularity of morbidity levels among the total population being characteristic of all three cities, in Andizhan one rise in morbidity within a period of 3 years (1975-1978) and in Tashauz one rise within a period of 5 years (1975-1980) were registered. The analysis of the dynamics of morbidity observed in individual age and social groups showed that these rises, especially those registered in 1976 in Andizhan and in 1977 in Tashauz, were determined by morbidity levels among school children and adults. This is also true for a rise in morbidity rate registered in Tashauz in 1985. In Andizhan the highest morbidity rates among adults were registered in districts insufficiently equipped with modern amenities. Cases of infection registered as hepatitis A (HA) among persons immune to HA at territories with high intensity of the epidemic process of HA at the above-mentioned periods seem to be due to viral hepatitis non A, non B with the fecal-oral mechanism of the transmission of the infective agent.     

A trial to decrease hepatitis A morbidity in Dzerzhinsk, Gorki Province

The results of experience in the comparative evaluation of the preseasonal immunoglobulin prophylaxis in two towns of the Gorki Province are presented. The work substantiates the economic and epidemiological effectiveness of immunoglobulin prophylaxis at the territory, relatively safe with respect to hepatitis A, under the conditions of its realization in the year of the predicted rise of morbidity, the timely organization of immunoglobulin prophylaxis (from July to the first half of October) and the coverage of "organized" children, exceeding 90%.     

The formulation of epidemiological hypotheses by using the methods of multivariate statistical analysis

The work demonstrates the main approaches to the use of the methods of multidimensional analysis for the creation of a hypothesis on the mechanism of the epidemiological process of dysentery in organized groups. The main risk factors have been established, and their role in the formation of annual, all-the-year-round and seasonal dysentery morbidity has been quantitatively evaluated. The results of analysis show the existence of diverse variants of the alimentary route of the transmission of infection, maintaining the epidemic process of dysentery, and the necessity of differentiating measures for the prophylaxis of all-the-year-round and seasonal morbidity.     

Hepatitis A in Estonia (1990-1999)

During recent 10 years (1990-1999) essential changes occurred the epidemiology of viral hepatitis A (VHA) in Estonia: simultaneously with a decreased level of morbidity (morbidity rate per 100,000 of the population was 78.4 in 1990 and 7.7 in 1996, or 1,241 and 112 cases, respectively), a shift in the age structure of patients from children of preschool age to older age groups took place. Everyday contacts were the main established route of VHA transmission in recent years, but in more than 80% of cases the risk factors of the virus transmission remained obscure. During the regional outbreak of VHA in North Estonia in 1998 (937 out of 989 cases registered in the country) a rise in morbidity was observed among young people aged 15-29 years, when a wide spread of parenteral viral hepatitides B and C and drug addiction were registered in this region. During this outbreak VHA was transmitted mainly through everyday contacts. Still the considerable prevalence of injection drug users who practiced the group use of syringes and needles and took drugs from common containers, a sufficiently high level of the mixed forms of the disease (more than 18% of all registered cases of VHA), detected for the first time, make it possible to suggest that the parenteral transmission route could appear among persons belonging to the above mentioned group. Vaccination is regarded as the most effective measure for the prophylaxis of VHA.     

The epidemic process of an acute streptococcal respiratory infection in large organized collectives of children

The study of the specific features of the development of the epidemic process of scarlet fever, tonsillitis, and acute respiratory diseases (ARD) in two large organized groups of children revealed the presence of some differences which depended on the character of prophylactic measures taken in these groups. Thus, in the absence of prophylaxis with bicillin a pronounced increase in the level of carriership, accompanied by an increase in the infective capacity of carriers, was noted. This resulted in a high level and unfavorable dynamics of morbidity in scarlet fever, tonsillitis, and ARD. On the contrary, the use of prophylaxis with bicillin ensured the stability of the level of carriership, while the infective capacity of carriers was not pronounced. At the same time a rise in ARD morbidity was insignificant, and morbidity in scarlet fever and tonsillitis was reduced to nil.     

Epidemiologic analysis morbidity with meningococcal infections in the USSR]

The authors present the analysis of the incidence of epidemic cerebrospinal meningitis in the USSR from 1937 to 1974, and of meningococcus infection from 1965 to 1974. A rise of the meningococcus infection incidence from 1969 to 1974 was recorded 28 years after the elevation of 1940-1942 and was 1.5 times below this latter rise. The rise in 1969-1974 was characterized by marked signs peculiar to the infection with the droplet transmission mechanism; among those who contracted the disease prevalence was seen among children aged under 14 years (63-72%). A marked affection of juveniles was noted. Three types of the dynamic of the meningococcus infection incidence in the republics located in different climatic-geographical zones of the USSR were noted: slow, gradual increase of the level, interrupted and explosive. Such character was determined in the dynamics of the seasonal elevations of morbidity. Antiepidemic measures including a complex of nonspecific measures could not be assessed as sufficiently effective. This finds reflection in the natural course of the epidemic process of the meningococcus infection which remains uncontrolled. From the patients with generalized form of the disease meningococci of group A were isolated in 80-100% of cases, from the number of those typed. The group-specific reference of the nasopharyngeal strains depended on the epidemic situation: strains of serological group A prevailed at the period of the morbidity elevation, and other serological groups (particularly of C and B) increased at its decline.     

Epidemiological pattern of scarlet fever in recent years

During the period of 1953-2001 scarlet fever morbidity level fluctuated from 670.3 to 65.9 per 100,000 of the population in Moscow and from 531.9 to 35.0 per 100,000 of the population of the Russian Federation. In recent years an increased morbidity was more pronounced in Moscow than in the Russian Federation as a whole. Children formed the greater part of scarlet fever patients, the cases of scarlet fever among children in Moscow occurring more often than, on the average, in Russia. As before, annual morbidity among children attending children's institutions was higher 3- to 4-fold than among children brought up at home. This difference was most sharply pronounced among young children during the first two years of their life. In contrast to morbidity observed during previous 20-30 years, a drop in morbidity among children during the first two years of their life was registered, while morbidity level among children aged 3-6 years and 7-14 years increased. Scarlet fever morbidity had a pronounced seasonal (autumn-winter) pattern. In a group of children aged 3-5 years who attended organized groups, on the average, 78.6% of scarlet fever cases fell on seasonal morbidity, the most prolonged one.     

Cholera morbidity problems in 1 of the departments of the Democratic and Popular Republic of Algeria

A total of 1,078 cases of bacteriologically confirmed cholera were analyzed at the period of 1979-1983. In 1981 Vibrio eltor, serotype Inaba, replaced V. cholerae, serotype Ogawa, and became the prevailing infective agent. Every year young children and persons over 50 years of age were most actively involved into the epidemic process. The peak of seasonal morbidity was observed in September-October. The appearance of the foci of infection in families was found to be slightly pronounced in cholera. 85.3% of the families had only a single case of cholera. The cases of cholera with the fatal termination of the disease were registered mostly at the beginning of the seasonal rise of morbidity and at its peak.     

The epidemiological differential diagnostic signs of viral hepatitis A and viral hepatitis E]

A retrospective epidemiologic analysis of cases diagnosed as hepatitis A (HA) has been made in territories characterized by high intensity (4 towns in Central Asia) and low intensity (Novomoskovsk, Tula Province) of the epidemic process development. Morbidity structures for different age and social groups of the population, as well as the morbidity time course, both annual and over many years, were analyzed over 1973-1986. Specific features in the development of the epidemic process in HA and hepatitis E (HE), formerly called hepatitis non-A, non-B with the fecal/oral mechanism of the infection transmission, were studied. Twelve epidemiological differential diagnostic signs of these two infections were formulated, classified, and validated. Contribution of centralized water supply and sewage systems to the development of HE epidemic process and the regulating role of infectious immunological mechanisms in the development of HA epidemic process were demonstrated.