Quantitative research on the cyclic fluctuations of the epidemic process in a number of infectious diseases in Bulgaria

The cyclic nature of the epidemic process in Bulgaria was studied by various methods (spectral analysis, etc.), forming a system. The morbidity dynamics in 10 infectious diseases (scarlet fever, rubella, measles, epidemic parotitis, whooping cough, diphtheria, typhoid fever, enterocolitis, bacterial dysentery, viral hepatitis) over the years of 1909-1983 were studied and cycles covering the periods of 3-4, 5-6, 10-11 and over 16 years were established. The data on the relative part of cyclic processes in the registered morbidity of infectious diseases, as well as information on the prognostication of the spread of infections in the absence of vaccinal prophylaxis, are presented.     

The 7th cholera pandemic in the world and the USSR

1,713,057 cases of cholera were registered in the world during the seventh pandemic of the disease at the period of 1961-1989. The pandemic still continues, being the most prolonged pandemic in comparison with earlier ones. During the period of the seventh pandemic 10,723 cases of cholera were registered in the USSR. Great outbreaks occurred in 1965 and 1970-1974. At present sporadic cases of cholera can be registered, and wide circulation of mainly avirulent, nontoxigenic strains of cholera vibrios in environmental objects is characteristic of the epidemic situation.     

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.     

A large-scale epidemic of diphtheria in Moscow in recent years: patterns of development

Data on the dynamics of diphtheria morbidity in Moscow in 1958-1999 are presented. The last epidemic which started at the end of the 1980s and reached its peak in 1994, giving a 59-fold rise in morbidity in comparison with the pre-epidemic period, is characterized in detail. During the epidemic 12,267 persons fell ill, 454 of them died (mortality rate was 4%). Having started in Moscow, the epidemic gradually spread not only over the territory of Russia, but also over some other republics of the former Soviet Union (Ukraine, Belarus, etc.). Possible causes of this epidemic emergency are considered. The ever increasing share of adult population among persons affected by the epidemic (75%) is noted. The infection adults is characterized by severity of clinical manifestations and increased morbidity among adults, is shown. Under complicated social and economic conditions (crisis situation) the increase of groups of high risk which included unemployed adults of working age, retirees as well as socially non-adapted persons, was registered. Mainly these groups determined tense epidemiological situation in diphtheria in Moscow.     

Evolution of the epidemiology of cholera

The problems of the evolution of cholera at the stages of its pandemic spread are described. A short characterization of endemic zones in the countries of Asia, Africa and Latin America, stipulating the preservation of infection and the appearance of periodic epidemics in the world, is presented. Special attention is paid to the genesis of epidemic outbreaks in endemic and introduced foci of cholera, differing in the specific features of their formation and the accumulation of the epidemic variant of the infective agent in aqueous habitat. The role of the ecosystem of surface water reservoirs in the prolonged survival of cholera vibrios is evaluated. The necessity of the detailed study of the mechanisms and forms of existence of serogroup 0139 vibrio in open water reservoirs is substantiated. In the system of epidemiological surveillance on cholera the microbiological monitoring of environmental objects assumes the leading importance.     

The development of HIV infection in the Far-Eastern region of the Russian Federation

By May 18, 1998, 108 HIV-infected persons were registered in the Far-Eastern region. In recent years young people using narcotic drugs were involved in the epidemic process. The sources of the infection were mainly migrants arriving to the Far East from the Ukraine. HIV-infected persons also were registered in settlements lying north of the Arctic Circle.     

HIV/AIDS epidemic in Eastern Europe: Recent developments in the Russian Federation and Ukraine among women

Background: The Russian Federation and the Ukraine are among the Eastern European countries with the fastest growing number of cases of HIV. According to data from the Joint United Nations Program on HIV/AIDS, nearly 90% of newly reported HIV diagnoses in Eastern Europe in 2006 were from the Russian Federation (66%) and the Ukraine (21%). A growing number of women are infected with HIV. The impact of gender on HIV/AIDS is an important factor in understanding the development and evolution of the HIV/AIDS epidemic in Eastern Europe.Objective: The aim of this study was to assess the importance of integrating gender consideration into the creation of HIV programs and to examine the effect of gender on HIV/AIDS.Methods: Reported HIV/AIDS cases from the official epidemiological register of the Ukrainian Centre for AIDS Prevention alongside data from the Russian Federal AIDS Center were analyzed. Joint United Nations Program on HIV/AIDS country fact sheets were reviewed and analyzed, and this information was supplemented with published HIV prevalence and sexually transmitted disease case reporting information, unpublished reports, and expert evaluations.Results: Of the newly registered cases of HIV, the proportion of women rose from 13.0% in 1995 to 44.0% in 2006 in the Russian Federation, and from 37.2% in 1995 to 41.9% in 2006 in the Ukraine. There has also been a considerable increase in mother-to-child transmission of HIV since 1995. Between 1987 and 1994, the proportion of children among the people newly infected with HIV in the Ukraine was 2.2%; in 2006 it was 17.6%. In 2006, 16,078 new HIV cases were registered in the Ukraine and 39,652 new HIV cases in the Russian Federation. Large increases in the number of HIV-infected women were reported from both countries.Conclusions: The data examined in this study suggest subregional differences in the magnitude of the HIV/AIDS epidemic in the Russian Federation and the Ukraine and the importance of the impact of gender on the rapid spread of the HIV/AIDS epidemic among women and women of child-bearing age. To protect women from HIV infection, it is important to find ways to empower them by implementing policies and specific prevention measures that increase their access to knowledge about HIV/AIDS; the empowerment of women is vital to reversing the HIV/AIDS epidemic.     

The epidemic situation in relation to HIV infection in Ukraine (1987-1997)

The analysis of the dynamics of the epidemic process for 10 years made it possible to find out the presence of two separate epidemic waves of HIV infection. The first wave (1987-1994) was manifested as the slow type of the development of the epidemic, characterized mainly by sexual transmission. During this period 398 persons with HIV infection were detected, 24 persons were found to have AIDS; of these, 13 persons died. The second epidemic wave began in 1995 and was due to the spread of HIV among users of drugs introduced by injection. By the end of 1995 the number of HIV carriers was 34 times greater than that of 1994, reaching 1490 persons. In 1996-1997 this figure increased 8 times (annually). The number of AIDS patients rose to 420 persons. The most unfavorable regions with respect to HIV infection and AIDS morbidity were determined. The western regions of the Ukraine were noted to be in a more favorable situation in this respect with infection indices being lower more than 30 times. Up to 80% of all infected persons were found to be addicts introducing drugs intravenously. Growing morbidity in sexually transmitted disease, particularly in syphilis, contributed to the deterioration of the epidemiological situation. The conclusion was made on the necessity of introducing new prophylactic programs and expanding current ones. The signs of stabilization in Odessa and Nikolayev were observed; in these cities pilot programs aimed at the strategy of the "decrease of harm" have been introduced (in collaboration with UNAIDS) since 1996.     

HIV infection in the penitentiaries of Ukraine

In connection with a sharp increase of the number of HIV-infected persons in the Ukraine the natural growth of the number of such persons in penitentiary institutions was registered, starting from 1995 (455 persons in 1995, 2,937 persons in 1996, 2,779 persons in 1997 and 173 persons during 5 months of 1998). 83% of HIV infection persons were drug addicts introducing drugs intravenously. In 1997 the strategy of decreasing the risk of infection in penitentiary institutions was worked out in collaboration with UNAIDS experts: repressive and isolation measures were replaced with measures aimed at the "decrease of harm". Special attention is given to circumstances aggravating the epidemic situation in HIV infection, and particularly at the sharp growth of morbidity in tuberculosis and syphilis (10.6 and 10.3 times respectively in 1997 in comparison with 1993). In addition, in 1997 the number of person having drug addiction was noted to increase 2.3 times in comparison with 1993. The necessity of taking constant information and educational measures aimed at decreasing the risk of the spread of HIV infection is emphasized.     

Vibrio cholerae serogroups O1 and O139: susceptibility to antibiotics during 7th cholera pandemic

The review presents data on circulation of antibiotic resistant and susceptible strains of Vibrio cholerae serogroups O1 and O139 isolated from cholera patients and healthy persons as well as from the environment, in Asia, Africa, Australia, and Europe (including New Independent States) during 7th cholera pandemic.     

The Role of China in the Global Spread of the Current Cholera Pandemic

Epidemics and pandemics of cholera, a severe diarrheal disease, have occurred since the early 19th century and waves of epidemic disease continue today. Cholera epidemics are caused by individual, genetically monomorphic lineages of Vibrio cholerae: the ongoing seventh pandemic, which has spread globally since 1961, is associated with lineage L2 of biotype El Tor. Previous genomic studies of the epidemiology of the seventh pandemic identified three successive sub-lineages within L2, designated waves 1 to 3, which spread globally from the Bay of Bengal on multiple occasions. However, these studies did not include samples from China, which also experienced multiple epidemics of cholera in recent decades. We sequenced the genomes of 71 strains isolated in China between 1961 and 2010, as well as eight from other sources, and compared them with 181 published genomes. The results indicated that outbreaks in China between 1960 and 1990 were associated with wave 1 whereas later outbreaks were associated with wave 2. However, the previously defined waves overlapped temporally, and are an inadequate representation of the shape of the global genealogy. We therefore suggest replacing them by a series of tightly delineated clades. Between 1960 and 1990 multiple such clades were imported into China, underwent further microevolution there and then spread to other countries. China was thus both a sink and source during the pandemic spread of V. cholerae, and needs to be included in reconstructions of the global patterns of spread of cholera.     

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.     

Spatio-Temporal Dynamics of Cholera during the First Year of the Epidemic in Haiti

Background

In October 2010, cholera importation in Haiti triggered an epidemic that rapidly proved to be the world''s largest epidemic of the seventh cholera pandemic. To establish effective control and elimination policies, strategies rely on the analysis of cholera dynamics. In this report, we describe the spatio-temporal dynamics of cholera and the associated environmental factors.

Methodology/Principal findings

Cholera-associated morbidity and mortality data were prospectively collected at the commune level according to the World Health Organization standard definition. Attack and mortality rates were estimated and mapped to assess epidemic clusters and trends. The relationships between environmental factors were assessed at the commune level using multivariate analysis. The global attack and mortality rates were 488.9 cases/10,000 inhabitants and 6.24 deaths/10,000 inhabitants, respectively. Attack rates displayed a significantly high level of spatial heterogeneity (varying from 64.7 to 3070.9 per 10,000 inhabitants), thereby suggesting disparate outbreak processes. The epidemic course exhibited two principal outbreaks. The first outbreak (October 16, 2010–January 30, 2011) displayed a centrifugal spread of a damping wave that suddenly emerged from Mirebalais. The second outbreak began at the end of May 2011, concomitant with the onset of the rainy season, and displayed a highly fragmented epidemic pattern. Environmental factors (river and rice fields: p<0.003) played a role in disease dynamics exclusively during the early phases of the epidemic.

Conclusion

Our findings demonstrate that the epidemic is still evolving, with a changing transmission pattern as time passes. Such an evolution could have hardly been anticipated, especially in a country struck by cholera for the first time. These results argue for the need for control measures involving intense efforts in rapid and exhaustive case tracking.     

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.     

霍乱弧菌检测方法的研究进展

烈性肠道传染病霍乱能引起大范围乃至世界性大流行,在我国被列为甲类传染病.霍乱弧菌是导致感染者严重腹泻、引起霍乱的病原菌.霍乱弧菌的快速、准确检测是霍乱预防、控制的重要依据.目前,国内、外针对霍乱弧菌建立了许多有效的检测方法,尤其是分子生物学相关技术的应用,为霍乱弧菌的检测提供了新的手段.本文综述了近年来霍乱弧菌检测方法...     

The Zymovars of Vibrio cholerae: multilocus enzyme electrophoresis of Vibrio cholerae

Zymovars analysis also known as multilocus enzyme electrophoresis is applied here to investigate the genetic variation of Vibrio cholerae strains and characterise strains or group of strains of medical and epidemiological interest. Fourteen loci were analyzed in 171 strains of non-O1 non-O139, 32 classical and 61 El Tor from America, Africa, Europe and Asia. The mean genetic diversity was 0.339. It is shown that the same O antigen (both O1 and non-O1) may be present in several genetically diverse (different zymovars) strains. Conversely the same zymovar may contain more than one serogroup. It is confirmed that the South American epidemic strain differs from the 7th pandemic El Tor strain in locus LAP (leucyl leucyl aminopeptidase). Here it is shown that this rare allele is present in 1 V. mimicus and 4 non-O1 V. cholerae. Non toxigenic O1 strains from South India epidemic share zymovar 14A with the epidemic El Tor from the 7th pandemic, while another group have diverse zymovars. The sucrose negative epidemic strains isolated in French Guiana and Brazil have the same zymovar of the current American epidemic V. cholerae.     

Epidemiologic and economic effectiveness of school closure during influenza epidemics and pandemics

Epidemiologic and economic effectiveness of school closure during influenza epidemics and pandemics is discussed. Optimal effect of school closure is observed when this measure is taken at the start of the epidemic or pandemic and for a sufficiently long time. School closure during high morbidity among schoolchildren, in the middle (at the peak) and by the end of epidemic or pandemic does not influence significantly the spread of influenza or morbidity. Significant economic losses and other negative consequences of school closure are noted. School closure may be the most appropriate during the emergence of influenza pandemic when the pandemic vaccine is not yet available, however timely mass immunization of schoolchildren against influenza may be a more appropriate measure than school closure for the reduction of influenza morbidity and spread during seasonal influenza epidemics.     

The types of the epidemic manifestations of cholera on the territory of the USSR

On the basis of the analysis of cholera cases for the period of 1965-1989 three main main types of epidemic manifestations of this infection on the territory of the USSR were determined with due attention to the complex of data, characterizing the intensity and types of the epidemic process, the danger of the outbreak and spread of cholera. This made it possible to differentiate and decrease the complex of prophylactic measures, depending on the type of the territory.