Conditions and factors determining the etiological structure of dysentery and its changes. Report 1. Epidemiological theory of etiological selectivity of the main (primary) pathways of infection and their differences in various nosological forms of dysentery]

The authors present the elaborated and formed epidemiological theory ("conformity theory") according to which the etiological structure of dysentery is determined by the etiological selectivity of the main (primary) waves of transmission of the infection differing in various nosological forms of dysentery. In Grigoriev-Shiga dysentery the domestic way of the spread of infection plays the main role, in Flexner and Newcastle dysentery--the water way, and in Sonne dysentery--the food way (particularly through the milk). Evolution of the etiological structure of dysentery serves as the reflection of evolution of the principal ways of transmission. The complex of prophylactic and antiepidemic measures in individual noslogical forms of dysentery should be differentiated and be directed in epidemiological sense to the neutralization of the corresponding main (primary) way of transmission of the infection.     

The spread of rotavirus gastroenteritis in the Republic of Tajikistan

The article deals with the results of the investigation which has demonstrated the spread of rotavirus infection on the territory of the Republic of Tajikistan. This infection has gained an important place in the regional pathology and requires increased epidemiological surveillance on its spread. As established in the course of this investigation, in patients with the clinical manifestations of pronounced gastroenteritis rotavirus plays the role of the etiological agent in 25.8% of cases in children aged up to 14 years and in 11.0% of cases in adults. Synchronism in the seasonal dynamics of morbidity in acute enteric infections of unclear etiology and rotavirus gastroenteritis among children aged 0-2 years, annually reaching morbidity peak in October, has been revealed. Rotavirus gastroenteritis requires close attention as regards its prophylaxis as one of the main nosological forms of acute enteric infections in the Republic.     

Epidemiological survey of a single-case focus of acute enteric infections

The aim, tasks and stages of the epidemiological survey of a single-cased focus of infection, taking into account present-day specific features of the epidemiology of acute enteric infections, have been formulated. The technical approaches to the detection of the source, routes, factors and conditions of the causative agent transmission are given. The patterns of the conclusion on the epidemiological survey of the focus are given.     

Epidemiological characteristics of Angola

The epidemiological analysis of infectious morbidity for recent years has been made and the main nosological forms existing in Angola (malaria, tuberculosis, lepra, African trypanosomiasis, plague, intestinal diseases, etc.) have been briefly characterized on the basis of primary medical reports and the data provided by the literature and experimental work. This analysis creates the necessary prerequisites which enable the local public health organs to determine the regularities of the epidemic process, thus making it possible to take rational prophylactic measures and to organize proper epidemiological supervision.     

Shigellosis and other acute intestinal infections in the Republic of Tajikistan: the epidemiological patterns

Acute enteric infections (AEI), including shigellosis, are characterized by their extremely wide spread in Tajikistan. Their hyperendemicity is due to a high activity of the water route of transmission under the conditions of hot climate. The morbidity level of AEI both in the republic as a whole and in its individual territories has been found to directly depend on the degree of the potential epidemiological danger of the water supply system, as well as on the quality of water used by the population in the presence of its pronounced deficiency. The important role of breast feeding for the prophylaxis of AEI among young children is shown.     

Epidemiologic situation in the quarantine of natural focal infections in the Southern Federal District

Materials on the situation in quarantine natural focal infections (anthrax, plague, tularemia, brucellosis, leptospirosis, etc.) in the Southern Federal District are presented. Experience in the provision of the epidemic safety in the above-mentioned diseases, based on the systematic surveillance on the activity of epizootological factors on the territory of the natural foci of infections, are described. The causes of the possible aggravation of the epidemiological situation in a number of nosological forms in connection with changes in natural and socio-economic factors are given. The results of the realization of regional programs, making it possible to improve the system interaction between the administrative territories, services and departments aimed at ensuring the epidemiological safety of the region, are shown.     

Toxoplasma gondii: from animals to humans

Toxoplasmosis is one of the more common parasitic zoonoses world-wide. Its causative agent, Toxoplasma gondii, is a facultatively heteroxenous, polyxenous protozoon that has developed several potential routes of transmission within and between different host species. If first contracted during pregnancy, T. gondii may be transmitted vertically by tachyzoites that are passed to the foetus via the placenta. Horizontal transmission of T. gondii may involve three life-cycle stages, i.e. ingesting infectious oocysts from the environment or ingesting tissue cysts or tachyzoites which are contained in meat or primary offal (viscera) of many different animals. Transmission may also occur via tachyzoites contained in blood products, tissue transplants, or unpasteurised milk. However, it is not known which of these routes is more important epidemiologically. In the past, the consumption of raw or undercooked meat, in particular of pigs and sheep, has been regarded as a major route of transmission to humans. However, recent studies showed that the prevalence of T. gondii in meat-producing animals decreased considerably over the past 20 years in areas with intensive farm management. For example, in several countries of the European Union prevalences of T. gondii in fattening pigs are now <1%. Considering these data it is unlikely that pork is still a major source of infection for humans in these countries. However, it is likely that the major routes of transmission are different in human populations with differences in culture and eating habits. In the Americas, recent outbreaks of acute toxoplasmosis in humans have been associated with oocyst contamination of the environment. Therefore, future epidemiological studies on T. gondii infections should consider the role of oocysts as potential sources of infection for humans, and methods to monitor these are currently being developed. This review presents recent epidemiological data on T. gondii, hypotheses on the major routes of transmission to humans in different populations, and preventive measures that may reduce the risk of contracting a primary infection during pregnancy.     

Prevention of acute enteric infections and viral hepatitis A in the Krasnodar Territory appearing in connection with a natural disaster in 2002

Materials on the sanitary and epidemiological situation in the Krasnodar Territory in connection with emergency situations (intensive snowfalls, heavy showers, high floods) in 2002 are presented. The scope of the destruction of the systems ensuring the life provision of the population in the affected regions of the territory is shown. To carry out the epidemiological surveillance on acute enteric infections, to make corrections of the planned prophylactic measures, as well as the timely solutions of problems connected with controlling the epidemiological situation, the daily monitoring of the level and dynamics of infectious morbidity in individual settlements among different age and professional groups, as well as the foci of infections, was established. 65 cases of acute enteric infection and 4 cases of viral hepatitis A were registered in the affected areas, which did not exceed the average morbidity figures for many years. A complex of sanitary, hygienic and prophylactic measures was carried out by the sanitary and epidemiological service of the territory, which made it possible to maintain human morbidity in acute enteric infections and viral hepatitis A in the affected areas on the sporadic level.     

A Bayesian Inference Framework to Reconstruct Transmission Trees Using Epidemiological and Genetic Data

The accurate identification of the route of transmission taken by an infectious agent through a host population is critical to understanding its epidemiology and informing measures for its control. However, reconstruction of transmission routes during an epidemic is often an underdetermined problem: data about the location and timings of infections can be incomplete, inaccurate, and compatible with a large number of different transmission scenarios. For fast-evolving pathogens like RNA viruses, inference can be strengthened by using genetic data, nowadays easily and affordably generated. However, significant statistical challenges remain to be overcome in the full integration of these different data types if transmission trees are to be reliably estimated. We present here a framework leading to a bayesian inference scheme that combines genetic and epidemiological data, able to reconstruct most likely transmission patterns and infection dates. After testing our approach with simulated data, we apply the method to two UK epidemics of Foot-and-Mouth Disease Virus (FMDV): the 2007 outbreak, and a subset of the large 2001 epidemic. In the first case, we are able to confirm the role of a specific premise as the link between the two phases of the epidemics, while transmissions more densely clustered in space and time remain harder to resolve. When we consider data collected from the 2001 epidemic during a time of national emergency, our inference scheme robustly infers transmission chains, and uncovers the presence of undetected premises, thus providing a useful tool for epidemiological studies in real time. The generation of genetic data is becoming routine in epidemiological investigations, but the development of analytical tools maximizing the value of these data remains a priority. Our method, while applied here in the context of FMDV, is general and with slight modification can be used in any situation where both spatiotemporal and genetic data are available.     

The status of the morbidity and the main trends in the improvement of the epidemiological surveillance of sexually transmitted infections in the city of Moscow

The present situation in sexually transmitted diseases (STD) is regarded as unfavorable. Differing tendencies in morbidity levels for various nosological forms have been established. The continuing growth of syphilis morbidity among children is considered to be specially alarming, and an increase in the number of cases of congenital syphilis is noted. The reasons of the growth of STD morbidity have not only medical, but mainly socio-economical, psychological, ethical and moral character. The main trends in the improvement of epidemiological surveillance on STD have been determined.     

A role for vector-independent transmission in rodent trypanosome infection?

Within host-pathogen systems where vector-borne transmission is the primary route of infection, little or no attention has been paid to the relative importance of secondary or alternative routes of transmission. Here, by contrast, we report the results from a controlled longitudinal field-scale experiment in which the prevalence of fleas (Siphonaptera) was manipulated and the occurrence and distribution of a flea-borne protozoan (Trypanosoma (Herpetosoma) microti) in a natural field vole (Microtus agrestis) population was monitored over a 2-year period. A non-systemic insecticide was applied to individual voles within two treatment grids and the prevalences of fleas and of T. microti were monitored on these and on two control grids. Blood samples were taken from all voles and PCR-based methods used to determine infection status. Insecticidal treatment was highly effective at reducing overall flea prevalence and recaptured animals (treated ca. 4 weeks previously) were very rarely infested (ca. 3%, compared with 50-70+% normally). On the other hand, the probability of trypanosome infection was reduced in treated animals on experimental grids to only around one-third of that normally observed. This suggests that direct, as opposed to flea-borne, transmission may not only occur, it may also be of epidemiological importance. The possibility that the importance of such transmission routes may have been underestimated in ‘vector-borne’ infections more generally is discussed.     

Prevention of acute enteric infections and viral hepatitis A in a period of an emergency situation on the territory of the Karachai-Chercasssian Republic

Information on the scope of destructions caused by the high flood, on the sanitary and hygienic situation on the affected territories of the Karachai-Chercassian Republic is given. Materials on the organization and realization of prophylactic measures on the territory of the Karachai-Chercassian Republic at the period the natural calamity, under the conditions of a high risk of the appearance of an outbreak of enteric infections and viral hepatitis A are presented. In these materials the main trends of the work are pointed out; due to the timely taken and effectively carried out measures on the anti-epidemic protection of the population, the sanitary and epidemiological service was shown to prevent the aggravation of the epidemiological situation in the republic.     

Prevention of acute enteric infections and viral hepatitis A appearing in connection with a natural disaster in the Republic of North Ossetia-Alana

Materials on the work of the sanitary and epidemiological service in the Republic of North Ossetia-Alania, aimed at the prophylaxis of acute enteric infections and viral hepatitis A under the conditions of the emergency situation caused natural calamities (inundation, high flood), are presented. The competent planning and operative realization of organizational, prophylactic and anti-epidemic measures have made it possible to keep morbidity in acute enteric infections and viral hepatitis A on a sporadic level.     

Sanitary and epidemiological provision of the personnel of the units and border formations of the North Caucasus Regional Command of the Border Guard Service of the Russian Federation

The factors affecting the environment of servicemen doing their duties in connection with the task of guarding the state frontier of the Russian Federation are presented. The main trends in the activity of the sanitary and epidemiological service, carried out under regular conditions and the period of the liquidation of the consequences of high floods in the Southern Federal District in 2002 with the aim of preventing the aggravation of the epidemical situation, were shown to be determined, and the corresponding measures taken, in due time, thus making it possible to prevent the growth of morbidity in enteric and other infections among the personnel of the units and formations of the North Caucasian Regional Command of the Federal Frontier-Guard Service of the Russian Federation.     

Hospital sources of Aspergillus: New routes of transmission?

With the continuing increase in the number of severely immunocompromised patients, hospitals are faced with the growing problem of invasive aspergillosis and other opportunistic fungal infections. Since treatment of these infections are difficult and outcome is often fatal, preventive measures are of major importance in the control of invasive filamentous fungal infections. Until recently, inhalation of airborne conidia was believed to be the primary route of acquiring Aspergillus infection. Despite the fact, that efforts to filter the hospital air has led to a reduction of airborne conidia paralleled by a decrease in the frequency of invasive infections, the correlation between the concentration of Aspergillus conidia in hospital air and the risk of invasive infections remains unclear. Furthermore, alternative modes of transmission may exist and should be recognized and investigated. The discovery of hospital water as a potential source of Aspergillus fumigatus and other filamentous fungi may suggest a new route for the transmission of invasive filamentous fungal infections. Epidemiological studies, based on molecular characterization and comparisons of fungal isolates recovered from patients and environment, are needed to expand our understanding of these alternative routes of transmission.     

From Leningrad to the day-care center. The ubiquitous Giardia lamblia.

Giardiasis is recognized as a worldwide public health problem. Seroprevalence data from both the developing and developed world show high rates of carriage in populations at risk for fecal-oral transmission, such as children in day-care centers. Outbreak investigation has expanded our understanding of reservoirs for Giardia lamblia and of the routes of transmission. Various host factors have been associated with infection. The pathogenesis of giardial infections is being elucidated, in particular the role of lectin activation in producing disease. Three standard chemotherapeutic agents are available in the United States. The institution of community-wide prevention measures is equally important. Current areas of investigation including antigenic composition and enzymatic variants should result in effective forms of immunotherapy, while more effective forms of chemoprophylaxis could assist in eradicating the pathogen from institutional settings.     

Morbidity in sexually transmitted infections in the Republic of North Ossetia-Alania and the improvement of epidemiological surveillance

The present situation in sexually transmitted diseases (STD) in the Republic of North Ossetia-Alania is characterized as unfavorable. Morbidity in different nosological forms has been found to show different tendencies. The causes of elevated morbidity in STD observed in recent years have social, economic, psychological, ethical and moral, rather than medical character. The main trends in the improvement of epidemiological surveillance on STD have been determined.     

Mathematical modeling and prognosis of incidence of enteric anthroponoses with aqueous route of transmission

Using data on long-term dynamics of epidemic process of acute enteric infections enteric with aqueous route of transmission (typhoid fever, shigellosis caused by Shigella flexneri, hepatitis A, rotavirus gastroenteritis, etc.)the equation of regression was developed with the help of Chebyshev's polynoms. Predicted incidences of these infections for 2005 were on 61.2-99.5% in agree with the real ones on two territories of north region of West Siberia. Predicted incidence for 2006 is reflecting tendencies of epidemic process of mentioned infections.     

Prevention of epidemiological consequences during an extreme situation caused by the natural disaster in the Republic of North Ossetia-Alania

Information on the organization of interaction between different services responsible for restoration works, sanitary cleaning, disinfection under the conditions of the emergency situation is presented. The activity of the sanitary and epidemiological services in the areas in the Republic of North Ossetia-Alania, affected by high flood, is described. Measures aimed at the epidemiological surveillance of acute enteric infections, the control of the quality of drinking water and foodstuffs, the bacteriological study of material samples taken from humans, vaccinal and phage prophylaxis have taken an important place in the work of the institutions of sanitary and epidemiological surveillance. As the result of all these measures the sanitary and epidemiological service has managed to prevent the aggravation of the sanitary and epidemiological situation in the republic.     

Comparison of Mucosal,Subcutaneous and Intraperitoneal Routes of Rat Leptospira Infection

Leptospirosis is a zoonosis found worldwide that is caused by a spirochete. The main reservoirs of Leptospira, which presents an asymptomatic infection, are wild rodents, including the brown rat (Rattus norvegicus). Experimental studies of the mechanisms of its renal colonization in rats have previously used an intraperitoneal inoculation route. However, knowledge of rat-rat transmission requires the use of a natural route of inoculation, such as a mucosal or subcutaneous route. We investigated for the first time the effects of subcutaneous and mucosal inoculation routes compared to the reference intraperitoneal route during Leptospira infection in adult rats. Infection characteristics were studied using Leptospira renal isolation, serology, and molecular and histological analyses. Leptospira infection was asymptomatic using each inoculation route, and caused similar antibody production regardless of renal colonization. The observed renal colonization rates were 8 out of 8 rats, 5 out of 8 rats and 1 out of 8 rats for the intraperitoneal, mucosal and subcutaneous inoculation routes, respectively. Thus, among the natural infection routes studied, mucosal inoculation was more efficient for renal colonization associated with urinary excretion than the subcutaneous route and induced a slower-progressing infection than the intraperitoneal route. These results can facilitate understanding of the infection modalities in rats, unlike the epidemiological studies conducted in wild rats. Future studies of other natural inoculation routes in rat models will increase our knowledge of rat-rat disease transmission and allow the investigation of infection kinetics.