The epidemiological patterns of pseudotuberculosis in Khabarovsk Territory]

Materials on the epidemiological characterization of pseudotuberculosis at the Khabarovsk Territory taken as a whole and in individual settlements, as well as on the evaluation of epizootic situation in natural foci of infection and foci created by human activities, are presented. The results of laboratory studies of vegetables, washings from environmental objects, soil specimens, material taken from rodents are demonstrated and the characterization of the virulent properties of isolated Yersinia pseudotuberculosis strains is given. Two periods (1976-1982 and 1983-1989) were distinguished by their main epidemiological features. The most important feature of the second period is the shift of the seasonal morbidity rise to the middle of summer, which is explained by activation of the mechanism of transmission of this infection due to the supply of early vegetables infected in local vegetable stores. An essential role of wild and synanthropic Muridae as the reservoir of infection is shown; these rodents and the soil maintain the circulation of the infective agent accumulating in the most favorable habitat, vegetable stores. The regularities established in this work contribute to the improvement of epidemiological surveillance.     

Epizootic characteristic of rabies today

During the 23 year period rabies was registered in the Moscow region in 163 cases among foxes, 22 cases among racoon-like dogs, 92 cases among dogs, 54 cases among cats. In 1991-2000 ten cases of rabies were registered among other wild animal other than foxes and raccoon-like dogs (hares, hedge-hogs, polecats, badgers, hamsters, martens, rats). Under today conditions the generalized epizootological pattern of rabies is characterized by the vector "natural foci-->anthropurgic foci" with wild and domestic animals playing an alternative role in the epizootic process and the circulation of the infective agent. Wild carnivorous animals maintain natural focal infection in time and space, while all domestic animals are a direct or indirect ecological impasse and took no part in the maintenance of the infection. Foxes are the main source of infection for the animals of the anthropurgic cycle: they play a special role in the development of the epizootic situation in the region as the main reservoir and source of the causative agent of rabies as a natural focal infection. Among other wild animals, raccoon-like dogs are involved into epizootic and epidemic chains. Dogs are the main objects to be infected in the anthropurgic cycles, while cats--a progressing group of risk. During the period of 25 years a decrease in the probability of natural rabies was noted.     

Characterization of the foci of meningococcal infection in closed groups of males

A total of 257 foci of meningococcal infection in groups of servicemen were selectively examined in 1982-2002. From these groups 353 patients with generalized forms of the disease underwent hospitalization. Most of the foci had a single infection, the proportion of foci with 10-40 patients was 82.6%. The meningococcal infection rate among humans in the foci was 25-37%, group A meningococci playing the leading role. In the structure of meningococcal infection generalized forms of infection constituted 16%, localized forms constituted 25% and inapparent forms (carriers)--59%. The formation of the morbidity structure was influenced by the type of the focus (with a single or multiple infection) and the character of morbidity for many years (during epidemic or at the period between epidemics). No absolute dependence of the level of meningococcal carrier state in the groups of servicemen on the appearance of the generalized forms of meningococcal infection was noted. Thus, both during epidemic and at the period between epidemics the population of meningococci, heterogeneous in its serological structure and differing in its clinical and epidemiological importance, constantly circulated with the leading role played by group A meningococci.     

Complex method for epizootiological and epidemiological surveillance

A complex method for the epizootological and epidemiological surveillance of a number of bacterial and viral infections on the territories inside and outside their natural foci has been developed. The investigation techniques are described and the data on the isolation rate of each causative agent in different geographical zones are presented. In the natural foci of plague and tularemia, as well as on the territories outside such foci, the causative agents of intestinal yersiniosis, pseudotuberculosis, salmonellosis, erysipeloid, staphylococci and streptococci, arena- and arboviruses have been isolated from the rodents and ectoparasites under study. The results of this investigation suggest that the method may be recommended for use in medical institutions dealing with the problems of infections originating from natural foci.     

The gene identification of bacterial species and serovariants by the polymerase chain reaction with universal oligonucleotides: the reidentification of earlier isolated strains of Yersinia pseudotuberculosis]

Genetic analysis of 19 standard strains belonging to 6 Yersinia species (Y. pestis, Y. pseudotuberculosis, Y. enterocolitica, Y. kirstensenii, Y. frederiksenii, Y. intermedia) revealed that gene typing by the method of polymerase chain reaction (PCR) with the use of universal primers permitted the identification of species in bacterial cultures by PCR patterns and the determination of Y. pseudotuberculosis serovars within 4 hours. By this method 23 Y. pseudotuberculosis strains (serovar 1), earlier isolated in different regions of the USSR from humans and rodents, were studied. The study showed that out of 14 strains of human origin only two strains could actually be classified with serovar 1, while the remaining strains were reidentified as belonging to serovar 5. Among 9 strains isolated from rodents those of serovar 1 prevailed (8 strains). The authors suppose that strains of serovar 5 cause outbreaks and sporadic cases of pseudotuberculosis, occurring considerably more often than it is commonly believed in the USSR.     

Water-borne outbreaks of rotavirus infections

The clinico-epidemiological characteristics of group rotavirus infection observed in one settlement in March-April is presented. 173 cases of infection were registered in all age groups (children under 7 years constituted only 10.4% of the patients). In most of the apartments found to be the foci of infection only one patient was registered. The virological study of fecal samples from 24 patients showed the presence of human rotaviruses in the feces of 10 patients (41.7%). Neutralizing antibodies in titers of 1:4 to 1:64 were detected in all taken paired sera (21). THe clinical study of 53 hospitalized patients showed that in all cases the infectious process had acute beginning. In most patients the disease took mild forms. The peculiarities of the distribution of the patients in different age groups, the location of the foci of infection and its seasonal character, as well as some objective data on the presence of pollutions in the water mains, indicated that this infection could spread through water via the system of centralized water supply.     

Tick-borne encephalitis in the Maritime Territory

On the basis of epidemiological analysis carried out at the period of 1940-1987, a decrease in tick-borne encephalitis (TBE) morbidity was registered; at the same time time the disease invariably took, as before, a clinically severe course. The most dangerous foci of TBE were found to be located in the southern Okhotsk region grown with dark coniferous forests. The subsiding and activation of the natural foci of TBE in different regions of the territory were established and some heretofore unknown foci in southern regions of the Maritime Territory were found. Ixodes mites inhabiting the Maritime Territory were shown to have a low level of virus carriership, thus causing the low level of population immunity to TBE virus. Combined foci of TBE and Powassan encephalitis were found.     

Study of the epidemiology of Far Eastern scarlatina-like fever in the Maritime Territory. I. Contamination of vegetables, root crops and pickled foods with the pseudotuberculosis microbe (Yersinia pseudotuberculosis) in foci of the scarlatina-like fever]

There was revealed high incidence of contamination with Yersinia pseudotuberculosis of vegetables, roots and pickled products (less frequently) in the vegetable store-houses of the majority of the far Eastern scarlatina-like fever foci in Primorie. Contamination of the mentioned food products increased by the spring-beginning of summer seasons; vegetables and roots which are often used raw--onion, carrots, cabbage--displayed the greastest contamination.     

Natural foci of leptospirosis in Moscow in 1995 - 2004

The article deals with the results of the 10-year study of the synanthropic urban foci of leptospirosis on the territory of Moscow. Information on the manifestation of the activity of the foci under study, rodents serving as the reservoir of infection in these foci, the etiological structure of the leptospires among these rodents, the state of leptospirosis morbidity among humans is presented.     

Activation of natural tularemia foci of the field-meadow and steppe types on the territory of Tula Province 1977-1978

Natural tularemia foci of the meadow and steppe type are extremely stable and become active in those years when the most favourable living conditions for rodents appear. For the first time during the last 30 years a great increase in the number of common voles, accompanied by widely spread epizooty covering the whole territory of the Tula region, was observed. House mice, common field mice, harvest mice and black rats were also involved in this epizooty and 235 tularemia patients with all clinical forms of the disease were registered, the pulmonary form of the disease being prevalent. The cases of the disease were observed among both urban and rural population. In spite of a high morbidity rate, no cases of group infection were registered in domestic conditions and among agricultural workers due to the existence of the numerous immune layer among the population. The formation of this layer resulted from planned vaccinal prophylaxis covering, on the average, 86.3% of the rural population of the region.     

Influence of the mechanism of transmission of the infective agent on the aetiological structure of leptospiral foci

It has been demonstrated that the differences observed in the aetiological structure of the individual foci of leptospirosis can be explained not only by the affinity of leptospiral serogroups to certain animal species, but also by different mechanisms of transmission of the causative agent of leptospiral infection which can be transferred both by sexual and alimentary routes (in water). It has been demonstrated that mostly one serotype of leptospires predominates in natural foci of leptospirosis, but several in anthropurgic ones. In the author's opinion, leptospiral infection in natural foci is mainly spread by the sexual route through the background species of animals--carriers of leptospirosis, and by the alimentary route in the anthropurgic foci. It is presumed that leptospires of the serogroups Javanica, Australis, Icterohaemorrhagiae, transmitted by the shrew-mice, hedgehogs and rats by the sexual route, are by their origin "ancient" serogroups of leptospires while the serogroups of leptospires isolated from domestic animals, showing predominantly the alimentary route of transmission of infection in the focus, are representatives of the "younger" forms of the evolutional development of leptospires.     

Pseudotuberculosis in the Krasnodar Territory. The clinico-epidemiological characteristics of its morbidity and the biological properties of its strains]

Group cases of pseudotuberculosis, first registered at health-restoring institutions of the health resort of Gelendzhik (the Krasnodar Territory), are described. The etiology of these cases of the disease was established on the basis of clinico-epidemiological data, specific seroconversion in 66% of the examined patients and the isolation of Yersinia pseudotuberculosis strains from the feces of four patients. The combination of signs observed in the isolated strains, viz. the presence of plasmids with molecular weights of 75 and 45 MD, resistance to bactericidal factors of normal human serum and autoagglutination in cell culture medium, made it possible to consider these strains to be virulent. The cases of infection were probably caused by the use of fresh cabbage salad. The study of 3,128 rodents caught in the Krasnodar Territory, including those caught in the area of the health resort, resulted in the isolation of 105 Y. enterocolitica strains and strains of 5 other Yersinia species, but not Y. pseudotuberculosis strains. The concept on the saprozoonotic nature of pseudotuberculosis was substantiated.     

Erysipeloid on the islands of the Ohhotsk Sea. 2. Landscape types of the natural foci of erysipeloid

Cases of skin (skin-artericular) form of erysipeloid were recorded in the islands of the Sea of Okhotsk. The natural foci of the causative agent of this infection were polyhostal and polyvectoral in character. The causative agent of erysipeloid exists among the animals habitating on land and sea. Mass species of animals characteristic of the island landscape served as the sources of infection. Their four landscape types (mountaineous-taiga, of sea coast and rocks, anthropurgic settlement, and of water bodies--salt and freshwater) were preliminarily distinguished by the combination of biocenological, epidemiological, and epizootological peculiarities of natural erysipeloid foci.     

Infectious diseases in natural reservoirs: epidemic situation and morbidity in the Russian Federation and prophylactic measures

The analysis of morbidity in infections with natural foci in Russia for the period of 1999-2000 indicates that a rise in the number of cases of hemorrhagic fever with the renal syndrome, tick-borne encephalitis, Crimean hemorrhagic fever and West Nile fever with a high proportion of urban population among the patients is registered annually. An increase in the epizootic activity of the natural foci of plague is noted in the absence of morbidity among humans. The appearance of the outbreaks of tularemia is linked nor only with the increased activity of the natural foci, but also with the reduced coverage of the population with prophylactic immunization in endemic regions. This analysis infers that morbidity prognosis in infections with natural foci for 2001 remains unfavorable. The growth of morbidity in these infections is mainly due to the reduction of measures for controlling their vectors both is open nature and in settlements, as well as to low coverage with prophylactic immunization. Urgent complex measures which may ensure effective antiepidemic and prophylactic work for controlling infections with natural foci are presented.     

Clinico-epidemiologic characteristics of infectious hepatitis in a populated area where hepatitis had not been reported for a long time

The analysis of the clinico-epidemiological characteristic of infectious hepatitis in a populated area in the Kashkadarya region of the Uzbek SSR, where the cases of infectious hepatitis were not formerly registered for a long time, is presented. The epidemic process was found to take and intensive course with the formation of a large number of foci with 2 or more patients, an in the age groups of 20-29, 40 years and older a comparatively high morbidity rate, exceeding that among the total population 2-3 times, was registered. A low proportion of patients under 14 years (21.1%) was probably due to the planned preventive gamma globulin immunization carried out in this area.     

Effect of common Brassica vegetables (Brussels sprouts and red cabbage) on the development of preneoplastic lesions induced by 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) in liver and colon of Fischer 344 rats

Aim of the present study was the investigation of effects of juices from commonly consumed Brassica vegetables (two cultivars of Brussels sprouts and two cultivars of red cabbage) on formation and development of preneoplastic lesions in colons (aberrant crypt foci, ACF) and livers (glutathione-S-transferase placental form, GST-P+) in male F344 rats. The foci were induced by 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), a widespread carcinogenic heterocyclic aromatic amine which is found in fried meats. Recently, we reported on pronounced protective effects in the two-organ foci model when the vegetable juices were given during the carcinogen treatment but several findings by other groups indicated that breakdown products of glucosinolates contained in Brassica vegetables cause tumour promotion in various organs of laboratory rodents. In the present study, the animals received the juices in the drinking water (5%) over a period of 20 days after treatment with IQ (100 mg/kg bw on 10 alternate days). To increase the foci yield (which facilitates the detection of modifying effects), the animals were fed with a modified (high fat, fibre free) AIN-76 diet. With exception of the sprout variety "Cyrus", all juices lowered the number of GST-P+ foci as well as the foci area in the liver, but none of these effects was statistically significant. In the colon, none of the juices had an impact on crypt multiplicity (number of crypts/focus), whereas the number of ACF was decreased; only with the sprout variety Maximus the protective effect was significant (reduction 49%). The present findings show that administration of vegetable juices to the animals after the carcinogen does not increase the number and size of IQ-induced preneoplastic lesions in liver and colon.     

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.     

准噶尔盆地荒漠景观不同地貌类型鼠、蚤多样性及分布特征

为揭示鼠、蚤空间分布特征与变化规律,本研究以准噶尔盆地鼠疫自然疫源地为靶区,基于鼠类和蚤类的样点采集数据,计算不同地貌的鼠、蚤生态学指标并分析其相关性。基于不同行政区生态学指标计算结果,借助Moran′s I指数、重心模型、标准差椭圆等分析方法探究不同行政区鼠、蚤生态学指标的聚类特征,开展鼠、蚤的空间分布特征及变化规律的相关研究。结果表明：(1)通过对不同地貌鼠、蚤生态指标的研究,可得出鼠、蚤的物种多样性和生态优势度呈负相关,表明在物种多样性较高的群落中,鼠、蚤生态优势度表现不明显。鼠类物种多样性较高的地貌类型与蚤类物种多样性呈正相关,证实鼠类(宿主)物种数量增加,蚤类(寄生)物种的数量也在增加。低海拔地区鼠、蚤群落的相似性总体上大于中海拔地区群落相似性,且相似性系数q值与Cody指数呈相反变化趋势;(2)不同鼠、蚤指标单变量Moran′s I指数表明,鼠类数量、子午沙鼠数量、蚤类均匀度的全局Moran′s I指数大于0,且P值小于0.05,表现出空间集聚现象。单变量局部空间自相关分析结果表明,部分鼠、蚤指标存在多种聚类模式,其中最为典型的聚类模式是高—高聚类模式。不同鼠、蚤指标双变量...     

Patterns in the spread and serovirological diagnosis of serous meningitis

The epidemiological and clinico-etiological study of cases of acute serous meningitis with unknown etiology in children was carried out in a large industrial city at the period of a considerable morbidity rise caused by this infection. The maximum morbidity was registered among younger children under school age attending children's institutions. In 26 closed groups of children group morbidity was revealed (4 cases and more), in 5 such groups small local outbreaks were registered. The clinico-instrumental methods of study permitted one to differentiate the groups of children having serous meningitis of supposedly enteroviral etiology, and sero virological studies carried out with the use of a wide range of diagnostic reagents revealed the etiological role of group B Coxsackie virus, mainly type 4, in 20.6% of cases, ECHO virus, serotypes 3 and 11, in 20.7% of cases, and parotitis virus in 5.3% of cases.     

Evaluation of the polymerase chain reaction effectiveness in the investigation of out-breaks of pseudotuberculosis

Data on the investigation of pseudotuberculosis epidemic outbreaks with the use of the polymerase chain reaction (PCR), are presented. Specific fragments of Yersinia pseudotuberculosis DNA were detected in 81.25% of patients, in 46.83% of cases confirmed by the isolation of Y. pseudotuberculosis cultures. The study of washings from vegetables and equipment in vegetable stores and kitchens yielded positive results in PCR in 8.52% and the survey of rodents--in 3.85% of cases. In the course of the bacteriological study of these specimens 6 Y. pseudotuberculosis cultures were isolated: 3--from vegetable products, 1--from a Norway rat and 2--from house mice. The coincidence of the data obtained by bacteriological study and PCR showed that the latter method gave objective results, while being capable of ensuring rather rapid analysis. PCR should be regarded as a signal test for the bacteriological search of the definite infective agent in the material under study.