Natural foci of leptospirosis on the territory of Moscow in 1995 - 2004

The results of ten-year observations of the natural foci of leptospirosis on the territory of Moscow are presented. Information on the foci, the main species of small mammals (the reservours of the infection), the etiological structure of leptospires, circulating among rodents and insectivores, is given.     

Rodents as the vectors of infective agents in the natural foci of infections in the Moscow megapolis

This work deals with the results of 40-year observations on the circulation of infective agents in the natural foci of infections (tularemia, leptospirosis, hemorrhagic fever with renal syndrome) among rodents and other small mammals in the territory of the Moscow. The monitoring of their frequency and the infection rates remains the main effective measure for the prophylaxis of dangerous infections among the population of the megapolis.     

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.     

The mechanisms maintaining epidemic foci of leptospirosis]

24,419 samples of blood serum, collected in the Azerbaijan SSR among different professional groups of the population, have been tested for leptospirosis. The comparison of the results with those obtained in the natural foci of leptospirosis and in the foci of this infection appearing as a consequence of human activities has made it possible to come to the conclusion that the epidemic foci of leptospirosis are maintained due to the existence of foci among cattle. The cases of contamination among persons professionally linked with large cattle breeding complexes have been found to exceed those among persons working at farms of a nonindustrial type.     

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.     

New findings concerning the spread of natural foci of infection in the transpolar region of eastern Siberia]

New materials are presented on the presence of the foci of anthropozoonozes in the Extreme North. For the first time there was established the existence in the subarctic tundra of the Taimyr peninsula of the arbovirus foci of the tick-borne encephalitis complex. A virus of the tick-borne encephalitis complex was isolated in 1973 from the gamasida ticks Haemogamasus ambulans Thorel. and Hirstionyssus isabellinus Oudms. and the nests of the Siberian lemming Lemmus lemmus L. This pointed to the existence in the Transpolar region of the foci or arboviruses in the nest-hole biocenoses of the lemmings outside the bird colonies. Cultures of tularemia bacilli (which proved the etiology of the epizootic among the lemmings observed in 1973 and also the presence of the lemming natural foci of tularemia and their combination with the arbovirus foci) were isolated from the lemmings at the same territory. The results of serological examination of the local population and of the animals pointed to the circulation in the Transpolar region of the causative agents of leptospirosis, toxoplasmosis, Q-fever and of the Asian tick-borne rickettsiosis.     

Immunologic monitoring of leptospirosis in the Maritime Territory

The epidemiological and epizootic situation in Leptospira infections at the Maritime [correction of Primorski] Territory is evaluated on the basis of complex studies carried out in 1984-1989. As revealed in these studies, cases of leptospirosis among humans have a sporadic character and are mainly registered among professional high risk groups of the population. In the immunological structure of persons covered by the survey L. hebdomadis, L. pomona and L. javanica prevail. The anthropourgic foci of leptospirosis caused by L. pomona are of the leading epidemiological importance. Swine serves as the main source of infection in these foci. The study revealed the epidemic danger of the natural foci of leptospirosis caused by L. grippotyphosa and L. javanica in rice fields where the decisive factors of leptospirosis proved to be reed voles and striped field mice serving as reservoirs of this infection, as well as the synanthropic foci of leptospirosis caused by L. hebdomadis with house mice serving as the main carriers.     

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.     

Features of leptospirosis in the Krasnodar Territory

The data on leptospirosis morbidity in the Krasnodar Territory, one of the most epidemiologically unsafe areas in this infectious disease in the Russian Federation, are presented. High morbidity registered in this territory greatly depends on the epidemic outbreaks appearing due to defects in the realization of a complex of sanitary and veterinary measures. The Krasnodar Territory is liable to be affected by natural calamities. In 1997 a severe outbreak of leptospirosis took place here in connection with the high flood. Due to timely prophylactic measures the epidemiological consequencies of the similar calamity occurring in 2002 were brought to a minimum.     

Self-maintenance of foci of bovine leptospirosis]

The relationship between the rate of cattle infection with leptospirosis and the total number of livestock at cattle-breeding farms has been established. The annual dynamics of this infection has been found to give two morbidity rises among the animals, occurring not due to their contacts with the natural foci of leptospirosis, but as a consequence of the animal vertical and horizontal "circulation". The mechanisms of self-maintenance of the foci of leptospirosis among cattle are discussed.     

Epidemiology of leptospirosis in the Kirov region

The dynamics of leptospirosis morbidity in the Kirov region for many years is presented. The wide spread of leptospirosis foci, both natural and formed as the result of human activities, in the region is shown. The main role in infecting humans with leptospires belonged to the latter foci in a number of districts in the region was established. The etiological structure of leptospirosis cases among humans was represented, primarily, by leptospires of serogroup Grippotyphosa, following by serogroup Canicola and then serogroups Pomona, Tarassovi, Sejroe, Australis, Javanica. The dominating serogroups of leptospires were Grippotyphosa in wild rodents and Sejroe in agricultural animals. Persons belonging to the age group constituting the mainstay of work force (20-49 years) prevailed among the patients: town dwellers, factory and office workers. The main role in the transmission of infection to the population was played by the water factor.     

Role of serodiagnosis in recognizing atypical forms of leptospirosis in Krasnodar Territory

The work deals with the epidemiological situation with respect to Leptospira infections in the Krasnodar territory. The work demonstrates that, in comparison with 1960-ies characterized by the prevalence of diseases caused by L. pomona and L. grippotyphosa, in 1970-ies the increase of the specific proportion of infections caused by L. icterohaemorrhagiae was registered. In recent 5 years (1980-1984) this leptospirosis constituted 73.5-94.8% of the total morbidity rate in the territory. Such situation was caused by active prophylactic measures in cattle breeding, as well as by the increase of the number of leptospirosis foci, appearing as the result of human activities and providing favorable conditions for the life and multiplication of Norway rats, the main source of infection caused by L. icterohaemorrhagiae as indicated by the fact that up to 23.9% of the Norway rats examined in this study proved to be contaminated. The detection of cases of leptospirosis among febrile patients and mistakes in clinical diagnosis confirm the necessity of the serological examination of febrile patients with the acute onset of the disease with temperature reaching 38 degrees C and higher for 3-5 days and the clinical picture of the disease being unclear in order to find out patients presenting with the atypical clinical picture of leptospirosis.     

Comparative study of the immunoglobulin content in persons from leptospirosis foci in different geographical zones of the RSFSR]

The authors carried out a comparative study of the content of serum immunoglobulins in persons from the leptospirosis foci of various geographical zones of the RSFSR: European part--the Centre (Moscow and Ryazan regions), the South (Checheno-Ingush ASSR and Krasnodar Territory), and Western Siberia (Altai territory), Leptospira of serological group Pomona, Grippotyphosa, and Hbedomadis served as the causative agents of the diseases. It appeared that the annual course of the climatic factors acted equally (inhibitory action) on the immuno-globulin metabolism in the residents of temperate and southern zones of the RSFSR at the warm period of the year (May-September), and in the Western Siberia- in winter. However, irrespective of the time of the year, the level of immunoglobulins G and A was greater in the residents of Western Siberia than in the native population of the European part. There proved to be no correlation between the levels of leptospirosis seropositivity in the foci of infection under study and the serum immunoglobulins in local residents of various geographical zones.     

Study data on ornithosis infection in the Azerbaijan SSR]

Data are presented on the study of epizootology and epidemiology of ornithosis. There were revealed natural foci of ornithosis in the Kyzyl-Agach preserve, at the Sary-Su lakes and at the Glinyany island; these foci were dihostal and polyhostal, as well as conjointed (ornithosis, arboviruses, Q-fever, Asian tick-borne typhus, leptospirosis). Anthropurgic foci were found in 12 populated localities, semi-wild dove serving as the main component. Fowl was found to be infected in 12 poultry-farms; occupational ornithosis was present among the bird-rearers. Immunological structure of the population in respect to ornithosis was studied. Patients with various diagnoses showed positive serological reactions retrospectively; there were 155 cases of ornithosis among them.     

Epidemiological surveillance on natural-borne infections in the Ulyanovsk region

The analysis of natural foci of haemorrhagic fever with renal syndrome (HFRS) and tick-borne borreliosis on the territory of the Ulyanovsk region is presented. Reduced rat control interventions result in a wide spread of these and other infections with natural focality. Monitoring of natural foci of HFRS, tick-borne borreliosis and arbovirus infections, their typing and determination of main reservoirs are the most promising among epidemiological surveillance methods.     

The functioning of a drained natural focus of leptospirosis in a nonchernozem area

The drainage of a natural focus of leptospirosis of the flood plain-swamp type, carried out over the period of 15 years, has led to changes in the species structure of small mammals and to an increase in the number of Leptospira-carrying species. Nevertheless, like before drainage, the prevalent species and the main carrier of leptospires is still the root vole (Microtus oeconomus Pallas). The intensity of the epizootic process among small mammals at the final stage of drainage has proved to be similar to that at the initial stage. At the same time the cultivated fields created on the drained territory of the natural focus abound, by the time of harvesting, with small mammals among whom the intensive epizootic process takes place.     

Topical problems of rabies: natural foci, the methods of study and control in Central Russia

This analytical review is dealing with the origin and evolution of modern rabies as well as hypotheses concerning the natural foci of rabies infection, the formation of the Central European nosological area of rabies and its eastward shift due to the systematic oral vaccination of the main hosts. The epizootological problems connected with the character of the natural foci of rabies, as well as the methods and prospects of the vaccination of foxes on the territory of Central Russia, are discussed.     

A small-mammal study in the northeastern Kara Kum for leptospirosis infectivity]

Search for natural foci of leptospirosis was carried out in 1987-1989 in humid biotopes of Tashauz Province, Turkmenistan. Such potential carriers of leptospirosis as house mice (Mus musculus) and tamarisk gerbils (Meriones tamariscinus) are widely spread in this area, and the size of their population can amount to great numbers. The sharpest fluctuations in the population size are characteristic of house mice inhabiting the shores of water collecting ponds and lakes in the regions of minimally used pastures. A moderate number of house mice was registered in spring and autumn at the area of irrigated agriculture. Only here and only in autumn a faint epizootic manifestation of the natural focus of L. grippotyphosa infection in house mice was registered for the first time in Turkmenistan. The titers in mouse blood sera, determined in the microagglutination test and the Leptospira lysis test, were 1:20 to 1:200. According to the data on the humidity and pH of the soil in the vicinity of irrigated fields, spring and summer months may be regarded as the most favorable period for the survival of leptospires in the environment. The probability of the aggravation of the epizootic situation seems to increase when irrigated fields adjoin pastures of are temporarily used as grazing ground for cattle.     

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.     

Major Neutrophilia Observed in Acute Phase of Human Leptospirosis Is Not Associated with Increased Expression of Granulocyte Cell Activation Markers

It has long been known that pathogenic Leptospira can mobilize the immune system but the specific contribution of neutrophils to control the infectious challenge remains to be clarified. We herein analyzed the phenotype of circulating neutrophils of patients with leptospirosis and healthy controls for the expression of toll-like receptor (TLR) type 2 (TLR2, to sense the leptospiral LPS) and several activation markers: interleukin 8 chemokine receptor CD182 (CXCR2), CD11b of the integrin/opsonin complement receptor type 3 (CR3) and CD15 (ligand of the selectin). The plasmatic level of the main CD182 ligand, interleukin 8 (CXCL8), was measured by ELISA. Hospitalized leptospirosis cases showed marked neutrophilia, particularly in the most severe cases. Interestingly, TLR2 was significantly increased in leptospirosis but identical levels of CD182 and CD11b were detected when compared to controls. CD15 was significantly decreased on neutrophils in leptospirosis but returned to normal within 1 month. Basal levels of IL-8 were measured in control subjects and were not increased in leptospirosis cases at the initial stage of the disease. In conclusion, we observed that neutrophils failed to regulate the expression of several of the receptors involved in cell activation and recruitment. This study further emphasizes the paradigm that neutrophils may be impaired in their overall capacity to thwart bacterial infection in leptospirosis patients.