Determination of natural foci of tularemia in the Tuva ASSR]

Eleven strains of tularemia causative agents were isolated in 1974 in bacteriological study of ixodes ticks Dermacentor nuttalli (13088 in all) by biotests on albino mice. Tularemia was confirmed retrospectively in two humans who contracted the disease from ondatra cadavers. Skin allergic test with tularin was used to examine 1733 residents of seven populated localities; a positive result was obtained in 2 persons. Finally, in examination of 240 sera of cattle agglutination reaction proved to be positive in 6 cases in titres of from 1:20 to 1:80. Thus, natural nidality of tularemia in Tuva was established for the first time.     

Effect of land reclamation on the transformation of the types of natural tularemia foci

Land reclamation measures carried out on the territory of a flood-plain-paludal focus of tularemia change the ecological and biocenotic links, which leads to the formation of a meadow-field focus with other-than-before sources and vectors of tularemia infection.     

The meadow-field type of tularemia foci in eastern Siberia

The article characterizes a meadow-type focus tularemia, discovered in Zalarinski'i District of Irkutsk Province in 1988. This focus and another similar focus discovered in 1985 at the Krasnoyarsk Territory belong to the meadow type, which makes it possible to regard their presence in Eastern Siberia as an established fact. The main reservoirs and sources of infection in these foci are two species of voles (Microtus gregalis and M. subarvalis).     

Genotyping of the Francisella tularensis strains isolated from natural foci of tularemia in the Rostov region by multilocus VNTR analysis

On the basis of an analysis of the VNTR alleles' distribution in 109 strains of F. tularensis it was established that 19 genotypes of the disease causative agent circulated in the Rostov Region from 1945 to 2002. The microbe-provoked infection episodes can be divided into polyclonal, monoclonal and cluster ones. A retrospective analysis of the genotypes' distribution is indicative of that strains of similar or of closely-related genotypes circulate simultaneously in the studied territory. All investigated F. tularensis strains could be differentiated into two groups; strains, whose genotypes are encountered almost evenly within the entire Region's territory, belong to group 1; and strains of group 2 displayed a trend towards being geographically bound. Isolations of cultures with similar (close) genotypic features made in prolonged time periods suggest that a part of F. tularensis clones can persist for a long time in environmental foci. A set of strains described by genotype can provide a foundation for a database of the tularemic microbe culture within the geo-information system of the South Federative Okrug of Russia.     

Tularemia in inactive natural foci

The data on the epidemiological and epizootological manifestations of tularemia on the territory of the Ulyanovsk region are presented. The characteristics describing the process of the of Francisella tularensis circulation as well as the environmental objects, most important for the manifestations of tularemia infection, are given.     

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.     

Culture properties of the causative agent of tularemia isolated in natural foci in Stavropol Territory, the Kalmyk ASSR and the Armenian SSR

The strains isolated in natural foci of the Stavropol Territory and the Armenian SSR have been found to belong to the holarctic race of Francisella tularensis, biovar II. In natural foci of the Kalmyk ASSR the strains belonging to biovars I and II have been isolated. The study of the tularecinogenicity of the cultures has revealed the existence of strains which are not sensitive to their own tularecins. The phenomenon of tularecinogenicity in F. novocida has been established. Avirulent strain 319/38 belonging to the non-arctic race is recommended as an indicator strain for the determination of tularecinogenicity.     

Exploration of natural foci of tularemia and plague in Armenia using the serological examination of bird droppings and excrements of predatory mammals]

Forty strains of tularemia and 619 of plague microbes were isolated in 1974 in bacteriological examination of natural plague and tularemia foci from a great number of small mammals and their ectoparasites. At the same time in serological examination (in the antibody neutralization test) of bird pellets, 52 mummified cadavers, and 34 excretion samples of mammalian beasts of prey collected in Armenia (its central and North-Western part) in 1973 the antigen of tularemia microbe was revealed in 73, 8, and 3, and of plagye--in 42, 5, and 1 cases, respectively. In one of the sites examined the number of positive findings failed to exceed 10--17%, this indicating a low intensity of the epizootic in the majority of the places. Judging by the mean titres of the serological test, which varied from 1:12 to 1:1428 in examination for tularemia and from 1:12 to 1428 in examination for plague, it was possible to detect both epizootics coursing during the examination, and those which occurred several monts ago. Tularemia and plague foci were not infrequently present at the same territories, and these diseases could involve the same individual animals of Microtus arvalis (Pall.). The data obtained pointed to the greater effectiveness of examination of bird's pellets and excretions of mammalian beasts of prey for the reconnaisance investigation of the natural foci of plague and tularemia in comparison with the bacteriological methods applied usually.