[Experimental assessment of the possible significance of argasid ticks in preserving the natural foci of West Nile virus infection].

Experiments indicated that the argasid ticks Alveonasus lahorensis were highly susceptible to West Nile virus when inoculated in the hemocoel. The virus concentration in the ticks reached high values when very low doses (0.01 PFU) of the pathogen were administered. The ticks kept at 3.0 +/- 1.0 degrees C retained the pathogen up to 116 days (a follow-up period). The infection rate of the ticks depending on the virus dose administered was in the range from 12 to 80%. The contaminated specimens successfully transmitted the virus to rabbits by blood suckling. The findings suggest that the argasid ticks may be involved in the preservation of West Nile virus in the interepidemic period and be responsible for the outbreak of this infection in summer and autumn months.

[Study of the possibilities of contamination and transmission by the mosquitoes Culex pipiens f. molestus Fors, a pathogen of West Nile fever].

Experimental studies have demonstrated that the mosquitoes Cx. p. f. molestus fed with virus-containing suspensions, by using an artificial membrane and hygroscopic surface, are infected in 60 to 100% cases and transmit the accepted pathogen of West Nile fever (WNF) to newborn albino mice on blood sucking. The mosquitoes of this species maybe involved in the spread of the pathogen of WNF during its epidemic outbreaks.

[Experimental study of relations of the argasid ticks Alveonasus lahorensis with Coxiella burnetii].

The argasid ticks A. lahorensis can be infected with Coxiella burnetii on feeding on an infected rabbit. The adoptive pathogen reproduces in the ticks and accumulates in them up to 10(10) ID50 g(-1). Coxiella persists in the ticks at this level up to 156 days (the time of observation). The infected ticks transmit Coxiella to guinea pigs while sucking. The ticks show transovarial transmission of Coxilla during metamorphosis. On this basis and with consideration for the fact that A. lahorensis uses a wide host range, it can long starve and retains Coxiella burnetii in the foci of Q fever.

[Experimental study of the inoculative transmission of Rickettsia typhi by gamasid mites (Gamasidae) Ornithonyssus bacoti].

The authors' studies have established that the concentration of Rickettsia typhi may increase about 100-fold in the infected Ornithonyssus bacoti mites. At the time, when on feeding 20 to 200 adult mites on guinea-pigs and albino rats 4 to 36 days after inoculation, they did not transmit Rickettsia typhi on blood sucking.

[Cultivation of the clothes lice adapted to feeding on rabbits].

A race of clothes lice adapted to feeding on rabbits is kept at a laboratory longer than 50 years. For this period, more than 850 insect generations undergoing no change in a number of biological tests and morphological indices have been obtained. They have retained a high susceptibility to Provacheck rickettsia infection. All infected lice die, partially with the signs of hemolytic imbibition. Their rickettsial accumulation is as high as 10(5.0) ID50 per insect for albino rats.

[Hemorrhagic fever with the renal syndrome: modern aspects of epidemiology and prophylaxis].

Hemorrhagic fever with the renal syndrome (HFRS) is a typical natural-and-focal virus infection having military-and-epidemiological importance for Armed Forces of most countries. Severe forms of this infection are typical for the Far East of Russia, countries of South-East Asia and especially for the American continent. The lethality from HFRS amounts to 15-50%. The main natural carriers and keepers of HFRS stimulus are various mouse-type rodents. In Russia besides well-studied natural focuses on the Far East, Siberia, Ural, Povolge other active HFRS focuses were determined not long ago (Moscow, Orel, Lipetsk, Tula and Voronezh regions, the territory of Big Sochi). A man is infected by an aerosol, forming during drying up of rodents' urine, feces, saliva containing HFRS virus. Vaccinal prevention of HFRS in Russia hasn't yet been worked out. Ribavirin is the most effective in the treatment for HFRS. The means of prevention of population and servicemen must exclude their contact with rodents both in natural conditions and in populated areas.

[Ecological aspects of human pathogens Ehrlichia and Bartonella]. / Ekologicheskie aspekty patogennykh dlia cheloveka bartonell i érlikhii.

The review presents data on the natural circulation of Bartonellas and Erlichias with the participation of lice, fleas, mosquitoes, Ixodes ticks, as well as rodents, large wild mammals, and domestic animals. It outlines the human infection routes that are mainly associated with the attack of infected carriers and with the contacts with different warm-blooded animals. The risk of bartonellosis spread is evidenced by the data showing that 12.3% of clothes lice collected from homeless individuals in Moscow turned out to be infected. In a focus of erlichiasis, the infection rates of Ambliomma americanum and Ixodes scapularis were 4.9 and as high as 20%, respectively; 100% of white-tailed deers (Odocoileus virginianus) were seropositive. However, many issues associated with the preservation of these natural vectors, with the route of their transmission to human beings and animals are to be studied.

[A comparative study of Coxiella burnetii strains differing in virulence in the intratracheal infection of guinea pigs]. / Sravnitel'noe izuchenie razlichaiushchikhsia po virulentnosti shtammov Coxiella burnetii pri intratrakheal'nom infitsirovanii morskikh svinok.

As found out in earlier investigations, after the intratracheal infection of guinea pigs with C. burnetii (the method of infection, most similar to aerogenic infection which is characteristic of Coxiella under natural conditions) the maximum amount of the infective agent is accumulated in the lungs of the animals, damaging the organs of the reticuloendothelial system. The present investigation has revealed that this method of infection makes it possible differentiate C. burnetii virulent strains, differing in the level of the accumulation of the infective agent in the lungs of guinea pigs.

[The pathogenesis of Q fever in the intratracheal infection of guinea pigs]. / Patogenez Ku-likhoradki pri intratrakheal'nom infitsirovanii morskikh svinok.

The intratracheal introduction of R. burnetii is the method of infection, highly similar to aerogenic infection, the most widespread route of R. burnetii infection in humans under natural conditions. This suggests that the study of the pathogenesis of Q fever resulting from the intratracheal infection of guinea pigs is highly topical. The authors have established that after the penetration of the infective agent generalized infection develops in the animals with rickettsiae accumulating mostly in the lungs and the organs of the reticuloendothelial system being affected; this infection is commonly more pronounced than that developing after the intraperitoneal inoculation of rickettsiae.

[Comparative evaluation of vaccinal and virulent strains of Rickettsia prowazekii by the plaque method]. / Sravnitel'naia otsenka vaktsinnogo i virulentnogo shtammov Rickettsia prowazekii metodom bliashek.

The comparative evaluation of R. prowazekii vaccine and virulent strains has revealed that strain Breinl possesses greater capacity for plaque formation than strain E. The possibility of using the plaque assay for differentiation of substrains 288 and 281 of strain E has been established.