[Ecological and epidemiological aspects of Q-fever].

Ecological and epidemiological features of Q-fever throughout its study are represented. The fact of transformation of Q-fever natural focuses to antropurgical focuses is proved. It is established that intraherd focuses, determining epidemiological status of Q-fever, have great persistence. Significant economical loss due to recurrence and chronization of the infection are proved, economical loss from one case of the disease is calculated.

[Medical geography in study of rickettsioses].

Shorts resume of medical-geographical studies of Q-fever, tsutsugamushi fever, rickettsioses of tick-borne spotted fever is represented. Influence of biotic and abiotic factors on spread and landscape tropism of infection agents is considered. Types of focuses on endemic territories are determined, regions with high risk of infection for humans are detected.

[Survival of Coxiella burnetii in soil].

For the first time the survival of Coxiella burnetii of five types in soils has been studied. The survival of C. burnetii has been found to depend on the content of organic substances in black earth, as well as soil temperature. The method for the prevention of an epidemic outbreak of Q fever directly under the natural conditions has been proposed.

Astrakhan fever rickettsiae: antigenic and genotypic analysis of isolates obtained from human and Rhipicephalus pumilio ticks.

Two spotted fever group rickettsia strains, A-108 and A-167, were isolated from the hemolymph of Rhipicephalus pumilio ticks collected in the Astrakhan region of Russia, which is area endemic for Astrakhan fever. These tick isolates were compared with a strain isolated from a patient suffering from Astrakhan fever and with reference spotted fever group rickettsiae strains. New tick isolates and the human strain were identical in their serologic, antigenic, and genetic characteristics by several methods: microimmunofluorescence, protein gel electrophoresis with immunoblotting, polymerase chain reaction followed by restriction endonuclease fragment length polymorphism analysis, and pulsed-field gel electrophoresis (PFGE). Astrakhan fever rickettsiae were found to be serologically and antigenically similar to Israeli spotted fever rickettsiae. Both of them probably belong to a single Rickettsia conorii pathotype complex. Only PFGE pattern analysis could clearly discriminate Astrakhan fever rickettsiae from other isolates.

Studies of a "new" rickettsiosis "Astrakhan" spotted fever.

The acute febrile disease with characteristic rash seen in Astrakhan region and named as "viral exanthema of unknown etiology" was proved to be a spotted fever group rickettsiosis. Serological examination of humans from endemic areas by complement fixation test revealed antibodies to R. conorii, R. akari and strains Netsvetaev and AR-74 of R. sibirica in titres from 20 to 640 in sera from ill persons. Of 429 sera from healthy persons, 5.1% were serologically positive in a titre of 20-40. The presence of spotted fever group rickettsiae was detected in 8 of 104 Rhipicephalus sanguineus ticks removed from dogs and tested by haemocyte test with Gimenez staining and indirect immunofluorescence technique. Attempts at isolation of rickettsiae in guinea pigs and cell cultures resulted in appearance of specific spotted fever group rickettsiae antibodies in guinea pigs (4 of 8 samples examined were positive) and detection of rickettsiae by immunofluorescence technique in cell cultures (in 2 of 12 samples tested).

Rickettsioses studies. 3. Natural foci of rickettsioses in south Bohemia.

Antibodies against Coxiella burnetii and against rickettsiae of the spotted fever group were found in human sera and in sera from domestic and wild animals collected in south Bohemia. Spotted fever group rickettsiae were also discovered in the tick Ixodes ricinus. These results indicate the presence of both types of rickettsiae in this part of Czechoslovakia. As no epizootics or epidemics of Q fever have as yet been reported in the area, it can be assumed that C. burnetii occurs in the latent state. The occurrence of spotted fever group rickettsiae is probably endemic among I. ricinus ticks and among small and larger wild mammals.

Rickettsioses studies. 1. Natural foci of rickettsioses in the Armenian Soviet Socialist Republic.

Ixodid ticks collected in the Armenian SSR during 1971 and 1974 were positive for rickettsiae of the spotted fever group, as confirmed by haemocyte tests and by isolation experiments. Serum specimens collected from human beings and from domestic and wild animals in the same areas contained antibodies against such rickettsiae and against Coxiella burnetii. These results indicate the existence of mixed natural foci of rickettsioses of the spotted fever group and of Q fever in the Armenian SSR.