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At least 19 recordsLinked to original sources

[Experimental studies on the transmission of hemorrhagic fever with renal syndrome virus by gamasidea mites and fleas].

Hemorrhagic fever with renal syndrome (HFRS) virus was isolated from 3 species of gamasidea mites (Haemolaelaps glasgowi, Laelaps jettmari, Eulaelaps shanghaiensis), and 2 species of fleas (Monopsyllus anisus, Leptopsylla segnis) collected from nests of HFRS virus-infected Apodemus agrarius, whereas HFRS virus was not recovered from Gamasidea mites and fleas collected from nests of uninfected Apodemus agrarius. It was thus confirmed that HFRS is a disease of animal origin with natural foci of infection. Experimental studies demonstrated that positive results of virus isolation were obtained from originally healthy population of Monopsylla anisus, Leptopsylla segnis and Haemolaelaps glasgowi 24-48 hours after they had sucked HFRS virus suspension, while positive results of virus isolation were still obtained from Haemolaelaps glasgowi but not from 2 species of fleas 7 days after they had sucked HFRS sirus suspension. It was confirmed that Monopsylla anisus and Leptopsylla segnis cannot propagate HFRS, and therefore their transmission would be mechanical. On the contrary, Haemolaelaps glasgowi might play the role of biological vector.

Animals↗

[The sympatry of closely related species of ixodid ticks and its possible role in the parasitic systems of natural foci of transmissible diseases].

Sympatry of the following pairs (or groups) of closely related species in the territory of the former Soviet Union amd some neighbouring countries has been revealed as a result of a revision of the fam. Ixodidae: I. persulcatus-I. ricinus, I. persulcatus-I. pavlovskyi, I. crenulatus-I. kaiseri, Dermacentor marginatus-D. silvarum-D. ushakovae, D. ushakovae-D. niveus, D. pavlovskyi-D. montanus, Rhipicephalus turanicus-R. sanguineus, R. turanicus-R. rossicus, R. turanicus-R. pumilio, R. rossicus-R. pumilio. Biotope and host relationships of sympatric species, as well as seasons of parasitizing have been described on the basis of the field researches conducted by the author, the collections of the Zoological Institute, Russian Academy of Sciences, and the publications substantiated by collection materials studied by the author. Hypothetic ways of the paleogenesis of each sympatric area and geological age have been considered. The recent sympatric area for I. persulcatus-I. ricinus (fig. 1) is of Holocene age (max. 8.000-10.000 years). During that period approximately 1600-2000 sympatric generations could have been realized. Some recent sympatric areas (I. persulcatus-I. pavlovskyi, and some species of other genera) are of Pleistocene and even Pliocene age (2-10 million years). In these areas the number of realized sympatric generations must have been much higher. Several variants of joint simultaneous and successive feeding on one and the same host individual have been established for stages of life cycles of sympatric species of ticks. Contacts of this kind could have created canals for multiple oscillatory exchange of pathogenic taxa (species, genospecies, strains) in a few or many thousands of sympatric generations of closely related vectors. Thus, the same taxon of a pathogen may be subject to different influence of ixodid vectors in sympatric area and in the area of separate habitat of close species of vectors.

Animals↗

Lyme disease: the latest great imitator.

Lyme disease is caused by the spirochete B. burgdorferi. Like its counterpart syphilis, it causes multisystem disease particularly affecting the skin, nervous system, heart and musculoskeletal system. It is endemic in several areas of the United States as well as in Europe. The prompt recognition of this disease and its diverse manifestations should lead to early treatment and resolution. Prevention is aimed at avoidance of the tick vector.

Animals↗

Theobald Smith--the discoverer of ticks as vectors of disease.

The cause of Texas fever in cattle, which is characterised by lysis of erythrocytes leading to anaemia, icterus, haemoglobinuria, and death, remained unsolved for many decades and assorted theories were proposed as an explanation for a disease being transmitted by apparently healthy animals. From 1889 to 1893, Theobald Smith and Frederick L. Kilbourne could demonstrate in elegantly conducted experiments how the disease was spread from cattle to cattle by ticks serving as the vector of transmission. Furthermore, they were able to identify the pathogen of Texas fever, an intra-erythrocytic protozoan which Smith named Pyrosoma bigeminum. Today it is recognised that either of two species of the now renamed genus Babesia, Babesia bigemina and Babesia bovis, may be involved in Texas fever and that babesiosis is generally transmitted by ticks. In animals, genera like Boophilus spp., Dermacentor spp. and Rhipicephalus spp. are possible vectors. The first case of tick-transmitted babesiosis in a human was reported by Skrabalo and Deanovic in 1957 and occurred near Ljubliana in the small town of Strmec, Croatia. In humans, the vectors of most reported cases are ticks of the genus Ixodes, which are among the most predominant ticks in Austria. However, cases of human babesiosis in Austria remain to be studied. Smith and Kilbourne's work was the first demonstration that ticks transmit disease of any kind. Furthermore, by proving that ticks carry Babesia microti--which causes babesiosis in animals and humans--this is the first account of a zoonotic disease and the foundation of all later work on the animal host and the arthropod vector.

Animals↗

[Study on natural infection of epidemic haemorrhagic fever virus in Leptotrombidium scutellare].

Leptotrombidium (L.) scutellare was considered to be the suspected vector of epidemic haemorrhagic fever (EHF). In order to clarify the relationship between this mite and EHF, from Oct to Nov 1988 and Oct of 1989, the larvae of this mite were collected from rats in areas with constantly high incidence of EHF in Shanxi Province and larvae with only small quantity of meal were selected and for more than 15 days before isolation of EHFV. Six strains of virus were isolated. The viruses isolated were identified to be EHFV by serum test, immunofluorescent blocking test as well as neutralization test. The above results further demonstrate this mite can naturally be infected by EHFV and therefore serve as vector of EHF.

Animals↗

[A new look at transmission and circulation of tick encephalitis virus in nature].

The author summarizes briefly the results of experiments which provide evidence of non-viraemic transmission of the virus from infected to non-infected ticks during co-feeding on a non-viraemic host. This mode of transmission originally found in the Thogoto virus and its vector, the tick Rhipicephalus appendiculatus, was proved also in the virus of tick-borne encephalitis and its vector Ixodes ricinus. Based on this fact some conclusions are drawn revising the accepted view regarding the life cycle of tick-borne encephalitis virus in nature and in particular the relationship: vector-host-virus.

Animals↗