Showing papers on "Ixodes ricinus published in 1990"

Development of Borrelia burgdorferi in Ixodes ricinus females during blood feeding.

Abstract: The development and modes of transmission of Borrelia burgdorferi during blood feeding of Ixodes ricinus were evaluated. Our results show that during the slow engorgement phase, the Lyme disease spirochete, B. burgdorferi ingested two hours before a blood meal or transmitted transstadially from the nymphs, multiplies in the midgut lumen of I. ricinus females. The deeper parts of the midgut diverticula appeared to be the preferred sites for this spirochete. In some gut-infected ticks, a few spirochetes can penetrate the midgut wall and induce a systemic infection, while the overwhelming majority of spirochetes persist in the midgut. Presence of B. burgdorferi in hemocoel, and in both acini and ducts of the salivary glands, leads us to suppose a salivary transmission of this spirochete by I. ricinus females.

Subadult Ixodes ricinus (Acari: Ixodidae) on rodents in Berlin, West Germany.

Abstract: To identify hosts that may serve as reservoirs for the agent of Lyme disease in Central Europe, we determined whether Ixodes ricinus L. feed most frequently on certain rodents and whether the abundance of these hosts corresponds to the season of feeding activity of the tick in four sites in Berlin, Federal Republic of Germany. In addition, we correlated abundance of I. ricinus with that of particular rodent hosts. Two small rodents were more abundant than any others; a mouse, Apodemus flavicollis , predominated in a wooded site and a vole, Clethrionomys glareolus , in three brush- or grass-covered sites. The tick was most abundant in the mouse-infested site. Although A. flavicollis comprised only about a third of rodents collected, nearly 60% of all such rodent parasitizing I. ricinus fed on this mouse. These ticks were more abundant on mice than voles in each of the study sites and throughout the year, and more larvae fed on these rodents than did nymphs. Although larval as well as nymphal I. ricinus are most abundant during midsummer, they feed on rodents from April through October. Taken together, these observations suggest A. flavicollis as a potentially important reservoir host for I. ricinus -borne infections.

Using satellite data to forecast the occurrence of the common tick Ixodes ricinus (L.).

Abstract: To forecast the incidence of the common tick, Ixodes ricinus, the authors used the finding that some types of vegetation may indicate the presence of the tick. To obtain the necessary information in a scope which would enable its practical application in medicine to prevent populational exposure to ticks, remote sensing data were utilized as obtained from the Multispectral Scanner operating aboard Landsat 5. A file was selected from the full scene representing a territory which measured 41 by 41 kilometers and in the centre of which there was an area known to have consistently high tick numbers, as revealed in a 25-year continuous study of I. ricinus, and which proved to be a natural focus of tick-borne encephalitis. This area (Potepl) was taken as a model and was compared with its surroundings. Six landscape classes were examined (1--coniferous forest, 2--leaved forest, 3--mixed forest, 4--water basins, 5--glades, 6--housing developments), the former three being of crucial importance to evaluate the probability of tick presence. The 6th category is significant in assessing human exposure to ticks. Data processing was carried out by supervised classification using the Baye's decision rule of maximum likelihood. The findings were obtained both in a graphic form and in the form of statistical reviews as regards the presence of appropriate landscape categories.

Longitudinal study of natural foci of Central European encephalitis virus in West Slovakia.

Abstract: A total of 2922 small terrestrial mammals of 12 species were collected in six localities of West Slovakia between 1981 and 1986. When examined for the prevalence of neutralizing antibodies (NA) to Central European encephalitis (CEE) virus we found that 14.6% had antibody. Nearly all (97%) of the 426 animals with antibody were Clethrionomys glareolus, the most abundant species (52.6% of mammals collected, 15.1% of those with antibody). Apodemus flavicollis (22.5% of mammals collected, 18.1% of those with antibody), Apodemus sylvaticus (14% of mammals collected, 8.5% of those with antibody), and Microtus arvalis (5.5% of mammals collected, 3.3% of those with antibody). In all locations studies the most abundant tick found on small mammals was Ixodes ricinus (larvae and nymphs). Less abundant, but present in all studied sites, were larvae and nymphs of Dermacentor reticulatus and Haemaphysalis concinna. Six strains of CEE virus were isolated from tissues of animals: four from Clethryonomys glareolus and one each from Apodemus flavicollis and Sorex araneus. Three of six isolates were from animals collected in February; none of the six had detectable neutralizing antibody to CEE virus. We discuss these observations with regard to possible mechanisms of persistence of CEE virus.

Borrelia burgdorferi in ticks of the Canton Tessin (Switzerland).

Abstract: In the northern Alps it is hard to find an Ixodes ricinus population which does not harbour Borrelia burgdorferi. The infection rates range from 5 to 34% for adults and nymphs to 3.1% for larvae. This study shows that the infection rates on the southern side of the Alps are similar, at 25% for adults, 36.2% for nymphs and 3.2% for larvae. With respect to tick species other than I. ricinus, we did not succeed in finding any spirochetes in Dermacentor marginatus, Haemaphysalis punctata, Ixodes hexagonus, Rhipicephalus sanguineus.

Prevalence of borreliae in Ixodes ricinus ticks from southern Moravia, Czechoslovakia.

Abstract: A total of 378 adult Ixodes ricinus ticks were collected by flagging vegetation in four localities of two districts (Breclav, Znojmo) in south Moravia and examined microscopically. Borreliae were identified in Giemsa-stained midgut smears from 32 (i.e. 8.5%) ticks (9.4% females, 7.2% males); the infection rate varied between 0.0 and 11.4% in the four localities examined. Among female ticks, significantly more were found to be infected in autumn (19.7%) than in spring (5.8%). Dark-field (DF) and Giemsa-stained smears (GS) examinations were compared for their sensitivity in detecting borreliae in 128 field-collected ticks; GS method showed a little higher sensitivity (11.7% ticks were positive) than DF procedure (9.4% ticks positive). Two strains of Borrelia burgdorferi were isolated from a total of 150 adult I. ricinus ticks cultured in BSK medium.

Time of repletion of subadult Ixodes ricinus ticks feeding on diverse hosts.

Abstract: For a comparison of the times of day at which the subadult stages ofIxodes ricinus detach from nocturnal vs diurnal hosts, these ticks were placed on a variety of indigenous and experimental animals. The time of detachment appears to depend more on properties of the host than on the periodicity of tick behavior. Ticks on rodents, regardless of host periodicity, tended to detach late in the afternoon; those on a hedgehog detached around midnight, and those on lizards and birds, during the morning. Ticks on carnivores (dog, cat) detached throughout the daylight hours. The ability of these parasites to survive to the next developmental stage and, ultimately, to come into contact with another suitable host may be influenced by the identity of the host and, hence, by the circumstances of detachment. SubadultI. ricinus probably concentrate in the host's nest when feeding on mammals but are scattered over the ground when feeding on lizard or avian hosts an aspect of engorgement behavior that may profoundly affect the capacity of this tick as a vector of agents of Lyme disease and other infections.

Incidence of tick-bite in man in Aland Islands: reference to the spread of Lyme borreliosis.

Abstract: The common tick Ixodes ricinus is a vector both for the virus of tick-borne viral encephalitis (Kumlinge disease, KD) and of Borrelia burgdorferi (Lyme borreliosis, LB). Bites of the tick are believed to be common in Aland, an island province of Finland in the Baltic Sea. KD has been seen there for many years, and cases of LB have been diagnosed lately. The purpose of this study was to find the incidence of tick-bite among the population with possible implications for the spread of LB. A questionnaire was sent to 561 persons greater than 8 years of age out of a total of 21,281 in order to record tick-bites and erythema chronicum migrans (ECM). The number of answers was 519 (92.5%). 441 persons (85%) had been bitten by ticks, 146 greater than 10 times. 14 probands had had ECM, 73 other rashes around the tick-bite. It is concluded that tick-bites are very common among the population, and thus conditions are favourable for the spread of any tick-borne infection such as LB. The number of patients with secondary or tertiary LB diagnosed in the area is presently 17. It is likely that there are many undetected cases in the area.

Occurrence of the tick Ixodes ricinus (L.) under the conditions of anthropopressure.

Abstract: The authors report on their findings of the tick Ixodes ricinus under urban conditions of Prague. The concrete data were taken as a basis for a general scheme of possible occurrence of this species in various town parts, determined by the state of vegetation and presence of large mammals. Discussed are also conditions for I. ricinus maintenance in another type of anthropogenous landscape, the spoil banks resulting from brown coal exploitation.

Occurrence of Borrelia burgdorferi in Ixodes ricinus in The Netherlands

Abstract: In a 1989 surveillance to study the infection rate of Ixodes ricinus ticks with Borrelia burgdorferi, a total of 1838 nymphal and adult Ixodes ricinus ticks were collected from 20 locations in The Netherlands. By means of a culture method using modified Barbour-Kelly-Stoenner medium nymphs were examined in pools of 4 and adults were examined individually. With 63 out of 75 isolates propagation and serological identification were possible. All of these 63 isolates were identified as Borrelia burgdorferi by means of an indirect immunofluorescence assay. In nymphs the minimal infection rate was 2.4%. The rate of infection for adults was shown to be 14.3%. These results are in agreement with the percentages found by other investigators in West-Europe. In all locations examined Ixodes ricinus were found to be infected with Borrelia burgdorferi, although the infection rate varied. The results indicate that the infection is widespread among ticks in The Netherlands and the potential risk of acquiring Lyme borreliosis after a tick bite is serious.

Francisella tularensis from ixodid ticks in Czechoslovakia.

Abstract: A total of 26,478 ixodid ticks (935 pools) were examined by intracerebral inoculation of suckling mice. Six species of ticks were tested: Ixodes ricinus (23,470 individuals), I. trianguliceps (12), Haemaphysalis punctata (831), H. concinna (39), Dermacentor reticulatus (69) and D. marginatus (2,057). The ticks were collected largely by flagging vegetation, a substantial minority (4%) from animals. Three strains of Francisella tularensis were isolated, one each from I. ricinus (males, district Breclav, southern Moravia), D. reticulatus (males, district Breclav) and D. marginatus (engorged females collected from sheep in Roznava district, eastern Slovakia). D. marginatus and D. reticulatus represent new vector species for Czechoslovakia.

Experimental infection of ticks Ixodes ricinus with tick-borne encephalitis virus under different microclimatic conditions.

Abstract: The influence of environmental temperature and relative air humidity on the development of ticks Ixodes ricinus and their infection rate with tick-borne encephalitis virus was studied. It was found that the temperature influenced significantly the development of ticks, but it did not influence their infection rate. To the contrary, the relative air humidity influenced the infection rate. It is assumed that the intrinsic factors play a primary role in the infection of ticks, while extrinsic factors have a secondary role; they are probably important at border values only.

[The role of large wildlife in the maintenance of natural foci of tick-borne meningoencephalitis in northern Croatia].

Abstract: Between 1986-1988 sera from 245 game animals--37 roe deers, 102 red deers, 81 wild boars and 25 hares--shot in 8 different localities of Nort Croatia, a well-known nosoareal of tick-borne encephalitis, were tested for TBE virus heminhibiting antibodies. The following percentages of positive animals were found: 24, 39, 39 and 0% respectively. Most of the animals examined, 180 of them, were shot in lowland woods of the commune of Nasice and its surroundings. There the percentage of positive animals was somewhat higher: 36, 41, 42 and 0 respectively. As these animals regularly participate in the feeding cycle of the ubiquitous wood tick Ixodes ricinus, the main vector of the tick-borne meningoencephalitis virus, it is infered that they (the hare being excluded in this study), apart from myomorphous mammals, play an important role in the transmission chain of the tick-borne meningoencephalitis virus in the respective natural foci of this zoonosis.

Immunity against female Ixodes ricinus L.: effect on feeding and haemoglobin digestion.

Abstract: Rabbits have been infested 3 times with 10 females and 10 males Ixodes ricinus. Immunity which is acquired when ticks feed on naive rabbits (first infestation) perturbs tick feeding on reinfested animals (third infestation). Then ticks ingest less blood (p less than 0.001). Blood meal digestion in also altered. It was estimated by measuring haemoglobin concentration in ixodid midgut during 20 days after their drop off. After the first infestation this concentration decreases linearly with time (r2(1) = 46.14%, n1 = 63, p less than 0.001). After 3 infestations it is no longer correlated with time, indicating an impaired digestive process (r2(3) = 7.15%, n3 = 49, p greater than 0.05). This observation was corroborated by an analysis of multiple regression. Haemoglobin concentration of tick midgut only correlates with time after a first infestation (r2(1) = 45.25%). In ticks fed on immune animals this concentration is predicted with the quantity of midgut C3 and the weight of fed ticks and not with time (r2(3) = 60.99%).

[Ixodes ricinus, Haemaphysalis concinna and Dermacentor reticulatus (Ixodida, Ixodidae) in the East German district of Leipzig].

Abstract: Haemaphysalis concinna and Dermacentor reticulatus mostly occur in narrow-limited humid biotopes of certain landscapes, whereas Ixodes ricinus--as wellknown--occurs more or less occupying the whole territory in kind of a mosaic; in regard of epidemiological questions at least, such a distribution may be resumed for Ixodes ricinus. Haemaphysalis concinna nearly regularly may be found in certain biotopes. Considering the possible role of Haemaphysalis concinna and Dermacentor reticulatus as vectors and reservoirs of transmissive agents special attention is paid to the transmitting of tick-borne borreliosis.

Borrelia sp. in the common tick (Ixodes ricinus) from the Prague area

Abstract: In the course of 1988 almost 3000 ticks were collected from various localities on the territory of Prague and examined by the method of indirect immunofluorescence (IFA) for the presence of Borrelia. The immunity rate of ticks varies between 1.9-22.0%. Positive ticks were found also in some areas practically in the centre of the town. These findings indicate the possible contact of the Prague population with the infectious agent on the very territory of the town. The authors give a list of potential carrier animals on the territory of Prague.

Lyme disease in Yugoslavia

Abstract: Presented are results of the last five-year period study of the lyme disease in Yugoslavia. On the basis of published papers and professional communications over 2500 cases of lyme disease.were detected in our country within this period. Presented are common epidemiologic and clinical features of the disease and particularly cases diagnosed in Belgrade. Since 1987 a group of various specialists has been working on the research project in collaboration with many centres in the country. Indirect immunofluorescence test as the diagnostic laboratory technique has been introduced in the Military Medical Academy in Belgrade in 1987. First species of Borrelia burgdorferi from ticks Ixodes ricinus have been isolated and cultivated in May and June 1990. Current problems concerning research work, medical and epidemiological aspects of the lyme disease are presented.

Incidence of Borrelia in the common tick (Ixodes ricinus) in the area of the city of Brno

Abstract: During the period between July and October 1988 more than 1000 ticks Ixodes ricinus were collected at 16 sites in the town of Brno and examined by indirect immunofluorescence (IFA) for the presence of Borrelia. The positivity of the tick population in 13 localities varied between 0.9-18.6%, ticks from three localities were negative. The results confirm the diffuse character of the presence of Borrelia in ticks I. ricinus in the urban environment and the possibility of infection of the urban population in the very town may be assumed.

Dual infection of Ixodes ricinus ticks with two viruses of the Tick-borne encephalitis complex

Abstract: Ixodes ricinus female ticks were inoculated with Skalica (SK) virus (non-pathogenic for adult albino mice by subcutaneous route) and 14 days later they were challenged with strain 198 of Tick-borne Encephalitis (TBE) virus (highly pathogenic for adult albino mice by subcutaneous route). After additional 14 days of incubation, 42.9 to 65.0% of the adult (10-12 g) albino mice infested with these double infected ticks developed antibodies to TBE without signs of sickness (transmission of SK virus), while paralysis or death was registered in 35.0 to 57.1% of infested mice (transmission of strain 198) depending on the concentration of strain 198 used for inoculation of ticks. However, a low degree of interference to superinfection with strain 198 was observed, when the dissected tick salivary glands were examined by subcutaneous inoculation of adult albino mice (more than 90% of examined salivary glands contained strain 198 virus).

The identification of Borrelia isolated in the Soviet Union and Czechoslovakia from Ixodes ricinus (L.) ticks

Abstract: Seven strains of the causative agent of Lyme borreliosis have been isolated from ticks of the species Ixodes ricinus (L.) obtained at the territories of Leningrad Province, Lithuania and Czechoslovakia. The strains have been studied in reactions with 5 types of monoclonal antibodies. All isolated strains belong to serotype II according to Barbour's system and are typical for European strains.

[Lyme disease: clinical and sero-epidemiological study of Borrelia burgdorferi infections in Belgium].

Abstract: Lyme disease is a multi-systemic infection caused by the spirochaete Borrelia burgdorferi: this bacterium, discovered in 1982 in the United States, is mainly transmitted by a tick bite, Ixodes ricinus in Europe. In Belgium, a first seroepidemiological study of 3 years has revealed 190 patients and the whole spectrum of clinical pictures was observed, including the early stage of this infection in the skin (erythema chronicum migrans), neurological involvement and arthritis. The Lyme borreliosis is endemic in our country: the incidence ranges from low near the coast to high in the south-eastern part of Belgium.