Development of Babesia gibsoni in the midgut of larval tick, Rhipicephalus sanguineus. (1/384)

Studies were made on the development of Babesia gibsoni in the midgut of the larval tick, Rhipicephalus sanguineus. Six hr after repletion, merozoites of B. gibsoni, freed from erythrocytes, were observed in the midgut contents of the tick. After that, within 24 hr, those merozoites were transformed into the ring-forms which were relatively large, 2-3 microns in diameter. Later, the ring forms developed into the spherical forms which were subelliptical in shape and 4-6 microns in diameter. Within 2-4 days, the elongated forms, 5-8 microns in length, were found. At this time, some of the binucleated fusion form has assumed a form intermediate between the spherical and elongated-forms. About 5-6 days after repletion, large round or elliptic zygotes, 8-10 microns in diameter, were observed in the tick gut.  (+info)

Development of Babesia gibsoni in the midgut of the nymphal stage of the tick, Rhipicephalus sanguineus. (2/384)

Studies were made on the development of Babesia gibsoni in the midgut of the nymphal stage of the tick, Rhipicephalus sanguineus. Six hr after repletion, merozoites of B. gibsoni, free of erythrocytes, were observed in the midgut contents of the ticks. After that, within 24 hr, those merozoites were transformed into ring-forms which were relatively large ring 1-2 microns in diameter. Later, the ring forms developed into spherical forms which were somewhat elliptical in shape and 3-4 microns in diameter. Within 2-4 days, bizarre forms (5-6 microns in diameter) developed into elongated forms (5-6 microns in length). About 5-6 days after repletion, large round or elliptic zygotes (7-9 microns in diameter) were observed in the ticks gut.  (+info)

Inhibition of Borrelia burgdorferi migration from the midgut to the salivary glands following feeding by ticks on OspC-immunized mice. (3/384)

Borrelia burgdorferi-infected ticks were fed on either OspC-immunized mice or normal, nonimmunized mice. After 72 h, the ticks were detached, followed by dissection and subsequent culturing in Barbour-Stoenner-Kelley II medium of the salivary glands from each tick to determine the presence of borreliae. Forty percent (10 of 25) of salivary glands from ticks that had fed on nonimmunized mice were culture positive, while only 7.4% (2 of 27) of salivary glands from ticks that had fed on OspC-immunized mice were culture positive, thus indicating a much reduced borrelial migration from the midgut when the bloodmeal contained anti-OspC antibodies. Fluorescent antibody staining of the corresponding midguts from ticks that had fed on the OspC-immunized mice showed that borreliae were present but did not produce OspC. In contrast, borreliae in midguts from ticks that had fed on normal mice demonstrated substantial ospC expression. This study provides evidence that, during tick feeding on an OspC-immunized host, transmission of borreliae from the tick is prevented; it also suggests that OspC functions in a tick-to-host transmission mechanism.  (+info)

Prevalence of Borrelia burgdorferi sensu lato in Ixodes ricinus ticks (Acari, Ixodidae) in different Polish woodlands. (4/384)

In 1996-1998, a total of 2285 Ixodes ricinus ticks (1063 nymphs, 637 males, 585 females) were collected from vegetation from 25 different localities in the 8 Polish provinces throughout the country. Ticks inhabited all 25 collection sites. The average number of ticks per collection site was 91.4 +/- 13.7. All 2285 ticks were examined for Borrelia burgdorferi sensu lato (s.l.) presence, of which 1333 specimens from 3 provinces were tested by routine indirect immunofluorescence assay (IFA) using polyclonal antibody PAB 1B29. The remaining 952 specimens from 5 provinces were examined by polymerase chain reaction (PCR), using FL6 and FL7 primers. The overall infection rate in ticks estimated by these 2 methods was 10. 2%. Nymphs showed lower positivity rate (6.2%) as compared to adult ticks (14.9% in females and 12.4% in males). The highest percentage of infected I. ricinus ticks (37.5%) was noted in the Katowice province while the lowest (4.1%) in the Bia ystok province. In particular collection sites, infection rates varied from 0-37.5%. The obtained results confirmed that B. burgdorferi s.l. is present throughout the distributional areas of I. ricinus in Poland and that a prevalence of spirochete-infected ticks may be high in some locations.  (+info)

Experimental infection of ponies with Borrelia burgdorferi by exposure to Ixodid ticks. (5/384)

Seven specific-pathogen-free (SPF) ponies, 1-5 years old, were exposed to Borrelia burgdorferi-infected adult ticks while being treated with dexamethasone over 5 consecutive days. One SPF pony (pony No. 178) was first exposed to laboratory-reared nymphs without B. burgdorferi infection and 3 weeks later was exposed to B. burgdorferi-infected adult ticks with concurrent dexamethasone treatment for 5 consecutive days. Four uninfected ponies treated with dexamethasone, exposed to laboratory-reared ticks without B. burgdorferi infection served as uninfected controls. Clinical signs, bacteriologic culture, polymerase chain reaction (PCR) for bacterial DNA, immunologic responses, and gross lesions and histopathologic changes were investigated during the experiment or at necropsy 9 months after tick exposure. In all of the seven challenged ponies, infection with B. burgdorferi was detected from monthly skin biopsies and various tissues at postmortem examination by culture and by PCR. However, pony No. 178 exposed to laboratory-reared nymphs (without B. burgdorferi infection) and challenged with B. burgdorferi-infected adult ticks 2 months later did not develop a B. burgdorferi infection. All of the infected ponies seroconverted. Control ponies and pony No. 178 were negative by culture, PCR, and serology. Except for skin lesions, we failed to induce any significant histopathologic changes in this study. This is the first report of successful tick-induced experimental infection in ponies by exposure to B. burgdorferi-infected ticks. This Lyme disease model will be very useful to evaluate efficacy of vaccines against the Lyme agent and the effect of antibiotic therapy on horses infected with B. burgdorferi.  (+info)

Impact of climatic change on the northern latitude limit and population density of the disease-transmitting European tick Ixodes ricinus. (6/384)

We examined whether a reported northward expansion of the geographic distribution limit of the disease-transmitting tick Ixodes ricinus and an increased tick density between the early 1980s and mid-1990s in Sweden was related to climatic changes. The annual number of days with minimum temperatures above vital bioclimatic thresholds for the tick's life-cycle dynamics were related to tick density in both the early 1980s and the mid-1990s in 20 districts in central and northern Sweden. The winters were markedly milder in all of the study areas in the 1990s as compared to the 1980s. Our results indicate that the reported northern shift in the distribution limit of ticks is related to fewer days during the winter seasons with low minimum temperatures, i.e., below -12 degrees C. At high latitudes, low winter temperatures had the clearest impact on tick distribution. Further south, a combination of mild winters (fewer days with minimum temperatures below -7 degrees C) and extended spring and autumn seasons (more days with minimum temperatures from 5 to 8 degrees C) was related to increases in tick density. We conclude that the relatively mild climate of the 1990s in Sweden is probably one of the primary reasons for the observed increase of density and geographic range of I. ricinus ticks.  (+info)

Detection of the agent of heartwater, Cowdria ruminantium, in Amblyomma ticks by PCR: validation and application of the assay to field ticks. (7/384)

We have previously reported that the pCS20 PCR detection assay for Cowdria ruminantium, the causative agent of heartwater disease of ruminants, is more sensitive than xenodiagnosis and the pCS20 DNA probe for the detection of infection in the vector Amblyomma ticks. Here, we further assessed the reliability of the PCR assay and applied it to field ticks. The assay detected DNA of 37 isolates of C. ruminantium originating from sites throughout the distribution of heartwater and had a specificity of 98% when infected ticks were processed concurrently with uninfected ticks. The assay did not detect DNA of Ehrlichia chaffeensis, which is closely related to C. ruminantium. PCR sensitivity varied with tick infection intensity and was high (97 to 88%) with ticks bearing 10(7) to 10(4) organisms but dropped to 61 and 28%, respectively, with ticks bearing 10(3) and 10(2) organisms. The assay also detected C. ruminantium in collections of Amblyomma hebraeum and Amblyomma variegatum field ticks from 17 heartwater-endemic sites in four southern African countries. Attempts at tick transmission of infection to small ruminants failed with four of these collections. The pCS20 PCR assay is presently the most characterized and reliable test for C. ruminantium in ticks and thus is highly useful for field and laboratory epidemiological investigations of heartwater.  (+info)

Crimean-congo haemorrhagic fever: a seroepidemiological and tick survey in the Sultanate of Oman. (8/384)

In 1995 and 1996, 4 persons from the Sultanate of Oman were confirmed with clinical Crimean-Congo haemorrhagic fever (CCHF). To assess the prevalence of CCHF virus infection in Oman, a convenience sample of imported and domestic animals from farms, abattoirs and livestock markets was examined by enzyme-linked immunosorbent assay (ELISA) for immunoglobulin G (IgG) antibodies to CCHF virus. Ticks were collected from selected animals, identified, pooled by species, host and location and tested for evidence of infection with CCHF virus by antigen-capture ELISA. Serum samples from individuals working in animal and nonanimal contact-related jobs were also tested for CCHF antibodies. Serological evidence of infection was noted in 108 (22%) of 489 animals. Most of the ticks collected (618 of 912) from all species of sampled livestock were Hyalomma anatolicum anatolicum, a competent vector and reservoir of CCHF virus. 243 tick pools were tested for CCHF antigen, and 19 pools were positive. Of the individuals working in animal contact-related jobs, 73 (30.3%) of 241 non-Omani citizens and only 1 (2.4%) of 41 Omani citizens were CCHF antibody-positive. Butchers were more likely to have CCHF antibody than persons in other job categories. The presence of clinical disease and the serological results for animals and humans and infected Hyalomma ticks provide ample evidence of the presence of CCHF virus in yet another country in the Arabian Peninsula.  (+info)

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