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PubMed1990

[Natural Anaplasma marginale infection in 2 cattle herds with different levels of Boophilus microplus tick infestation].

The dynamics of natural infections by Anaplasma marginale was studied in two adjacent dairy farms with different levels of Boophilus microplus infestation. The farms were located in the enzootic area of bovine anaplasmosis of the Northwest of Argentina. The study was carried out in 35 calves from birth in March-August 1985 to March 1986. The infection rate by A. marginale was evaluated by the observation of blood films and by determination of specific antibodies. The degree of infestation by B. microplus was also evaluated. The tick was found all over the year in farm A with peaks of 100 and 95% of infested calves in October and January, respectively. In farm B, B. microplus was found only in December and January with a maximum of 50% of infested calves. Natural infections by A. marginale started in June until the end of the study when 89% (farm A) and 81% (farm B) of the calves proved to be infected. According to the active serological reactors, the rate rose to a maximum of 85% (farm A) and 81% (farm B) at the end of the study. It is remarkable that 69% of primo-infections by A. marginale in farm B occurred when B. microplus was absent. Moreover, no direct relationship between the peaks of tick infestation and primo-infections with the rickettsie was detected in farm A. The authors concluded that B. microplus could have less importance in the transmission of A. marginale than previously assumed under the local conditions.

Anaplasmosis↗
PubMed2006

World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) guidelines for evaluating the efficacy of parasiticides for the treatment, prevention and control of flea and tick infestation on dogs and cats.

These guidelines are intended to assist the planning and conduct of laboratory and clinical studies to assess the efficacy of ectoparasiticides applied to dogs or cats for the purpose of treating, preventing and controlling flea and tick infestations. The term ectoparasiticide includes insecticidal and acaricidal compounds, as well as insect growth regulators. The range of biological activities accruing from animal treatment that are considered include: repellency and anti-feeding effects, knockdown, speed of kill, immediate and persistent lethal effects, and interference with egg fertility and subsequent development of off-host life cycle stages. Information is provided on the selection of animals, dose determination, dose confirmation and field studies, record keeping, interpretation of results and animal welfare. These guidelines are also intended to assist registration authorities involved in the approval and registration of new parasiticides, and to facilitate the worldwide adoption of harmonized procedures.

Animals↗
PubMed1999

Ticks infesting domestic animals in Italy: current acarological studies carried out in Sardinia and Basilicata regions.

The note reviews published and unpublished data on acaralogical studies carried out by different parasitologists' groups in Sardinia and Basilicata regions. In Sardinia 72 collecting sites were investigated and a total of 4,086 ticks were collected from hosts (cattle, sheep, goats and pigs) and from soil. So far 2,413 ticks belonging to six genera have been identified: Rhipicephalus (67.2%), Haemaphysalis (24.1%), Hyalomma (2.7%), Boophilus (0.7%), Dermacentor (4.9%), Ixodes (0.3%). Host-associated ticks were collected from 50 out of 200 selected farms in Basilicata. About 4,000 tick specimens were collected and 1,794 ticks have been identified (of which 1,215 were adults, 6 larvae and 573 nymphs). The following genera were identified: Ixodes (20%), Rhipicephalus (27%), Hyalomma (31%), Haemaphysalis (18%), Dermacentor (6%). The seasonal distribution of the species identified in the two regions studies is discussed from a geographical and climatic point of view.

Animals↗
PubMed1991

Tick infestations on Zebu cattle in western Kenya: individual host variation.

Monthly collections were made of all ticks from 25 mature East African Zebu cattle and 5 yearlings for 13 mo on Rusinga Island, Lake Victoria, Kenya, from September 1986 to September 1987. The most common species were Rhipicephalus appendiculatus Neumann and Amblyomma variegatum F.; Boophilus decoloratus Koch and Rhipicephalus evertsi evertsi Neumann also were present in fewer numbers. Cattle were ranked according to their degree of resistance to each of the four species and to each stage in the life cycle of the three-host ticks. Ranking according to infestations of females and nymphs of R. appendiculatus, nymphs and larvae of A. variegatum, or all three stages of these two species when compared with the total burden gave statistically significant correlations. Sampling difficulties prevented the ranking of cattle for infestations of larvae of R. appendiculatus, although the numbers on cattle were high. On the other hand, failure of attempts to rank the cattle on females of A. variegatum, B. decoloratus, or R. e. evertsi counts was attributed to the small differences between tick numbers on cattle. Highly resistant cattle showed little or no seasonal fluctuations in tick numbers for most of the period compared with animals of low resistance, which showed an up to sevenfold increase in the magnitude of the tick burden when the tick challenge was high. Cattle with low resistance were responsible for much of the tick multiplication in the field, whereas highly resistant animals tended to limit the populations. There were no distinct differences between the numbers of each tick species on yearlings and mature cattle.

Animals↗
PubMed2000

Decorin-binding protein A (DbpA) of Borrelia burgdorferi is not protective when immunized mice are challenged via tick infestation and correlates with the lack of DbpA expression by B. burgdorferi in ticks.

Previous studies showed that decorin-binding protein A (DbpA) of Borrelia burgdorferi was a protective immunogen in the murine model of Lyme borreliosis when mice were challenged (needle inoculated) intradermally with in vitro-cultivated spirochetes. In the present study, DbpA-immunized C3H/HeJ mice were not protected from infection when infested with Ixodes scapularis nymphs harboring virulent B. burgdorferi 297. This lack of protection correlated with the failure to detect DbpA on B. burgdorferi in ticks, suggesting that DbpA is not available as a target for bactericidal antibodies in serum when B. burgdorferi-infected ticks take their blood meal from an immunized host. The failure of DbpA immunization to protect tick-challenged mice contradicts the results of earlier needle inoculation vaccination experiments and suggests that DbpA may not be suitable as a Lyme disease vaccine.

Adhesins, Bacterial↗
PubMed1993

A comparison of field tick infestation on N'Dama, Zebu and N'Dama x Zebu crossbred cattle.

Tick burdens, estimated from cumulative tick counts, were determined on N'Dama, Zebu and F1 N'Dama x Zebu crossbred cattle. N'Dama showed significantly fewer ticks than the Zebu and F1 cattle (P < 0.001). A previous trypanosomosis infection did not affect tick burdens on the three genotypes. Amblyomma variegatum had a prevalence of 84.8% and Hyalomma spp. 15.2%, with the ratio similar on all cattle breeds. Trypanosomosis infection increased the serological prevalence of Anaplasma marginale in Zebu and F1 cattle but not in N'Dama cattle. These observations supported the view that N'Dama cattle are less susceptible to tick attachment than Zebu cattle.

Animals↗
PubMed1991

Parasites of domestic and wild animals in South Africa. XXVI. The mosaic of ixodid tick infestations on birds and mammals in the Mountain Zebra National Park.

Sixteen species of ixodid ticks were collected over varying periods of time from 6 species of ground-frequenting birds and 15 species of small and large mammals in the Mountain Zebra National Park, Karoo, Cape Province. Margaropus winthemi followed by Rhipicephalus glabroscutatum and Rhipicephalus evertsi evertsi were the most abundant species. The host preferences of 14 tick species and the seasonal abundances of 13 species were determined. Small numbers of immature stages of only a few tick species were generally recovered from ground-frequenting birds, mice and rats. Amongst the slightly larger animals the smallest number of ticks and species were recovered from springhares and the largest numbers from scrub hares. Amongst the larger mammals, very few ticks were harboured by springbuck and black wildebeest, while heavy infestations of several species were encountered on Cape mountain zebras and eland.

Animals↗
PubMed1991

Tick infestations on Zebu cattle in western Kenya: quantitative assessment of host resistance.

Groups of previously tick-exposed East African Zebu cattle together with tick-susceptible Friesian steers as controls were artificially infested with adults, nymphs, and larvae of Rhipicephalus appendiculatus Neumann on two occasions. Comparison of the feeding performance data from the two different breeds of cattle showed significant differences in the number and weight of engorged females and the weight of engorged nymphs. Data from the first challenge were used to derive a function for discriminating between resistant and susceptible categories. The use of the function gave repeatable results on resistance rankings when compared with original ranking of cattle based on natural tick counts following natural exposure. The function was converted into an index that could then be used to monitor the seasonal and annual fluctuations in tick resistance rankings of individual animals in a herd.

Animals↗
PubMed1997

Ixodid ticks infesting rodents and sheep in diverse biotopes of southern India.

A total of 127 rodents were trapped in southern India. Examination of these rodents revealed the presence of 2 species of ticks, Haemaphysalis spinigera and Rhipicephalus ramachandrai. The former species is the principal vector of Kyasanur Forest Disease (KFD) in India, and the latter's role, if any, is unknown. Sheep grazing in 1 of the study area were infested with another ixodid tick. Haemaphysalis intermedia, which is a vector of Bhanja virus in India. The presence of H. spinigera on domestic rats is important from the standpoint of KFD enzootiology. This tick shows a narrow habitat preference but a wide host range. In peridomestic situations, the field rodent Bandicota bengalensis did not harbor any tick species. Contiguity of feral and domestic biotopes in some areas contributed to the transfer of R. ramachandrai from its preferred wild rodent host, Tatera indica, to domestic rats Rattus sp.

Animals↗
PubMed1999

Successive tick infestations selectively promote a T-helper 2 cytokine profile in mice.

Several studies have revealed that T lymphocytes and cytokines play a crucial role in determining the outcome of parasitic infections in terms of protective immunity. In this study we found that Rhipicephalus sanguineus tick saliva stimulates transforming growth factor-beta (TGF-beta), and reduces interleukin-12 (IL-12) secretion by cells from normal C3H/HeJ mice. Moreover, murine lymph node cells harvested 6 days after the fourth infestation with ticks presented an 82.4% decrease in their proliferative response to concanavalin A (Con A) compared with the response of control cells. In addition, lymph node cells cultured in the presence of Con A showed a T-helper 2-type (Th2-type) cytokine profile, represented by augmented IL-4 and IL-10 and TGF-beta. On the other hand, the IL-2, interferon-gamma (IFN-gamma) and IL-12 synthesis was significantly inhibited. These results indicate that ticks may modulate the host's immune response through saliva injection. Considering that C3H/HeJ mice develop no protective immunity to R. sanguineus infestation, our results suggest that tick-induced Th2-type cytokines and a decreased proliferative response probably lead the host to a susceptible state to both tick and tick-transmitted pathogens.

Animals↗