Showing papers on "Tick published in 1984"

Discovery of the Lyme disease spirochete and its relation to tick vectors.

Abstract: The various hypotheses concerning the etiologic agent of erythema chronicum migrans of Europe and of Lyme disease in the United States are reviewed, and an account of events that led to the discovery of the causative spirochetal agent in Ixodes dammini is presented. Spirochetes morphologically and antigenically similar, if not identical to, the organism detected in I. dammini were also found for the first time in Ixodes pacificus and Ixodes ricinus, the vectors hitherto incriminated, respectively, in western United States and Europe. In most infected ticks, spirochetal development was found to be limited to the midgut. Ticks with generalized infections were shown to transmit spirochetes via eggs, but infections decreased in intensity and became restricted to the central ganglion as filial ticks developed to adults. Although the mechanisms of transmission to a host are still under investigation, the spirochetes may be transmitted by saliva of ticks with generalized infectious and possibly also by regurgitation of infected gut contents, or even by means of infected fecal material.

Epidemiology of tick-borne diseases of cattle in Zimbabwe. I. Babesiosis

Abstract: A survey on the incidence of antibodies to Anaplasma marginale in one- to three-year-old cattle was carried out in Zimbabwe using the capillary tube agglutination test. Antibodies were detected in all but one of 118 batches of sera collected from different localities throughout the country. There was no clear relationship between the frequency of occurrence of positive serological reactors, which was similar in both commercial and communal farming areas, and the incidence of clinical anaplasmosis. However, the highest numbers of cattle exhibiting positive reactions were generally recorded from the areas that were most heavily tick infested. There was evidence that wild ungulates may serve as reservoirs of infection as antibodies to A. marginale were detected in sera from buffalo (Syncerus caffer) and impala (Aepyceros melampus).

Effect of deer reduction on abundance of the deer tick (Ixodes dammini).

Abstract: To evaluate the role of deer in regulating the abundance of the deer tick (Ixodes dammini) we attempted to treat with acaricide, but eventually removed, about 70 percent of deer from Great Island, Cape Cod, Massachusetts. Deer were captured in box traps, a corral, an entanglement net, and with rifle-fired tranquilizer. Failure of these attempts, combined with ineffective acaricides, led us to deer destruction begun in fall 1982. Larval tick abundance on mice was monitored before and after deer removal. We concluded that deer removal, to the extent accomplished, did not markedly reduce the abundance of the tick. Reduced abundance of deer may not result in reduced abundance of immature ticks if deer removal follows the period of adult tick feeding, or if intensity of infestation per deer increases, or if other mammals substitute as suitable hosts. Reduced tick abundance may be delayed if unattached immature ticks survive more than one year.

Vectorial capacity of North American Ixodes ticks.

Abstract: Ixodes dammini, the vector of Lyme disease and babesiosis, is distributed in various locations in the northeastern quadrant of the United States and nearby Canada. The life cycle of this tick, which includes larval, nymphal, and adult stages, spans at least two years. The tick over-winters between larval and nymphal feeding. Horizontal transmission of pathogens is facilitated by a feeding pattern in which both the larval and nymphal stages feed on the white-footed mouse, Peromyscus leucopus, and by a seasonal pattern of activity in which nymphs precede larvae. The species range appears to have expanded from a single island location, and has invaded new sites since the 1940s, some as recently as 1980. This increased abundance appears to be related to the increased abundance of deer, the preferred host of the adult stage. I. muris predominated in coastal Massachusetts before I. dammini became abundant, but is probably now extinct. I. scapularis, which is present in the southern U.S., is a poor vector of mouse parasites because about 90 percent of these immature ticks feed on lizards. To the extent that horizontal transmission occurs, we suggest that mice serve as the principal reservoir for the Lyme spirochete as well as Babesia microti.

Lyme disease: a selective medium for isolation of the suspected etiological agent, a spirochete.

Abstract: A simple procedure with a new selective culture medium for the isolation of the suspected etiological agent of Lyme disease from ticks is described. Live ticks (Ixodes dammini) were ground with a mortar and pestle, and the suspensions were inoculated into a selective and nonselective medium. The selective medium, which contained kanamycin and 5-fluorouracil, yielded positive spirochete cultures from 100% of the pooled ticks and from 79% of the single tick specimens. The isolation rate for the nonselective medium was 0% from the tick pools and 58% from the single tick specimens.

Experimental Lyme disease in rabbits: spirochetes found in erythema migrans and blood.

Abstract: In attempts to produce experimental Lyme disease, 33 rabbits were inoculated with Lyme spirochetes by tick feeding or from tick organ homogenates or cultures. Two rabbits developed erythema chronicum migrans at the site of inoculation, in one instance 2 days after injection of a tick organ homogenate and in the other instance, 17 days after feeding of infected Ixodes dammini ticks. Spirochetes were seen in skin biopsy specimens of the second lesion with Warthin-Starry and immunoperoxidase stains. Spirochetes were also recovered from blood cultures of two additional rabbits 2 weeks post-inoculation. These findings are characteristic of early Lyme disease in humans and give additional support for the spirochetal etiology of Lyme disease.

Tick resistance and the major histocompatibility system.

Abstract: 199 3/4 Brahman 1/4 Shorthorn cattle, whose resistance to the cattle tick Boophilus microplus had been determined by clinical trial, were tested for 19 bovine lymphocyte antigens. Of eleven antigens detected at a frequency greater than 5%, two were found to be associated with tick resistance and a third was associated with susceptibility to ticks. However, none of these antigens accounts for more than 2.1% of the variance, indicating that these associations are not strong.

Passage of hemolysins through the midgut epithelium of female Ixodes ricinus L. fed on rabbits infested or reinfested with ticks.

Abstract: Antibodies considered in this study are hemolysins synthesized by rabbits against sheep red blood cells. Ingested with the blood meal, they cross the tick midgut epithelium and retain their immunological properties in the hemolymph. During a reinfestation of rabbits, more ticks present these antibodies, and titres are generally higher than during a first infestation. Hemolysins are only found in ticks weighing 180 mg or more.

Mixed infections with tick-borne viruses in a seabird colony in Eire

Abstract: Viruses were isolated from 2 tick species collected from the nesting areas of seabirds on Great Saltee Island, Eire. Bunyaviruses of the Uukuniemi serogroup were isolated from hard ticks(Ixodes uriae andI. rothschildi), bunyaviruses of the Hughes serogroup from soft ticks(Ornithodoros maritimus), and orbiviruses of the Kemerovo serogroup fromI. uriae andO. maritimus. The results indicate that the bunyaviruses, but not the orbiviruses, show “tick specificity”. Neutralising activity against members of all 3 serogroups was detected in sera from chicks in the nesting areas; neutralising antibodies were probably maternal.

Rickettsia conorii isolated from Rhipicephalus sanguineus introduced into Switzerland on a pet dog.

Abstract: A tick/rickettsial survey in a household near Geneva, Switzerland, revealed that 30 (40%) of 75 nymphs and adults of the brown dog tick,Rhipicephalus sanguineus, were infected with a rickettsial agent biologically and antigenically indistinguishable fromR. conorii, the causative agent of boutonneuse fever. Introduced in 1976 from either southern France of Italy by the family's pet dog, the tick infestation had steadily increased until 1981 when control measures were initiated. During 1980 and 1981, four persons associated with the household's pet dog contracted a febrile illness diagnosed as boutonneuse fever.

Susceptibility and reservoir potential of the dog to spotted fever-group rickettsiae.

Abstract: This study was initiated to determine the degree of susceptibility of dogs to virulent and nonvirulent spotted fever-group rickettsiae and to evaluate dogs as sources of infection for ticks. Dogs were exposed either by inoculation (syringe) or by infective tick bite to the following rickettsial serotypes: (1) Rickettsia rickettsii (Wachsmuth and Sawtooth female 2 strains), (2) R montana (M/5-6 B strain), and (3) R rhipicephali (3-7-female 6 strain). Results indicated that dogs inoculated with 1,000 or 10,000 egg infective doses of virulent R rickettsii developed a rickettsemia that was detectable as early as 4 days after inoculation to as late as 10 days. Conversely, none of the dogs inoculated with R montana (M/5-6 B) or R rhipicephali (3-7-female 6) or exposed to ticks infected with these strains developed detectable rickettsemia, fever, or other observable clinical signs. None of the 394 ticks that fed on rickettsemic dogs (R rickettsii) infected by inoculation became infected, and only 3 of 348 ticks (0.9% infection rate) were infected after feeding on dogs which had been infected by tick bite. All ticks fed on dogs exposed to R rhipicephali and R montana were shown to be free of rickettsiae. The largest concentrations of plaque-forming units (PFU) in Vero cell culture from undiluted whole blood were found on day 6 and on day 7 in dogs that were inoculated with 10,000 and 1,000 R rickettsii, respectively, of the Sawtooth female 2 strain. The highest rickettsial concentration observed for the dog infected by tick feeding was on day 9.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies to spirochetes in white-tailed deer and prevalence of infected ticks from foci of lyme disease in connecticut

Abstract: White-tailed deer (Odocoileus virginianus) were examined for the tick, Ixodes dammini, and sera were analyzed for antibodies to spirochetes during 1982 Of the 323 animals inspected in four areas endemic for Lyme disease, 188 (58%) had adult ticks; parasitism ranged from 43% at Haddam to 82% at East Lyme Direct and indirect fluorescent antibody tests detected spirochetes in 18 of 133 (14%) ticks Indirect immunofluorescence tests revealed antibodies at titers of 1:64–1:4,096 to this bacterium in 93 (28%) of the 332 sera assayed There is a close correlation among the distribution of spirochete-infected I dammini, deer with antibodies, and human cases of Lyme disease

Survival of the Lone Star Tick, Amblyomma Americanum (Acari: Ixodidae), in Contrasting Habitats and Different Years in Southeastern Oklahoma, USA

Abstract: Engorged larval, nymphal, and female lone star ticks, Amblyomma americanum , were released at monthly intervals in different habitats in southeastern Oklahoma during April–October in 1978–1980 to study their development and survival. Bottomland oak-hickory, upland oak-hickory, and upland pine habitats were nearly equally suitable areas for tick survival during 1978–1979 when rainfall and temperature were similar. High temperatures and low humidities in 1980 reduced tick survival in all habitats by at least 50% from that observed in 1978 and 1979. However, the bottomland oak-hickory habitat had significantly higher survival of ticks than the 2 upland wooded sites during the summer drought of 1980 and was the only habitat in which ticks molting in 1979 survived the summer of 1980. The 4th habitat, a meadow, was much less suitable for tick survival and development during all 3 consecutive years. Survival of ticks that had molted in polyester packets in 1978 in the bottomland habitat was: oversummer 1978 = 96% of the adults and nymphs; overwinter 1978–1979 = 91% of the adults and 59% of the nymphs; oversummer 1979 = 51% of the adults and 26% of the nymphs; and overwinter 1979–1980 = 30% of the adults and 2% of the nymphs. Larvae in polyester packets were able to overwinter from 1978–1979 and 1979–1980. Quantitative data on activity and development of lone star ticks are reported for 3 years of study in natural habitats.

The immunization of calves against heartwater : subsequent immunity both in the absence and presence of natural tick challenge

Abstract: Cattle, vaccinated as calves with Cowdria ruminantium-infected tick stabilate, were challenged 6, 12 and 24 months later. In the absence of tick challenge, vaccination of calves induced a partial immunity against subsequent challenge at 12 and 24 months. In animals exposed to ticks, the resistance was no better than that of control, unvaccinated cattle. When they were challenged at 6 months of age there was no difference between vaccinated and unvaccinated calves, either in the absence or presence of tick challenge, and all the animals manifested a high degree of natural resistance. This study therefore suggests that the value of vaccinating Afrikander-cross calves in heartwater endemic areas should be further investigated. The indirect fluorescent antibody (IFA) test proved to be a valuable means of monitoring the serological response of vaccinated animals and detecting the sero-conversion of animals exposed to tick infection. On one hand, there was good correlation between the febrile reaction and the results of the IFA test on the sera of vaccinated and control cattle challenged with the heartwater agent, in that all sero-positive animals were resistant to challenge. On the other hand, though, a considerable percentage of the animals that were serologically negative were also resistant to challenge.

Significant changes in epidermal Langerhans cells of guinea-pigs infested with ticks (Dermacentor andersoni).

Abstract: Resistance to tick feeding has previously been shown to be an acquired, immunologically mediated phenomenon in guinea-pigs, associated with cutaneous basophil hypersensitivity to tick antigens. In this study, Langerhans cells (LC) in the epidermis of guinea-pigs were monitored during tick infestations of susceptible and resistant animals. A specific adenosine triphosphatase (ATPase) staining technique was used to identify epidermal LC. The numbers of LC decreased significantly around the sites of tick attachment during primary infestations. Early in the secondary infestations, increases in numbers of LC were observed in the epidermis surrounding tick mouth-parts. These changes in LC populations resemble those previously described in contact dermatitis reactions of guinea-pigs.

Age-Related Effects on Water, Lipid, Hemoglobin, and Critical Equilibrium Humidity in Unfed Adult Lone Star Ticks (Acari: Ixodidae)

Abstract: Age-related changes over 12 months were examined in 2 laboratory-reared populations of ticks. Most ticks survived and water content did not change significantly with increasing tick age. The measured critical equilibrium humidity for all ticks other than those that had recently molted was 80–85%. Recently molted ticks did not absorb water from unsaturated air. There was an apparent decline in body lipid, but variation between replicates was large. Of the parameters studied with increasing tick age, the greatest change was observed in heme content.

Resistance to Natural Tick Infestations in Different Breeds of Cattle in the Sudan

Abstract: Whole body tick collections, carried out at 6-day intervals for 2 months at Nisheishiba, showed significant differences in tick counts between three breeds of cattle. Crossbred (Bos taurus × B. indicus) cows carried 4.5 times more ticks (mean tick count 70.5 ± 84.8) than the B. indicus Kenana (mean tick count 16.7 ± 24.4) and Butana cows (mean tick count 15.0 ± 18.4). In all cases, the SD's were larger than the means reflecting the usual wide variability in tick numbers between individuals. Significant differences also existed in the degree of engorgement achieved by female Hyalomma anatolicum anatolicum ticks on different breeds of cattle. The weight of detaching fully engorged females feeding on Kenana and crossbred cattle was 374.8 mg and 422.0 mg respectively. This was reflected in the amounts of eggs laid by the females which were 191.3 mg for the Kenana-fed ticks and 261.1 mg for those from the crossbreds. The resulting larval challenge from the crossbred-fed ticks was 36.5% greater than from the ticks fed on Kenana cattle.

Quantity of Blood Ingested by Four Species of Hard Ticks (Acari: Ixodidae) Fed on Domestic Dogs

Abstract: The amount of blood ingested from domestic dogs by adult female ticks averaged as follows: lone star tick, Amblyomma americanum (L.), 0.81 ml; brown dog tick, Rhipicephalus sanguineus (Latreille), 0.55 ml; American dog tick, Dermacentor variabilis Say, 1.45 ml; and the blacklegged tick, Ixodes scapularis Say, 0.51 ml. The blood ingested by immature stages of A. americanum and R. sanguineus contained the following quantities of blood, respectively: larvae, 1.34 and 0.78 μl; nymphs, 27.40 and 24.02 μl. Results are compared with published data on blood imbibition from different hosts by the ticks. On the basis of the engorged weights and quantities of blood imbibed by species of ticks tested, it is apparent that the domestic dog is an acceptable host for all four tick species.

Ixodid ticks on feral swine in florida

Abstract: More than 99% of the 645 feral swine (Sus scrofa L.) in southern Florida harbored ixodid ticks. Dermacentor variabilis (American dog tick) was present on 99.6% of the swine and comprised 82.5% of the ticks collected. Amblyomma maculatum (Gulf Coast tick) occurred on 85.9% of the hosts and 17.4% of the collections were of this species. Amblyomma americanum (Lone Star tick) and Ixodes scapularis (Black-legged tick) were found infrequently and together constituted <0.1% of the ticks. Pigs were infested by 7–22 days of age and 95% carried ticks by 6 wk of age. Only adult ticks were found on swine from southern Florida, but immature stages of A. americanum were present from a small sample of swine from northern Florida. Each species had a different pattern of distribution on the feral swine. No Ornithodoros species were found among the 36,616 ticks collected from feral swine during this survey.

Epidemiology of Rocky Mountain spotted fever in Ohio, 1981: serologic evaluation of canines and rickettsial isolation from ticks associated with human case exposure sites.

Abstract: A survey for the prevalence of Rocky Mountain spotted fever (RMSF) antibodies in dogs associated with confirmed human cases in Ohio was conducted during 1981. Twelve of 14 confirmed cases (85%) had a history of dog association prior to onset of RMSF. A total of 29 dogs were included in the study, with 16 dogs providing serum samples for antibody testing and the remainder providing tick samples. Serum samples tested by indirect microimmunofluorescence techniques revealed 12/16 dogs (75%) to be seropositive for Rickettsia rickettsii. A total of 310 ticks were collected from study dogs and the vegetation surrounding RMSF case exposure sites. Twenty-two (7.1%) of these ticks (all Dermacentor variabilis) were found to be infected with spotted fever group rickettsiae. Four ticks (1.3%) were infected with R. rickettsii, 13 (4.2%) with Rickettsia montana, and four (1.3%) with Rickettsia bellii. R. montana, a nonpathogen, was the only rickettsia found in dogs (antibodies) and ticks (isolation) associated with human cases in Southern Ohio.

Effects of ultraviolet irradiation on the acquisition and expression of tick resistance in guinea-pigs.

Abstract: In guinea-pigs it has been shown that resistance to ticks is an acquired, immunologically mediated phenomenon. It has been suggested recently that epidermal Langerhans cells (LC) may play roles in the mechanisms of resistance to ticks. The ATPase-positive epidermal LC of guinea-pigs have been shown to be depleted for a period of several days following u.v. irradiations. In this study, u.v. treatment of guinea-pigs' ears before primary tick infestations resulted in a significant reduction of acquired resistance to ticks. When u.v. treatments were applied to resistant animals prior to the challenge infestations, a marked reduction in expression of resistance to ticks was demonstrated. These results can be interpreted to imply that functional LC in the epidermis are required for both the normal acquisition and the expression of the guinea-pig's immune responses to D. andersoni infestations.

Bloodmeal ingestion and utilization as a component of host specificity in the tick,Boophilus microplus

Abstract: Details are given of an in vitro system for feeding femaleBoophilus microplus, the cattle tick, during the final phase of engorgement. Using this system, it has been shown that ticks fed bovine, rabbit, rat or guinea pig blood will commence feeding on all four, but engorge and oviposit successfully only when fed the blood of the natural host. They not only feed less on the blood of other species, but also concentrate blood components of the meal to a lesser degree. This is likely to be one factor explaining the host specificity of the tick.

Boophilus microplus tick burdens on grazing cattle in Colombia.

Abstract: This study was conducted at Carimagua Research Centre in a well-drained savanna area in the eastern plains of Colombia. The objectives were to note the effect of ecological factors on tick burdens, principally the effect of the environment given by four grasses on the seasonal variations of tick populations. Adult female tick counts were carried out on heifers grazing four pastures and tick larvae on the grass detected by cloth dragging. Tick counts were significantly higher on animals grazing Brachiaria decumbens than those grazing Andropogon gayanus, Melinis minutiflora or native pastures. Tick larvae counts on the grass showed a similar tendency. Introduced grasses and intensification of production will require greater care to control tick infestations since increases in stocking rate and ground coverage could augment tick populations.

Seasonal prevelance of ixodid ticks on cattle in the Windhoek District of South West Africa/Namibia

Abstract: The seasonal prevalence of ixodid ticks was determined over a 2-year period by the weekly removal from at least 5 cattle of all adult ticks and the immature stages of Rhipicephalus evertsi mimeticus in the ears. The highest mean weekly burden was 286,6 adult ticks/cow/week in March 1979, and the lowest 6,9 adult ticks/cow/week in July 1979. Virtually no tick control is practised in this area. Rhipicephalus capensis group adults peaked in the summer from October to March/April. Rhipicephalus evertsi mimeticus adults were present throughout the year, though in slightly greater numbers from November to May. Immature stages of this species in the ears showed a peak in February/March in addition to variably-timed high peaks in the first 2 winters. Hyalomma marginatum rufipes and Hyalomma truncatum peaked from December to March. Very small numbers of Boophilus decoloratus and Rhipicephalus oculatus were recovered. Tick burdens of all major species differed significantly in the 2 study years.

Geographical distribution and density of Ixodes dammini (Acari: Ixodidae) and relationship to Lyme disease transmission in New Jersey.

Abstract: As part of continuing studies of Lyme disease, deer were surveyed during three hunting seasons in 1981 to obtain information on geographic distribution and density of I. dammini in New Jersey. I. dammini occurred throughout central and southern New Jersey. Four deer management zones (DMZs) were shown to have high tick densities. Geographical distribution and density data were independently regressed against 25 environmental and physical factors. Elevation was shown to be the most important factor in explaining the variability in both I. dammini distribution and density. Lyme disease cases were closely associated with the distribution of I. dammini and 57.3 percent of 117 Lyme disease cases occurred in the four DMZs previously identified as having the highest tick density.