Ticks (Acari: Ixodidae) associated with wild animals in the Pantanal region of Brazil

This paper describes the identification of ticks from wild animals of the Pantanal region in Brazil as part of a comprehensive study about established and emerging tick-host relationships and related pathological aspects. Eighty-one animals were captured (representing 13 species, six orders), and ticks were found on 63 (78%). Tick species identified included Boophilus microplus (Canestrini), Amblyomma cajennense (F.), Amblyomma parvum Arag?o, Amblyomma pseudoconcolor Arag?o, Amblyomma scalpturatum Neumann, Amblyomma nodosum Neumann, Amblyomma ovale Koch, and Amblyomma tigrinum Koch. Dragging from grasslands yielded negative results compared with the high concentration of ticks that were collected from leaves in the forests.     

Ticks (Acari: Ixodidae) infesting wild birds in the Atlantic Forest in northeastern Brazil, with notes on rickettsial infection in ticks

A total of 232 individuals representing 46 species of birds were mist-netted and screened for ticks in a region of the Atlantic Forest, State of Bahia, Brazil. Thirty-eight (16.4%) of these birds representing 17 species were found infested by immature stages of Amblyomma ticks, namely, Amblyomma longirostre (Koch, 1844) (15 larvae and seven nymphs), Amblyomma nodosum (Neumann, 1899) (nine nymphs), Amblyomma calcaratum (Neumann, 1899) (five nymphs), Amblyomma cajennense (Fabricius, 1787) (seven larvae), and Amblyomma parkeri (Fonseca and Arag?o, 1952) (four larvae). Overall, 21 larvae and five nymphs collected from birds could not be identified to species and were morphologically identified as Amblyomma spp. Among 13 A. longirostre larvae and two A. parkeri larvae, two individuals of A. longirostre (15.4%) were found infected by Rickettsia amblyommii. This study provides some bird species found infested by A. longirostre, A. parkeri, A. calcaratum, A. nodosum, or A. cajennense for the first time and expands the distribution of R. amblyommii-infected A. longirostre ticks.     

Ticks (Acari: Ixodidae) infesting wild birds in the eastern Amazon, northern Brazil, with notes on rickettsial infection in ticks

The aim of the study was to report tick infestations on wild birds in a region of the eastern Brazilian Amazon and evaluate the rickettsial infection of these ticks. Wild birds captured by mist nets were examined for the presence of ticks, which were collected and identified to species by morphology or molecular methods. In addition, part of these ticks was individually tested by polymerase chain reaction targeting portions of the rickettsial genes gltA and ompA. Among 331 captured birds, representing 56 species, 133 individuals (40.2%) from 34 species were found infested by 443 ticks, being Amblyomma longirostre (Koch) the most common (103 larvae, 12 nymphs), followed by Amblyomma humerale Koch (15 larvae, 3 nymphs), Amblyomma geayi Neumann (seven larvae, one nymph), Amblyomma calcaratum Neumann (one larva, four nymphs), Amblyomma coelebs Neumann (two larvae), and Haemaphysalis juxtakochi Cooley (one larva, two nymphs). Other 285 larvae and 7 nymphs collected from birds could not be identified to species and were morphologically identified as Amblyomma spp. The species A. humerale and A. geayi are recorded for first time parasitizing birds in the Neotropical region. Among 67 A. longirostre and 7 A. geayi, 38 (56.7%) and 4 (57.1%), respectively, were found infected by Rickettsia amblyommii. In spite of R. amblyommii being not currently recognized as human or animal pathogen, there has been serological evidence for human and canine infection by this agent in the USA and in the Brazilian western Amazon.     

Larval behavioral diapause regulates life cycle of Amblyomma cajennense (Acari: Ixodidae) in Southeast Brazil

Previous studies have determined that Amblyomma cajennense (F.) produces one generation per year in Southeastern Brazil. Larvae predominate from April to July, nymphs from July to October, and adults from October to March. In the current study, we observed engorged females, their eggs, and respective larvae in the field. Engorged females were released in grass plots under natural conditions, at monthly intervals, from October 2000 to March 2001. Preoviposition periods lasted 1-2 wk, and mean egg incubation periods lasted 5-7 wk. Consequently, larvae hatched at different periods from early December 2000 to early April 2001. However, all hatched larvae stayed confined to the plot ground, under the vegetation, until late April or early May 2001, when some larvae were seen questing on top of vegetation for the first time. Thereafter, larvae were always seen on this questing position until August 2001, when all larvae had died on the plots. In addition, premolt period data of engorged larvae and nymphs held in laboratory at different temperatures were used to construct a premolt mathematical model, which was applied to reported seasonal dynamic data of A. cajennense in the field. The premolt model indicated that the field intervals between larvae and nymphs and between nymphs and adults are controlled solely by nondiapause events, such as ground temperature. We concluded that the 1-yr generation pattern of A. cajennense in Southeastern Brazil is primarily controlled by larval behavioral diapause, shown by larvae born during spring/summer months, before their activity period at next autumn.     

Ticks (Acari: Ixodidae) and spirochetes (spirochaetaceae: spirochaetales) recovered from birds on a Georgia Barrier Island

From September 1997 through July 1999, 300 individuals and 46 species of birds were mist-netted and screened for ticks and spirochetes on St. Catherine's Island, Liberty County, GA. Seventy-six (25%) of the birds were parasitized by a meal intensity of 4.6 ticks. Seasonally, more birds were infested with ticks during the summer (50% in 1998, 34% in 1999) than in spring (15% in 1998, 11% in 1999) or fall (21% in 1997, 20% in 1998), mainly because of severe infestations on some birds by immature stages of the lone star tick, Amblyomma americanum (L.), during this season. Eight species ofticks were recovered from 14 species of birds during this study: A. americanum (74 nymphs, 168 larvae); the blacklegged tick, Ixodes scapularis Say (11 nymphs, 28 larvae), the Gulf Coast tick, Amblyomma maculatum Koch (two nymphs, 29 larvae); Ixodes minor Neumann (16 larvae); the rabbit tick. Haemaphysalis leporispalustris (Packard) (one nymph, 14 larvae); the bird tick Ixodes brunneus Koch (two larvae); the American dog tick, Dermacentor variabilis (Say) (one nymph); and Ixodes affinis Neumann (one larva). The Carolina wren was parasitized by more species of ticks (seven) than any other bird species, followed by the northern cardinal (five), white-throated sparrow (four) and painted bunting (three). Spirochetes were isolated in BSK II medium from one tick (a nymphal A. americanum) and from skin biopsies of 12 (4%) of the individual birds (three downy woodpeckers, three northern waterthrushes, two Carolina wrens, one American redstart, one pine warbler, one Swainson's thrush, and one white-eyed vireo) all in fall 1997. This concentrated phenology of spirochete isolations might reflect periodic amplification or recrudescence of spirochetes in reservoir avian hosts.     

Phytotherapeutic Activity of Euphorbia Cyparissias Extracts on Ixodidae (Acari) Female Ticks

Background

Given its numerous biologically active components, Euphorbiaceae has been found to be a large plant family and polyvalent with quite interesting therapeutic activity that can be studied.

Materials and Methods

The ixodicidal activity of Euphorbia cyparissias extracts was studied in vitro and in vivo. Tested concentrations were 10, 5, 2, 1, 0.5 and 0.25%.

Results

For the in vitro study, conducted on field-collected female specimens of Dermacentor marginatus and Haemaphysalis punctata, the efficacy results showed that the ticks died after exposure in the case of 10, 5, and 2% tincture concentrations. The effects appeared after 30 minutes and became more visible 120 minutes after each exposure. The statistical differences regarding the used concentrations were found to be: F = 6.51, df = 5, P < 0.001. The in vivo study of the efficacy of E. cyparissias concentrations was performed on 35 naturally infested sheep and on 30 bovines parasitized with Ixodes ricinus, sprayed with tincture and glycerinate dilutions (bovines) on days 0 and 7. The results revealed detrimental effects on the survivability of female ticks, the most prominent being the reduction of their movement capacity. In sheep in vivo efficiency observed within 24 hrs varied, between 1 and 23% for D. marginatus and between 7 and 27% for H. punctata and respectively between 2 and 53% after 24 hrs, for I. ricinus, comparable effects being also found 72 hrs after the second administration of Euphorbia extracts.

Conclusion

Extracts from E. cyparissias may be used, with results, as an ecologic alternative tick control management method, being a cheap solution, with a sizeable role in reducing the use of synthetic and/or other harming and resistance source ixodicidal conditionings.     

Ticks (Acari: Ixodidae) of the Nile monitor on Rusinga Island, Kenya

In the course of a study of ticks of livestock, five Nile monitor lizard specimens were caught and examined for ticks. Although none of the tick species infesting livestock were found on the reptiles, a large number of adults and presumed nymphs and larvae of Aponomma flavomaculatum (Lucus) and adults of Amblyomma sparsum (Neumann) were collected. The ticks demonstrated a distinct predilection for their attachment sites. This is the second report of A. flavomaculatum from this part of Kenya.     

Rickettsial infection in ticks (Acari: Ixodidae) collected on birds in southern Brazil

The aim of the study was to evaluate rickettsial infection in ticks from wild birds of the Semidecidual and Atlantic Rainforest remnants of three municipalities of the State of Paraná, southern Brazil. Overall, 53 larvae and nymphs collected from birds were checked for the presence of Rickettsia DNA by molecular tests. Five tick species were tested: Amblyomma aureolatum (Pallas), Amblyomma calcaratum Neumann, Amblyomma longirostre (Koch), Amblyomma ovale Koch, and Amblyomma parkeri Fonseca and Arag?o. A. longirostre ticks were infected with the spotted fever group agents Rickettsia amblyommii strain AL (32.3% infection rate) and Rickettsia parkeri strain NOD (5.9% infection rate). A new rickettsial genotype was detected in the tick A. parkeri (50% infection rate), which had never been reported to be infected by rickettsiae. Through phylogenetic analysis, this new genotype, here designated as strain ApPR, grouped in a cluster composed by different strains of Rickettsia africae, Rickettsia sibirica, and R. parkeri. We consider strain ApPR to be a new genotype of R. parkeri. This study reports for the first time rickettsial infection in ticks from birds in southern Brazil. The role of migrating birds in the dispersal of these rickettsial strains should be considered in ecological studies of spotted fever group agents in Brazil.     

Tick infestations on Zebu cattle in western Kenya: host resistance to Rhipicephalus appendiculatus (Acari: Ixodidae)

Tick-susceptible Friesian steers were used as bait animals to assess the availability of adult Rhipicephalus appendiculatus Neumann on the pasture. Assuming that initial gross pickup rates of ticks by cattle were similar, the numbers of female ticks that attached and the numbers that subsequently fed to maturity on individual cattle were compared based on data obtained from bait animals. The proportion of successful attachments on high-resistance (HR) cattle (0.30) was significantly less than that on the low-resistance (LR) animals (0.51). Similarly, the proportion of attached ticks that fed to maturity also was significantly lower on HR animals (0.15) than on LR animals (0.33). Female survival was calculated as the product of these two parameters. On the HR cattle, female survival (0.05) was significantly less than on LR (0.18). About 12% of the cattle had low resistance, and up to 73% of the females survived on them. These animals were responsible for much of the tick multiplication in the field population.     

Acaricidal activity of eugenol on Rhipicephalus microplus (Acari: Ixodidae) and Dermacentor nitens (Acari: Ixodidae) larvae

The aim of this study was to evaluate the acaricidal activity of eugenol, with different solubilizations and concentrations, on Rhipicephalus microplus and Dermacentor nitens larvae and to determine the lethal time. The study consisted of four experiments, and the mortality was assessed using the larval packet test with adaptations. The mortality observed in the first experiment was 100?% for all the groups treated with eugenol solubilized in different solvents. In the second, the hydroethanolic formulation of eugenol was used, and the mortality rates for R. microplus and D. nitens was 100?% starting from the concentration of 5.0?μl/ml. In the third experiment, the mortality was 100?% for larvae of both R. microplus and D. nitens after 1?h of contact. And in the fourth experiment, the mortality was above 90?% and statistically similar (p?>?0.05) for the four methods the test evaluated.     

Ticks (Acari: Ixodidae) associated with wildlife and vegetation of Haller park along the Kenyan coastline

This artcile describes the results obtained from a tick survey conducted in Haller park along the Kenyan coastline. The survey aimed at evaluating tick-host associations, assessing tick population density, and providing baseline information for planning future tick control and management in the park. Ticks (2,968) were collected by handpicking from eight species of wildlife and by dragging in 14 selected sites within the park. A considerable proportion of ticks were also collected from leaves, stems, and bark of most dominant trees, namely, Casuarina equisetifolia L. (Forst. and Forst.), Cocos nucifera L., Adansonia digitata L., Musa paradisiaca L., and Azadiracta indica Adr. Juss. Dragging was conducted in sites predominantly occupied by Cynodon dactylon L. (Pers.), Cenchrus ciliaris L., Stenotaphrum dimidiatum L. (Kuntze.) Brongn., and Brachiaria xantholeuca Hack. Ex Schinz Stapf. and Loudetia kagerensis K. Schum. Hutch. Eight tick species were identified, and the collection included Rhipicephalus pravus D?nitz 1910, Rhipicephalus pulchellus Gerst?cker 1873, Hyalomma marginatum rufipes Koch 1844, Amblyomma gemma D?nitz 1910, Amblyomma hebraeum Koch 1844, Amblyomma sparsum Neumann 1899, Amblyomma nuttalli D?nitz 1909, and Boophilus decoloratus Koch 1844. Given that the identified tick species are known to parasitize humans as well as livestock, there exist risks of emergence of zoonotic infections mediated by tick vectors. In the recreational environment of Haller park, where tick vectors share habitats with hosts, there is a need to develop sustainable and effective tick control and management strategies to minimize economic losses that tick infestation may cause.     

New records and laboratory-rearing data for Ixodes schulzei (Acari: Ixodidae) in Brazil

Ixodes schulzei Arag?o and Fonseca was described from Brazil in 1951 based on female ticks collected on wild rats from the states of Rio de Janeiro and Santa Catarina. Since that time, there have been no additional reports of I. schulzei in the literature. We report two new records of I. schulzei: a female collected on the water rat Nectomys squamipes (Brants) from Minas Gerais State, and another female from this same host species from S?o Paulo State. This last specimen was engorged and oviposited fertile eggs in the laboratory. Larvae hatched from these eggs were used for subsequent infestations under laboratory conditions, as were nymphs obtained from the engorged larvae. Naive laboratory rats (Rattus norvegicus Berkenhout) and wild mice (Calomys callosus Rengger) were used to feed ticks. C. callosus was a more suitable host than R. norvegicus, as significantly more ticks (P < 0.05) were recovered and successfully molted after feeding on the former host species. A significantly (P < 0.05) greater proportion of larvae detached from C. callosus during daylight (71.3%) when compared with those that detached from R. norvegicus in the same period (54.8%). A total of nine engorged nymphs (one from R. norvegicus, and eight from C. callosus) were recovered in the infestations. All of them successfully molted to adults, which were all females. The male of I. schulzei remains unknown.     

Prevalence of Ehrlichia canis (Rickettsiales: Anaplasmataceae) in dogs and Rhipicephalus sanguineus (Acari: Ixodidae) ticks from Brazil

The current study evaluated the prevalence of Ehrlichia canis Donatien and Lestoquard in domestic dogs, Canis familiaris L., and Rhipicephalus sanguineus (Latreille) (Acari: Ixodidae) ticks from different areas of Brazil. In Monte Negro County (state of Rond?nia, Brazilian western Amazon), the indirect immunofluorescence assay detected E. canis-reactive antibodies (titer > or = 40) in 58/153 (37.9%) and 40/161 (24.8%) dogs from the urban and rural areas, respectively. These values were significantly different between the two areas. Ticks from a household in the urban area of Monte Negro, and from households in three other localities (162-165 adult ticks per household) in the state of S?o Paulo (SP) were tested by polymerase chain reaction (PCR) targeting an erlichial dsb gene fragment. The prevalence of infected ticks (given as minimal infection rate) was 2.3, 6.2, and 3.7% for populations 1 (Monte Negro), 2 (Jundiaí, SP), and 3 (S?o Paulo I, SP), respectively, which were statistically similar. In contrast, no infected tick was detected in population 4 (S?o Paulo II, SP). DNA sequences were determined for some of the PCR products generated from ticks and dogs from populations 1-3, being all identical to each other and to available sequences of E. canis in GenBank. These results reinforce previous records of E. canis-infecting dogs in Brazil. Natural infection of R. sanguineus ticks by E. canis is reported for the first time in Brazil, where this tick is the commonest species infesting dogs.     

The dog factor in brown dog tick Rhipicephalus sanguineus (Acari:Ixodidae) infestations in and near human dwellings

Three cases of the tick Rhipicephalus sanguineus infiltration in or near human dwellings caused by dogs, and their influence on epidemiological features of human habitats have been investigated, (a) The observation of dogs kept indoors proved that single tick females could engorge and oviposit inside apartments followed by the development of subadults. (b) Abundant micropopulations of ticks were formed in small yards or gardens near the dwellings where dogs lived in kennels, (c) A huge field population of R. sanguineus was observed on a farm where watchdogs constantly patrolled along the farm perimeter. Tick abundance near the kennels and in the permanent resting sites of the dogs reached more than 30 adults per 10 min of collecting, while the number of adults on a dog reached 100. Unfed adult females under conditions of constant dog availability had a larger scutal index than females collected in the control field site. On the basis of circumstantial evidence it is possible to conclude that under the above conditions tick development may change from the normal 3-host cycle to a 2-host cycle. Ticks in the field had one complete generation per year. Ticks on the farm, as well as ticks in kennels, developed faster and a significant part of their population had two complete generations per year. R. sanguineus is the main vector and reservoir of a pathogen from the Rickettsia conorii complex, the causative agent of Israeli tick typhus. The described conglomerations of R. sanguineus create a great risk to humans who can be attacked by infected ticks in and around their homes, even in large towns. Such a feature of the tick life history most likely exists not only in Israel but in other countries as well.     

Immune responses of interferon gamma (IFN-gamma) knock out mice to repeated Haemaphysalis longicornis (Acari: Ixodidae) nymph infestations

To investigate the immunological mechanisms of acquired resistance to tick infestation, interferon gamma (IFN-gamma) deficient mice (IFN-gamma mice) were used to assess interleukin-4 (IL-4) and antibody production levels against tick salivary gland antigen on three successive infestations with Haemoaphysalis longicornis Neumann nymphs. The engorged body weight of the ticks decreased during the second and third infestations. Similar observations were noted in IFN-gamma+/+ mice. However, the engorged body weight of the ticks from IFN-gamma +/+ mice were considerably lower than those from IFN-gamma-/- mice. A marked increase in antibody production during the second and third infestations was observed indicating that IFN-gamma-/- mice could acquire immunological resistance against H. longicornis nymphs. Moreover, IL-4 levels were higher during the first and third infestations but decreased during the second infestation. IL-4 levels were significantly higher in IFN-gamma-/- mice than in IFN-gamma+/+ mice. We have shown here that the statistically significant high IL-4 levels observed in IFN-gamma-/- mice may be a result of type 2 helper cell (Th2) polarization. However, the apparently higher IL-4 levels during the first and third infestations and the notable decline during the second infestation suggest that other cytokines or factors in the host immune system may play a part in regulating IL-4 levels.     

Immunization against ticks: use of salivary gland antigens and infestations with Rhipicephalus appendiculatus (Acari: Ixodidae) in rabbits

Comparative immunogenicity of salivary gland antigens (SGA) derived from adult Rhipicephalus appendiculatus (Neumann) and experimental infestations with the three stages of the tick was investigated. The best immunization schedule judged by reduction of engorgement weights and hatchability resulted from nymphal and adult tick infestations. Inoculation of rabbits with SGA in Freund's incomplete adjuvant (FIA) induced immune responses comparable to those associated with larval infestations, but less than those produced by nymphal or adult tick infestations. High antibody titers directed against SGA were detected only in the vaccinated and adult tick-infested rabbits. The results of this experiment suggest that SGA prepared from partially fed ticks can be used in the experimental induction of immunity to ticks and that the antigen has potential as a vaccine against R. appendiculatus ticks.