Environmental risk factors for Ixodes ricinus ticks and their infestation on lambs in a changing ecosystem: Implications for tick control and the impact of woodland encroachment on tick-borne disease in livestock

Despite global deforestation some regions, such as Europe, are currently experiencing rapid reforestation. Some of this is unintended woodland encroachment onto farmland as a result of reduced livestock pasture management. Our aim was to determine the likely impacts of this on exposure to ticks and tick-borne disease risk for sheep in Norway, a country experiencing ecosystem changes through rapid woodland encroachment as well as increases in abundance and distribution of Ixodes ricinus ticks and tick-borne disease incidence. We conducted surveys of I. ricinus ticks on ground vegetation using cloth lure transects and counts of ticks biting lambs on spring pastures, where lambs are exposed to infection with Anaplasma phagocytophilum, the causative agent of tick-borne fever in livestock. Pastures had higher densities of I. ricinus ticks on the ground vegetation and more ticks biting lambs if there was more tree cover in or adjacent to pastures. Importantly, there was a close correlation between questing tick density on pastures and counts of ticks biting lambs on the same pasture, indicating that cloth lure transects are a good proxy of risk to livestock of tick exposure and tick-borne disease. These findings can inform policy on environmental tick control measures such as habitat management, choice of livestock grazing area and off-host application of tick control agents

Lyme Disease and the Workplace

{Excerpt] Lyme disease, an infection by the bacterium Borrelia burgdorferi, was named after a Connecticut town where a group of arthritis cases in children appeared in the early 1970s. These bacteria are carried by infected blacklegged ticks and are transmitted to humans through tick bites. While deer feed ticks and spread them around — actually mice infect the majority of ticks carrying Lyme in the Northeast. A mouse might have dozens of ticks covering its ears and face and can infect up to 95% of those ticks. Climate change is part of the surge in Lyme disease cases, but a big factor has been the history of land use in the Northeast. When the area was first settled, early farmers clear-cut nearly all of the forests to plant crops and raise livestock, as well as cutting down trees for commercial use and for firewood. While a lot of forest has come back, today it\u27s broken up by roads, farms, and housing developments. Mice tend to thrive in these fragmented landscapes because their predators -- foxes, hawks, owls -- need big forests to survive

Hard tick species of livestock and their bioecology in Golestan Province, North of Iran

Background: A survey on tick species composition was carried out in Golestan Province Iran during year 2010- 2011.The aim was to determine tick species parasitizing domestic ruminants and their seasonal population dynamics. Methods: A total of 124 sheep, 92 goats, 84 cattle, 74 camels and 12 horses in several villages were inspected for tick infestation. The collected ticks preserved in 70% alcohol and then were identified. Results: The overall 1059 ticks (453 female, 606 male) were collected. The ticks occur on sheep, goats, cattle, camels and horses as 72.1%, 77.3%, 75.8%, 69.3%, and 50% respectively. The frequency of ticks in spring was more than other seasons and the least was observed in winter. In the spring and summer, infestation rate in domestic ruminants were calculated as 100%. Six genus and fourteen hard and soft tick species were identified including Rhipicephalus sanguineus, R. bursa, Ixodes ricinus, Haemaphysalis punctata, H. sulcata, H. erinacei, H. inermis, Hyalomma marginatum, Hy. asiaticum, Hy. dromedarii, Hy. excavatum, Hy. anatolicum, Hy. detritum, Boophilus annulatus and Argas persicus. Rhipicephalus sanguineus was the most abundant species in the study area. The largest number of ticks was collected from animal ears and tails. Haemaphysalis, Hyalomma, Rhipicephalus and Boophilus occurred in mountainous, forest and plateau areas of Golestan Province but Ixodes occurred only in mountainous and forest areas, whereas Rhipicephalus and Hyalomma were present in coastal areas of Golestan Province. Conclusion: The result of this study is a survey on tick species from domestic animals in Iran and implication of possible prevention measures for diseases transmitted by ticks

Geospatial Analysis of Rickettsial Species

Rickettsia species are obligate intracellular, arthropod-borne bacteria with a potential to cause multiple diseases including Rocky Mountain spotted fever (RMSF). Fleas, mites, and ticks serve as vectors for Rickettsia, but ticks are the primary vector of interest. RMSF and other rickettsial diseases have continued to gain importance in both human and veterinary medicine as RMSF is the most common tick-borne disease within the United States according to the Lyme and Tick-Borne Disease Research Center. A statewide citizen science project was utilized to determine the prevalence of Spotted Fever Group (SFG) Rickettsia in Arkansas. This project yielded results in 64 of Arkansas’s 75 counties. Results were utilized to determine prevalence in each of the represented counties, and then compiled into a geospatial representation of the data. It was determined that 34.32% of the ticks sampled were carriers of one or more rickettsial species. As the samples were divided by county, multiple counties were shown to have concerningly high exposure risk for SFG Rickettsia. There were six species of ticks represented throughout this study with Amblyomma americanum being the most common. There were also six species of Spotted Fever Group Rickettsia found within the samples. The small portion of ticks that underwent further analysis to determine the specific rickettsial species present, indicated that Rickettsia amblyommatis is likely the most common SFG Rickettsia in Arkansas

Can the Gram-negative bacterium Escherichia coli colonize the gut of Lone Star Tick (Amblyomma americanum)?

Ticks are obligate blood feeding ectoparasites and vectors of several mammalian pathogens (Williams-Newkirk et al, 2014). In addition to pathogens they also carry a bacterial community with commensal and symbiotic relationships (Bonnet et al, 2017). Using a culture-dependent approach we previously reported a high prevalence of Gram-positive bacteria in the gut of field collected lone star ticks (Amblyomma americanum). These results suggested that epithelial immunity functions to control Gram-negative bacteria in A. americanum. In this study, we used a culturing and non-culturing approach to measure the outcome of E.coli (Gram-negative) when fed to female adult lone star ticks (n=16). Results showed a significant reduction of E.coli at Days 1, 3 and 7 post bacterial feeding. qPCR of 16S rDNA confirmed reduction of bacterial rDNA when compared to water fed ticks (n=16). Our results suggest that there is a midgut epithelial immune response in place, which mainly targets Gram-negative bacteria

Neuronal in vitro impact of Amblyommaamericanumsalivary glands extracts

When a tick feeds off a host, the salivary glands of the tick excrete saliva to assist the tick in feeding (1). The reason saliva assists the tick in consuming its blood meal is due to its immunosuppressive, anti-inflammatory, and anti-coagulant properties (2).Tick salivary glands also play an important role in the transmission of tick-borne pathogens (3). We wanted to investigate the effect of tick salivary gland extracts (SGE) on human neurons. For our experiment, the organism whose salivary gland extract we used was the Amblyomma americanum. We compared the effects of salivary gland extract from ticks collected in the field and ticks reared in a lab colony. Our results showed that the salivary gland extract from the two types of ticks affected the neurons differently, and the salivary gland extract of the field tick was more damaging to the neurons. This indicates that SGE from field ticks, together with infectious agents, could result in a more severe neuronal impairment in a human host than the infectious agent alone

Tick Sweats

Ticks are obligatory ectoparasites of many vertebrate hosts including human. Osmoregulatory functions of ticks are crucial for the survival, especially, in the off-host ticks in arid area. We found that injection of water in the body cavity of tick immediately triggers excretion of solution through the exoskeletal cuticles, like sweating. This response occurred in a bilateral asymmetric manner; the injection on left side of the body induced the sweating on only the left half, while the injection into right side did not induce sweat. The sweating response was reduced in the injections of high osmolar Naci (1 M). This is the first description of sweating physiology in maintenance of water homeostasis in the Lone star tick

Metagenomic-based Surveillance of Pacific Coast tick Dermacentor occidentalis Identifies Two Novel Bunyaviruses and an Emerging Human Ricksettsial Pathogen.

An increasing number of emerging tick-borne diseases has been reported in the United States since the 1970s. Using metagenomic next generation sequencing, we detected nucleic acid sequences from 2 novel viruses in the family Bunyaviridae and an emerging human rickettsial pathogen, Rickettsia philipii, in a population of the Pacific Coast tick, Dermacentor occidentalis in Mendocino County sampled annually from 2011 to 2014. A total of 250 adults of this human-biting, generalist tick were collected from contiguous chaparral and grassland habitats, and RNA from each individually extracted tick was deep sequenced to an average depth of 7.3 million reads. We detected a Francisella endosymbiont in 174 ticks (70%), and Rickettsia spp. in 19 ticks (8%); Rickettsia-infected ticks contained R. rhipicephali (16 of 250, 6.4%) or R. philipii (3 of 250,1.2%), the agent of eschar-associated febrile illness in humans. The genomes of 2 novel bunyaviruses (>99% complete) in the genera Nairovirus and Phlebovirus were also identified and found to be present in 20-91% of ticks, depending on the year of collection. The high prevalence of these bunyaviruses in sampled Dermacentor ticks suggests that they may be viral endosymbionts, although further studies are needed to determine whether they are infectious for vertebrate hosts, especially humans, and their potential role in tick ecology

High prevalence of <i>Rickettsia africae</i> variants in <i>Amblyomma variegatum</i> ticks from domestic mammals in rural western Kenya: implications for human health

Tick-borne spotted fever group (SFG) rickettsioses are emerging human diseases caused by obligate intracellular Gram-negative bacteria of the genus Rickettsia. Despite being important causes of systemic febrile illnesses in travelers returning from sub-Saharan Africa, little is known about the reservoir hosts of these pathogens. We conducted surveys for rickettsiae in domestic animals and ticks in a rural setting in western Kenya. Of the 100 serum specimens tested from each species of domestic ruminant 43% of goats, 23% of sheep, and 1% of cattle had immunoglobulin G (IgG) antibodies to the SFG rickettsiae. None of these sera were positive for IgG against typhus group rickettsiae. We detected Rickettsia africae–genotype DNA in 92.6% of adult Amblyomma variegatum ticks collected from domestic ruminants, but found no evidence of the pathogen in blood specimens from cattle, goats, or sheep. Sequencing of a subset of 21 rickettsia-positive ticks revealed R. africae variants in 95.2% (20/21) of ticks tested. Our findings show a high prevalence of R. africae variants in A. variegatum ticks in western Kenya, which may represent a low disease risk for humans. This may provide a possible explanation for the lack of African tick-bite fever cases among febrile patients in Kenya

Rickettsias del grupo de las fiebres manchadas en garrapatas del género Amblyomma, capaces de infestar humanos, en áreas rurales del noroeste de Argentina

This work was performed to detect Rickettsia species of the spotted fever group in Amblyomma ticks likely to infest humans in rural areas from northwestern Argentina. Free-living ticks were collected and determined as Amblyomma tigrinum, Amblyomma neumanni and Amblyomma tonelliae. Rickettsia infection was determined by polymerase chain reactions which amplify fragments of the rickettsial genes gltA and ompA. A high frequency (35/44, 79.5%) of Candidatus “Rickettsia andeanae” was observed in A. tigrinum ticks, and Candidatus “Rickettsia amblyommii” was found in three out of 14 nymphs of A. neumanni. All 14 Amblyomma tonelliae ticks were negative for rikettsiae. The infection with spotted fever group rickettsiae in ticks aggressive for humans reveals the potential risk of exposure to tick-borne pathogens of people inhabiting rural areas of northwestern Argentina.Fil: Saracho Bottero, María Noelia. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Tarragona, Evelina Luisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; ArgentinaFil: Nava, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentin