Spread Of Tick-borne Diseases Research Articles

Revealing the Tick Microbiome: Insights into Midgut and Salivary Gland Microbiota of Female Ixodes ricinus Ticks.

The ectoparasite Ixodes ricinus is an important vector for many tick-borne diseases (TBD) in the northern hemisphere, such as Lyme borreliosis, rickettsiosis, human granulocytic anaplasmosis, or tick-borne encephalitis virus. As climate change will lead to rising temperatures in the next years, we expect an increase in tick activity, tick population, and thus in the spread of TBD. Consequently, it has never been more critical to understand relationships within the microbial communities in ticks that might contribute to the tick's fitness and the occurrence of TBD. Therefore, we analyzed the microbiota in different tick tissues such as midgut, salivary glands, and residual tick material, as well as the microbiota in complete Ixodes ricinus ticks using 16S rRNA gene amplicon sequencing. By using a newly developed DNA extraction protocol for tick tissue samples and a self-designed mock community, we were able to detect endosymbionts and pathogens that have been described in the literature previously. Further, this study displayed the usefulness of including a mock community during bioinformatic analysis to identify essential bacteria within the tick.

Virome analysis of ticks and tick-borne viruses in Heilongjiang and Jilin Provinces, China

Ticks transmit diverse human and animal pathogens, leading to an increasing number of public health concerns. In the forest area of northeast China, the spread of tick-borne diseases (TBDs) is severe; however, little is known about the tick virome composition and evolution. Herein, we investigate the geographical distribution of tick species and related viruses in Heilongjiang and Jilin Provinces in Northeast China. To reveal the diversity of tick-borne viruses in parts of Heilongjiang and Jilin, ticks were collected at 9 collection points in these provinces in 2018. Morphology and molecular biology were used to identify tick species, and 1411 ticks from nine sampling sites were collected and analysed by next-generation sequencing (NGS). Four Ixodidae were identified, including Ixodes persulcatus, Haemaphysalis japonica, Dermacentor silvarum, and Haemaphysalis concinna. After removal of host genome sequences, 13,003 high-quality NGS reads were obtained and annotated as viruses. Further phylogenetic analysis based on amplicons revealed that these viral sequences belong to Beiji nairovirus, Alongshan virus, bovine parvovirus-2, and tick-associated circovirus; some distinct sequences are closely related to Songling virus, Changping tick virus, Norway luteo-like virus 2, and Norway partiti-like virus 1. In summary, this study describes the prevalence of local ticks and variety of tick-borne viruses in northeastern China, providing a basis for further research on tick-borne viruses in the future.

The environment, the tick, and the pathogen - It is an ensemble.

Ixodes scapularis is one of the predominant vectors of Borrelia burgdorferi, the agent of Lyme disease in the USA. The geographic distribution of I. scapularis, endemic to the northeastern and northcentral USA, is expanding as far south as Georgia and Texas, and northwards into Canada and poses an impending public health problem. The prevalence and spread of tick-borne diseases are influenced by the interplay of multiple factors including microbiological, ecological, and environmental. Molecular studies have focused on interactions between the tick-host and pathogen/s that determine the success of pathogen acquisition by the tick and transmission to the mammalian host. In this review we draw attention to additional critical environmental factors that impact tick biology and tick-pathogen interactions. With a focus on B. burgdorferi we highlight the interplay of abiotic factors such as temperature and humidity as well as biotic factors such as environmental microbiota that ticks are exposed to during their on- and off-host phases on tick, and infection prevalence. A molecular understanding of this ensemble of interactions will be essential to gain new insights into the biology of tick-pathogen interactions and to develop new approaches to control ticks and tick transmission of B. burgdorferi, the agent of Lyme disease.

Розробка комплексної схеми боротьби з іксодовими кліщами

In the context of globalization, climate changing and the spread of tick-borne diseases, the control of ixodid ticks is becoming increasingly important. The uncontrolled use of chemicals to limit the harmful effects of ticks has led to the development of acaricide resistance of ticks, as is observed with most pest control chemicals. There are many reasons for lack of success in the control of ticks and the diseases they transmit. The tick ecology is problematic and has not yet been fully explored. It is believed that effective methods of tick control require the development of integrated methods. The development of a program for the control of ectoparasites is required to take into account seasonality, species composition of parasites, features of biological development. The purpose of our study was to create an effective way of elimination of the ticks in the environment. During 2019, the research was conducted in the Khmelnytsky region. As a result of the preliminary parasitological examination, natural biotopes of Dermacentor reticulatus ticks were found. In natural conditions, the treatment was carried out to eliminate ticks in the environment. Three plots, two test plots, and a control plot were identified for the research. At the first tested plot, the efficiency of chemical treatment with Tsiflur-Kombi after 24 hours of the application was 92.6%, at the second site - 100%. The highest efficacy was obtained in the two groups on day 7 after administration and continued for 35 days. During this period, no ticks were detected in the test plots. During the whole period, the average number of ticks per plot - 26 individuals was observed on the control plot. The acaricide Tsiflur-combi has shown high effectiveness in controlling of ixodid ticks at a concentration of 0.2% and 0.5% for five weeks in natural biotopes. The duration of the repellent and acaricidal effect on ticks after treatment with the Tsiflur-combi preparation was 35 days. It is recommended that prophylactic application be carried out every 4 weeks, but it’s necessary to take into account the region's acarological indicators. An effective and safe way to eliminate ticks in the environment has been developed. Synthetic pyrethroids have a long residual acaricidal effect on different surfaces, and when used in small quantities, do not pose a risk to mammals.

The distribution limit of the common tick, Ixodes ricinus, and some associated pathogens in north-western Europe

In north-western Europe, the common tick, Ixodes ricinus, is widely established, its distribution appears to be increasing and the spread of tick-borne diseases is of increasing concern. The project ‘Flått i Nord’ (Ticks in northern Norway) commenced in spring 2009 with the intention of studying the tick’s distribution and that of its pathogens in northern Norway. Several methods were used: cloth-dragging, collecting from trapped small mammals, and collecting from pets. Since 2010, the occurrence of ticks in the region of northern Norway was determined directly by cloth-dragging 167 times in 109 separate locations between the latitudes of 64 °N and 70 °N (included seven locations in the northern part of Trøndelag County). The northernmost location of a permanent I. ricinus population was found to be Nordøyvågen (66.2204 °N, 12.59 °E) on the Island of Dønna. In a sample of 518 nymphal and adult ticks, the Borrelia prevalence collected close to this distribution limit varied but was low (1–15 %) compared with the locations in Trøndelag, south of the study area (15–27 %). Five specimens (1 %) were positive for Rickettsia helvetica. The length of the vegetation growing season (GSL) can be used as an approximate index for the presence of established populations of I. ricinus. The present study suggests that the threshold GSL for tick establishment is about 170 days, because the median GSL from 1991 to 2015 was 174–184 days at sites with permanent tick populations, showing a clear increase compared with the period 1961–1990. This apparent manifestation of climate change could explain the northward extension of the range of I. ricinus.

Surveillance of ticks and associated pathogens in free-ranging Formosan pangolins (Manis pentadactyla pentadactyla)

Chinese pangolins are critically endangered insectivorous mammals distributed in several South and Southeast Asian countries. In recent years, there has been an increase in spread of tick-borne diseases in both humans and animals worldwide. Currently, limited information is available on ticks and associated pathogens infesting pangolins. The objective of the present study was to survey ticks and associated pathogens in the Formosan pangolin population in Southeastern Taiwan. Free-ranging Formosan pangolins captured during ecological survey were examined for the presence of ticks. DNA extracted from these ticks was used to identify the tick species and also to detect the tick-borne pathogens, by molecular methods. In the present study, we found 25% (13/52) of pangolins captured during 2012–2014 infested with ixodid ticks. A total of 21 ticks were collected and 3 species were identified: Haemaphysalis hystricis (14/21), Haemaphysalis formosensis (2/21) and Amblyomma testudinarium (5/21). We detected four different tick-borne pathogens, where one was identical to Anaplasma sp. strain An.H1446 while others showed close resemblance to Rickettsia conorii subsp. caspia A-167, Ehrlichia sp. TC251-2 and Cytauxzoon spp., respectively. The present study is the first survey of ticks infesting the free-ranging Chinese pangolins and pathogens harboured by these ticks. This information is important to know the diversity of ticks and tick-borne pathogens, and its conservation significance to pangolins and other sympatric wildlife. Important future step should be regular surveillance of ticks and tick-borne diseases at human-domestic animals-wildlife interface, which can provide a useful insight into the dynamics of these pathogens and can help control and prevent outbreak of zoonoses.

Ixodid ticks (Acari: Ixodidae) infesting humans in Tokat Province of Turkey: species diversity and seasonal activity.

Ixodid ticks (Acari: Ixodidae) are the major vectors of pathogens threatening animal and human health. Tokat Province, Turkey, is a suitable habitat for extended tick activity with its moderate climate and vegetation. In the present study, we surveyed humans visiting health centers to determine the species diversity, geographical distribution, and seasonal activity of ixodid ticks infesting them. Out of 5,999 adult ticks collected from humans from April to September, 2008, 800 ticks were identified to species, while the remaining were identified to genus according to their distinct morphological characteristics. Hyalomma marginatum, Hyalomma detritum, Rhipicephalus bursa, Rhipicephalus (Boophilus) annulatus, Haemaphysalis punctata, Dermacentor marginatus, and Ixodes laguri were the most prevalent tick species among 24 ixodid tick species infesting humans in the region. One of these tick species, Hyalomma isacii was identified as a new record for the ixodid tick fauna of Turkey. Hyalomma species were the most abundant in summer, while Dermacentor and Ixodes species displayed the lowest frequency. Hyalomma aegyptium infestation was very common on humans in the province. Results indicated that a variety of ixodid tick species infest humans depending on the season in the target area. It is possible that a variety of ixodid tick species may contribute to the spread of tick-borne diseases such as Crimean-Congo haemorrhagic fever virus (CCHFV), which is endemic in the region.

Ecology of the American Dog Tick, Dermacentor variabilis,1 in a Study Area in Virginia. 3. Studies on Dispersal of Immature Ticks by Small-Mammal Hosts2

Dispersal of radioisotope-tagged immature ticks, Dermacentor variabilis (Say), by small-mammal hosts was observed, extending to 990 feet from an area where they were released. Most dispersal occurred during the spring activity period, when survivors of the marked population released the previous summer were seeking hosts. Wide-ranging white-footed mice, Peromyscus leucopus (Rafinesque), appeared to have been especially important in dispersing these ticks. White-footed mice infested with tagged ticks in the control area (where no tagged ticks had been released) had significantly greater spacing and range than other mice in the same area not infested with these ticks. This information may be important in evaluating the potential spread of tick-borne diseases, e.g. Rocky Mountain fever.