Metapopulation Models in Tick-Borne Disease Transmission Modelling

Mice Against Ticks is a community-guided ecological engineering project that aims to prevent tick-borne disease by using CRISPR-based genome editing to heritably immunize the white-footed mice ( Peromyscus leucopus ) responsible for infecting many ticks in eastern North America. Introducing antibody-encoding resistance alleles into the local mouse population is anticipated to disrupt the disease transmission cycle for decades. Technology development is shaped by engagement with community members and visitors to the islands of Nantucket and Martha's Vineyard, including decisions at project inception about which types of disease resistance to pursue. This engagement process has prompted the researchers to use only white-footed mouse DNA if possible, meaning the current project will not involve gene drive. Instead, engineered mice would be released in the spring when the natural population is low, a plan unlikely to increase total numbers above the normal maximum in autumn. Community members are continually asked to share their suggestions and concerns, a process that has already identified potential ecological consequences unanticipated by the research team that will likely affect implementation. As an early example of CRISPR-based ecological engineering, Mice Against Ticks aims to start small and simple by working with island communities whose mouse populations can be lastingly immunized without gene drive. This article is part of a discussion meeting issue ‘The ecology and evolution of prokaryotic CRISPR-Cas adaptive immune systems’.

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Tick species from cattle in the Adama Region of Ethiopia and pathogens detected

Experimental and Applied Acarology ◽

10.1007/s10493-021-00623-5 ◽

2021 ◽

Author(s):

Tafese Beyene Tufa ◽

Silke Wölfel ◽

Dana Zubriková ◽

Bronislava Víchová ◽

Martin Andersson ◽

...

Keyword(s):

Disease Transmission ◽

Tick Species ◽

Pathogenic Bacteria ◽

Intergenic Spacer ◽

Farm Animals ◽

Ehrlichia Ruminantium ◽

Intergenic Spacer Region ◽

Dna Yield ◽

Rhipicephalus Pulchellus ◽

Tick Borne Disease

AbstractTicks will diminish productivity among farm animals and transmit zoonotic diseases. We conducted a study to identify tick species infesting slaughter bulls from Adama City and to screen them for tick-borne pathogens. In 2016, 291 ticks were collected from 37 bulls in Adama, which were ready for slaughter. Ticks were identified morphologically. Total genomic DNA was extracted from ticks and used to test for Rickettsia spp. with real-time PCR. Species identification was done by phylogenetic analysis using sequencing that targeted the 23S-5S intergenic spacer region and ompA genes. Four tick species from two genera, Amblyomma and Rhipicephalus, were identified. Amblyomma cohaerens was the dominant species (n = 241, 82.8%), followed by Amblyomma variegatum (n = 22, 7.5%), Rhipicephalus pulchellus (n = 19, 6.5%), and Rhipicephalus decoloratus (n = 9, 3.0%). Among all ticks, 32 (11%) were positive for Rickettsia spp. and 15 (5.2%) of these were identified as R. africae comprising at least two genetic clades, occurring in A. variegatum (n = 10) and A. cohaerens (n = 5). The remainder of Rickettsia-positive samples could not be amplified due to low DNA yield. Furthermore, another 15 (5.2%) samples carried other pathogenic bacteria: Ehrlichia ruminantium (n = 9; 3.1%) in A. cohaerens, Ehrlichia sp. (n = 3; 1%) in Rh. pulchellus and A. cohaerens, Anaplasma sp. (n = 1; 0.5%) in A. cohaerens, and Neoehrlichia mikurensis (n = 2; 0.7%) in A. cohaerens. All ticks were negative for Bartonella spp., Babesia spp., Theileria spp., and Hepatozoon spp. We reported for the first time E. ruminatium, N. mikurensis, Ehrlichia sp., and Anaplasma sp. in A. cohaerens. Medically and veterinarily important pathogens were mostly detected from A. variegatum and A. cohaerens. These data are relevant for a One-health approach for monitoring and prevention of tick-borne disease transmission.

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Emerging Tick-Borne Diseases

Clinical Microbiology Reviews ◽

10.1128/cmr.00083-18 ◽

2020 ◽

Vol 33 (2) ◽

Cited By ~ 15

Author(s):

Susan Madison-Antenucci ◽

Laura D. Kramer ◽

Linda L. Gebhardt ◽

Elizabeth Kauffman

Keyword(s):

Public Health ◽

Disease Transmission ◽

Emerging Diseases ◽

Disease Prevalence ◽

Immunological Methods ◽

Health Issues ◽

Appropriate Treatment ◽

Tick Borne Disease ◽

Ecology Of Ticks ◽

Selection Of

SUMMARY Increases in tick-borne disease prevalence and transmission are important public health issues. Efforts to control these emerging diseases are frustrated by the struggle to control tick populations and to detect and treat infections caused by the pathogens that they transmit. This review covers tick-borne infectious diseases of nonrickettsial bacterial, parasitic, and viral origins. While tick surveillance and tracking inform our understanding of the importance of the spread and ecology of ticks and help identify areas of risk for disease transmission, the vectors are not the focus of this document. Here, we emphasize the most significant pathogens that infect humans as well as the epidemiology, clinical features, diagnosis, and treatment of diseases that they cause. Although detection via molecular or immunological methods has improved, tick-borne diseases continue to remain underdiagnosed, making the scope of the problem difficult to assess. Our current understanding of the incidence of tick-borne diseases is discussed in this review. An awareness of the diseases that can be transmitted by ticks in specific locations is key to detection and selection of appropriate treatment. As tick-transmitted pathogens are discovered and emerge in new geographic regions, our ability to detect, describe, and understand the growing public health threat must also grow to meet the challenge.

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The Unexpected Holiday Souvenir: The Public Health Risk to UK Travellers from Ticks Acquired Overseas

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17217957 ◽

2020 ◽

Vol 17 (21) ◽

pp. 7957

Author(s):

Emma L. Gillingham ◽

Benjamin Cull ◽

Maaike E. Pietzsch ◽

L. Paul Phipps ◽

Jolyon M. Medlock ◽

...

Keyword(s):

Public Health ◽

Disease Transmission ◽

Tick Species ◽

Native Species ◽

Travel History ◽

The Public ◽

Overseas Travel ◽

Tick Borne Disease ◽

Species Specific ◽

The Uk

Overseas travel to regions where ticks are found can increase travellers’ exposure to ticks and pathogens that may be unfamiliar to medical professionals in their home countries. Previous studies have detailed non-native tick species removed from recently returned travellers, occasionally leading to travel-associated human cases of exotic tick-borne disease. There are 20 species of tick endemic to the UK, yet UK travellers can be exposed to many other non-native species whilst overseas. Here, we report ticks received by Public Health England’s Tick Surveillance Scheme from humans with recent travel history between January 2006 and December 2018. Altogether, 16 tick species were received from people who had recently travelled overseas. Confirmed imports (acquired outside of the UK) were received from people who recently travelled to 22 countries. Possible imports (acquired abroad or within the UK) were received from people who had recently travelled to eight European countries. Species-specific literature reviews highlighted nine of the sixteen tick species are known to vector at least one tick-borne pathogen to humans in the country of acquisition, suggesting travellers exposed to ticks may be at risk of being bitten by a species that is a known vector, with implications for novel tick-borne disease transmission to travellers.

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Diversity of Hard Tick Populations and Their Geographical Variations in Northwestern Iran

Journal of Arthropod-Borne Diseases ◽

10.18502/jad.v15i2.7487 ◽

2021 ◽

Author(s):

Rohollah Moradi ◽

Eslam Moradi-Asl ◽

Zakkyeh Telmadarraiy ◽

Seyedeh Zahra Parkhideh ◽

Yavar Rassi

Keyword(s):

Disease Transmission ◽

Diversity Index ◽

Hemorrhagic Fever ◽

Hard Tick ◽

Geographical Variations ◽

Four Seasons ◽

Eastern Iran ◽

North Eastern ◽

Risk Areas ◽

Tick Borne Disease

Background: Ticks are forced vertebrate ectoparasites, including humans, and are vectors of serious diseases such as Crimean Congo Hemorrhagic Fever, Relapsing Fever, and various forms of encephalitis. Spatial assessment of the prevalence of ticks and detection of high risk areas for tick-borne disease transmission and evaluation of ecological measures are key aims of this research. Methods: Ticks were collected using standard methods from 27 villages in the region of Sarab County in north-eastern Iran during the four seasons of 2018–2019 and identified using valid keys. The calculations of indices for biodiversity were based on the Margalef index, Shannon-Weiner index and Simpson index. R2.15 Statistical software was used for statistical analysis of indices of biodiversity, and ArcMap10.4.1 software, IDW and GeneralG methods were used. Analysis were used to investigate spatial distribution and to determine important tick hotspots. Results: A total of 2500 animals surveyed, 35% of them were infected. In total, 1416 ticks were caught, 74.6 %, 23.9% and 1.4 % were adult, nymph and larvae respectively. 94% of the ticks were hard ticks including 6 genera. According to the Margalef diversity index, the highest species biodiversity was related to summer (1.4234), and the lowest was related to winter (0.7379), Conclusion: Large hotspot area was found in the central part of the study area. The area of study was very prone to tick-borne disease transmission in terms of tick diversity and tick species richness. Tick-borne disease control is an important measure.

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Phylogeography of Borrelia spirochetes in Ixodes pacificus and Ixodes spinipalpis ticks highlights differential acarological risk of tick-borne disease transmission in northern versus southern California

PLoS ONE ◽

10.1371/journal.pone.0214726 ◽

2019 ◽

Vol 14 (4) ◽

pp. e0214726 ◽

Cited By ~ 6

Author(s):

Ian Rose ◽

Melissa Hardstone Yoshimizu ◽

Denise L. Bonilla ◽

Natalia Fedorova ◽

Robert S. Lane ◽

...

Keyword(s):

Disease Transmission ◽

Southern California ◽

Ixodes Pacificus ◽

Tick Borne Disease

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Effects of Coinfection on the Dynamics of Two Pathogens in a Tick-Host Infection Model

Complexity ◽

10.1155/2020/5615173 ◽

2020 ◽

Vol 2020 ◽

pp. 1-14

Author(s):

Bei Sun ◽

Xue Zhang ◽

Marco Tosato

Keyword(s):

Disease Transmission ◽

Host Population ◽

Infection Model ◽

Uniform Persistence ◽

Reproduction Numbers ◽

Boundary Equilibrium ◽

Tick Borne Disease ◽

Host Infection ◽

The Impact ◽

Disease Free

As both ticks and hosts may carry one or more pathogens, the phenomenon of coinfection of multiple tick-borne diseases becomes highly relevant and plays a key role in tick-borne disease transmission. In this paper, we propose a coinfection model involving two tick-borne diseases in a tick-host population and calculate the basic reproduction numbers at the disease-free equilibrium and two boundary equilibria. To explore the impact of coinfection, we also derive the invasion reproduction numbers which indicate the potential of a pathogen to persist when another pathogen already exists in tick and host populations. Then, we obtain the global stability of the system at the disease-free equilibrium and the boundary equilibrium, respectively, and further demonstrate the existence conditions for uniform persistence of the two diseases. The final numerical simulations mainly verify the theoretical results of coinfection.

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Connectivity sustains disease transmission in environments with low potential for endemicity: modelling schistosomiasis with hydrologic and social connectivities

Journal of The Royal Society Interface ◽

10.1098/rsif.2008.0265 ◽

2008 ◽

Vol 6 (35) ◽

pp. 495-508 ◽

Cited By ~ 61

Author(s):

David Gurarie ◽

Edmund Y.W. Seto

Keyword(s):

Mathematical Model ◽

Disease Transmission ◽

Parasitic Diseases ◽

Parasite Control ◽

Optimum Control ◽

Social Contacts ◽

Transport Pathways ◽

High Infection ◽

Metapopulation Models ◽

Host Movement

Social interaction and physical interconnections between populations can influence the spread of parasites. The role that these pathways play in sustaining the transmission of parasitic diseases is unclear, although increasingly realistic metapopulation models are being used to study how diseases persist in connected environments. We use a mathematical model of schistosomiasis transmission for a distributed set of heterogeneous villages to show that the transport of parasites via social (host movement) and environmental (parasite larvae movement) pathways has consequences for parasite control, spread and persistence. We find that transmission can be sustained regionally throughout a group of connected villages even when individual village conditions appear not to support endemicity. Optimum transmission is determined by an interplay between different transport pathways, and not necessarily by those that are the most dispersive (e.g. disperse social contacts may not be optimal for transmission). We show that the traditional targeting of villages with high infection, without regard to village interconnections, may not lead to optimum control. These findings have major implications for effective disease control, which needs to go beyond considering local variations in disease intensity, to also consider the degree to which populations are interconnected.

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Spatial clustering of fourteen tick species across districts of Zimbabwe

BMC Veterinary Research ◽

10.1186/s12917-021-02792-2 ◽

2021 ◽

Vol 17 (1) ◽

Author(s):

Munyaradzi Davis Shekede ◽

Silvester Maravanyika Chikerema ◽

Moregood Spargo ◽

Isaiah Gwitira ◽

Samuel Kusangaya ◽

...

Keyword(s):

Spatial Distribution ◽

Disease Management ◽

Disease Transmission ◽

Tick Species ◽

Common Species ◽

Geographic Region ◽

High Morbidity ◽

Amblyomma Hebraeum ◽

Hotspot Analysis ◽

Tick Borne Disease

Abstract Background Ticks transmit several diseases that result in high morbidity and mortality in livestock. Tick-borne diseases are an economic burden that negatively affect livestock production, cost countries billions of dollars through vaccine procurement and other disease management efforts. Thus, understanding the spatial distribution of tick hotspots is critical for identifying potential areas of high tick-borne disease transmission and setting up priority areas for targeted tick disease management. In this study, optimised hotspot analysis was applied to detect hotspots and coldspots of 14 common tick species in Zimbabwe. Data on the spatial distribution of tick species were obtained from the Epidemiology Unit of the Division of Veterinary Field Services of Zimbabwe. Results A total of 55,133 ticks were collected with Rhipicephalus decoloratus being the most common species (28.7%), followed by Amblyomma hebraeum (20.6%), and Rhipicephalus sanguineus sensu lato (0.06%) being the least common species. Results also showed that tick hotspots are species-specific with particular tick species occupying defined localities in the country. For instance, Amblyomma variegatum, Rhipicephalus appendiculatus, Rhipicephalus decoloratus, Rhipicephalus compostus, Rhipicephalus microplus, Rhipicephalus pravus, and Rhipicephalus simus were concentrated in the north and north eastern districts of the country. In contrast, Amblyomma hebraeum, Hyalomma rufipes, Hyalomma trancatum and Rhipicephalus evertsi evertsi were prevalent in the southern districts of Zimbabwe. Conclusion The occurrence of broadly similar hotspots of several tick species in different districts suggests presence of spatial overlaps in the niche of the tick species. As ticks are vectors of several tick-borne diseases, there is high likelihood of multiple disease transmission in the same geographic region. This study is the first in Zimbabwe to demonstrate unique spatial patterns in the distribution of several tick species across the country. The results of this study provide an important opportunity for the development of spatially-targeted tick-borne disease management strategies.

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