Publications by authors named "Jolyon M Medlock"

81 Publications

Ixodes ricinus and Borrelia burgdorferi sensu lato in the Royal Parks of London, UK.

Exp Appl Acarol 2021 Jul 14;84(3):593-606. Epub 2021 Jun 14.

Medical Entomology & Zoonoses Ecology, Emergency Response Department Science & Technology, Public Health England, Porton Down, UK.

Assessing the risk of tick-borne disease in areas with high visitor numbers is important from a public health perspective. Evidence suggests that tick presence, density, infection prevalence and the density of infected ticks can vary between habitats within urban green space, suggesting that the risk of Lyme borreliosis transmission can also vary. This study assessed nymph density, Borrelia prevalence and the density of infected nymphs across a range of habitat types in nine parks in London which receive millions of visitors each year. Ixodes ricinus were found in only two of the nine locations sampled, and here they were found in all types of habitat surveyed. Established I. ricinus populations were identified in the two largest parks, both of which had resident free-roaming deer populations. Highest densities of nymphs (15.68 per 100 m) and infected nymphs (1.22 per 100 m) were associated with woodland and under canopy habitats in Richmond Park, but ticks infected with Borrelia were found across all habitat types surveyed. Nymphs infected with Borrelia (7.9%) were only reported from Richmond Park, where Borrelia burgdorferi sensu stricto and Borrelia afzelii were identified as the dominant genospecies. Areas with short grass appeared to be less suitable for ticks and maintaining short grass in high footfall areas could be a good strategy for reducing the risk of Lyme borreliosis transmission to humans in such settings. In areas where this would create conflict with existing practices which aim to improve and/or meet historic landscape, biodiversity and public access goals, promoting public health awareness of tick-borne disease risks could also be utilised.
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http://dx.doi.org/10.1007/s10493-021-00633-3DOI Listing
July 2021

Assessing the suitability for Aedes albopictus and dengue transmission risk in China with a delay differential equation model.

PLoS Negl Trop Dis 2021 03 26;15(3):e0009153. Epub 2021 Mar 26.

State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, WHO Collaborating Centre for Vector Surveillance and Management, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.

Dengue is considered non-endemic to mainland China. However, travellers frequently import the virus from overseas and local mosquito species can then spread the disease in the population. As a consequence, mainland China still experiences large dengue outbreaks. Temperature plays a key role in these outbreaks: it affects the development and survival of the vector and the replication rate of the virus. To better understand its implication in the transmission risk of dengue, we developed a delay differential equation model that explicitly simulates temperature-dependent development periods and tested it with collected field data for the Asian tiger mosquito, Aedes albopictus. The model predicts mosquito occurrence locations with a high accuracy (Cohen's κ of 0.78) and realistically replicates mosquito population dynamics. Analysing the infection dynamics during the 2014 dengue outbreak that occurred in Guangzhou showed that the outbreak could have lasted for another four weeks if mosquito control interventions had not been undertaken. Finally, we analyse the dengue transmission risk in mainland China. We find that southern China, including Guangzhou, can have more than seven months of dengue transmission per year while even Beijing, in the temperate north, can have dengue transmission during hot summer months. The results demonstrate the importance of using detailed vector and infection ecology, especially when vector-borne disease transmission risk is modelled over a broad range of climatic zones.
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http://dx.doi.org/10.1371/journal.pntd.0009153DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7996998PMC
March 2021

Rodent Ectoparasites in the Middle East: A Systematic Review and Meta-Analysis.

Pathogens 2021 Jan 31;10(2). Epub 2021 Jan 31.

School of Life Sciences, College of Agriculture, Engineering & Science, University of KwaZulu Natal, Durban 40000, South Africa.

Rodents carry many ectoparasites, such as ticks, lice, fleas, and mites, which have potential public health importance. Middle Eastern countries are hotspots for many emerging and re-emerging infectious diseases, such as plague, leishmaniasis, Crimean Congo hemorrhagic fever, and Q fever, due to their ecological, socioeconomic, and political diversity. Rodent ectoparasites can act as vectors for many of these pathogens. Knowledge of rodent ectoparasites is of prime importance in controlling rodent ectoparasite-borne zoonotic diseases in this region. The current systematic review and meta-analysis performs a comprehensive synthesis of the available knowledge, providing an evidence-based overview of the ectoparasites detected on rodents in Middle Eastern countries. Following a systematic search in Pubmed, Scopus, and Web of Science, a total of 113 published articles on rodent ectoparasites were studied and analyzed. A total of 87 rodent species were documented, from which , , and were found to be the most common. Fleas were the most reported ectoparasites (87 articles), followed by mites (53), ticks (44), and lice (25). , , , and were the most commonly described fleas, lice, mites, and ticks, respectively. Based on the reviewed articles, the median flea, louse, mite, and tick indices were highest in Israel (4.15), Egypt (1.39), Egypt (1.27), and Saudi Arabia (1.17), respectively. Quantitative meta-analysis, using a random-effects model, determined the overall pooled flea prevalence in the Middle East as 40% (95% CI: 25-55, = 100%, < 0.00001), ranging between 13% (95% CI: 0-30, = 95%, < 0.00001) in Iran and 59% (95% CI: 42-77, = 75%, < 0.00001) in Israel. The overall pooled louse prevalence was found to be 30% (95% CI: 13-47, = 100%, < 0.00001), ranging between 25% in Iran (95% CI: 1-50, = 99%) and 38% in Egypt (95% CI: 7-68, = 100%). In the case of mites, the pooled prevalence in this region was 33% (95% CI: 11-55, = 100%, < 0.00001), where the country-specific prevalence estimates were 30% in Iran (95% CI: 4-56, = 99%) and 32% in Egypt (95% CI: 0-76, = 100%). For ticks, the overall prevalence was found to be 25% (95% CI: 2-47, = 100%, < 0.00001), ranging from 16% in Iran (95% CI: 7-25, = 74%) to 42% in Egypt (95% CI: 1-85, = 100%). The control of rodent ectoparasites should be considered to reduce their adverse effects. Using the One Health strategy, rodent control, and precisely control of the most common rodent species, i.e., , , and , should be considered to control the rodent-borne ectoparasites in this region.
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http://dx.doi.org/10.3390/pathogens10020139DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7911898PMC
January 2021

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

Int J Environ Res Public Health 2020 10 29;17(21). Epub 2020 Oct 29.

Medical Entomology and Zoonoses Ecology, Emergency Response Department, Public Health England, Porton Down, Salisbury SP4 0JG, 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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http://dx.doi.org/10.3390/ijerph17217957DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7663673PMC
October 2020

Working towards a Co-Ordinated Approach to Invasive Mosquito Detection, Response and Control in the UK.

Int J Environ Res Public Health 2020 07 17;17(14). Epub 2020 Jul 17.

Medical Entomology and Zoonoses Ecology Group, Emergency Response Department Science and Technology, Public Health England, Porton Down, Salisbury, Wiltshire SP4 0JG, UK.

The United Kingdom (UK) has reported a single detection of the eggs of the invasive mosquito vector in each of the three years from 2016 to 2018, all in southeast England. Here, we report the detection of mosquito eggs on three occasions at two sites in London and southeast England in September 2019. Mosquito traps were deployed at 56 sites, in England, Scotland, Wales, and Northern Ireland, as part of a coordinated surveillance programme with local authorities, Edge Hill University, and government departments. Response to each detection was coordinated by Public Health England's (PHE) local health protection teams, with technical support from PHE's Medical Entomology group, and control conducted by the respective local authority. Control, including source reduction and larviciding, was conducted within a 300 metre radius of the positive site. The response followed a . Although the response to these incidents was rapid and well co-ordinated, recommendations are made to further develop mosquito surveillance and control capability for the UK.
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http://dx.doi.org/10.3390/ijerph17145166DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7400339PMC
July 2020

Detection of Exotic Mosquito Species (Diptera: Culicidae) at International Airports in Europe.

Int J Environ Res Public Health 2020 05 15;17(10). Epub 2020 May 15.

Centre for Monitoring of Vectors, Netherlands Food and Consumer Product Safety Authority, Geertjesweg 15, 6706 EA Wageningen, The Netherlands.

In Europe, the air-borne accidental introduction of exotic mosquito species (EMS) has been demonstrated using mosquito surveillance schemes at Schiphol International Airport (Amsterdam, The Netherlands). Based upon these findings and given the increasing volume of air transport movements per year, the establishment of EMS after introduction via aircraft is being considered a potential risk. Here we present the airport surveillance results performed by the Centre for Monitoring of Vectors of the Netherlands, by the Monitoring of Exotic Mosquitoes (MEMO) project in Belgium, and by the Public Health England project on invasive mosquito surveillance. The findings of our study demonstrate the aircraft mediated transport of EMS into Europe from a wide range of possible areas in the world. Results show accidental introductions of and , as well as exotic and specimens. The findings of at Schiphol airport are the first evidence of accidental introduction of the species using this pathway in Europe. Furthermore, our results stress the importance of the use of molecular tools to validate the morphology-based species identifications. We recommend monitoring of EMS at airports with special attention to locations with a high movement of cargo and passengers.
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http://dx.doi.org/10.3390/ijerph17103450DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7277938PMC
May 2020

Study of general practitioner consultations for tick bites at high, medium and low incidence areas for Lyme borreliosis in England and Wales.

Zoonoses Public Health 2020 08 11;67(5):591-599. Epub 2020 Mar 11.

Medical Entomology and Zoonoses Ecology, Emergency Response Department, Public Health England, Salisbury, UK.

Lyme borreliosis (LB) is a tick-borne disease caused by Borrelia burgdorferi sensu lato complex. In Europe, it is predominately transmitted by the sheep tick, Ixodes ricinus. Compared with other European countries, the United Kingdom (UK) is considered to have a low incidence of LB, although this varies regionally. To determine whether an association exists between tick bite consultations and LB incidence in the UK, retrospective questionnaires were sent to general practitioners (GPs) in high (Wiltshire), medium (Cumbria) and low (Wales) incidence areas. During 2011, the greatest incidence of consultations for tick bites was reported by GPs in Cumbria (204 consultations per 100,000 inhabitants), followed by Wiltshire (160 per 100,000 population) and Wales (54 per 100,000 population). In Wiltshire and Cumbria, GPs predominantly provided advice on tick removal, whilst Welsh GPs mostly advised patients on tick bite prevention. Focusing on Cumbria during 2011-2013, 72.5% of GPs removed ticks from patients (incidence of 101 consultations per 100,000 population), and more GPs diagnosed LB based on clinical features than laboratory-confirmed diagnoses. To date, this is the first study to investigate the incidence of tick bite consultations and LB in England and Wales.
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http://dx.doi.org/10.1111/zph.12694DOI Listing
August 2020

Ticks on the Channel Islands and implications for public health.

Ticks Tick Borne Dis 2020 05 4;11(3):101405. Epub 2020 Feb 4.

Medical Entomology and Zoonoses Ecology, Emergency Response Department, Public Health England, Porton Down, Salisbury, SP4 0JG, UK; NIHR Health Protection Research Unit in Environmental Change and Health, UK; NIHR Health Protection Research Unit in Emerging and Zoonotic Infections, UK.

The Channel Islands are British Crown dependencies located in the English Channel to the west of the Normandy coast in northern France. Whilst there have been studies investigating tick occurrence and distribution in different habitats on the mainland of the UK and in France, the Channel Islands have been relatively understudied. As such, little is known about whether the sheep tick, Ixodes ricinus, is present, and whether there is a potential risk of Lyme borreliosis on the Channel Islands. To ascertain the presence of I. ricinus on the three largest islands in the archipelago: Jersey, Guernsey and Alderney, surveys of ticks questing in the vegetation and ticks feeding on hosts were undertaken during April and May 2016. Across all three islands, the highest numbers of ticks were found in woodland habitats. Ixodes ricinus was the predominant questing tick species found on Jersey, and Ixodes ventalloi the most common questing tick species on Alderney and Guernsey, with little or no evidence of questing I. ricinus on either island. During field studies on small mammals, I. ricinus was the predominant tick species feeding on Jersey bank voles (Myodes glareolus caesarius), with Ixodes hexagonus the most common species infesting hedgehogs on Guernsey. We propose that the greater diversity of small mammals on Jersey may be important in supporting immature stages of I. ricinus, in contrast to Guernsey and Alderney. Morphological identification of tick species was confirmed by PCR sequencing based on amplification of the cytochrome c oxidase subunit one (cox1) gene (COI DNA barcoding). To date, there have been few records of human tick bites in the Channel Islands, suggesting that the current risk from tick-borne disease may be low, but continued reporting of any human tick bites, along with reporting of cases of Lyme borreliosis will be important for continued assessment of the impact of tick-borne diseases in the Channel Islands.
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http://dx.doi.org/10.1016/j.ttbdis.2020.101405DOI Listing
May 2020

Equine infectious disease surveillance: surveillance concepts and international outbreak reporting systems.

Vet Rec 2019 11;185(21):651-653

Medical Entomology and Zoonoses Group, Public Health England, Salisbury, UK.

of the Animal Health Trust takes a look at equine infectious disease surveillance and the sources of information available.
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http://dx.doi.org/10.1136/vr.l6735DOI Listing
November 2019

Detection of new endemic focus of tick-borne encephalitis virus (TBEV), Hampshire/Dorset border, England, September 2019.

Euro Surveill 2019 Nov;24(47)

Virology and Pathogenesis Group, National Infection Service, Public Health England, Porton Down, United Kingdom.

The presence of tick-borne encephalitis virus (TBEV) was detected in a questing tick pool in southern England in September 2019. Hitherto, TBEV had only been detected in a limited area in eastern England. This southern English viral genome sequence is distinct from TBEV-UK, being most similar to TBEV-NL. The new location of TBEV presence highlights that the diagnosis of tick-borne encephalitis should be considered in encephalitic patients in areas of the United Kingdom outside eastern England.
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http://dx.doi.org/10.2807/1560-7917.ES.2019.24.47.1900658DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6885748PMC
November 2019

A probable case of tick-borne encephalitis (TBE) acquired in England, July 2019.

Euro Surveill 2019 Nov;24(47)

Immunization Unit, Robert Koch Institute, Berlin, Germany.

The United Kingdom (UK) has thus far been considered to be free from tick-borne encephalitis (TBE), yet in July 2019, a German infant developed serologically diagnosed TBE following a tick bite in southern England. This first report of a probable human case together with recent findings of TBE virus in ticks in foci in England suggest that TBE may be acquired in parts of England and should be considered in patients with aetiologically-unexplained neurological manifestations.
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http://dx.doi.org/10.2807/1560-7917.ES.2019.24.47.1900679DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6885749PMC
November 2019

Using imperfect data in predictive mapping of vectors: a regional example of Ixodes ricinus distribution.

Parasit Vectors 2019 Nov 14;12(1):536. Epub 2019 Nov 14.

Department of Veterinary and Animal Science, Northern Faculty Scotland's Rural College, An Lòchran, 10 Inverness Campus, Inverness, IV2 5NA, UK.

Background: Knowledge of Ixodes ricinus tick distribution is critical for surveillance and risk management of transmissible tick-borne diseases such as Lyme borreliosis. However, as the ecology of I. ricinus is complex, and robust long-term geographically extensive distribution tick data are limited, mapping often relies on datasets collected for other purposes. We compared the modelled distributions derived from three datasets with information on I. ricinus distribution (quantitative I. ricinus count data from scientific surveys; I. ricinus presence-only data from public submissions; and a combined I. ricinus dataset from multiple sources) to assess which could be reliably used to inform Public Health strategy. The outputs also illustrate the strengths and limitations of these three types of data, which are commonly used in mapping tick distributions.

Methods: Using the Integrated Nested Laplace algorithm we predicted I. ricinus abundance and presence-absence in Scotland and tested the robustness of the predictions, accounting for errors and uncertainty.

Results: All models fitted the data well and the covariate predictors for I. ricinus distribution, i.e. deer presence, temperature, habitat, index of vegetation, were as expected. Differences in the spatial trend of I. ricinus distribution were evident between the three predictive maps. Uncertainties in the spatial models resulted from inherent characteristics of the datasets, particularly the number of data points, and coverage over the covariate range used in making the predictions.

Conclusions: Quantitative I. ricinus data from scientific surveys are usually considered to be gold standard data and we recommend their use where high data coverage can be achieved. However in this study their value was limited by poor data coverage. Combined datasets with I. ricinus distribution data from multiple sources are valuable in addressing issues of low coverage and this dataset produced the most appropriate map for national scale decision-making in Scotland. When mapping vector distributions for public-health decision making, model uncertainties and limitations of extrapolation need to be considered; these are often not included in published vector distribution maps. Further development of tools to better assess uncertainties in the models and predictions are necessary to allow more informed interpretation of distribution maps.
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http://dx.doi.org/10.1186/s13071-019-3784-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6857280PMC
November 2019

Seasonality and anatomical location of human tick bites in the United Kingdom.

Zoonoses Public Health 2020 03 8;67(2):112-121. Epub 2019 Nov 8.

Medical Entomology and Zoonoses Ecology Group, Emergency Response Department, Public Health England, Salisbury, UK.

Tick bites on humans can occur in a variety of habitats and may result in the transmission of tick-borne pathogens, such as the causative agent of Lyme borreliosis (LB), Borrelia burgdorferi sensu lato. As the risk of transmission of this pathogen to the host increases with the duration of tick feeding, the recognition and removal of ticks as soon as possible following attachment is important for reducing the risk of infection. Performing a thorough body examination for ticks following potential exposure is recommended by tick awareness campaigns. Knowledge of where on the body feeding ticks are frequently found, and at which times of year peak tick exposure occurs, provides important information for public health messaging and may aid those bitten by ticks to engage more effectively with tick-checking behaviour. This paper summarizes human tick bites in the United Kingdom (UK) during 2013-2018 reported to Public Health England's passive Tick Surveillance Scheme and further examines the anatomical location and seasonality of bites from the most commonly encountered tick and LB vector Ixodes ricinus. A total of 1,328 tick records from humans were received of which 93% were I. ricinus. Humans were most commonly bitten by I. ricinus nymphs (70% bites). Tick bites were recorded on all parts of the body, but there were significant differences in their anatomical location on adults and children. Most tick bites on adults occurred on the legs (50%), whereas on children tick bites were mostly on the head and neck (43%). Bites from I. ricinus were recorded throughout the year but were most numerous during May to August. This study adds to the body of research on the seasonality and anatomical location of human tick bites in temperate Europe and highlights the importance of data collected through passive surveillance in addition to research and epidemiological studies.
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http://dx.doi.org/10.1111/zph.12659DOI Listing
March 2020

Tick-Borne Encephalitis Virus, United Kingdom.

Emerg Infect Dis 2020 01 17;26(1):90-96. Epub 2020 Jan 17.

During February 2018-January 2019, we conducted large-scale surveillance for the presence and prevalence of tick-borne encephalitis virus (TBEV) and louping ill virus (LIV) in sentinel animals and ticks in the United Kingdom. Serum was collected from 1,309 deer culled across England and Scotland. Overall, 4% of samples were ELISA-positive for the TBEV serocomplex. A focus in the Thetford Forest area had the highest proportion (47.7%) of seropositive samples. Ticks collected from culled deer within seropositive regions were tested for viral RNA; 5 of 2,041 ticks tested positive by LIV/TBEV real-time reverse transcription PCR, all from within the Thetford Forest area. From 1 tick, we identified a full-length genomic sequence of TBEV. Thus, using deer as sentinels revealed a potential TBEV focus in the United Kingdom. This detection of TBEV genomic sequence in UK ticks has important public health implications, especially for undiagnosed encephalitis.
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http://dx.doi.org/10.3201/eid2601.191085DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6924911PMC
January 2020

West Nile fever in Europe in 2018: an emerging problem or just an anomaly?

Vet Rec 2019 09;185(12):365-368

Medical Entomology and Zoonoses Group, Public Health England, Salisbury, UK.

Last summer saw an unusually high number of cases of West Nile fever in horses and people in south and south-east Europe, but it is too early to tell if this was a one-off increase or a sign of things to come. Here, , , and discuss the various West Nile fever surveillance and control mechanisms in place in the UK.
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http://dx.doi.org/10.1136/vr.l5748DOI Listing
September 2019

Field testing of a lightweight, inexpensive, and customisable 3D-printed mosquito light trap in the UK.

Sci Rep 2019 08 6;9(1):11412. Epub 2019 Aug 6.

London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, United Kingdom.

Mosquito surveillance is a fundamental component of planning and evaluating vector control programmes. However, logistical and cost barriers can hinder the implementation of surveillance, particularly in vector-borne disease-endemic areas and in outbreak scenarios in remote areas where the need is often most urgent. The increasing availability and reduced cost of 3D printing technology offers an innovative approach to overcoming these challenges. In this study, we assessed the field performance of a novel, lightweight 3D-printed mosquito light trap baited with carbon dioxide (CO) in comparison with two gold-standard traps, the Centers for Disease Control and Prevention (CDC) light trap baited with CO, and the BG Sentinel 2 trap with BG-Lure and CO. Traps were run for 12 nights in a Latin square design at Rainham Marshes, Essex, UK in September 2018. The 3D-printed trap showed equivalent catch rates to the two commercially available traps. The 3D-printed trap designs are distributed free of charge in this article with the aim of assisting entomological field studies across the world.
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http://dx.doi.org/10.1038/s41598-019-47511-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6684613PMC
August 2019

Disease and ticks on horses.

Vet Rec 2019 05;184(19):592

The Barn Equine Surgery, Ringwood Road, Three Legged Cross, Wimborne, Dorset BH21 6RE.

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http://dx.doi.org/10.1136/vr.l2056DOI Listing
May 2019

Hyalomma rufipes on an untraveled horse: Is this the first evidence of Hyalomma nymphs successfully moulting in the United Kingdom?

Ticks Tick Borne Dis 2019 04 9;10(3):704-708. Epub 2019 Mar 9.

Medical Entomology and Zoonoses Ecology Group, Emergency Response Department, Public Health England, Porton Down, Salisbury, SP4 0JG, UK; NIHR Health Protection Research Unit in Environmental Change and Health, UK; Virology & Pathogenesis, National Infection Service, Public Health England, Porton Down, Salisbury, SP4 0JG, UK.

During September 2018, a tick was submitted to Public Health England's Tick Surveillance Scheme for identification. The tick was sent from a veterinarian who removed it from a horse in Dorset, England, with no history of overseas travel. The tick was identified as a male Hyalomma rufipes using morphological and molecular methods and then tested for a range of tick-borne pathogens including; Alkhurma virus, Anaplasma, Babesia, Bhanja virus, Crimean-Congo Haemorrhagic fever virus, Rickettsia and Theileria. The tick tested positive for Rickettsia aeschlimannii, a spotted fever group rickettsia linked to a number of human cases in Africa and Europe. This is the first time H. rufipes has been reported in the United Kingdom (UK), and the lack of travel by the horse (or any in-contact horses) suggests that this could also be the first evidence of successful moulting of a Hyalomma nymph in the UK. It is postulated that the tick was imported into the UK on a migratory bird as an engorged nymph which was able to complete its moult to the adult stage and find a host. This highlights that passive tick surveillance remains an important method for the detection of unusual species that may present a threat to public health in the UK. Horses are important hosts of Hyalomma sp. adults in their native range, therefore, further surveillance studies should be conducted to check horses for ticks in the months following spring bird migration; when imported nymphs may have had time to drop off their avian host and moult to adults. The potential human and animal health risks of such events occurring more regularly are discussed.
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http://dx.doi.org/10.1016/j.ttbdis.2019.03.003DOI Listing
April 2019

Assessment of the Public Health Threats Posed by Vector-Borne Disease in the United Kingdom (UK).

Int J Environ Res Public Health 2018 09 29;15(10). Epub 2018 Sep 29.

Medical Entomology Group, Public Health England, Emergency Response Department, Porton Down, Salisbury, Wiltshire SP4 0JG, UK.

In recent years, the known distribution of vector-borne diseases in Europe has changed, with much new information also available now on the status of vectors in the United Kingdom (UK). For example, in 2016, the UK reported their first detection of the non-native mosquito , which is a known vector for dengue and chikungunya virus. In 2010, , a principal mosquito vector for West Nile virus was detected in large numbers in the Thames estuary. For tick-borne diseases, data on the changing distribution of the Lyme borreliosis tick vector, , has recently been published, at a time when there has been an increase in the numbers of reported human cases of Lyme disease. This paper brings together the latest surveillance data and pertinent research on vector-borne disease in the UK, and its relevance to public health. It highlights the need for continued vector surveillance systems to monitor our native mosquito and tick fauna, as well as the need to expand surveillance for invasive species. It illustrates the importance of maintaining surveillance capacity that is sufficient to ensure accurate and timely disease risk assessment to help mitigate the UK's changing emerging infectious disease risks, especially in a time of climatic and environmental change and increasing global connectivity.
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http://dx.doi.org/10.3390/ijerph15102145DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6210260PMC
September 2018

Multi-locus sequence typing of Ixodes ricinus and its symbiont Candidatus Midichloria mitochondrii across Europe reveals evidence of local co-cladogenesis in Scotland.

Ticks Tick Borne Dis 2019 01 31;10(1):52-62. Epub 2018 Aug 31.

Institute of Infection & Global Health, University of Liverpool, 146 Brownlow Hill, Liverpool L3 5RF, UK. Electronic address:

Ticks have relatively complex microbiomes, but only a small proportion of the bacterial symbionts recorded from ticks are vertically transmitted. Moreover, co-cladogenesis between ticks and their symbionts, indicating an intimate relationship over evolutionary history driven by a mutualistic association, is the exception rather than the rule. One of the most widespread tick symbionts is Candidatus Midichloria, which has been detected in all of the major tick genera of medical and veterinary importance. In some species of Ixodes, such as the sheep tick Ixodes ricinus (infected with Candidatus Midichloria mitochondrii), the symbiont is fixed in wild adult female ticks, suggesting an obligate mutualism. However, almost no information is available on genetic variation in Candidatus M. mitochondrii or possible co-cladogenesis with its host across its geographic range. Here, we report the first survey of Candidatus M. mitochondrii in I. ricinus in Great Britain and a multi-locus sequence typing (MLST) analysis of tick and symbiont between British ticks and those collected in continental Europe. We show that while the prevalence of the symbiont in nymphs collected in England is similar to that reported from the continent, a higher prevalence in nymphs and adult males is apparent in Wales. In general, Candidatus M. mitochondrii exhibits very low levels of sequence diversity, although a consistent signal of host-symbiont coevolution was apparent in Scotland. Moreover, the tick MLST scheme revealed that Scottish specimens form a clade that is partially separated from other British ticks, with almost no contribution of continental sequence types in this north-westerly border of the tick's natural range. The low diversity of Candidatus M. mitochondrii, in contrast with previously reported high rates of polymorphism in I. ricinus mitogenomes, suggests that the symbiont may have swept across Europe recently via a horizontal, rather than vertical, transmission route.
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http://dx.doi.org/10.1016/j.ttbdis.2018.08.016DOI Listing
January 2019

The importance of wildlife in the ecology and epidemiology of the TBE virus in Sweden: incidence of human TBE correlates with abundance of deer and hares.

Parasit Vectors 2018 Aug 29;11(1):477. Epub 2018 Aug 29.

Swedish Meteorological and Hydrological Institute (SMHI), Gothenburg, Sweden.

Background: Tick-borne encephalitis (TBE) is one tick-transmitted disease where the human incidence has increased in some European regions during the last two decades. We aim to find the most important factors causing the increasing incidence of human TBE in Sweden. Based on a review of published data we presume that certain temperature-related variables and the population densities of transmission hosts, i.e. small mammals, and of primary tick maintenance hosts, i.e. cervids and lagomorphs, of the TBE virus vector Ixodes ricinus, are among the potentially most important factors affecting the TBE incidence. Therefore, we compare hunting data of the major tick maintenance hosts and two of their important predators, and four climatic variables with the annual numbers of human cases of neuroinvasive TBE. Data for six Swedish regions where human TBE incidence is high or has recently increased are examined by a time-series analysis. Results from the six regions are combined using a meta-analytical method.

Results: With a one-year time lag, the roe deer (Capreolus capreolus), red deer (Cervus elaphus), mountain hare (Lepus timidus) and European hare (Lepus europaeus) showed positive covariance; the Eurasian elk (moose, Alces alces) and fallow deer (Dama dama) negative covariance; whereas the wild boar (Sus scrofa), lynx (Lynx lynx), red fox (Vulpes vulpes) and the four climate parameters showed no significant covariance with TBE incidence. All game species combined showed positive covariance.

Conclusions: The epidemiology of TBE varies with time and geography and depends on numerous factors, i.a. climate, virus genotypes, and densities of vectors, tick maintenance hosts and transmission hosts. This study suggests that the increased availability of deer to I. ricinus over large areas of potential tick habitats in southern Sweden increased the density and range of I. ricinus and created new TBEV foci, which resulted in increased incidence of human TBE. New foci may be established by TBE virus-infected birds, or by birds or migrating mammals infested with TBEV-infected ticks. Generally, persistence of TBE virus foci appears to require presence of transmission-competent small mammals, especially mice (Apodemus spp.) or bank voles (Myodes glareolus).
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http://dx.doi.org/10.1186/s13071-018-3057-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6114827PMC
August 2018

Competence of mosquitoes native to the United Kingdom to support replication and transmission of Rift Valley fever virus.

Parasit Vectors 2018 05 18;11(1):308. Epub 2018 May 18.

School of Veterinary Medicine, University of Surrey, Guildford, UK.

Background: Rift Valley fever phlebovirus (RVFV) is a mosquito-borne arbovirus causing severe disease in humans and livestock. It is endemic in Africa and spread to the Arabian Peninsula in 2000 raising concerns it could emerge in Europe. The ability of temperate mosquitoes from the United Kingdom (UK) to support replication and transmission of RVFV is unknown.

Methods: In this study, two colonised lines of Culex pipiens, wild-caught Aedes detritus and Ae. rusticus from the UK were infected with pathogenic strains of RVFV to assess their vector competence. Mosquitoes were offered artificial blood-meals containing 10 or 10 plaque forming units (PFU)/ml RVFV, simulating natural peak viraemia in young ruminants, and maintained at 20 °C or 25 °C for up to 21 days. Bodies, legs and saliva were collected and tested for the presence of viral RNA and infectious virus to determine the infection, dissemination and transmission potential.

Results: Across temperatures, doses and strains the average infection, dissemination and transmission rates were: 35, 13 and 5% (n = 91) for Cx. pipiens (Caldbeck); 23, 14 and 5% (n = 138) for Cx. pipiens (Brookwood); 36, 28 and 7% (n = 118) for Ae. detritus. However, despite 35% (n = 20) being susceptible to infection, Ae. rusticus did not transmit RVFV. Survival of Aedes species was negatively affected by maintenance at 25 °C compared to the more representative peak average British summer temperature of 20 °C. Increased mortality was also observed with some species infected with 10 PFU/ml compared to 10 PFU/ml.

Conclusions: It can be concluded that temperate mosquito species present in the UK demonstrate a transmission potential for RVFV in the laboratory but, even at high temperatures, this occurred at low efficiency.
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http://dx.doi.org/10.1186/s13071-018-2884-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5960175PMC
May 2018

The Role of Culex pipiens L. (Diptera: Culicidae) in Virus Transmission in Europe.

Int J Environ Res Public Health 2018 02 23;15(2). Epub 2018 Feb 23.

Animal and Plant Health Agency, Woodham Lane, Addlestone, Surrey KT15 3NB, UK.

Over the past three decades, a range of mosquito-borne viruses that threaten public and veterinary health have emerged or re-emerged in Europe. Mosquito surveillance activities have highlighted the species complex as being critical for the maintenance of a number of these viruses. This species complex contains morphologically similar forms that exhibit variation in phenotypes that can influence the probability of virus transmission. Critical amongst these is the choice of host on which to feed, with different forms showing different feeding preferences. This influences the ability of the mosquito to vector viruses and facilitate transmission of viruses to humans and domestic animals. Biases towards blood-feeding on avian or mammalian hosts have been demonstrated for different ecoforms and emerging evidence of hybrid populations across Europe adds another level of complexity to virus transmission. A range of molecular methods based on DNA have been developed to enable discrimination between morphologically indistinguishable forms, although this remains an active area of research. This review provides a comprehensive overview of developments in the understanding of the ecology, behaviour and genetics of in Europe, and how this influences arbovirus transmission.
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http://dx.doi.org/10.3390/ijerph15020389DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5858458PMC
February 2018

Surveillance of British ticks: An overview of species records, host associations, and new records of Ixodes ricinus distribution.

Ticks Tick Borne Dis 2018 03 3;9(3):605-614. Epub 2018 Feb 3.

Medical Entomology & Zoonoses Ecology, Emergency Response Department Science & Technology, Public Health England, Porton Down, SP4 0JG, United Kingdom; Health Protection Research Unit in Environment and Health, Porton Down, Salisbury, UK; Health Protection Research Unit in Emerging and Zoonotic Infections, Porton Down, Salisbury, UK.

Public Health England's passive Tick Surveillance Scheme (TSS) records the distribution, seasonality and host associations of ticks submitted from across the United Kingdom (UK), and helps to inform the UK government on emerging tick-borne disease risks. Here we summarise data collected through surveillance during 2010-2016, and compare with previous TSS data from 2005 to 2009, particularly in relation to the primary Lyme borreliosis vector Ixodes ricinus. 4173 records were submitted, constituting >14,000 ticks; 97% were endemic tick records (13,833 ticks of 11 species), with an additional 97 records of imported ticks (438 ticks of 17 species). Tick submissions were mainly from veterinary professionals (n = 1954; 46.8%) and members of the public and amateur entomologists (n = 1600; 38.3%), as well as from academic institutions (n = 249; 6.0%), wildlife groups (n = 239; 5.7%) and health professionals (n = 131; 3.1%). The most commonly reported hosts of endemic ticks were dogs (n = 1593; 39.1% of all records), humans (n = 835; 20.5%) and cats (n = 569; 14%). New host associations were recorded for a number of tick species. Ixodes ricinus was the most frequently recorded endemic tick species (n = 2413; 59.2% of all records), followed by I. hexagonus (n = 1355; 33.2%), I. canisuga (n = 132; 3.2%) and I. frontalis (n = 56; 1.4%), with other species each making up <1% total records. 81% of I. ricinus recorded from humans were nymphs, whereas 93.4% of I. ricinus from companion animals were adults. Recent TSS records of I. ricinus in the UK add a considerable amount of new presence data for this species, particularly in the southern regions of England, and confirm that this species is widespread across the UK. The scheme remains a valuable method of collecting continuous national distribution data on ticks from a variety of host species.
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http://dx.doi.org/10.1016/j.ttbdis.2018.01.011DOI Listing
March 2018

Potential risk posed by the importation of ticks into the UK on animals: records from the Tick Surveillance Scheme.

Vet Rec 2018 01 7;182(4):107. Epub 2017 Dec 7.

Department of Medical Entomology & Zoonoses Ecology, Emergency Response Department - Science & Technology, Public Health England, Porton Down, UK.

In order to monitor important tick vectors in the UK, Public Health England's Tick Surveillance Scheme (TSS) receives specimens from across the country for identification. In recent years, an increasing number of these specimens have been removed from animals with a recent history of travel outside the UK. This paper presents all data collated by the TSS on ticks entering the country on recently travelled or imported animals since surveillance commenced in 2005. Ten different tick species representing six different genera were identified, entering the UK from 15 different countries. Key themes appear to be emerging from the last 10 years of data, including canine travel from Cyprus and Spain being associated with importation, and canine travel from France being associated with the importation of multiple tick species and canine illness. In addition, more unusual importation routes have been uncovered, such as the importation of on a dog. Some companion animal owners may not be fully aware of the risks associated with ticks, and may not seek advice from a veterinarian before travel or importing a pet. Promoting awareness of ticks and tickborne disease risk during and after travel or animal importation is needed and veterinarians play an importation role in disseminating this information to their clients.
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http://dx.doi.org/10.1136/vr.104263DOI Listing
January 2018

Surveillance of Ixodes ricinus ticks (Acari: Ixodidae) in Iceland.

Parasit Vectors 2017 Oct 10;10(1):466. Epub 2017 Oct 10.

Emergency Response Department, Medical Entomology Group, Public Health England, Porton Down, Salisbury, Wiltshire, UK.

Background: Ixodes ricinus is a three-host tick, a principal vector of Borrelia burgdorferi (s.l.) and one of the main vectors of tick-borne encephalitis (TBE) virus. Iceland is located in the North Atlantic Ocean with subpolar oceanic climate. During the past 3-4 decades, average temperature has increased, supporting more favourable conditions for ticks. Reports of I. ricinus have increased in recent years. If these ticks were able to establish in a changing climate, Iceland may face new threats posed by tick-borne diseases.

Methods: Active field surveillance by tick flagging was conducted at 111 sites around Iceland from August 2015 to September 2016. Longworth mammal traps were used to trap Apodemus sylvaticus in southwestern and southern Iceland. Surveillance on tick importation by migratory birds was conducted in southeastern Iceland, using bird nets and a Heligoland trap. Vulpes lagopus carcasses from all regions of the country were inspected for ticks. In addition, existing and new passive surveillance data from two institutes have been merged and are presented. Continental probability of presence models were produced. Boosted Regression Trees spatial modelling methods and its predictions were assessed against reported presence.

Results: By field sampling 26 questing I. ricinus ticks (7 males, 3 females and 16 nymphs) were collected from vegetation from three locations in southern and southeastern Iceland. Four ticks were found on migratory birds at their arrival in May 2016. A total of 52 A. sylvaticus were live-trapped but no ticks were found nor on 315 V. lagopus carcasses. Passive surveillance data collected since 1976, reports further 214 I. ricinus ticks from 202 records, with an increase of submissions in recent years. The continental probability of presence model correctly predicts approximately 75% of the recorded presences, but fails to predict a fairly specific category of recorded presence in areas where the records are probably opportunistic and not likely to lead to establishment.

Conclusions: To the best of our knowledge, this study represents the first finding of questing I. ricinus ticks in Iceland. The species could possibly be established locally in Iceland in low abundance, although no questing larvae have yet been detected to confirm established populations. Submitted tick records have increased recently, which may reflect an increase in exposure, or in interest in ticks. Furthermore, the amount of records on dogs, cats and humans indicate that ticks were acquired locally, presenting a local biting risk. Tick findings on migratory birds highlight a possible route of importation. Obtaining questing larvae is now a priority to confirm that I. ricinus populations are established in Iceland. Further surveys on wild mammals (e.g. Rangifer tarandus), livestock and migratory birds are recommended to better understand their role as potential hosts for I. ricinus.
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http://dx.doi.org/10.1186/s13071-017-2375-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5634879PMC
October 2017

How often do mosquitoes bite humans in southern England? A standardised summer trial at four sites reveals spatial, temporal and site-related variation in biting rates.

Parasit Vectors 2017 Sep 15;10(1):420. Epub 2017 Sep 15.

The Pirbright Institute, Ash Road, Woking, Surrey, UK.

Background: This field-based study examined the abundance and species complement of mosquitoes (Diptera: Culicidae) attracted to humans at four sites in the United Kingdom (UK). The study used a systematic approach to directly measure feeding by mosquitoes on humans at multiple sites and using multiple volunteers. Quantifying how frequently humans are bitten in the field by mosquitoes is a fundamental parameter in assessing arthropod-borne virus transmission.

Methods: Human landing catches were conducted using a standardised protocol by multiple volunteers at four rural sites between July and August 2013. Collections commenced two hours prior to sunset and lasted for a total of four hours. To reduce bias occurring due to collection point or to the individual attractiveness of the volunteer to mosquitoes, each collection was divided into eight collection periods, with volunteers rotated by randomised Latin square design between four sampling points per site. While the aim was to collect mosquitoes prior to feeding, the source of blood meals from any engorged specimens was also identified by DNA barcoding.

Results: Three of the four sites yielded human-biting mosquito populations for a total of 915 mosquitoes of fifteen species/species groups. Mosquito species composition and biting rates differed significantly between sites, with individual volunteers collecting between 0 and 89 mosquitoes (over 200 per hour) of up to six species per collection period. Coquillettidia richiardii (Ficalbi, 1889) was responsible for the highest recorded biting rates at any one site, reaching 161 bites per hour, whilst maximum biting rates of 55 bites per hour were recorded for Culex modestus (Ficalbi, 1889). Human-biting by Culex pipiens (L., 1758) form pipiens was also observed at two sites, but at much lower rates when compared to other species.

Conclusions: Several mosquito species are responsible for human nuisance biting pressure in southern England, although human exposure to biting may be largely limited to evening outdoor activities. This study indicates Cx. modestus can be a major human-biting species in the UK whilst Cx. pipiens f. pipiens may show greater opportunistic human-biting than indicated by earlier studies.
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http://dx.doi.org/10.1186/s13071-017-2360-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5602952PMC
September 2017

The mosquito in England.

Vet Rec 2017 09;181(9):243

Norfolk Museums Service, Shirehall, Market Avenue, Norwich NR1 3JQe-mail:

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http://dx.doi.org/10.1136/vr.j4048DOI Listing
September 2017

(Eckstein, 1918) (Diptera, Culicidae), a new country record for England, contrasted with (Meigen, 1838).

Zookeys 2017 27(671):119-130. Epub 2017 Apr 27.

Medical Entomology & Zoonoses Ecology group, Emergency Response Department, Public Health England, Porton Down, Salisbury, SP4 0JG, UK.

We report the discovery of (Eckstein, 1918) in the New Forest of southern England, bringing to 36 the number of mosquito species recorded in Britain. Because it seems that this species has been misidentified previously in Britain as the morphologically similar (Meigen, 1838), the two species are contrasted and distinguished based on distinctive differences exhibited in the adult and larval stages. The pupa of is unknown, but the pupa of is distinguished from the pupae of other species of by modification of the most recent key to British mosquitoes. The history of the mosquito fauna recorded in the UK is summarized and bionomical information is provided for the two species.
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http://dx.doi.org/10.3897/zookeys.671.12447DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5523212PMC
April 2017
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