https://www.ncbi.nlm.nih.gov/pubmed/30876825

2019 Apr;10(3):704-708. doi: 10.1016/j.ttbdis.2019.03.003. Epub 2019 Mar 9.

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

Abstract

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
  • 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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A ProMED-mail post

A tick capable of carrying a host of killer illnesses has been found in the UK for the very 1st time, health officials have revealed.

The _Hyalomma rufipes_ tick – a small blood-sucking arachnid – is usually confined to Africa, Asia and parts of southern Europe. But Public Health England [PHE] has now revealed one of the ticks, 10 times larger than others, was discovered in Dorset last year [2018]. The creature itself wasn’t found to be carrying the deadly Crimean-Congo Haemorrhagic fever virus (CCHF).

The disturbing find, which could ‘present a threat to public health in the UK’, has been documented in the journal Ticks and Tick-borne Diseases.

A vet at The Barn Equine Surgery in Wimborne removed the tick from a horse last September [2018]. They then sent it to PHE’s tick surveillance team. Writing in the journal, the PHE team said: ‘This is the first time _Hyalomma rufipes_ has been reported in the United Kingdom. ‘The lack of travel by the horse – or any in-contact horses – suggests that this could also be the 1st evidence of successful moulting of a _Hyalomma_ nymph in the UK.’

The team of researchers who found the tick was led by Kayleigh Hansford, of PHE’s medical entomology and zoonoses ecology group.

Writing in the journal, they said it is suspected the tick hitched a ride on a migratory bird before landing in the UK. Neither the infested horse, nor other horses in the stable had travelled anywhere and no further ticks were detected on any of the horses. It is thought the tick travelled on a swallow because they are known to nest in the stables of horses and migrate from Africa to the UK for summer.

The UK climate, known to be getting warmer, is thought to be a major limiting factor for the survival of _Hyalomma rufipes_. However, the unusually warm weather experienced during the summer of 2018 may have been a factor for helping it moult – become an adult.

Currently, the ticks are found in Greece, Northern China, Russia, Turkey, Iraq, Syria, Pakistan, Egypt, Yemen and Oman.

The World Health Organization last year [2018] named CCHF as one of 10 pathogens that pose the most ‘urgent’ threat to humanity.

Figures show the virus – most often spread through tick bites – kills around 40% of humans that it strikes. The horrific illness is said to manifest ‘abruptly’, with initial symptoms including fever, backache, headache, dizziness and sore eyes.

[Byline: Stephen Matthews]


Communicated by:
ProMED-mail Rapporteur Mary Marshall

[Not mentioned in detail in the above report, the PHE team, using morphological and molecular methods, 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.

The critical question is if this is a single tick transported into Dorset, or represents one tick of a local breeding population. Transportation of a single tick by a migrating bird is a reasonable possibility. Immature (nymph) _Hyalomma_ usually feed on birds, rodents, and hares. Nymphs are often transported from one place to another by migrating birds. For example, a migrating bird carrying a CCH virus-infected _Hyalomma marginatum_ nymph can introduce the virus into new localities and infect humans and domestic livestock (Larry S.Roberts, 2009). Continued surveillance in the area where the single tick was found, as well as generally in the UK over the spring and summer months, would be prudent.