Louping Ill

Tick borne diseases are on the rise across Europe on the whole, but Louping Ill (LI) in particular is becoming a major cause for concern in the UK, and for the first time not just in Scotland.

Louping Ill (LI) is a viral disease associated with sheep tick (Ixodes Ricinus). The disease attacks the central nervous system of the host, leaving them with severe motor deficits and often leading to death.

The potentially catastrophic impact of LI on Grouse Moors has long been recognised, but many people have previously shied away from the problem, believing it to only affect isolated Highland Moors. Cases of LI have risen exponentially in the last twelve months across Scotland, but also as far south as the Peak District, with the negative effects already being felt. 

The reason for the rise in recent cases is largely believed to be a result of the sharp increase in tick numbers in what has been a prolific year for them, due to ideal weather conditions. 

As most will be aware, ticks are small arachnids which require blood meals to complete their life cycle. There are over 800 species worldwide, but it is ticks of the Ixodidae (‘Hard Ticks’) variety which cause the most issues in the UK.

They are ‘three-host ticks’ meaning they feed three times in their life cycle with an adult being able to ingest 5ml of blood in a meal – enough to cause significant issues to lambs and Grouse alike. The life cycle can last from two months to three years, and during that time female adults can lay several thousand eggs after blood meals.

They are effectively blind and detect their prey through heat and CO2. Once attached to a host, the tick will insert its hypostome (a long barbed mouth in effect) into the host and begin to feed. Tick saliva is spread to the host during the feeding process and contains anaesthetic, anticoagulants, immunosuppressive and anti-inflammatory substances. It is this saliva which infects the host with pathogens, spreading diseases such as LI. 

The consequences of widespread LI across the UK would be dire, with Grouse stocks being massively reduced. The disease is also a very real threat for Upland Sheep Farmers, with sheep being similarly impacted. 

The only way the threat of LI can be managed is through rigorous tick control, and there are three main avenues to this; Pasture/Habitat Management, animal treatments and management of grazing and wildlife.

Due to recent restrictions on the use of Asulam, widespread treatment of bracken beds is no longer possible, meaning that animal treatments and Grazing/Wildlife Management will be the key tactics in the near future. Based on this, we believe that the basis of any effective Tick Management Plan, is an effective and functional ‘Tick Mop’.

A ‘Tick Mop’ is a flock of sheep present on a Moor, which are treated on rotation with acaricides (crovect, dysect etc.) and actively shepherded to cover all corners of the Moor. The treated sheep will gather ticks as they roam the hill, which will succumb to the treatments on the sheep, thus reducing the number of ticks present.

It is crucial to have a flock of the correct size to properly cover and treat the Moor, and also to do as much as is possible to control ‘Tick Taxis’ – other hosts which spread ticks such as deer. 

Previously the industry had a stronger defence against ticks than just acaricides in the form of a vaccine which was administered to sheep. However, the previous vaccine was discontinued in 2017.

Since the discontinuation of the vaccine, it is anecdotally reported among Upland Farmers that there has been a 25-30% increase in LI cases in young sheep. Perhaps more reputably, the Moredun Institute has formally recorded an undeniable increase in the number of LI cases among Red Grouse since the reduction in the number of vaccinated sheep on UK Moors.

Given the evidence we are presented with, it is time for the whole industry to recognise the importance of proper Tick Management to combat LI and all that it brings.  

The only positive news in the midst of so much tick borne despair is that there is a new vaccine in the final stages of development, which is in the final stages of testing.

The stumbling block for the vaccine will be its economic viability with the mass production expected to cost in the region of £2,000,000. With any commercial funding unlikely due to the incredibly niche requirement we currently have in the UK for an LI vaccine, it may well be necessary for us to fund this as an industry. Therefore, we must all decide whether we will take Tick Management seriously, and if so what resources we will commit to it.