Tick Borne Encephalitis (TBE), a viral disease, has been reported in UK ticks for the first time and Public Health England (PHE) has updated its risk assessment. The risk of catching TBE is considered by PHE as Low to Very Low, even in ‘at risk’ groups like forestry workers, but LDA warns against complacency.
Like Lyme disease, the picture of tick-borne illness is always developing, as this recent news shows. It seems likely that TBE has arrived in ticks on imported pets or migrating birds. It has been found in ticks in two very small areas – one in Thetford Forest, Norfolk (where is is thought to be established) and the other on the Hampshire/Dorset border. The only confirmed human case so far is in a European visitor bitten by a tick in the New Forest and diagnosed when back home.
There are thousands of cases of LB every year in Britain and, because of a lot of work campaigning, raising awareness, and striving for research, GPs are now more aware of Lyme disease and should know how to treat it. While both diseases are contracted through the bite of an infected tick, and symptoms are in some ways similar, there are significant differences between TBE and Lyme Borreliosis (LB).
- TB is a viral illness, while LB is bacterial.
- There is an effective licensed vaccine for TBE but not for LB.
- TBE is transmitted by the tick in minutes, whereas transmission of LB usually takes several hours.
- While both are confirmed by serology (detection of antibodies in the blood), there is no diagnostic rash with TBE as there is with LB (the so-called ‘Bulls-eye’ or Erythema Migrans).
- TBE runs a bi-phasal course, beginning with mild ‘flu-like symptoms. There may then be a marked asymptomatic ‘lull’ in symptoms before it progresses to neurologic symptoms varying from mild meningitis to severe encephalitis, with or without myelitis, and spinal paralysis. These are potentially fatal effects.
- There is evidence that TBE can be acquired from unpasteurised milk and possibly transplacentally, or through blood and organ donation. There is no evidence for these modes of transmission for LB.
- There is no treatment for TBE, but LB is treated with antibiotics.
- Patients contracting either TBE or LB may take many months to recover.
Both these diseases can make you very unwell, so vigilance is key. Protection from ticks and prompt, correct, removal of any attached tick is essential and the use of tick repellents more important than ever.
How was all this discovered?
To assess whether TBE is present in the UK, blood samples were taken from culled deer because they are known to develop a long lasting antibody response to TBE. When antibody positive deer had been identified, ticks collected from carcasses culled within a 15Km radius of these were tested for TBE genetic material.
1323 deer serum samples were collected from across England and Scotland (none from Wakes). Norfolk had the highest seroprevalence (51.3%), followed by Hampshire (14.3%), Suffolk (10.7%), and Scottish Highlands (8.6%). The high level in Thetford Forest is thought to be indicative of the established presence of TBE in the local wildlife.
In the Netherlands, deer samples tested positive for TBE some 6 years before the first human case, so finding this data now is a useful warning.