Lyme disease cases in England jumped more than 20 per cent last year, with 1,168 laboratory-confirmed infections recorded in 2025, according to data published by the UK Health Security Agency (UKHSA). The figure represents a sharp increase from the 959 cases reported in 2024, though public health officials note the total is broadly comparable to 2023, when 1,151 cases were confirmed.
Dr Claire Gordon, head of the rare and imported pathogens laboratory at UKHSA, said the year-on-year rise should be viewed with caution. “While the number of laboratory-confirmed acute cases of Lyme disease in 2025 is an increase on numbers reported in 2024, we expect overall case rates to vary year to year depending on awareness, testing rates and factors that impact outdoor activities such as weather,” she said. “Broader trends in 2025 remain consistent.”
The true burden of Lyme disease is likely to be significantly higher. UKHSA cautions that many cases are treated clinically without laboratory confirmation, particularly among people who develop the characteristic bullseye rash. The charity Lyme Disease UK estimates that roughly 70 per cent of patients with the rash are treated immediately and never tested.
Alongside the Lyme data, two probable cases of tick-borne encephalitis (TBE) complex were identified in 2025, bringing the total number of locally acquired TBE cases to six since the virus was first detected in the UK in 2019. TBE is a viral infection spread by ticks; most infections cause mild flu-like illness, but rare cases can attack the central nervous system. The risk of contracting TBE in Britain is considered very low.
Causes and symptoms
Lyme disease is caused by the bacterium Borrelia burgdorferi, which lives in the gut of ticks — tiny, spider-like creatures found in grassy and wooded areas, as well as urban parks and gardens. Ticks feed on the blood of birds and mammals, including humans, and transmit the bacteria through their bite. The longer a tick remains attached, the greater the risk of infection. Not all ticks carry the bacteria, and prompt removal is thought to reduce the chance of transmission.
Dr Gordon said tick distribution across the UK has been expanding. “In recent years, we have seen an increasing geographical distribution of ticks across the UK,” she said. “But tick numbers continue to vary due to changes in weather conditions, climate trends, habitat changes and shifting host populations.” High-risk areas include southern England and the Scottish Highlands, and warmer winters mean tick bites are now being reported year-round. Tick activity typically rises in late spring, peaks in June, and acute Lyme cases peak in late summer.
Early symptoms of Lyme disease can include a spreading, circular rash that often resembles a bullseye, appearing three to 30 days after a bite — though up to one-third of infected individuals may not develop a rash at all. Flu-like symptoms such as fever, headache, muscle and joint pain, fatigue, chills and neck stiffness are also common. If left untreated, the condition can progress to more severe complications, including inflammatory arthritis, neurological problems such as numbness, facial paralysis and memory difficulties, heart palpitations, and, in rare cases, meningitis. Even among patients who receive antibiotics, some report persistent symptoms. The term “chronic Lyme disease” is sometimes used to describe these ongoing non-specific symptoms, though they can overlap with conditions such as fibromyalgia and chronic fatigue syndrome.
Current prevention advice for humans centres on avoiding tick bites: using insect repellents containing DEET, covering exposed skin, tucking trousers into socks, wearing light-coloured clothing to make ticks easier to spot, and staying on clear paths. Prompt removal of ticks using fine-tipped tweezers or a removal tool is vital. In contrast, pet owners have access to monthly oral tablets and vaccinations that protect dogs and cats from Lyme disease.
Linden Hu, a professor of immunology at Tufts medical school, said there were several reasons for the gap between veterinary and human approaches. “It’s easier to do studies in animals because you can control the situation. You can put infected ticks on them to test if it’s going to work, which you really can’t do with humans,” he explained. Real-world human field trials are expensive and risky because it is unclear how many cases of Lyme will occur during the study period.
Vaccine challenges and new treatments
A human Lyme vaccine has been tried before. LYMErix was authorised in the United States and showed 76 per cent efficacy after a third dose, but was withdrawn from the market in 2002 after sales collapsed. Professor Hu pointed to several factors behind the failure: the US Centers for Disease Control and Prevention recommended it only for people at high risk; there were unsubstantiated concerns that the vaccine might be linked to arthritis; and negative media coverage combined with a lack of public trust drove demand even lower.
Two new vaccine candidates are now in development, both designed to avoid activating the immune pathway that some researchers suspect may have caused the arthritis worries with LYMErix. Moderna is working on an mRNA-based Lyme vaccine that has reached phase 2 clinical trials — a jab Professor Hu has contributed to. Pfizer, in partnership with Valneva, has developed a vaccine called VLA15 that targets multiple strains of Borrelia found in Europe and North America. Its phase 3 trial encountered an unusual problem: there were fewer cases of Lyme disease among participants than expected, meaning that while the vaccine appeared to have an efficacy of more than 70 per cent, the results were not as statistically robust as hoped. Despite this, the vaccine is to be submitted to regulatory authorities. If approved, it could become available in the UK as early as 2027.
Several other approaches are being explored. Tonix Pharmaceuticals is developing a long-acting monoclonal antibody, TNX-4800, that targets the Borrelia bacteria and could provide seasonal prevention before exposure; it is advancing toward phase 2/3 trials. A different strategy comes from Tarsus Pharmaceuticals with a drug called lotilaner, already used to protect dogs and cats. Unlike vaccines, lotilaner kills ticks rather than the bacteria they carry, working rapidly enough to prevent transmission of Lyme and potentially other tick-borne diseases. Professor Hu is also involved in that work.
Additional research includes a promising antibiotic called hygromycin A, which cleared Lyme infections in mice and is now entering human trials; combination therapy regimens using existing drugs such as dapsone and disulfiram for chronic symptoms; and a mouse vaccine designed to reduce tick infection rates in the wild.
Julia Knight, of the charity Lyme Disease UK, questioned whether a human Lyme vaccine would be widely adopted in Britain given the official case numbers — which are likely a significant underestimate because of unreported rashes and misdiagnoses. “Obviously any advances in science that prevents Lyme disease is always welcome, but whether people will welcome a vaccine or not in the current climate of vaccine hesitancy remains to be seen,” she said.