Irish Daily Mail

At last! A jab to protect against Lyme disease

- By PAT HAGAN

FOR the past four years it has been possible to vaccinate dogs against Lyme disease, the infection caught from a contaminat­ed tick’s bite, but the same protection has not been available for humans.

However, scientists at the University of Massachuse­tts Medical School in Boston have now developed a jab that, during tests on mice, was 100 per cent effective — completely halting the transmissi­on of infection-causing bacteria from ticks into the bloodstrea­m. They plan to run human trials over the next two to three years.

Although labelled a ‘vaccine’, the new jab does not work like normal inoculatio­ns — which prime the immune system to recognise a virus or bacteria as foreign by exposing it to tiny amounts of the bug itself.

Instead, the Lyme disease jab — called Lyme PReP — actually contains a specific antibody (a type of protein) designed to target the harmful bacteria, Borrelia

burgdorfer­i, that causes the condition. As soon as an infected tick bites, the antibody — which floats around in the bloodstrea­m — detects the bacteria and binds to, and destroys, each bacterial cell.

But because the antibody itself only has a lifespan of six to nine months, the jab would be given annually before the high-risk summer months, when the chances of being bitten by ticks lurking in long grass are greatest. Dr Mark Klempner, an expert in infectious diseases, who helped to develop the jab, says mice were injected with the antibody and bitten by up to seven infected ticks each — a far higher exposure than humans would ever be likely to encounter.

None of the mice developed Lyme disease in the six-month trial. Dr Klempner says: ‘We think giving a person a comparable amount of antibody to the mice will provide protection during the tick season.’

It’s hoped the jab, costing around £150 (€170) each, could prevent many cases of Lyme disease in Britain, where official figures state that 3,000 people a year are infected. Some charities argue the real figure is nearer 15,000 as many people affected don’t seek medical help for the achy joints and flu-like symptoms it can cause. According to the HSE website, the number of Lyme disease cases in Ireland is between 50 and 100 every year. However, similar to Britain, this figure may actually be much higher because of limited screening nad misdiagnos­is.

Symptoms typically develop between two and 30 days after being bitten, usually starting with a bull’s-eye-shaped rash which signals the bacteria from the tick are spreading round the site of the bite. The bugs then pass through the bloodstrea­m, attacking the joints and nervous system, before spreading to the brain or heart.

While antibiotic­s can stop the spread of the bacteria, if left untreated, Lyme disease can cause severe damage by triggering a powerful attack by the immune system, which leads to harmful inflammati­on that damages the heart’s rhythm.

Dog owners have been able to get their pets immunised since 2013, but not themselves. Merilym 3, an annual jab costing around €78 and available to puppies from 12 weeks old, is thought to work in a similar way to the one being developed for people. But the dog jab has never been tested in humans and is not judged safe for human use. However, a human vaccine was approved by the US Food and Drug Administra­tion almost 20 years ago. Lymerix, developed by Smith Kline Beecham (now part of GSK), was on the market for four years before the company withdrew it voluntaril­y after a series of lawsuits (none of them successful) from patients alleging that it caused severe arthritis.

But interest in Lyme disease vaccines has been reignited thanks to a rise in European cases since 2011, believed to be caused by milder winters and damper summers.

Professor Hany Elsheikha, an expert on veterinary parasitolo­gy, warns it is too soon to say if the jab will work and even if it does, it may not be the best approach.

‘These are promising early results but we don’t know if it will have the same effect in humans,’ he says. ‘It would be more costeffect­ive and clinically effective to encourage people to protect against bites, with simple prevention measures that are much better than resorting to drugs.’ According to the HSE, these include long-sleeved shirts and tucking trousers into socks while walking in long grass or woods, checking pets’ fur and applying repellent on skin.

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