New look at vaccine to combat Lyme disease in France

Continuing research has published promising results in ‘antibody vaccine’ method

Walking in forested areas increases the risk of getting bitten by a tick

France could be one step closer to a vaccine against Lyme disease after researchers published promising new results from a national development programme.

Lyme disease is spread by infected ticks, and there were around 83 new cases per 100,000 people for the years 2017-2019, a sharp rise in comparison to the period 2010-2012 (42.3 per 100,000).

The condition can cause debilitating symptoms, including muscle pain, headaches, nausea, and vomiting. Without treatment, it can also cause neurological issues. Early diagnosis is key, but this can be difficult because the symptoms often appear similar to those caused by other conditions.

A 'bullseye' rash after a tick bite with Lyme disease

Around 10-20% of ticks in France are estimated to carry Lyme. A tick bite with Lyme often forms a ‘bullseye’ ring around the bite, with a red centre, white ring, and red rash outline.

In the past seven years, more than 72,000 tick bites have been reported in France. No vaccination against the disease exists yet.

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Researchers have long been considering a way to limit the risk of infection, even if the person is bitten by an infected tick. This has included looking at ways to imbue blood with antibodies against the disease.

This route is considered to be more realistic than attempts to slow the spread of the ticks themselves.

Researchers at public food and environmental research institute INRAE, in collaboration with human and animal food agency Anses, and the École Nationale Vétérinaire d'Alfort, are working together in a bid to develop a vaccine targeting the tick’s ‘microbiota’ (the bacteria in the tick).

Read also: Lyme disease: Researchers work on a vaccine to reduce danger of ticks

An early paper, published in the scientific journal Microbiome, explored the researchers’ unusual approach, which focuses on ‘indirect’ vaccination. This introduces antibodies into the patient’s blood that are designed to neutralise the bacteria responsible for Lyme disease.

This is called ‘indirect’ vaccination, because - in contrast to most other vaccines - the injection would not introduce a weakened or inactivated form of the targeted disease.

“This vaccine induces a change in the tick's microbiota, i.e. the bacteria present in its intestine,” said Professor Alejandro Cabezas-Cruz, an INRAE researcher who led the study, to Le Figaro. “In this way, the vaccinated host is protected from the pathogen by modulating the tick's microbiota.”

The vaccine contains a harmless strain of E. coli bacteria, which, when injected into the bloodstream, stimulates the production of protective antibodies. Then, when a tick bites a vaccinated human, they ingest a small quantity of antibodies in their blood. This changes the tick’s own bacteria, which blocks the development of the Lyme bacteria (Borrelia).

“This modification of the microbiota makes the environment less favourable to Borrelia, which blocks its development," said Prof Cabezas-Cruz.

Promising results and animal development

So far, the vaccine has only been tested in mice, but initial results are promising. The infection rate of ticks who bit vaccinated mice was significantly lower than that of ticks that bit unvaccinated mice. 

Researchers are already planning a vaccination strategy for farm animals, as the testing process is faster than that for humans. The method could help to target “several tick-borne diseases such as babesiosis, theileriosis and anaplasmosis” within three to five years, said Prof Cabezas-Cruz.

Human potential

And while a vaccine for humans could take at least 10 years to become available, should the principle continue to be successful, it could be extended to other serious insect-borne (tick and mosquito) viruses.

This could include dengue fever, Zika and malaria.

To that end, Professor Cabezas-Cruz has already started working with researchers from Lyon, as well as teams from Brazil and Lithuania.

How can I avoid being bitten by a tick?

Bites are most common in summer and typically happen in forest areas, fields and areas of long grass, and damp or marshy spaces.

To avoid being bitten, health authority Santé publique France recommends:

  • Wearing a hat to protect against ticks falling from trees

  • Tuck your trousers into your socks to avoid ticks climbing up from the ankles

  • Wear long-sleeve tops and long trousers

  • Stay on paths and avoid going into the long grass

  • Spray anti-tick and anti-insect repellent on your clothes and skin

It is estimated that between 30-50% of tick bites occur in gardens and countryside parks, not only in wild forests.

After you return from spending time outdoors, you are advised to check for ticks. The forestry office l'Office national des forêts recommends:

  • Inspect your body in detail, especially in skin folds and creases

  • Check your scalp, behind your ears and neck

Ticks are only 1-3mm wide, so can be easy to miss. Pets can also be affected, so be sure to brush them or de-tick them after they come indoors, too. You can also wash your clothes at 60C, or tumble dry them for at least an hour, as ticks do not like dry heat.

What if I suspect a bite?

The Assurance Maladie website Ameli recommends:

  • Taking out the tick as soon as possible. Use a tick removal device (un tire-tique) to get hold of the tick and pull it out, without crushing it.

  • If in doubt, ask for advice at a pharmacy or GP office

  • After taking out the tick, disinfect the area and keep watch on the area for the next month

Ameli adds: “If you see a red rash or inflammation start to spread, between three and 30 days after the bite, you should see a doctor.”