Lyme disease, or Lyme borreliosis, is an infectious disease transmitted to man through the bite of a tick infected with the bacterium Borrelia burgdorferi.

How is Lyme disease transmitted?

In Europe it is mainly ticks of the species Ixodes ricinus, also called “sheep ticks”, which transmit the Borrelia burgdorferi bacterium to human beings through a bite.

The risk of transmission of the Borrelia burgdorferi bacterium increases with the length of time that the infected tick is attached and it is estimated to be low when the tick is removed within 12 and 24 hours.

The infection caused by the Borrelia burgdorferi bacterium cannot be transmitted between humans; it is only transmitted from the infected tick to a human.

An infection by the Borrelia burgdorferi bacterium in the past or one that is still active does not confer protective immunity. It is therefore possible to be infected several times.

The tick can be a vector for other bacteria, such as Anaplasma phagocytophilum or Rickettsiae spp or also the tick-borne encephalitis virus (TBEV).

Where are ticks found?

Ticks like:

  • a wet environment favourable to their survival (shaded places with dense undergrowth)
  • low-growing vegetation (carpets of leaves, long grass, ferns, bushes, etc.)
  • wooded areas where there are vegetation and hosts (forests of broad-leaved trees, conifers, natural reserves, etc.).

Most tick bites occur therefore during walks in forests, but also in fields, dunes, urban green areas and even in one’s own garden.

Ticks are found everywhere in Belgium, but mainly in the provinces of:

  • Luxembourg
  • Limburg
  • Antwerp
  • Brabant.

The number of ticks in the environment can vary from year to year depending on several factors:

  • a milder climate favouring winter survival
  • the presence of hosts (rodents, game, etc.)
  • the landscape and the type of vegetation.

When are the ticks active?

Ticks are present all year round but they are only active when the temperature is at least 10° to 12°.

In regions with a temperate climate and variable seasons like Belgium, ticks are mainly active between Spring and Autumn (from March to October), when it is hot and wet.

Do ticks also bite domestic animals?

Ticks of the Ixodes ricinus species may also feed on domestic animals, rodents and birds, which would explain why ticks can be also found in parks, private gardens or even inside houses, where they cannot survive.

Human beings and  domestic animals are accidental hosts.

4 reasons for not being alarmed

  • Not every bite is infectious (in Belgium only about 10% of ticks are infected).
  • An infected tick does not necessarily transmit the bacteria.
  • An infected person does not necessarily develop the disease.
  • Lyme disease can be treated effectively with antibiotics if it is diagnosed in time.



Sciensano ensures epidemiological surveillance of Lyme disease through a monitoring network of laboratories and general practitionersand a National Reference Centre  for Borrelia burgdorferi. 

QR code

QR code for this page URL