The risks of a tick bite

Nowadays it is very common to carry out sports activities in the open air, including running, not only in urban spaces, but also in the countryside, in the forest or on rural roads, either in a recreational way or in organized activities (cross, orienteering races …).

The climate in which we live (especially in the Mediterranean rather than the Atlantic, with a predominance of warm temperatures, relative humidity and a virtual absence of extremes), in areas where there is an abundance of low bushes or shrubs, favours the living (and proliferation) of insects or small organisms that can generate potentially significant health problems if we do not have a minimum idea of what to do if we are bitten or stung.

One of these small organisms is ticks. They are considered a subspecies of mites, called arthropod ectoparasites (they feed on blood) and consist of an oval body, with 4 pairs of legs and a pair of claws that are anchored to the head, which they use to bite the being they parasitize (dogs, cats, birds and even humans).

There are several species of ticks, but the predominant species in our forests are those of the genus Ixodes ricinus (although migratory phenomena have led to the identification of other species originally not native to our area (such as Ixodes persulcatus, or Ixodes scapularis). And in each of these genera there are several subspecies (such as the Rhipicephalus sanguineus, or brown canine tick, also called brown dog tick).

Ticks can live in shrubs and bushes, but their main source of food is the blood of animals. Rubbing against an infested plant causes ticks to jump up and down, anchoring themselves to the skin of their “victim” with their front claws. From this moment on, if they do not come out (or they fall out because the host – dog, cat, human – shakes it, or because they come out when they die), they feed on the blood they suck.

Apart from the initial discomfort (not always perceptible) of the bite itself (they can cause pain, itching, eczema or the appearance of one – or less frequently, several – rounded and red lesions, with a central spot and a “peripheral satellite ring”, called erythema migrans), the real problems can appear if we leave the tick stuck to the host’s body for several days and do not remove it correctly.

Within the gastric juice of the tick, small microorganisms (predominantly bacteria and viruses) can live and reproduce. If these microorganisms are inoculated into the host that has been bitten by the tick, and are not identified and treated, they can cause serious health problems (in this case to the human).

The tick reflexively returns its own gastric juices that can mix with the blood of the infected organism. If these gastric juices are infected, these infections can be transmitted to humans (and in the best case, the infected person’s own immune system can eliminate them).

Among the organisms that nest in the gastric juice of ticks, and depending on the area of the planet where we are, we can find: mainly bacteria such as Borrelia, Erhlichia, Bartonella, Mycoplasma, Rickettsia and Chlamydia (each one of them with several subspecies); but also parasites, such as Babesia.

One of the emerging diseases in recent years (not so much because of its prevalence – which seems to have remained stable over the years – but because diagnostic techniques have improved) is Lyme Disease (which in many cases has become known because some famous or well-known person has suffered from it).

This disease is caused by a bacterium called Borrelia (and the predominant one in our environment is Borrelia burgdorferi); more than 50 subspecies of it are known and, depending on this, they can generate different symptoms and it can be easier or more complicated to treat it). It is a gram-negative bacterium, of the spirochete class.

It has been known for more than 100 years and the disease it causes (Lyme) is named after a region of Connecticut (United States) where in the mid-1970s several clinical cases of young people with similar symptoms were described. The common denominator was the diagnosis of “juvenile rheumatism” and having been bitten by ticks before (it is an endemic area).

If it is transmitted to people (it is necessary that the tick – which is infected – remains anchored to the human for a minimum of 48 hours, which is the time it takes for the bacteria to migrate from the stomach to the wound). Within the first week (especially from the 3rd or 4th day), symptoms appear that simulate a flu (discomfort, joint and muscle pain, fever, headache).

Between the 2nd and 4th week (in almost 80% of cases), in the area of the bite, an erythema migrans appears, which tends to disappear spontaneously and can cause itching (and in some cases pain).