Ticks: Tiny Vectors, Big Problems

For some time, mosquitoes have been recognized as the most dangerous animal in the world, capable of transmitting diseases such as malaria, dengue or Zika, but with the first autochthonous case of Crimea Congo haemorrhagic fever (CCHF) in our country, ticks have captured media attention. 

Although not all ticks are infected, those that are cause a wide range of diseases worldwide

These small but widespread arachnids feed from blood of different animals (including humans) throughout their life cycle, and by doing so can transmit pathogens (viruses or bacteria) that cause disease in humans. Although not all ticks are infected, those that are cause a wide range of diseases worldwide – from bacterial infections like borreliosis or tick spotted fever, to viral ones such as CCHF or even parasitic infections like the poorly known babesiosis.   

In Europe, the main tick-borne diseases are Lyme disease, a borreliosis that can cause long-term neurological problems and is preventable by antibiotic treatment; central European encephalitis, a viral disease that can cause brain inflammation and the only one that can be prevented by a vaccine; and CCHF, a haemorrhagic viral disease that can be transmitted from one person to another via biological fluids, although the probability of contracting it in Spain remains extremely low. 

In Europe, the main tick-borne diseases are Lyme disease, central European encephalitis and CCHF

In addition to becoming famous, ticks are becoming increasingly global. On one hand, they are more active in more places and during longer periods of the year (beyond spring and summer, their maximal periods of activity) due to climate change. On the other hand, migratory birds, also affected by climate change, modify their flight routes and carry infected ticks to places where they didn’t previously exist.  Imported livestock can also contribute to the spread of infected ticks. In addition, human encroachment of natural habitats for agricultural activities, ecotourism and adventure travel increase the probability of contact between humans and ticks. For international travellers, 14 tick-borne diseases have been described (including Lyme disease, African tick fever, and tularemia) but the number will likely increase with the emergence of new pathogens in new tourist areas.

And so, what can we do against those small but potentially dangerous vectors? The first thing is protect ourselves when we go out to the woods or fields by wearing light-coloured clothes that cover the whole body and using DEET, an insect repellent that is efficient against ticks when used at a concentration of 30% or higher. We should avoid high vegetation and should always sleep in sleeping bags or a mattress that isolates us from the ground. Contrary to common belief, ticks not always fall from trees. Some species like Hyalomma (the CCHF vector) hide on the ground and, upon sensing a passing host, can actively follow it during more than 10 minutes, covering a distance of up to 100 meters!  Other ticks, in contrast, adopt a more patient strategy: they sit on a leaf or bush and wait until a host brushes by.   

For international travellers, 14 tick-borne diseases have been described but the number will likely increase with the emergence of new pathogens

In any case, when coming back from the field, carefully inspect the body for ticks: remember that they can be very small, smaller than a fingernail, and their bites frequently go unnoticed. If you detect a tick, remove it immediately by pulling it out with fine-tipped tweezers, never by crushing or burning it. The less they feed on our blood, the less likely they are to transmit pathogens.  

At another level, as experts in tropical medicine we keep ourselves updated on all tick-borne disease outbreaks in our country and worldwide, we establish protocols to quickly identify possible cases of haemorrhagic fever and prevent further transmission, and we inform the public in general and travellers in particular on the appropriate preventive measures. 

These small arthropods, although frequently ignored, are the first disease vector in Europe and the second in the world

Although the probability of contracting a severe tick-borne disease in Spain is very low, it is important to be alert, follow the preventive measures and ensure the preparedness of health facilities and authorities. For the time being, those are the best weapons against these small arthropods that, although frequently ignored, are the first disease vector in Europe and the second in the world. A record that makes them usual suspects, to be considered as dangerous, and worthy of a place among our infographic series on vectors.

More information

Infographic. 6 tiny vectors that represent a huge treat to our health: 04 Tick

Other infographics of the Usual Suspects serie

001 Anopheles Mosquito

002 Aedes Mosquito

003 Triatomine Bug