Like every good hunter, before leaving home Felix Valcárcel Prepare your weapons well, study the terrain and calculate the pieces you can get in today’s raid. But don’t imagine him cleaning shotguns or setting stocks. Nor pointingor to partridges or deer. Because what this CSIC scientist hunts are ticks. Small arthropods of just a few millimeters that, however, can pose a threat to public health due to the diseases they are capable of transmitting.
Valcárcel does not hunt ticks to kill them, but to study them. He wants to know what species there are on the peninsula, what their life cycle is like, what their distribution is, what pathogens they harbor… This veterinarian, leader of the Animal Parasitology Group of the National Institute of Agrarian Technology (INIA-CSIC), is one of the coordinators of the GARES Project whose objective is to develop a resource that did not exist: a global map of ticks in Spain and the possible diseases they can transmit.
«Until now, there was nothing that reflected the global situation since the distribution data we had came from specific actions by different working groups and there were many gaps and unsampled areas. For the first time, the country’s leading tick experts have come together and are working together to lay the foundations for a tick monitoring plan in Spain,” explains the researcher as he takes out the tools he needs for his particular hunt from the car.
To know more
Crimea-Congo, West Nile or dengue, the other emerging viruses that threaten us
Crimea-Congo, West Nile or dengue, the other emerging viruses that threaten us
We are close to Jarama River, just half an hour by car from the center of Madrid, but in a place remote enough so that not a single soul passes by during the time the sampling lasts. Only the planes that occasionally fly over us at a short distance remind us how close the city is. «This is a point where wild animals come to drink and rest. Here we are going to find specimens,” Valcárcel predicts. And she immediately deploys the weapon that she has prepared: a piece of thick, white cloth, about two meters long that is attached to an adjustable broomstick. As if it were a fishing net, she throws it into the field, and begins to drag it.
Precautions to avoid ticks
Outfit. Protect yourself from ticks if you go to the countryside. Wear long sleeves and long pants and wear light-colored clothing. This will make it easier to check if there are any ticks on it.
Footwear. Avoid sandals or any type of open footwear. Better closed boots and high socks that should cover the bottom of the pants. The shirt is also better tucked into the pants.
Roads. As far as possible, walk in the central area of the paths, avoiding contact with nearby vegetation. Also avoid sitting on the ground in areas with vegetation.
Check your body. At the end of the day in the field, examine your body for any tick bites. Above all, armpits, groin, hair, behind the knees, inside and outside the ears, in the navel…
«Ticks are hematophagous, they feed on blood, so they need to climb onto a host to eat. And to achieve this, they use different strategies. For example, when the grass is tall, they can climb the vegetation and wait there for it to pass using different sensors that tell them if there is movement, vibrations, the emission of carbon dioxide, etc. Some species, following these same stimuli, can also chase the host. And with this cloth we pretend that we are an animal. Our movement, our breathing, our footsteps alert the ticks, which climb onto the fabric thinking it is an animal,” explains the scientist.
As he speaks, with a precise gesture that he has repeated thousands of times throughout his career, he turns the cloth over. And there they are: two copies of Hyalomma lusitanicum which Valcárcel recognizes at a glance and immediately collects in a transparent container. They will be the first of many. «This is a native species that, although it prefers other hosts, can also bite people. Of course, it doesn’t get hooked quickly,” he clarifies. This tick, he continues, “does not like the cold and with the increase in temperatures in Madrid We are seeing it in some places where it was not found before.. What we have observed here with this species is what we want to know if it happens or not in other parts of the country and other types of ticks,” he says.
He confirms his words from his laboratory at the Complutense University, Sonia Olmedacoordinator together with Valcárcel of the GARES project: “the initiative is based on the need to know the current distribution of ticks in Spain as a starting point to be able to ensure, with guarantees, whether a certain species is increasing its population or distribution.”
The researcher praises the information that in this sense is being collected not only by the professionals working on the project but also by the 268 collaborators “who are contributing their grain of sand in the creation of the map.” Beekeepers, ranchers, pest control companies and individuals have joined the initiative, contributing with their own data and specimens. «The population has shown interest and is participating intensely, providing unique information, impossible to obtain in any other way. “We are very happy as scientists and proud as citizens,” he remarks.
While continuing to hunt, Valcárcel clarifies that at each sampling point, three males and three females are selected in separate tubes and, among all the captured ticks, “are analyzed for possible pathogens.” As he explains, the Iberian Peninsula has a unique biodiversity, also when it comes to ticks. And, in fact, in space “more species of ticks coexist than in Central Europe”, which also implies a greater variety of transmitted diseases. In the most humid Spain, the species of ticks are similar to others that exist in Europe, such as the species Ixodes ricinus, whose main risk is Lyme disease, a bacterial infection that can leave chronic and serious consequences. On the other hand, in drier Spain, there are other species of ticks such as Dermacentor marginatus and Rhipicephalus sanguineus, which are related to bacterial infections such as rickettsiosis. But, in this area, without a doubt, one of the risks that is most worrying is that posed by the Crimean-Congo hemorrhagic feveran emerging zoonosis whose lethality can reach 40% and which is transmitted by ticks of the genus Hyalomma. On the peninsula, in addition to Hyalomma lusitanicumthere is also the Hyalomma marginatuma first cousin of the first who, however, has much more interest in people than she does.
A discovery through twitter
The circulation of the virus in our country was known since 2010, after the pathogen was identified in ticks captured on deer on a hunting farm in Cáceres. And for a long time it was thought that, in Spain, the first cases in humans had occurred in 2016. But, in reality the first documented case dates back to 2013, as the researcher demonstrated retrospectively and thanks to Twitter. Miguel Ángel Jiménez Claverospecialist in emerging viruses at the Animal Health Research Center (CISA).
«In the summer of 2020, I commented in a tweet that had quite an echo the confirmation of a fatal case from Crimea-Congo in a 69-year-old man in the province of Salamanca. As a result of that, a person who had suffered a very serious illness after being bitten by a tick in 2013, in the south of Ávila, contacted me through the social network and wanted to know if it could be the same. It immediately seemed to me that the symptoms could fit with the disease and we decided to investigate it,” recalls the scientist who contacted the medical team that had treated her at the Salamanca Hospital and, after several tests, was able to verify that the patient had antibodies against the virus. and the illness had actually passed.
“This study alerts us to the possibility that there have been more cases that have gone unnoticed, even previously,” says the researcher, who calls for “effective surveillance and promoting knowledge of this disease among health personnel.” Since 2013, a total of 13 cases have been confirmed, of which four ended up dying.
«Tick-borne diseases must be addressed from a very transversal perspective, from different disciplines, such as public, medical and veterinary health, as well as environmental health and management and health entomology. Therefore, it is essential that all these disciplines collaborate to understand, study and prevent diseases transmitted by ticks. It is necessary to create that flow of communication,” Olmeda also claims.
The objective of the GARES project is to develop an exhaustive mapping that allows us to know both the type of tick that is in a given place and the risk of disease transmission to try to minimize the possibility of contagion. «Although we still do not have all the data, what the preliminary results tell us is that there is less prevalence of viral pathogens in ticks than expected, which is good news, but the mapping will allow us to better understand the areas of greatest “risk,” says Valcárcel as he slowly removes a tick that fearlessly climbs up his pants. The researcher remembers that The spread of pathogens does not occur before 24 or 48 hours after the bite of the tick, so if upon returning from an area where this type of arthropods may be present, the body is carefully inspected and any tick that is detected is removed, the risks are minimized. “But please, no traditional methods, they don’t work. It is held firmly with blunt-edged, fine-tipped tweezers and pulled upwards, trying not to crush it,” warns Valcárcel, who in more than 30 years of career, 17 of which have been dedicated almost exclusively to ticks, can count on the fingers of one hand how many times he has been stung.
Before we leave, the scientist wipes an area with tall vegetation again. Bingo again. But those three won’t be the last ticks of the day. On the way to the city, already in the car, a specimen climbs up Valcárcel’s arm while he is behind the wheel. Calmly, he grabs a can next to the shifter and captures her. And he doesn’t even need to step on the brakes a bit.