Chikungunya infections multiply by seven and most are detected in Catalonia

BarcelonaCatalonia has the right temperature, the type of mosquitoes, and the necessary flow of travelers for tropical diseases to become increasingly frequent, especially during the summer months. The climate crisis is advancing relentlessly, and every year thousands of people travel to areas where these pathologies circulate intensely, increasing the risk of autochthonous cases and for transmission to become endemic. Chikungunya disease is one of those infections that worries health authorities, and since the beginning of the year, 43 cases have already been detected throughout the State, seven times more than last year in the same period, when only 6 had been diagnosed. Of these, 28 are in Catalonia, all imported cases from countries where outbreaks are currently occurring.

This means that almost two out of every three cases detected in the State have been diagnosed in Catalan health centers. More than half have been treated at the Drassanes International Health Center, according to Israel Molina, head of the Infectious Diseases service at Vall d'Hebron Hospital, which manages this facility. The vast majority are people who have traveled to a country with active outbreaks: in 2026, about twenty countries have already reported Chikungunya contagion hotspots, more than 32,000 cases have been detected worldwide, and there have been at least nine deaths. Most are American countries, but in Europe, outbreaks have also been reported in Italy and France.

The Chikungunya virus is transmitted by a mosquito bite, which acts as a transmission vector: if the insect feeds on the blood of an infected person, it can infect up to about 10 days after the bite. Approximately one week after the bite, the person will begin to have fever, headache and muscle pain, as also happens with other mosquito-borne diseases such as dengue or West Nile fever. However, Molina explains that they all have some peculiarity that is usually decisive for diagnosis. In the case of Chikungunya, people with the virus have joint pain and arthritis. Most recover completely, but the arthritis can persist for months or even years, warns Molina.

"The tip of the iceberg"

The fact that France or Italy detect more cases of Chikungunya than Spain makes Molina think that there are sick people who are not being diagnosed. In the same vein, Jacobo Mendioroz, Deputy Director General of Public Health Surveillance and Response, expressed himself last summer when a series of actions were announced to reduce the risk of outbreaks. "When we detect cases in humans, we see the tip of the iceberg; we can have many more circulating and unidentified," warned the expert, who acknowledged that it is most likely that these pathologies will end up circulating normally in Catalonia due to rising temperatures, the proliferation of mosquitoes, and the arrival of thousands of tourists from all over the world. "To think that we will get rid of them is a bit naive".

Even so, last summer the Department of Health intensified mosquito prevention and control and deployed circuits to act quickly if cases of any of these tropical diseases were detected, and the predicted impact was minimized. Looking ahead to this summer, Mendioroz explains to ARA that they have an ace up their sleeve in case outbreaks are detected that they cannot control. "There are vaccines against dengue and Chikungunya that we could use if necessary to control an outbreak, as countries like Brazil have already done." However, for the moment they do not contemplate mass vaccination, nor have they made any vaccine purchases.

According to Public Health, Catalonia has had an interdisciplinary control plan in place for years that has "good results", which is why "additional measures would not be necessary, in principle". When a positive case of any of these diseases is detected that is not associated with any international travel, mosquito control centers are activated, they move to the area and identify larvae and mosquito species to determine the risk of expansion. Once the evaluation is done, the larvae and even some mosquitoes are eradicated, and then the action is monitored to ensure that no further measures are needed. All contacts of infected people are also monitored to cut transmission chains.

Molina explains that from the tropical health unit they provide training to professionals in primary care centers so that if a person with compatible symptoms arrives, they know how to recognize them in time and act accordingly. It should be taken into account that in Catalonia there is the tiger mosquito, which can transmit dengue, Chikungunya and Zika, and the common mosquito can transmit West Nile virus. For this reason, Health insists on the importance of controlling these two species. Furthermore, there is also a surveillance program for West Nile virus to early detect circulation in birds and horses and identify risk areas.