The tiger mosquito can transmit various diseases (it is a vector of diseases), of which the most widely known are dengue, chikungunya or Zika.
These diseases are caused by viruses and can result in fever and joint and muscle pain, among other symptoms, and can lead to a need for hospitalization. The virus is transmitted when a mosquito of the Aedes genera (such as the tiger mosquito) bites a person after having been previously infected by biting another person with the disease.
In Spain these diseases are not endemic. An endemic disease means that it is maintained for a long period of time among a large number of infected people. In countries in which these diseases are endemic they sometimes cause large-scale infectious breakouts. Since dengue and chikungunya are not endemic in Spain, the risk of transmission is very low; nonetheless, the risk of transmission still exists to high human mobility and the established presence of the tiger mosquito in some European countries, and especially during the period of activity of the tiger mosquito (roughly from June to October).
People who have recently returned from trips to countries in which these diseases are endemic and notice symptoms should go to a medical centre, provide information about their trip, and take precautionary measures to avoid being bitten by mosquitos.
To prevent transmission of these diseases is crucial to know the presence of these species, minimize them in areas where they are resident and control its expansion. To do this, the cooperation of citizens, along with the work of scientists, governments and managers of vectors and vector-borne diseases is essential.
If you want to know more about viruses which are transmitted by mosquitos, and in particular about dengue and chicungunya, or about vigilance and control campaigns, see:
Outbreak of Chicungunya in the Americas Region Rapid Evaluation of Risk for Spain
Protocol for vigilance and control of arboviruses transmitted by mosquitos in Catalonia