Asian tiger mosquitos which can transmit more than 20 fatal viruses are giving many European nations a health nightmare, experts said.

“For countries like Italy, France and Spain, this is already a very bad scenario. They cannot eliminate the Asian tiger mosquito anymore, they just try to reduce mosquito numbers and minimize effects,” Soeren Metelmann, an academic at U.K.-based University of Liverpool said in an email interview.

“The Asian tiger mosquito can transmit more than 20 different viruses such as dengue, chikungunya, Zika, yellow fever and also some of the filarial worms, such as the dog heart worm,” he

Read more: Invasive tiger mosquito real threat for Europe: Experts