The Zika virus is expected to reach parts of Europe this summer, but the World Health Organization (WHO) says the risk of an outbreak is "low to moderate".

According to WHO, areas most at risk are Madeira and parts of Russia and Georgia on the Black Sea coast. These places are said to have populations of the Aedes Aegypti mosquitoes, which are known to carry the Zika virus.

Report also said that 18 countries, which is about a third of Europe, are at moderate risk due to the presence of Aedes albopictus mosquitoes. This include popular tourist destinations Spain, France, Italy and Greece. Others with moderate risk are Malta, Croatia, Israel, Monaco, San Marino, Turkey, Switzerland, Bulgaria, Romania, Slovenia, Georgia, Albania, Bosnia and Herzegovina, and Montenegro.

Thirty-six countries or 66% have low risk or no likelihood of risk, which includes the U.K.

WHO's European risk analysis considered multiple factors, which include the presence of Zika-transmitting mosquitoes, suitable climates for mosquito breeding, previous history of transmission of other viruses such as dengue or chikungunya, ship and flight connections, and population density and urbanization.

WHO is pushing countries to eliminate mosquito-breeding sites and to make sure that people, especially pregnant women, are provided enough information about the potential harmful effects of the disease.

Zsuzsanna Jakab of the WHO said in a news release: "We call particularly on countries at higher risk to strengthen their national capacities and prioritize the activities that will prevent a large Zika outbreak."

According to the organization, mosquito-borne transmission of the virus is present in 58 countries. Recent reports show that 23 U.K. travellers have been infected after visiting affected regions.

There have been over 400 imported Zika cases in Europe. However, the virus hasn't spread locally, reports say.

Majority of those infected of Zika virus may have no symptoms at all, but for others it may cause fever, rashes and headache. For pregnant women, the virus can also cause a birth defect called microcephaly, a condition where babies are born with abnormally small heads and underdeveloped brains.