The UK Foreign and Commonwealth Office (FCO) advises: "You should consider preventative measures to minimise exposure to mosquitoes, for example using mosquito repellent when outdoors and closing doors or windows or using screens".
About 20% experience mild, flu-like ailments including fever, headaches and general aches, only 1% will go on to develop a serious illness, according to the US Centers for Disease Control and Prevention, the paper said.
"There have been enough cases to know that this is now a public health issue", Danai Pervanidou, who heads the office for vector-borne diseases at the national organisation for public health (Keelpno), told The Guardian.
With signs that 2019 will see the end of a record run of tourism seasons in Greece, visitors - as well as residents - are being warned of some perils, such as wildfires, but especially the mosquito-borne West Nile Virus, that can be deadly.
The department said one death was reported previous year due to West Nile complications, and 11 Idaho counties reported finding mosquito pools that tested positive for the virus. As always, it is prudent for travellers to take out comprehensive travel and medical insurance before they travel to avoid running into potentially devastating medical expenses.
Greek authorities are now treating it as a "public health issue".
Nearly 2.4 million Britons visit Greece every year, making the United Kingdom the third highest provider of tourists after Macedonia and Germany.
The most at-risk populations are children, people over 60, pregnant women and those with chronic illnesses, local health officials said.
Fifty Greeks died after picking up the virus a year ago with a further 266 people infected with the West Nile Virus.
Thirty people citywide suffered from neuroinvasive effects a year ago, with six in Brooklyn, according to the Health Department.
Normally those infected with the virus will exhibit no symptoms. The department said West Nile virus is contracted from the bite of an infected mosquito and is not spread from person-to-person through casual contact.
The most effective way to control mosquitoes is to eliminate any standing water, the Health Department says.