The man  was diagnosed with Crimean-Congo hemorrhagic fever (CCHF) after being bitten by a tick in the city of Leon in northwestern Spain.

The unnamed patient was taken to another hospital by the Pentagon on Thursday after being admitted to Leon last week.

According to  WHO, CCHF has a mortality rate of 30 percent.

Symptoms include fever, pain, dizziness, mood swings, confusion, and bleeding, especially around the eyes and  skin.

First discovered in Crimea in 1944, it is endemic to Africa, Asia, the Middle East and the Balkan Peninsula.

Cases are rare in Northern Europe, with only three cases in Spain since 2011.

In March, a British woman was diagnosed with CCHF. This is the  fourth case in the UK since 2012.   She was treated at  Royal Free in London.

Then doctor Susan Hopkins, Senior Medical Advisor to the UK Health and Security Agency. The virus "does not spread easily among people and the overall risk to the public is very low," he said.