A statement from the U.N. agency says Turkey has reported more than 240 cases of the Crimean-Congo haemorrhagic fever, which is transmitted by tick bites and by contact with the infected blood of livestock.
The fever results in high temperatures, muscle pain and internal bleeding. It has a high mortality rate in humans and there is no vaccine against it.
Turkey's health ministry reported most of the recent cases in six northeastern provinces.
The WHO said one of the recent fatalities was a health worker who acquired the infection while treating human cases. However, human-to-human transmission is rare.
The disease is named after the Crimea and the Congo where it was first observed.
The WHO says the disease is endemic in many countries in Africa, Europe and Asia, and usually infects farm and slaughterhouse workers.
