Volunteers carry bodies in a center run by Medecins Sans Frontieres for Ebola patients in Kailahun, Sierra Leone, Aug. 2, 2014. Reuters

Health officials in Thailand are keeping an eye on 21 tourists arriving to the country from West Africa amid concern over the Ebola virus that has plagued Guinea, Sierra Leone, Liberia and Nigeria. It’s unclear whether the tourists are displaying any symptoms of Ebola, but they're within the virus’ incubation period of up to 21 days.

Since June 8, health authorities in Thailand have monitored 300 tourists from West Africa, where Ebola has killed nearly 900 people as of Aug. 1, Sophon Mekthon, director-general of Thailand’s Department of Disease Control, told the English-language Bangkok Post.

While the threat of Ebola to Thailand is considered low, Mekhton said health officials “are taking serious precautions” in screening travelers for the virus, which has a fatality rate of up to 90 percent. The disease is only spread through contact with blood and bodily fluids, which makes it unlikely for the disease to be spread through air travel.

Nevertheless, Thai Airways, the country’s flag carrier, has taken precautions due to the Ebola virus outbreak. The airline is screening passengers and ground customers and are disinfecting planes more often than usual, Sqn Ldr Pongpeera Paisarnkulwong, vice president for aviation safety, security and standards, told the Bangkok Post.

Thailand’s health officials are monitoring passengers with suspicious symptoms at five international airports, including Suvarnabhumi and Don Mueang airports, which serve Bangkok.