Cambodia is closely watching the situation of yellow fever virus, though the country has not seen any case of the virus, said a joint statement from the Health Ministry and the World Health Organization on Wednesday.

Yellow fever is an acute viral hemorrhagic disease transmitted by infected mosquitoes, the statement said, adding that the yellow in the name refers to the jaundice that affects some patients up to 50 percent of severely affected persons without treatment will die from yellow.

“There is currently no reported case of yellow fever in Cambodia. The Ministry of Health will continue to monitor the situation for both Cambodia and within the region,” Health Minister Mam Bunheng said in the statement. “The Ministry is requesting people travelling to affected countries with yellow fever to ensure that they have received yellow fever vaccination one month before travelling.”

According to the statement, there is no specific treatment for yellow fever, and vaccination is the most important preventive measure against the virus and available at the Institut Pasteur in Cambodia.

The statement said there are an estimated 130,000 cases of yellow fever reported yearly, causing 44,000 deaths worldwide each year, with 90 percent occurring in Africa.

After exposure, the yellow fever virus incubates in the body for 3 to 6 days, the statement said, adding that the illness can occur in one or two phases. The first, acute, phase usually causes fever, muscle pain with prominent backache, headache, shivers, loss of appetite, and nausea. Most patients improve and their symptoms disappear after 4 days.

However, 15 percent of patients then enter a second phase which is more toxic and develops jaundice and complains of abdominal pain with vomiting, the statement said. Bleeding can occur from the mouth, nose, eyes or stomach.