CDC lowers temperature threshold for Ebola fever

Without explanation, the federal Centers for Disease Control and Prevention has lowered its threshold for suspecting that someone might be infected with Ebola from 101.5 degrees to 100.4.

The presence of fever remains the indication most relied upon by CDC-trained personnel at airports in the Ebola-stricken countries of West Africa for prospective travelers seeking to fly to the U.S. and elsewhere.

According to CDC Director Thomas Frieden, 150 passengers per day — or 1,050 a week — arrive in the U.S. from Liberia, Sierra Leone and Guinea.

A CDC spokesman, Tom Skinner, confirmed the changed standard late Wednesday in response to questions by email, saying only, “The threshold at airports is 100.4 degrees.”

Frieden was asked about the change at a House hearing Thursday, but answered that the threshold was 100.4, without elaborating.

The CDC’s lowering of the threshold for fever was not reflected in some guidance materials posted for the general public. For instance, a CDC Web page titled, “What You Need to Know About Ebola,” still advised as of Wednesday night that signs of Ebola include fever “higher than 101.5” degrees.

The same Web page said, “A person infected with Ebola can’t spread the disease until symptoms appear.”

CDC’s lowering of its threshold came in close sequence with the identification Wednesday morning of a third case of Ebola on American soil: a Dallas-based nurse, Amber Vinson, who was among those who had cared for Thomas Eric Duncan, the Liberian who died of the disease on Oct. 8.

Vinson had flown to Cleveland on Oct. 10, and back to Dallas on Monday. Frieden said she measured her temperature at 99.5 before boarding the return flight. Vinson was transferred to Emory University Hospital in Atlanta on Wednesday evening.

Another nurse who helped treat Duncan in Dallas, Nina Pham, was diagnosed with Ebola over the weekend. On Thursday evening, she was transferred to the National Institutes of Health in Bethesda, Md.

david.willman@latimes.com