This is a Physician in the Loop special topic.

Twenty-one days

The Bundibugyo Ebola outbreak has passed 10,000 confirmed cases and reached Kenya and Nigeria. There is no approved vaccine or treatment, and American rules turn on a 21-day window.

The Ebola outbreak caused by Bundibugyo virus is now the second-largest on record, according to the Centers for Disease Control and Prevention. As of Oct. 28 the CDC counted more than 10,300 confirmed cases and nearly 5,000 confirmed deaths, almost all of them in the Democratic Republic of the Congo. In October travelers carried the virus to Kenya and Nigeria. From the night of Nov. 3, everyone boarding a flight to the United States must attest that they have not been in Congo in the previous 21 days.

The World Health Organization's most recent Disease Outbreak News, published on Oct. 23 with data to Oct. 20, puts Congo at about 9,700 confirmed cases and 4,700 deaths in eight provinces, with Ituri and North Kivu the most widely affected. Nearly half of confirmed patients have died. The figures are confirmed cases only, since Congo's official count leaves out probable cases and, for now, suspected ones, the CDC notes. In late August the WHO welcomed the end of Uganda's outbreak, which had counted 20 confirmed cases. France treated one patient, a health or aid worker back from Congo.

Kenya's first patient fell ill in Congo and traveled to Kenya through Uganda on Oct. 3. The eight cases that followed were all linked to that patient, and four were health and care workers. By Oct. 23 Kenya had counted nine cases and two deaths, the CDC reports. In Nigeria, a woman who had flown from Uganda to Abuja, also on Oct. 3, was admitted to hospital on Oct. 11 and tested on Oct. 19, after officials learned of her travel. Most of the 44 contacts first identified were health workers.

There is no approved vaccine or specific treatment for Bundibugyo virus, the WHO says. It is one of several ebolaviruses, and the vaccine and antibody drugs the Food and Drug Administration has approved are for another, Zaire ebolavirus. The vaccine, Ervebo, is not expected to protect against Bundibugyo, the CDC said in May, and the efficacy of the two antibody drugs, Inmazeb and Ebanga, has not been established against other species. The WHO says some findings suggest possible cross-protection from Ervebo, but the evidence cannot show whether it meaningfully protects people, and it recommends using it only within research protocols. With intense supportive care and fluid replacement, death rates may be lowered, the CDC's advisory says.

In Congo, a treatment trial sponsored by the WHO had begun enrolling patients by early July to test an antibody, MBP134, from Mapp Biopharmaceutical, and Gilead's antiviral remdesivir. A vaccine trial, Tumaini, registered for about 3,600 people, enrolls contacts of newly confirmed cases. Each participant is assigned at random to a candidate vaccine or a comparison shot and receives the other four weeks later, so all are offered a candidate. Enrollment began in Bunia on Oct. 23, the WHO says. The first shot given in the trial was Ervebo, Agence France-Presse reported, with a vaccine from the University of Oxford and a messenger RNA vaccine from Moderna expected to follow.

No case linked to the outbreak has been reported in the United States, the CDC says. An American missionary doctor infected while performing surgery in Bunia was flown to Berlin for treatment in May and released after recovering in June. In July a second American infected in Congo, an aid worker, was transferred to Germany, ABC News reported. Under a CDC order issued on May 18 and last renewed on Oct. 11, foreign nationals, green-card holders included, who have been in Congo, Uganda or South Sudan in the past 21 days may not enter, with some exceptions. Travelers who were in Congo in that window, Americans included, cannot board flights to the United States. Americans who were in Uganda or South Sudan in that window are routed through Dulles, Atlanta or New York's Kennedy airport for screening and asked to watch their health for 21 days.

The CDC rates the overall risk to the American public as low and says its entry order is necessary to protect the country from the serious risk of Ebola's introduction. The WHO advises against any restriction of travel to or trade with affected countries. Its director-general declared the outbreak a public health emergency of international concern on May 17, and the temporary recommendations issued days later did not recommend suspending flights from countries with documented cases or denying entry to their travelers. After the emergency committee met again in August, the director-general determined that the epidemic in Congo still met that standard.

The CDC's advice to clinicians is in a health advisory of May 19 on the outbreak in Congo and Uganda and in its clinical guidance. The advisory asks clinicians to consider Bundibugyo disease in a patient with symptoms such as fever, headache, muscle pain, gastrointestinal illness or unexplained bleeding who had an exposure in the 21 days before symptoms began, such as direct contact with a living or dead person suspected or confirmed to have the disease, or attending funeral rituals. It asks them to test for malaria and other common causes without delaying routine care. A patient with both an exposure and symptoms is to be isolated in a single room and admitted, with staff in protective equipment, until a specimen taken at least 72 hours after symptoms began tests negative. The health department is to be called at once, testing is arranged through a consultation with the CDC, and a patient who tests positive is transferred to a regional or state-designated special pathogens treatment center.

Twenty-one days is the maximum incubation period for Ebola, the CDC notes, and the same window appears in its entry order, boarding rules, monitoring of travelers and advice to clinicians. The newest of those measures, the attestation for every passenger, takes effect a minute before midnight, Eastern time, on Nov. 3.

This special topic was read by an AI voice. Its sources are linked at physicianintheloop.org.