GENEVA — An outbreak of Ebola that has killed at least 87 people in Africa is drawing aid from U.S. disease fighters who will help track the deadly path of a virus with no cure that is fatal in about 90 percent of its cases.

There have been 134 cases in Guinea and Liberia, the World Health Organization said Tuesday.

A five-person team from the U.S. Centers for Disease Control and Prevention arrived March 31 in Guinea, where they’ll help contact anyone who has been in touch with people infected, said Steve Monroe, a CDC official. A second team may soon go to Liberia, he said, and the agency is assessing the need for more laboratory assistance to analyze samples.

Last week, when Canadian officials feared that a severely ill patient who had recently been to Liberia may have been infected with deadly Ebola, the U.S. took notice. It was a “false alarm,” Monroe said, “that reminded us that any of these diseases are only a plane ride away.”

The U.S. is well prepared to handle infected patients on its soil with 20 CDC quarantine stations in place at U.S. airports that are designed to deal with anyone who has symptoms of a wide range of infectious illnesses, including Ebola, according to Christine Pearson, an agency spokeswoman. Despite the outbreak, she said, there are no special requests or guidelines to airlines related to Ebola, though the agency has issued a travel alert.

“The time it takes to travel from rural Guinea to anywhere in the U.S. is more than enough time to incubate the virus and be symptomatic,” said Laurie Garrett, a senior fellow with the Council on Foreign Relations in New York who has written two books on emerging infectious disease. “Even if you could get on an airplane, you’d be carried out on a gurney.”

The CDC team arrived in Guinea’s capital Conakry late on March 31 after receiving a request for assistance from Guinea’s health ministry and the World Health Organization, said Monroe, who is deputy director for the agency’s National Center for Emerging and Zoonotic Infectious Diseases.

First identified in 1976 near the Ebola River in what is now the Democratic Republic of Congo, the virus is transmitted to people through blood and other secretions of wild animals such as chimpanzees, gorillas, bats and porcupines, according to the WHO.

Humans transmit the virus to each other through contact with blood and other body fluids. A WHO report on the 1976 outbreak wrote of alarming bleeding symptoms including “slow oozing from gums to brisk hemorrhage from multiple sites in fulminating cases.” The report concluded that, with an 88 percent mortality rate, the new disease was the deadliest on record except for rabies.

The virus is one of a handful of diseases that are so deadly that they pose a risk to national security, according to the CDC, which lists the virus as a Category A bioterrorism agent, along with anthrax and smallpox.

Since 1976, outbreaks from various forms of the virus have surfaced periodically in Africa.

The virus revisited the Democratic Republic of Congo in 1995 and again in 2007, taking the lives of hundreds of people each time as it spread through families and hospitals. In Uganda, another Central African neighbor, 149 people died in a 2007 outbreak. The last time the virus was found in West Africa was in 1994, when a single person was found with the disease in Cote d’Ivoire, according to the WHO.

Still, Ebola doesn’t travel through the air, making it harder to transmit than other pathogens, such as influenza, as long as adequate health-care practices are followed, said David Heymann, a professor of infectious disease epidemiology at the London School of Hygiene and Tropical Medicine, who has worked on Ebola since the first outbreak.

While the virus is unlikely to leave the continent, according to most experts, the stigma and fear associated with Ebola can prompt people who catch it to flee local communities and seek care in hospitals outside the affected area, spreading the virus within the continent, said Garrett, who won a Pulitzer Prize as a reporter for Newsday covering the 1995 outbreak in the Democratic Republic of Congo.

“These are desperately poor places, so the odds that someone’s going to get on an airplane is tiny,” she said. Instead, the concern is waves of transmission pushing Ebola across local borders.

“If those hospitals are not aware of what’s coming, they will quickly become cauldrons, and spread the virus internally,” Garrett said. “Then people flee to the next hospital, and the next. The most crucial thing right now is to identify who’s infected, remove them from the general population to protect their families, and clean up the hospitals to stop panic exodus.”

This is exactly how the virus reached the coastal capital Conakry.

While cases have so far have been concentrated in the towns of Gueckedou and Macenta, in southeast Guinea, near its borders with Liberia and Sierra Leone, the virus spread 413 miles to Conakry after an infected patient traveled there to seek medical attention, Gregory Hartl, a WHO spokesman, said Tuesday at a briefing in Geneva. So far, there have been five suspected cases in the capital.

Liberia has reported seven suspected or confirmed cases, including four deaths, though all were exposed to the virus in Guinea, Hartl said. Five suspected infections in Sierra Leone tested negative for the virus, he said.

“This is the first time we’re looking at a multination outbreak where all the issues related to trade and economics and politics are playing out,” Garrett said. “Guinea has outlawed eating bushmeat, but the two other countries haven’t so far.”

Senegal closed its southern border with Guinea. Sierra Leone has not taken similar action, but the chief medical officer said people should avoid traveling to the affected areas in Guinea. The WHO said travel and trade restrictions “don’t make public health sense.”

Currently, there are no approved drugs or vaccines to treat or prevent Ebola infection, though several products are in development. The CDC doesn’t comment for security reasons on what drugs it has stockpiled in case of an Ebola outbreak or attack in the U.S., said David Daigle, a CDC spokesman.

The idea of an attack isn’t necessarily far-fetched, said Heymann, the infectious disease epidemiology professor.

“If you can weaponize it and get it into a form which is easily aerosolized, which maybe they could do, it could then infect everybody who was in contact,” he said.