New Ebola and Hantavirus Outbreaks Confound Science

why virus – A hantavirus outbreak on a cruise ship and an Ebola flare-up in Africa have alarmed the public—and puzzled even scientists—because both outbreaks are behaving in ways that don’t match the names on the label. Researchers say the incidents expose gaps in how lit

This month, two outbreaks took over headlines in a way that feels almost designed to confuse: a hantavirus crisis aboard the cruise ship M.V. Hondius that spread from person to person, and an Ebola flare-up in Africa that—so far—has produced more than 900 infections and 220 deaths.

Even scientists, who have spent years mapping how these viruses usually travel, have been thrown off. The hantaviruses weren’t acting like hantaviruses. The Ebola viruses weren’t behaving like Ebola viruses.

Hantaviruses are carried by rodents and other animals. Typically, they infect people after inhaling dried animal urine and saliva. But on the M.V. Hondius, hantaviruses were moving from person to person—an ability that doesn’t usually belong in the standard story scientists tell about the group.

Ebola has its own script. In Africa. scientists have made major strides in recent years. creating vaccines that can slow the spread of the disease and antiviral drugs that can cure infections. Yet those tools may be weak or useless against the current surge because it is likely a different kind of Ebola than the one researchers have been targeting.

Behind both outbreaks is a deeper problem: the limited way science names and groups the living world of viruses—an enormous “virosphere” that researchers say may contain millions, perhaps even trillions, of virus species.

Jens Kuhn. a virologist who serves on the International Committee on Taxonomy of Viruses. said the outbreaks are case-use examples of why taxonomy matters. “These are case-use examples of why taxonomy is important,” he said. “Is something the same, or is it different?. Well, if it’s different, then stuff we know about the other thing will not work on it.”.

The naming of Ebola itself shows why that warning lands. Ebola viruses were named after the Ebola River. where one of the first documented outbreaks occurred in 1976 in what was then Zaire. now the Democratic Republic of Congo. When scientists examined blood from victims, they isolated long, snakelike viruses distinct from anything previously known.

But 1976 also brought another deadly outbreak hundreds of miles to the east, in what was then Sudan, now South Sudan. Those infected also harbored snakelike viruses. When researchers compared the viral genes, they found a striking number of differences.

Decades later. Ebola outbreaks have occurred dozens of times. and in most cases the viruses resembled either the type first seen in Zaire or the type seen in Sudan. Eventually, Dr. Kuhn and colleagues formally recognized those two kinds of viruses as two distinct species. giving them Latin names: Orthoebolavirus zairense and Orthoebolavirus sudanense.

That still didn’t end the story. In 2007, in the Bundibugyo District of Uganda, 149 people came down with hemorrhagic fevers, and 37 died. The virus they carried was genetically over 30 percent different from the viruses isolated in Zaire and Sudan—enough to define a new species. now known as Orthoebolavirus bundibugyoense.

A second small Bundibugyo outbreak occurred in 2012 before the virus returned this month. The vaccines and drugs developed for the Zaire species don’t work against the Bundibugyo virus. which belongs to a different evolutionary lineage. That’s one reason public health experts are so worried: treatment designed for one Ebola species may fail when the outbreak is driven by another.

Hantavirus naming carries a similar lesson, rooted in geography. Hantaviruses are named for the Hantan River, which flows through North and South Korea. In a region where a mysterious kidney disease struck people every year. researchers isolated the cause in 1978: a virus carried by striped field mice.

Since then, scientists have found hantaviruses lurking in rodents and other mammals around the world. Some cause kidney damage; others strike the heart and the lungs. The personal toll can be sudden and devastating. The actor Gene Hackman’s wife. Betsy Arakawa. died at their New Mexico home last year after being infected with a type of hantavirus called Sin Nombre. Hackman had been diagnosed earlier with Alzheimer’s, and he died days after her.

As hantaviruses adapted to rodents and other mammals across much of the world, they evolved an enormous diversity. Dr. Hoeg and his colleagues recognize 38 species in the genus Orthohantavirus. By comparison, the Ebola genus includes only six species.

Even within a single species, diversity can be fierce. As viruses replicate, strains can pick up new mutations that can drastically change their biology.

The spring outbreak on M.V. Hondius was caused by a species called Orthohantavirus andesense, carried by a number of rodents in South America. But there are four strains of this species, and the outbreak was caused by one called Andes virus. Unlike the other three strains—and unlike the 37 other species of hantaviruses—Andes virus can spread directly from one person to another.

“It seems like there are some mutations that under certain circumstances can make Andes virus person-to-person transmissible,” Dr. Kuhn said. No one knows what those mutations are.

Dr. Kuhn suspects that the other strains related to Andes virus are still out there in rodents and may share the ability to spread among people. After the M.V. Hondius outbreak. he predicted scientists in Argentina and Chile would “go into their freezers with all the samples and sequence the crap out of everything and figure out — what are all these things?”.

Ebola, too, may still be hiding surprises. Dr. Kuhn points to Orthoebolavirus taiense, also known as Taï Forest virus. The first and last time anyone saw this species was in 1994, when it infected a scientist dissecting a dead chimpanzee. She developed Ebola symptoms but eventually recovered. “I’m sure it’s still out there, but nobody focuses on it because it caused only one case,” Dr. Kuhn said. “I think that’s a big mistake.”.

He also suggested that other Ebola-like species that have yet to be discovered and named may be lurking in African animals. The classification system Dr. Kuhn has helped create is meant to make that search easier.

Dr. Kuhn doesn’t expect people to recite Latin names like Orthohantavirus andesense in casual conversation. But he urges a different kind of accuracy when outbreaks are described: instead of referring to the cause of the outbreak in Africa as the Ebola virus. he suggests calling it Bundibugyo virus (pronounced boon-dee-boo-joh).

“The moment you mix up Bundibugyo virus and Ebola virus, the impression will be, ‘Oh, we’ve got something for that,’” Dr. Kuhn said. “But we don’t.”

hantavirus Ebola virology taxonomy outbreak M.V. Hondius Bundibugyo virus Orthoebolavirus bundibugyoense Orthoebolavirus zairense Orthoebolavirus sudanense Orthohantavirus andesense Andes virus