Ebola Outbreak In Uganda: Where Did It Come From, And Will It Spread?

ANALYSIS

on July 31 2012 8:05 AM
Ebola Virus
Ebola virus virion. Created by CDC microbiologist Cynthia Goldsmith, this colorized transmission electron micrograph (TEM) revealed some of the ultrastructural morphology displayed by an Ebola virus virion. CDC

At least 14 people have died in Uganda this month following an outbreak of the Ebola virus. Local officials are working with international agencies to contain the disease, but there is still a chance that this easily transmissible virus will continue to spread.

Despite decades of recorded existence, Ebola remains a mysterious affliction; it has no cure, and no vaccine. It tends to flare up sporadically -- years can pass without any trace of the ailment worldwide, but it can kill hundreds whenever it does crop up.

To make matters worse, the current outbreak in Uganda was uniquely elusive. Those who were initially infected did not exhibit the bleeding symptoms usually associated with Ebola, and this slowed diagnosis and response time.

But now, the country is on full alert as Ugandan officials work to contain the disease to the best of their abilities.

Slow Progess

Ebola is a viral disease that results in kidney problems, fever, headache, vomiting and hemorrhaging. Most people who contract the disease die, though some overcome it to make a full recovery.

Survival depends on both the strain of Ebola contracted and the speed of treatment -- in various outbreaks over the past three decades, anywhere from 10 to 63 percent of those infected have made a full recovery.

Researchers around the world are working on treatments for this deadly illness. One of them is Dr. Thomas Geisbert, a microbiology professor at the University of Texas Medical Branch.

"Progress has been pretty significant," he said. "There are candidate vaccines that have been shown to completely protect monkeys against Ebola, and there are also a number of treatments that look promising for treating animals after exposure."

On the other hand, human cases that have progressed beyond the initial stages are still nearly impossible to treat.

"If someone comes into the hospital with a full-blown case of Ebola, they'd get first-rate care. But I don't think there's much that could be done at that point," said Geisbert. "The earlier the treatment, the better."

Mysterious Origins

As medical professionals work to contain the damage and prevent continued transmissions in Uganda, biologists are trying to determine exactly why Central Africa is so prone to Ebola outbreaks.

The key to understanding the source of an infectious disease is to look for what is called a reservoir: a person, place or animal that provides a suitable host environment for the virus to thrive.

Humans, pigs and monkeys are susceptible to Ebola infections, but cannot serve as viable hosts in the long term. They are transmitters, not sustainable reservoirs.

Instead, said Geisbert, "The theory is that fruit bats are the reservoir hosts. The virus can replicate in -- but doesn't necessarily kill -- fruit bats in that particular region."

Monkeys coming in contact with these fruit bats can contract the virus. And when those monkeys are hunted by people, the virus can climb up the food chain and result in a deadly human outbreak.

Crossing the Line

Considering the ease of Ebola transmission and a history of outbreaks in several Central African countries, many are wondering whether the Uganda outbreak poses a threat to other regions of the world. After all, it would be quite possible for a person to contract the virus, board a plane, and land on another continent before ever realizing they were infected.

But considering the fact that there have been several deadly outbreaks in Central Africa over the last few decades with virtually no spillover into other regions, there is little reason to think that this outbreak will spread further.

Central Africa, then, remains the focal point of global concern. There, substandard medical treatment facilities have created extra challenges in battling Ebola.

"Historically, a lot of the outbreaks [in Africa] have been perpetuated by nosocomial transmission," said Geisbert, meaning that Ebola tends to spread among patients and doctors within medical treatment centers.

"But those countries have been better and better," he added, thanks to continued improvements and international assistance.

"I think there's much better infrastructure now then there was before. The key is containing an outbreak and keeping it from getting out of control. So in the United States and in Europe, that would probably be easier to do."

Under Strain

Meanwhile, in the African countries of Gabon, Uganda, Sudan and the Democratic Republic of Congo, hundreds have died in various outbreaks since 1976. The virus comes in several forms, and this makes it even more difficult for researchers to find a single systematic approach to treatment.

There are five known strains of the Ebola virus, each named for the location of their first recorded outbreak.

Ebola-Zaire was the first strain to raise alarm bells in 1976, when it infected 318 people in what is now the Democratic Republic of Congo, killing 280. Another strain called Ebola-Sudan infected 284 people that same year, killing 151. The Ebola-Bundibugyo strain was discovered in 2007 when it infected 131 people in western Uganda and eastern DRC, killing 42.

Another strain, which infected laboratory monkeys in Virginia, U.S., was dubbed Ebola-Reston; it has so far killed no humans. Nor has the Ebola-Côte d'Ivoire strain, though a few humans were infected in West Africa.

Both the Zaire and Sudan strains have resurfaced several times, with the Zaire strain proving the most deadly so far.

The virus currently infecting people in Uganda has been declared by the Ministry of Health to be of the Sudan strain. The fatalities-per-infection rate for this strain stands around 65 percent.

Quarantine

Compared to other outbreaks of recent years, the situation in Uganda remains fairly under control -- it remains to be seen whether the situation will worsen.

"This particular outbreak, it's too early to say how large it'll be. It'll take more time to make a good assessment on it. But in general, these outbreaks have been really well-contained, and containment is really the key," said Geisbert.

Ugandan President Yoweri Museveni issued a public service announcement via special broadcast on Monday, urging citizens to take every precaution against the spread of Ebola.

"Ebola spreads by contact when you contact each other physically. ... Avoid shaking of hands, because that can cause contact through sweat, which can cause problems," he said.

"Do not take on burying somebody who has died from symptoms that look like Ebola -- instead call health workers because they know how to do it."

The Ugandan Ministry of Health is working to track down anyone who has had contact with infected individuals, and those showing symptoms have been rushed to quarantine stations. If these efforts are successful, this Ebola outbreak could yet be staunched before it claims more lives.

But this will be challenging in coming days, with many people likely to avoid treatment and some practitioners failing to adhere to protocol in their interactions with infected individuals.

"I appeal to you to first of all report all cases which appear to be like Ebola," Museveni said. "When you handle this case well you can eliminate Ebola quickly."

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