It’s been in the news. I’ve mostly ignored it. An outbreak of Ebola in Uganda. OK, it’s so highly lethal and typically has an outbreak back in some remote village that it just isn’t much of a problem, really. The village rapidly dies, and that’s it. An effective disease needs high survival of the hosts. (Over time, diseases evolve to become parasites for just that reason. Killing the host is a bad idea…)
In the news today were yet more cases and a bit more worry. I decided to actually read some of the news on it. That lead me to two Very Bad Things. No, I’m still not really worried about it. There are several more hurdles for the bug to cross before it’s a big issue. Still, these things matter.
The first one is that this is a different strain of Ebola than the typical. Ebola is a “hemorrhagic fever”. You bleed a lot from all over. That “signature” makes it easy to spot (so folks get quarantined fast) and it enhances the lethality; so outbreaks tend to ‘burn out’ as they burn through the available hosts faster than they can spread to new ones. This one has much less tendency to present with hemorrhage.
Teams in Uganda are trying to track down anyone who came into contact with patients infected with the Ebola virus, which has killed at least 14 people there this month, authorities said Monday.
“This is very, very important, to trace every contact and to watch them for an incubation period of 21 days,” World Health Organization spokesman Gregory Hartl said.
This month’s outbreak in western Uganda initially went undetected because patients did not show typical symptoms, Health Minister Dr. Christine Ondoa told CNN on Sunday. Patients had fevers and were vomiting, but did not show other typical symptoms, such as hemorrhaging.
The Ebola virus is a highly infectious, often fatal agent spread through direct contact with bodily fluids. Symptoms can include fever, vomiting, diarrhea, abdominal pain, headache, a measles-like rash, red eyes and, at times, bleeding from body openings.
But diagnosis in an individual who has only recently been infected can be difficult since early symptoms, such as red eyes and skin rash, are seen more frequently in patients who have more common diseases, according to the U.S. Centers for Disease Control and Prevention.
Uganda’s Ministry of Health declared the outbreak in Kibaale district Saturday after getting confirmatory results from the Uganda Virus Research Institute identifying the disease as Ebola hemorrhagic fever, Sudan strain.
The fatality rate for those infected with that strain is about 65%, Hartl said.
OK, we’ve got up to 20 days latency, and it’s not showing the typical strong symptoms that cause folks to take appropriate protective actions. It’s learned to spread more effectively… At 65% lethality, it’s a disaster in the making as folks with non-typical symptoms will be willing to interact more with others and / or leave the area of infection (taking the infection with them to other areas).
It still has some pretty rough symptoms and it does require physical contact to spread (not ‘air born’ – however a sneeze in your face is effectively ‘wet contact’; and the admonitions to avoid sexual contact are unlikely to be effective as they never are… yes, ebola can be spread in any ‘wet contact’…). So at this point we are largely dependent on two things to prevent a really horrific outbreak: It requires physical contact and folks who have it are obviously pretty sick. (Reduced from ‘obviously bleeding’ but still a reasonable level of ‘scare symptoms’ exist.) It typically shows up out in the boonies and doesn’t spread fast enough to beat out the lethality rate. (But this strain has 35% survivors and a-typical symptoms so has better spread potential.)
So we’ve got a somewhat higher risk for spreading. How much more is hard to quantify, but from the description of what people did in this case leads me to think we’re in a race condition. Faster spread is in competition with the rate at which folks learn that they need to be extra cautious even with “ordinary” symptoms. And they are not learning all that fast.
Patients with symptoms of Ebola infection had been reported early in the month in Kibaale district.
Some people delayed seeking treatment, in part, because they believed that “evil spirits” had sickened them, according to a report from district health authorities.
Though “seeking treatment” doesn’t do much. There isn’t an effective treatment. But at least it lets the outbreak be identified.
How close are we to spread to an urban center?
Urban Ebola? Why the Latest Outbreak in Uganda Raises Worries
The presence of an infected person in the country’s capital, Kampala, has got the city freaked out — and it could be a rehearsal for the next great pandemic
By Bryan Walsh August 1, 2012
At least one person has made it to a major urban center. Oh Dear.
There is no treatment and no vaccine.
That’s why the latest Ebola outbreak in western Uganda, which has involved at least 20 cases and 14 deaths so far, has received so much attention. According to the World Health Organization (WHO), the outbreak originated in a family in Nyanswiga village in Uganda’s Kibaale district, 140 miles (225 km) west of Kampala, the capital. Such rural outbreaks are not unusual for Ebola — like many emerging infectious diseases, including HIV, it first jumped from primates like gorillas and chimpanzees to human beings, and outbreaks often begin with sick animals. It’s not surprising then that the first infections would often take place in the African countryside, where the hunting and consumption of wild animals is not uncommon, as I discovered when I visited Cameroon for a TIME story last year.
So typically it’s something that pops up in a rural village somewhere from folks using “bush meat”.
What’s got people worried in this case is that one infected patient managed to travel to a hospital in Uganda’s capital, Kampala, a city of 1.5 million people with air connections to the rest of Africa and the world. Although there has been no evidence yet that Ebola is actively spreading in the city, Kampala residents are, to put it simply, freaked out — so much so that people immediately fled the hospital once word spread that an Ebola patient was being treated there. Ugandan President Yoweri Museveni also raised alarm bells when he called on citizens to avoid physical contact to prevent transmission of the disease:
OK, so “one patient” and they are in a hospital so not out kissing friends… except…
The most at-risk group for secondary Ebola infections is actually health care workers, which is why the 20 doctors and nurses who made the journey with the infected patient from Kibaale are in quarantine, just in case they too contracted the disease.
from that CNN article:
As of Monday, two people with the virus remained hospitalized in stable condition, said WHO. One was a 38-year-old woman who had attended to her sister, the medic who died, and the other was a 30-year-old woman who had helped bury another victim.
Though both patients had symptoms that included fever, vomiting, diarrhea and abdominal pain, neither had shown signs of hemorrhaging, the ministry said Sunday.
One patient suspected of being infected with the virus ran away from a hospital Sunday morning, but was tracked to her home and returned to the hospital in Kibaale, Catherine Ntabadde, a spokeswoman for the Uganda Red Cross in Kampala, told CNN in a telephone interview.
“The concern is where she could have gone to when she ran away,” she said.
Note that chain of transmission. A “medic who died” and her caretaker… Those hospital staff are subject to quarantine until such time as they outbreak is over and the incubation period is past. We also have the ‘issue’ of that patient running around for a day or so…
Note, too, that the behaviour of folks was NOT “we’ve been exposed, everyone get into quarantine”; but to ‘run away’ and thus increase the risk of spreading. IF a real urban outbreak happens, it will be rapidly disbursed to other areas.
For more on Ebola (in some technical detail) along with a type description of Ebola Sudan see:
Ebola Sudan Virus (SEBOV)
This is a second kind of species of ebola virus that is believed to have originated in Nzara, Sudan in 1976. The first case of Sudan ebola virus origin can be traced to the cotton factory workers of Sudan who were exposed to the same. The outbreak of Sudan ebola virus has been simultaneous with the outbreak of Zaire ebola virus. The disease also broke out in 1979, 2000 and 2004, most recently. The agent of transmission for Sudan ebola virus is still unknown but it has an average fatality rate.
Not a whole lot is known… That the outbreak happened in a ‘cotton factory’ isn’t all that good. Unless there’s a lot more kissing going on in cotton mills than one might expect, it has the potential for handshakes and sneezes to be modes of transmission. (Or beverage sharing or…) That “agent of transmission of Sudan ebola virus is still unknown” is not particularly encouraging either.
So we have a variation on Ebola that has atypical symptoms leading to better transmission potential, we don’t know the “agent of transmission” very well, it has lower lethality than the 90% of some other strains (so has better opportunities to spread) and it has made it to a major urban center that is 24 hours by air away from everywhere else in the world. Folks who get it or are exposed to it are scattering instead of doing voluntary quarantine and we don’t know how many folks have it and where they all might be.
OK, we’re one patient away from a disaster. Did that one escapee patient infect some others? Will the race condition between the low-symptom virus and education be won by the virus, or not? Nobody knows, and we won’t know for about a dozen days. (Typical incubation). If cases ramp down and education gets a lead, we’re likely done. If cases start to ramp, folks are not getting the message (so worried about ‘spirits’ or asking family to tend them), and / or panic starts a diaspora of carriers; we’re going to find out how this strain does in a Major Urban Center somewhere else in the world.
Pop some popcorn, put on your rubber gloves and face mask, and curl up in the bedroom (alone) with the TV. ;-)
FWIW, I expect this outbreak to be contained. This strain has a couple of new tricks, but I think it has not quite gotten over the hump. It needs a slightly longer incubation with low or no symptoms to be a real problem. If it can slow the onset of significant symptoms to a ‘few days’ while staying infective, it can spread ahead of the “contact trace” fast enough to get an exponential ramp going. As of now, it looks like about linear, so some extra effort on our part contains it. The only open question is how much an urban high density environment enhances the rate of transmission…