(No pun intended)
This just sucks:
As cholera rampages through Haiti, some epidemiologists are warning that the country could face more than half a million cases over the coming year. Yet tracking and treating the disease is proving increasingly difficult as civil unrest grips the county.
As if Haiti hasn't already suffered enough. Vibrio cholerae, the bacterium that causes the disease is transmitted in contaminated water, and can divide rapidly in the digestive tract. The bacterium causes disease by secreting cholera toxin, a group of proteins that hitches a ride into the cell, sneaks itself into the cytoplasm, and then sets to work giving the poor unfortunate host massive diarrhea.
The mechanism for this is deviously ingenious.
In order for a cell to maintain the proper balance of water and salt in the cell, there are several receptors and pumps that detect subtle changes and turn on and off according to cues in the environment. Cholera toxin upsets this delicate balance by blocking the ability of one of these receptors to turn off, causing affected cells to release loads of ions into the intestine. And where ions go, water follows. The diarrhea seems to be the main point of all this effort - it gets bacteria into the water supply to infect a new round of hosts.
The worst part of an epidemic like this is this disease should be the easiest thing in the world to treat and prevent. People die of dehydration, and the principal method of transmission is contaminated water, so all you need for prevention AND treatment* is clean water. But Haiti's infrastructure was bad before the earthquake, and now there's just no way to get clean water to the thousands of people affected. Death rates for most outbreaks can be kept below 1%, but Haiti had a death rate around 9%. Efforts by aid groups had gotten it down to ~4%, but then:
That gain, however, has been wiped out by riots that were fanned by rumours that Nepalese UN peacekeepers were the source of the outbreak. The row over the source has been self-defeating, says Jon Andrus, deputy director of the Pan American Health Organization (PAHO), the regional office of the World Health Organization. With many of the sick unable to get past roadblocks to reach treatment centres, and deliveries of supplies held up, death rates have again soared past 9%, he says[...]
Last week, PAHO announced that the epidemiology suggested that 200,000 more cases could be expected in Haiti over the next year, but Andrus says that more recent estimates are likely to raise that figure to more than 500,000.
We really need to get those oral vaccines online, like yesterday.
*Re-hydration is usually sufficient - if you can keep the patient alive long enough, the infection will usually clear on its own, but sometimes intravenous saline is required since dehydration can occur so quickly.
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Sounds like they could use some Life Straws!
There are far too many people in the world - we should stop wasting resources trying to fight the inevitable self-correction unless those in receipt of aid agree to embrace contraception and sustainability.
Thanks for the concise explanation of how the bacteria actually causes diarrhea!
As far as vaccination, a cholera vaccine does exist, but the problem isn't just administration - although, as you say, a vaccine that could be taken orally would be great. NPR's Richard Knox explains why a cholera vaccine might not be very useful in Haiti. Adults have to get two doses and children three, which would be challenging logistically, and then it takes a few more weeks for immunity to develop. There may not be enough doses of the vaccine available, even if a large-scale campaign were mounted. And such a campaign would probably take resources from the current treatment efforts and prevention campaigns - which, since they emphasize hygiene promotion and clean water, can help prevent transmission of other diseases, too.
That doesn't mean a cholera vaccine is totally off the table in Haiti, but it might not be what health officials want to emphasize in the initial response phase.
@ Vince - As a share of resource consumption, I'd be willing to bet that you're more costly than 100 Haitians. If you're so worried about sustainability that you'd be willing to let people die, I think you're better off killing yourself.
@Liz - I agree completely, I didn't mean to imply that a vaccine could effectively contain the outbreak in Haiti. Right now, the easiest thing to do (which is not to say it's easy!) would be to get clean water to people.
Vince, might I suggest you consider the following website: http://www.vhemt.org/
In addition, you might want to consider one of the reasons Bill Gates has for supporting vaccination in poor countries. He believes that if you vaccinate infants and lower their mortality rate then you actually lower population growth as their parents are now more confident that they will survive and therefore have fewer children.
Ya geçen hafta oyuncuların da bol olduÄu bir masada sohbet muhabbet derken, ciddi ciddi Ezelâin senaryosunun deÄiÅtirilip 8â²i yani Kıvanç TatlıtuÄâu yeniden diriltmeye çalıÅtıkları konuÅuluyordu.
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Ben refleks olarak öyle bir âYok artık, çüÅ!â demiÅim ki, masadakiler irkildi. Evet evet vallahi yanlıŠduymadınız. Ezel âin reytingleri düÅtüÄü ve seyirci Kıvanç TatlıtuÄ, yani 8â²i dizide görmek istediÄi için senaristler de onu diriltmenin yollarını arıyormuÅ. Ah ah vallahi dönerse çok büyük kahkaha atacaÄım. bende :)
It's nice to see someone routinely posting interesting, fun and engaging science at science blogs. It nearly always used to be that way, but it's become harder to find anything other than tedious ranting lately, espcially after a lot of the solid science bloggers, such as Yong, Switek, and Chu-Carroll left. I don't mind a good rant now and then but when it becomes prevalent rather than incidental, it's boring. Please keep up this great blogging. You obviously enjoy your work and it shows in everything you post.
Ian - that's probably the nicest thing you could have said to me, and it absolutely made my morning. It's been a rough few days (more on that later), and reading this has been a wonderful tonic. Thanks for reading and commenting, and if I ever get tedious or boring, please don't hesitate to call me on it.
My next post might just be a rant, but I promise I won't make a habit of it. Feel free to skip it, and forgive me for indulging, but I need some catharsis. If you do read it, I hope you'll understand.