October 23, 2010

MALARIA KILLING MORE PEOPLE THAN WE THOUGHT?

Malaria has always been one of humanity’s biggest killers, but it may be far bigger than we realised. An unprecedented survey of the disease suggests that it kills between 125,000 and 277,000 people per year in India alone. In contrast, the World Health Organization puts India’s toll at just 16,000.

Other countries using similar accounting methods, such as Indonesia, may also be underestimating deaths from malaria. That means it could be killing many more than the WHO’s official estimate of nearly 1 million people a year worldwide, suggesting more money should be spent to fight it.

It’s too bad the malaria eradication efforts were allowed to fail.

UPDATE: Reader Kevin O’Brien writes:

Glenn

Just FYI I am a contractor for USG working on novel-pathogen preparedness issues. This contract has caused me to dig deep into the books (my background is not in biology, but as a Special Forces operator, and my education is in history and business, undergrad and grad). The problem is: eradicating diseases is a very very brutally difficult thing to do. Most bacteriologists, virologists and parasitologists will tell you that in the end-game that they see, the bugs might well win. And malaria is a bastard of a hard pathogen to eradicate.

First, these things are organisms and Ma Nature disinclines them to shuffle gently off the world stage. They adapt and mutate. What we see as extermination forces, the organism experiences as environmental pressures, to which its response is selective adaptation. In other words, we have to hit it hard as the hammers of hell or there will be survivors who may have a survival trait that breeds generations we can’t kill. (True, this is more a problem with fast-mutating viruses, say, than it is with a more complex parasite like plasmodium. But the same principles are at work in all organisms, just at different velocities).

Second, most of them have multiple hosts. That means that even if we get them out of the human population we need to persistently inoculate and/or treat every new cohort of humans, or the thing comes roaring back from its reservoir in other animals (where it may be benign). We were able to eradicate natural smallpox with a combination of surveillance and inoculation, but it took 20 hard years of international effort, and variola major has no other host than humans. (This is a double-aged sword: it means if we can kill off the virus in humans, we’ve made it extinct in nature; but it also means we haven’t had usable animal models for it until recently, when bioterror concerns motivated some research). Of course, one problem now is that no one has immunity any more, but stocks of the virus still exist, and it’s also possible in theory to synthesize it in the lab, since its genome has been published. Pleasant thought, eh? An engineer rebuilding it might even decide to alter it for greater pathogenicity, or resistance to attack by the antibodies created by current vaccines.

Third, eliminating one organism may create an evolutionary, life-niche vacancy that becomes an opportunity for a new parasite or pathogen. This is true not only of the pathogen itself, but also of its vectors or non-human hosts, if that’s where we choose to attack it.

Yeah, the best way to attack plasmodium is probably to attack the mosquito that’s its vector (from a human standpoint) and its host for a key part of its life cycle. And the best way to attack the skeeter remains that vilified molecule, DDT. But eliminating a human scourge has only been done once — variola — and it’s only been done because of that germ’s peculiar vulnerability as a human-only pathogen.

You know, back from its kickoff in 1959 through the US entry in 1965, the smallpox eradication program almost didn’t start, because a previous malaria-eradication effort failed. There was also cold-war politics: the USSR favored eliminating smallpox, but the USA was focused on malaria. But the malaria eradication effort (even with DDT) choked, and people were not willing to try another eradication program… but somebody talked LBJ into backing it, and when the US swung around to agree with the USSR on eradication targets, the world as a whole was able to beat this monstrous plague. In 20 years of massive effort.

If you want to learn about the smallpox eradication project, you’re in luck. The guy that ran the project was an American from CDC, D.A. Henderson, and he’s written a great, readable book on the subject, Smallpox: Death of a Disease.

Here’s a Smithsonian article about him:

http://www.smithsonianmag.com/people-places/henderson.html

There’s a list of his academic publications on this page. As you see, his interests span a much wider range than just smallpox.

http://faculty.jhsph.edu/default.cfm?faculty_id=306

And he’s also discussed at length in Richard Preston’s The Demon in the Freezer. I make new guys on our project read all of Preston’s bio-hazard stuff. Not like it’s a hard penance, Preston’s a compelling writer.

Finally, if you want to look at malaria in particular, some of the difficulties are brought out in a July 2007 National Geographic article that’s available online.

Now, Henderson himself has come to believe that further eradications are not possible.

While I understand and respect his reasoning, I still support eradication efforts for reasons that I know you understand. We cannot decide to shrink from massive tasks because we might fail. (Cue the Stripes Pearl Harbor speech….) But we need to be aware of how we might fail, and what victory short of pathogen extinction looks like. Because we can’t work to eradicate all pathogens at once: we need to prioritize our work. And certainly, probability of success has to be part of that prioritization. I think malaria is a good next target, but it’s a dreadfully hard one.

Remember when you say, “faster, please,” there’s a lot of really good people out here pedaling as fast as we can. One thing we sure could use is more young Americans taking up hard sciences. I expect a lot of progress from molecular biology as the cost of DNA/RNA sequencing drops, the speed increases, other molecular analysis tools open up, and human knowledge and bioinformatics capability expand. But there’s always room for more smart folks in biology. I’d sure rather see the kids here in this field than mired in the law-school bubble, destined for hating life on doc review in a basement somewhere on a case where only the litigants care about the outcome.

Indeed.

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