An effective intervention against dengue fever
June 10, 2021 9:41 AM   Subscribe

A pivotal mosquito experiment could not have gone better. A microbe which stops mosquitoes from spreading the virus that causes dengue fever was previously tested in Australia. In a recent experiment in Indonesia, it reduced the number of dengue hospitalizations by 86%. Previously.
posted by russilwvong (21 comments total) 33 users marked this as a favorite
 
Wow! This is really great news - and the article is very well written, making the experiment and its results clear and easy to understand.
Dengue fever is caused by a virus that infects an estimated 390 million people every year, and kills about 25,000; the World Health Organization has described it as one of the top 10 threats to global health. ... People who recover from one serotype can still be infected by the other three; if that happens, they’re more likely to develop severe and potentially lethal symptoms.
The dismaying thing is that they've only been able to start work on such a small area so far. I know things take time, but I wish they could scale this up to cover the world within a year or two. It seems so promising:
Wolbachia also seems to work against the other diseases that Aedes aegypti carries, including Zika and yellow fever.
This is really fantastic news, russilwvong. Thank you so much for sharing it with us!
posted by kristi at 10:51 AM on June 10 [5 favorites]


Ed Yong's I Contain Multitudes (strongly recommended) included a chapter on the early phases of this research. It's fantastic news that initial promise is being borne out, and I bet he's delighted to be able to pass along the news in this followup.
posted by Drastic at 10:55 AM on June 10 [4 favorites]


This seems a lot easier in the long run than the strategy being tested in the Florida Keys where they are releasing genetically modified male mosquitoes in an attempt to basically eliminate the whole mosquito population by preventing them from reproducing. I'd have no problem with that if it weren't for the wildlife that eats the damned things having a decent chunk of their food supply cut off.

Perhaps still worth it, but not so much if there are alternatives as described in the article. When possible, it's always better to choose the path with fewer side effects.
posted by wierdo at 12:22 PM on June 10 [1 favorite]


I'd have no problem with that if it weren't for the wildlife that eats the damned things having a decent chunk of their food supply cut off.

The Aedes aegypti mosquitoes affected by the Florida GMO mosquito project (and this dengue fever intervention) are not native to the Americas (or Indonesia). And while the dengue intervention is extremely promising, eliminating the invasive mosquito population outright would also control yellow fever, Zika, and several other A. aegypti-borne illnesses.

The GMO approach could also pave the way for eliminating the Anopheles mosquitoes that carry malaria. Even outright elimination in their native ranges may not have a significant effect on the ecosystem, since no known species predated on Anopheles exclusively, and evidence suggests that removing Anopheles would just lead to an increase in other, non-malarial mosquito populations.
posted by jedicus at 12:33 PM on June 10 [17 favorites]


TFA is highly optimistic! You would never guess from TFA what a complex collection of things is contained in the bin labeled Wobachia, nor at the range of effects that Wolbachia infection produces in different kinds of hosts, or at the range of organisms Wolbachia can infect.

You would not know, for example, that Wolbachia infection is part of the life cycle of the worms that cause river blindness or elephantiasis, or that some strains of Wolbachia actually enhance the transmission of some pathogens by some mosquitos. Or that Wolbachia strains infecting fruit flies in California have mutated in the wild to enhance rather than suppress the reproductive capacity of said flies.

The kind of ecological engineering described in TFA never does just one thing, and while that's not in and of itself a reason to argue against deploying the strategy in TFA at scale, it would be well to wonder what sort of unintended effects it might have. Previously-innocuous nematodes becoming the next river blindness? Can it infect bees? Those are just the first two questions that occurred to me.
posted by Aardvark Cheeselog at 1:01 PM on June 10 [8 favorites]


Is Wolbachia only specific to this species of mosquito? If not, there could well be unintended knock-on effects on insect populations outside of this particular mosquito that support a broader ecosystem — and said populations are collapsing across the board. Dengue and other viral diseases that are spread by Aedes aegypti are terrible, but my scientific training leads me to larger questions about this approach.
posted by They sucked his brains out! at 1:03 PM on June 10


Here's the dengue fever ep from my very favorite podcast - This Podcast Will Kill You. Yes, I'm a public health geek.

bonus ep on river blindness, including the importance of Wolbachia.
posted by gingerbeer at 1:13 PM on June 10 [1 favorite]


Here in Hawai‘i we have the perfect natural laboratory for testing this stuff. There are no native mosquitos AND mosquitos have been responsible for the absolute devastation of native birds (due to Avian malaria). Sadly, there seems to have been a lot of heel-dragging (as well as a lot of public fear and mistrust of anything "GMO", even for solutions that don't actually use anything genetically modified).
posted by deadbilly at 4:36 PM on June 10 [2 favorites]


wow wow wow this is great news.
posted by bluesky43 at 7:07 PM on June 10


I'm glad that people in the comments are talking about the potential knock-on effects, because I wondered about them but had no idea how to start researching it.

This may be a profoundly dumb question, but how did mosquitos get to places like Hawaii? When did they arrive?
posted by rednikki at 7:12 PM on June 10


and evidence suggests that removing Anopheles would just lead to an increase in other, non-malarial mosquito populations.

Is this where I get to write (in best Jeff Goldblum imitation possible):

"Life, uh, finds a way."

(I mean: great news, really. But unintended consequences, etc. Best to be cautious.)
posted by Insert Clever Name Here at 7:26 PM on June 10


i think the question is not whether this bacteria approach does or does not have bad side effects, but whether the risk of that is lower or higher than other solutions like pesticides. or accepting the human toll from the disease.

if the last year has taught us anything, it's that everything has risks, everything has costs, everything is a tradeoff. there is no such thing as perfect knowledge of the entire ecosystem in advance of doing something. if we can eradicate dengue without obvious risks (like spraying tons of insecticide), then we should.
posted by wibari at 9:14 PM on June 10 [7 favorites]


I'd have no problem with that if it weren't for the wildlife that eats the damned things having a decent chunk of their food supply cut off.

What? Who says this? My understanding is this is a species we've (well, biologists, zoologists) identified we can remove here and it will make the world a better place for humans and fauna alike. Like they aren't important in the food chain or anything.

Why not make this niche open for better mosquitos to fill?
posted by floam at 7:26 AM on June 11


Are you a mosquito, weirdo?
posted by floam at 7:32 AM on June 11


how did mosquitos get to places like Hawaii? When did they arrive?

On the first ships from elsewhere. Nowadays, via airplanes.
posted by Rash at 8:29 AM on June 11


In Australia they poison cats because they are an invasive species. I won't describe the methods because "killing cats" is probably not what anyone is here for and they are disturbing if you like the furry things at all. But, yeah, feral cats wreak havoc on local life and that's what you need to do. (To be clear, I'm typing this while my sweet feline sits on my lap.)

Similarly, A. aegypti was brought to most of the world by European colonists. For example, the Caribbean was infamous for its mortality rate due to yellow fever and malaria, but neither of those diseases existed there until after the Europeans arrived.

This mosquito a deadlier and way less charming pest. Caution is worthwhile, but if I'm not protesting cat eradication I'm definitely not sticking up for those bastards.
posted by mark k at 9:02 AM on June 11 [2 favorites]


Pre-pandemic I spent a lot of time in an area where dengue is endemic. Like a couple years ago people to the left, right and above me were catching it. A couple were evacuated to hospitals elsewhere, one was given last rites after getting it for the third time. The current fix is monthly fogs with DDT, not an ideal solution when so much of life there is al fresco so this is very welcome news.
posted by TWinbrook8 at 11:20 AM on June 11 [2 favorites]


What? Who says this?

You're talking past each other a bit. The difference is that the op's comment assumes we're removing ALL mosquito species from the area rather than just one, non-native species (I had also misread TFA in the same way).

Removing ALL mosquitoes is almost certainly a bad idea. But targeting one specific species, especially one that's invasive to the area sounds like a win provided the side effects aren't too bad. It just didn't occur to me that this method would work to ONLY target a specific species which is super cool!
posted by VTX at 11:58 AM on June 11


Also: this isn't removing the species. It's introducing a deliberate change into that species' microbiome that prevents them from carrying/transmitting dengue. They'll be sucking just as much blood as ever, but if it continues to work, that's suddenly an unpleasant annoyance rather than, you know, the death and immiseration of millions of people across generation after generation. That's a really important part of the risk analysis and tradeoffs that it's tragically easy for people not in affected areas to forget.
posted by Drastic at 12:13 PM on June 11 [1 favorite]


this isn't removing the species

Correct, not by this intervention. But a tangible solution for e.g. malaria, dengue fever that I think we are on board with is making these disease-carrying mosquito species locally or even globally extinct, perhaps best done via a gene drive. I'm all for biodiversity but fuck viruses, parasites, insects that cause human suffering at a scale even other humans have not rivaled, if it won't have serious repercussions. (And yes, of course Mother Earth will shake us off like a bad case of fleas when we go extinct. Until then...)
posted by floam at 1:47 PM on June 11 [1 favorite]


TFA is highly optimistic! You would never guess from TFA what a complex collection of things is contained in the bin labeled Wobachia, nor at the range of effects that Wolbachia infection produces in different kinds of hosts, or at the range of organisms Wolbachia can infect.

Everything I know about Wolbachia I learned from Metal Gear Solid 5 but based on that lesson I can only say: the rest of your comment is less complex and weird than I expected based on what video games taught me.
posted by pwnguin at 1:47 PM on June 11


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