Tag Archives: health

Using mosquitoes’ sweet tooth to control Zika transmission

Now that everyone wants to kill mosquitoes that transmit Zika virus, can somebody please make a transgenic plant that expresses mosquitocidal Bti (Bacillus thuringiensis subsp. israelensis) toxins? Just stick the Bti gene behind a phloem-specific promoter so that the protein gets pumped into the nectar. Then when males and female mosquitoes drink (and almost all do), they die. You could then plant acres of the modified plant nearby towns to protect people from Zika (and anything else transmitted by mosquitoes). The beauty of this method is that you could reduce populations of mosquitoes from an area without spraying, and do so for generations if you modified nectar-producing perennials. I know it’s trendy to dislike GMOs (like vaccines), but I think many people would support them under these circumstances.

And yes, apparently Bti toxins can kill adult mosquitoes (including Aedes aegypti), not just larvae. Klowden and Bulla 1984 demonstrated it, for example. And yes, Aedes aegypti drinks nectar (and probably fruit juice).

Of course, even if somebody had the incentive to make such a plant, it could take a decade to wade through the red tape involved in getting non-regulated status from governments. So if you want to do something today, leave out containers of sugar water (10%) that is laced with Bti (e.g., Mosquito Dunks, which you can buy online or at hardware stores). Maybe add something floral to attract them, too. (A review of olfactory cues suggests that imitation cherry and apple can work. If you don’t have those sitting around, I’d wager a few drops of jasmine flavoring or rose water would work, and those are easily found at local stores.) Even if the Bti doesn’t immediately kill the adult, adults sucking up a big sugar meal can transfer the bacteria to water where they lay eggs, and thus eventually cause the death of any larvae that develop. Note that bees and ants might get interested in your sugar water, but the Bti is completely harmless to them.

And if you don’t want to use Bti, there are plenty of articles on using sugar baits laced with insecticides (e.g., Qualis et al. 2013, Junilla et al. 2015). They really can work: mosquitoes absolutely love sugar and will drink up poisons in the process. These are great if you don’t want to use crop dusters to destroy all insects in the area.

If you have kids and want to entertain them, add food dyes to the sugar bait and then challenge them to find mosquitoes with bellies full of sugar water. For older kids that might be amused by actual science, use two dyes to test attractiveness of two different volatiles (or different sugars). It’s probably rare to recapture one right after a nectar meal, but when distended they reveal gut contents nicely.

Colin Purrington Photography: Insects &emdash; White-footed woods mosquito (Psorophora ferox) nectaring on goldenrod

FYI, the photograph above is a white-footed woods mosquito (Psorophora ferox), not Aedes aegypti. It doesn’t transmit Zika, but illustrates to the unbelieving that mosquitoes drink nectar. 

Teaching kids about sugar content of beverages

One out of three kids these days is overweight or obese, and consumption of sugary drinks is a big reason why. Sugary drinks also cause tooth decay (I know, big surprise there), and might even cause kids to be aggressive (or if kids think sugar has that effect, it might have a placebo effect). So I got to wondering what public schools could do … and I think that making a “sugar content” poster in kindergarten is is the way to go. The idea is to construct a display for the hallway or classroom wall that visually shows how much sugar is hidden in common beverages.

This project would fit in perfectly with most state standards (for example, see page 10 in Health Education Content Standards for California Public Schools). And because it includes numbers (of teaspoons), teachers can use the poster content to visually drive discussions about addition and subtraction. If this poster was done in a fun way, the experience might vaccinate kids against over-consumption of sugary drinks for the remainder of their lives. The parallel to brushing teeth might be appropriate: you teach kids how to do it before school … even though the chemistry of decay is beyond their understanding: if you don’t brush and floss, your breath will be nasty and you’ll lose your teeth. Like many health lessons, that’s best taught to young kids.

There are lots of ways to make the poster, but what I like about the one above is that water (no sugar) and plain milk (contains lactose … which is a sugar) are included. There should also be a sampling of common juices (apple, orange, e.g.) because they are loaded with sugar. And just for scale, it might be good to show how many teaspoons of sugar are in a typical bag of candy (e.g., Skittles).

Poster titles matter here, just like they do at a scientific meeting, in that they can provide a take-home message. “Rethink your drink” is a popular title (it rhymes), but I prefer something that confronts the point more directly. Here are some ideas: “Don’t drink dessert all day”, “Don’t drink your dessert”, or “Sugary drinks are candy drinks”. If snark is allowed in your district, then something like, “Sugary drinks are a sweet way to gain weight and rot teeth!” The idea is to be direct and memorable and to not shy away from the point: sugary drinks can (and do!) make kids fat.

If you want some background information relevant to lesson plans on sugar for K-3 levels, here are some resources from BrainPOP. If you’re looking for more examples of posters, here’s a Pinterest board where I collect them:

Pinterest board Educating kindergartners about sugary drinks on Pinterest.

Seasonal plea for informed antibiotic usage

The Centers for Disease Control recently announced that the 2012 flu season is gearing up to be heavy, so I wanted to make my yearly plug for greater clarity in antibiotics names.  Here’s why: according to a Pew study, approximately 36% of adults believe that antibiotics can help treat viral infections.  This percentage, the study contends, reflects a populace that is ignorant and fingers these people as contributors to the rise of antibacterial resistance (they ask their physicians for antibacterials when they have the flu), which is an enormous public health problem worldwide.

Graphic illustrating the types of antibioticsA painfully easy and cheap solution to the ignorance problem is for everyone to stop misusing the word, “antibiotic.”  When people hear the word “antibiotic,” they quite reasonably assume that it describes a drug that is effective against “biotic” thingies (that’s the technical term) and thus might treat viral infections, too.  Indeed, when “antibiotic” was first dreamed up as a word, it meant “anti-infective” (see details in last year’s plea).

Imagine, for example, if the CDC starting using “antibacterial” in all instances when it meant antibacterial.  Doing a search/replace on their website and PDFs could catalyze similar changes across the planet and could lead to a marked drop in the lay confusion about the efficacy of antibacterials on viruses.   Of course, the reply I usually get is, “but everyone knows that antibiotic means antibacterial, plus the medical community has been misusing it for years, and it would be a pain to change.” For all the billions of dollars that are spent on public awareness programs and development of new antibacterials worldwide, a virtually  cost-free switch to a more explicit naming scheme for anti-infectives should be a no brainer. Come on, folks, give it a try.

At the very least, if you poll people about the specificity of antibacterials, try asking, “Are antibacterials effective for treating viral infections?” I’d wager that the percentage saying, “yes” would be about 3%, not 36%.

If you’re on board, here’s printable version of this post’s graphic to print for your patient waiting room: antibiotic-wall-chart (PDF).  Patients who are gearing up to ask for antibacterials will be 90% less hostile when you say “no.” OK, I made up that 90%. You can also leave a stack 8 1/2 x 11″ versions on the counter along with a box of Crayons for the little ones.  Can’t start too soon in fighting ignorance.