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Dengue and Wolbachia

June 8, 2012

So NPR has discovered the work of Scott O’Neill, and colleagues around the globe, to fight Dengue fever (also known as breakbone fever) by releasing mosquitos. Dengue is a painful viral flu-like disease now spreading from the tropics, thanks to global warming, which brings the mosquitoes north–France had its first case last year.

But why release mosquitoes? The mosquitoes are infected by an intracellular microbe called Wolbachia. This excerpt from my textbook explains how Wolbachia bacteria infect a different invertebrate, the filarial nematode that causes elephantiasis. Wolbachia have tiny genomes that shrink even more when the bacteria become ensconced in an invertebrate host, where they provide key amino acids while obtaining just about everything else from their host cells. Because of Wolbachia, we can treat elephantiasis with antibacterial antibiotics–the host invertebrates actually depend on their endosymbionts.

In insects, Wolbachia has all kinds of weird behavior, such as altering the sex of the offspring of infected eggs. In the mosquitoes that carry dengue, the behavior is less clear.  Dengue fever is caused by a virus. How does Wolbachia exclude dengue  virus?  We don’t know, but apparently the exclusion is reliable enough that populations of Wolbachia-infected mosquitoes are free of dengue.

In The Highest Frontier, dengue is what Jenny was afraid of getting from the invading mosquitoes. And release of engineered mosquitoes was one proposal to address them. No doubt we’ll be hearing more about mosquito release in the future.

Which pests would you like to engineer for release, and why?

  1. June 8, 2012 10:45 am

    Fascinating. I hadn’t known that. Thank you. My husband is a microbiologist, specialized in virology, but retired now these 30+ years and the world has changed. But this I shall share with him; I know he’ll like it. He still carries on about the damage DDT did to crops near his hometown in the Andes, because the mosquitoes carried a virus that kept the citrus healthy — not unlike what you describe here. And your comments like this add to my enjoyment of The Highest Frontier.

  2. heteromeles permalink
    June 8, 2012 10:51 am

    If there’s ever a decent tie-in between lack of metazoan intestinal parasites and autoimmune diseases like asthma, I’d definitely vote for some relatively harmless tapeworms or hookworms.

    Otherwise, I’ll should note that mosquitos (especially male mosquitos) are primary pollinators for a number of plants, including some fairly rare orchids. The females need blood for reproduction. They aren’t all bad.

  3. heteromeles permalink
    June 8, 2012 11:44 am

    Related fun: I don’t know of any animal parasites that pull this particular trick, but they might be out there.

  4. fari permalink
    June 8, 2012 3:57 pm

    During the last month in the east cities of Iran( near Afghanistan and Pakistan) 4 or 5 people were killed by Dengue fever, among whom there was also a young physician.It is said that because of high price of red meat due to sanctions on Iran ,smugglers are busy with unlawful import of meat from Afghanistan.The government rather tries to stop the spreading of the news than the disease itself. Some information tells to freeze red meat for 48 hours and then cook it.Sheep stations have to use insecticide and I doubt if it is taken seriously enough.

  5. Jonathan Cole permalink
    June 8, 2012 4:00 pm

    The ticks could use some reprogramming. Perhaps they could be altered to find the taste of humans absolutely repulsive.

  6. SFreader permalink
    June 8, 2012 9:43 pm

    Maggots are already being used by some medical practitioners to remove gangrene safely and with less scarring than other alternatives. Would be great if maggots could be reprogrammed to go after solid cancer tumors and/or polyps within the body.

    Tape worms as a biological alternative to the gastric band/bypass surgeries that have become quite popular but which apparently have quite a few unpleasant side-effects. Or, to make this more sci-fi, biologically reprogram tape worms to preferentially digest specific problem sugars in order to help balance insulin levels.

    • JamesPadraicR permalink
      June 9, 2012 1:06 pm

      Fly larvae (sounds better than Maggots) have been used to remove dead flesh from wounds for centuries, not always intentionally. A Napoleonic War era doctor noticed that wounded soldiers with larvae healed better and sooner than those without. It’s only in the last couple decades that it has made a comeback. They’re used in part because they don’t burrow into live flesh, and only eat the dead.

      Leeches have also returned to doctors repertoire, often put on the fingertips of reattached hands to prevent build-up of blood (iirc).

  7. June 9, 2012 6:01 pm

    I’d like to make mosquitoes that act as a hostile environment to malaria and West Nile virus and have their population established here in California before climate change makes those a bigger threat around here…

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