Parasite trickery

In honor of April Fool's Day we highlight some of the tricks that parasites play on hosts - not only one day a year, but especially worthy of recognition today

Every year, on April 1, homes, offices and the internet are filled with pranks and hoaxes. Even the most skeptical individuals can be tricked on this day. We thought we’d honor this annual tradition by highlighting some of the most unusual antics that parasites employ to hoodwink their hosts:

  1. The tongue-eating louse: The parasitic isopod, Cymothoa exigua, has an unusual way of life. It lives in the mouth of fish – and actually removes the fish’s tongue, so that it can take its place. The isopod attaches itself to where the tongue used to be and feeds of the host’s blood and mucus. It can be found in several species of reef fishes – both in the Atlantic and Pacific Oceans. It’s quite a disguise!
Isopod parasite (Cymothoa exigua) disguised as a fish tongue. Image from Guadeloupe.
  1. Swimming crickets: Freshwater hairworms infect crickets, but require freshwater to mate, oviposit (lay eggs), and produce infective stages. So how do hairworms get from land-dwelling crickets into freshwater? They actually trick crickets into jumping into freshwater by manipulating their attraction to light. Once crickets are in water, the hairworms emerge. Don’t worry though – the crickets can recover and go on to live long, healthy lives and produce offspring of their own.
  2. Hiding in plain site: Several parasites live within their hosts – but to do so for any period of time, they must develop strategies to evade recognition and destruction by immune cells. Trypanosomes change their appearance by switching the antigens they display, constantly switching surface antigens and avoiding detection. Immature schistosome eggs avoid detection from macrophages through some unknown secretions. There are many strategies to avoid detection and destruction but all allow parasites to evade the immune system while profiting from resources within the host.
  3. Zombie ants: Lastly, we couldn’t not mention the amazing antics of Ophiocordyceps fungal parasites. This diverse parasitic genus infects invertebrates but also alters the behavior of its hosts.  The fungus can manipulate the behavior of ants to increase its chances of being passed on. Infected ants will crawl up vegetation and grip onto stems before the fungus grows fruiting bodies and is released. This helps the fungus spread to new hosts and disperse across the forest.
    Ant with Cordyceps Fungus. Nicaragua. Image credit.


    The tricks that these parasites employ are only a fraction of the amazing behaviors that parasites use to evade host immunity and find ways to spread. Happy April Fool’s Day!

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