Zombie worms: How parasites hack into the minds of their hosts

The animal world is full of incredible stories, from adventure, romance to tragedy. Recently, however, scientists at Brown University uncovered a creepy new story involving worms that manipulate the genome of their shrimp hosts to take over their minds. The discovery adds to a growing body of research on parasites that can control the behavior of their hosts.

The phenomenon of parasitic mind control is not new. For example, the cordyceps fungus infects ants and manipulates their nervous system, causing them to climb to a high vantage point and cling to a leaf. From there, the fungus germinates spores and infects more ants. Similarly, parasitic wasps can “zombify” spiders, causing them to build a special spider cocoon for their larvae.

Of particular interest is the parasite Levinseniella byrdi, which can only reproduce in the intestines of some species of wading birds. However, before settling down and starting a family, this worm goes on a journey. Its eggs enter the environment through bird droppings and are then eaten by sea snails. The larvae develop inside the snail and then emerge and swim in the water column until they enter the gills of a harmless crustacean, the amphipod.

Amphipods are usually fearful creatures, hiding under vegetation and with dull coloration. But once infected with L. byrdi, they undergo a remarkable transformation. Infected amphipods change their color to bright orange and become more daring, preferring to stay in the open. These changes make them more vulnerable to birds of prey – exactly what the worm needs to complete its life cycle.

In a recent study at Brown University, scientists have figured out how L. byrdi manipulates the biology of its host, the amphipod. Using RNA sequencing, they identified genes in the amphipod genome that correspond to changes caused by the parasite. They found that the worms activate pigmentation genes, disrupt the host’s ability to detect external stimuli, and suppress immune response genes that normally fight the parasite.

While these studies are interesting in their own right, their implications go beyond simply understanding the intricacies of host-parasite interactions. David Rand, one of the study’s authors, emphasizes that this knowledge could help in the fight against human pathogens. “Characterizing the molecular mechanisms of manipulation is important for advancing our understanding of host-parasite coevolution,” he explains. Studying how parasites manipulate their hosts may provide valuable insights for the management of pathogens affecting humans.”

The study, published in the journal Molecular Ecology, sheds light on another example of the unusual ways in which parasites can control their hosts. By unraveling the molecular mechanisms underlying these manipulations, scientists hope to further understand host-parasite coevolution and develop strategies to combat human infectious diseases.

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