3D tech uncovers parasite behaviour

A PARASITE THAT CONTROLS the brain of its host organism and causes its eventual demise? You’d be forgiven if you thought this was the plot of the latest blockbuster horror film.

For farmers, this phenomenon exists outside the movies and has very real impacts.

One of the most widely recognized parasites, organisms that live on or in a host, is Dicrocoelium dendriticum (D. dendriticum), a liver fluke whose infective stages are mainly found in ant abdomens, with one or two invading the ant’s brain. The parasite causes unusual behaviours, such as making the ant cling to vegetation that is eaten by animals, including cattle and sheep. This can have a devastating impact, as consuming the parasite can cause the livestock animals to develop liver diseases and a host of other issues that are difficult to diagnose and treat, which costs farmers time and money.

While common and well studied, the D. dendriticum parasite’s methods have eluded scientists as they attempted to diagnose how exactly it influenced the ant’s behaviour. This is in part due to the fact that there were no effective ways to inspect the ant.

Thanks to a breakthrough in his work, Dr.

Douglas Colwell, a research scientist at Agriculture and Agri-Food Canada, was able to see that D. dendriticum was manipulating the ant’s behaviour through a visual scan of the ant’s brain.

“This was a good example of how science should work — discussing ideas with colleagues, following our instincts wherever they take us, and in this instance, making a discovery,” said Colwell.

Using modern micro computed tomography (micro-CT) scanning, a non-invasive imaging tool, Dr. Colwell, along with colleagues at the University of Lethbridge and the Natural History Museum in London, England, created virtual three-dimensional (3D) models of the ants infected with D. dendriticum that showed the precise location of the parasite in the ant’s brain. They also showed that the parasite grabs onto a portion of the nerves that control the ants’ jaw muscles.

The discovery is expected be a big help to scientists in understanding how the parasite works and how they can potentially alter its destructive behaviour. Researchers can also use the findings to develop similar scanning technologies to study a wide range of animal and insect parasites.

[SUBMITTED] A) Illustration of the lifecycle of Dicrocoelium dendriticum, image from the CDC (Centers for Disease Control and Prevention). (B) Schematic illustration of the setup used to scan specimens.