In the animal world, zombies are not creatures drawn from the imagination. Some pathogens are able to take over the brain or body of their hosts to get the most out of them.
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Zombie rats attracted to cats
The Toxoplasma gondii is a species of intracellular parasite that infects up to a third of all humans worldwide, as well as most mammals and birds. It causes a disease called toxoplasmosis.
The vast majority of infected humans and animals show no symptoms, with the exception of mice and rats. The parasite has the effect of suppressing the innate fear that rodents have towards cats. Mice and rats then become attracted to the scent of the feline they normally flee from.
Research suggests that it is an evolutionary adaptation intended to help the Toxoplasma gondii complete its life cycle. The parasite reproduces only in the intestine of the feline, when the latter eats the infected rodent.
“How this pathogen changes the behavior of rats and mice is not fully understood, but it is known that they engage in risky behaviors that make them more susceptible to being chased by cats,” says the biology professor. at the University of Ottawa, Allyson MacLean.
“Researchers have suggested that the parasite alters regions of the brain of infected rodents, including the region responsible for sexual attraction, and causes attraction to cats,” adds the president of the Association des microbiologistes du Québec, Marc Hamilton. .
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Studies have also linked toxoplasmosis to behavioral changes in humans, according to a published article in the scientific journal Nature. People infected with the parasite would be more at risk of having a road accident, for example.
People with schizophrenia would also be more likely than the general population to have been infected with Toxoplasma gondii.
Zombified frogs turned sex beasts
A fungal disease that attacks amphibians all over the planet might spread by making the mating calls of infected males more attractive to females.
pathogenic fungus, Batrachochytrium dendrobatidis (Bd), causes chytridiomycosis (also called chytrid fungus disease), which kills amphibians by destroying their skin, disrupting their immune system and causing heart failure. It poses a threat to a third of frogs, salamanders and other amphibians worldwide.
Stan Behal/Toronto Sun/QMI Agency
And according to research carried out in South Korea on tree frogs, the fungus facilitates its spread by manipulating the behavior of infected individuals.
Frogs that contract Bd normally become lethargic, but males seem to react differently to it. The disease would rather improve their reproductive success. By attracting more females, he infects his mate, who in turn infects his offspring.
Suicidal Crickets
Nematomorphs are worms present in all aqueous environments and parasitize different jumping insects, such as crickets. They are nicknamed “body thieves”.
During their development, the nematomorphs pass in a few weeks from a microscopic stage to a gigantic worm compared to the size of the host. When they reach maturity, they must reach the water to reproduce.
“The worm manages to manipulate the crickets into jumping into the water, which becomes suicidal for them, as they are afraid of water. They end up drowning because they can’t swim,” explains Marc Hamilton of the Association des microbiologistes du Québec.
Ladybugs enslaved by a wasp
A parasitoid wasp native to Quebec uses spotted ladybugs as surrogate mothers. During the laying period, she stings her to inject her eggs into her abdomen before fleeing.
MIKE DREW/CALGARY SUN/QMI Agency
The egg hatches in the ladybug and feeds on its body without killing it. The wasp larvae will grow inside her, then extricate themselves from her body regarding twenty days later, ”said Mr. Hamilton.
But once released, the ladybug behaves strangely. Rather than running away, she will play “bodyguard” with the cocoon for six to nine days. “The ladybug takes care of the larva outside its body as if it were its child,” adds the microbiologist.
Research suggests that this manipulation is due to a ribonucleic acid (RNA) virus, which causes neurodegeneration in the ladybug and then paralysis.
Up to 70% of ladybugs would survive the parasite, and 25% would return to normal behavior following the departure of the young wasp, according to biologist Jacques Brodeur who studied the organization of this parasitoid wasp.
