Imagine that pesky tabby cat has been pooing in your backyard again. Unbeknown to you, it has transposed some of the parasite spores “its been” carrying onto your herb plot. Unintentionally, while preparing a appetizing salad, you forget to bath your hands and infect yourself with the Toxoplasma gondii spores. For months you display no evidences, then after six months you are driving your vehicle more aggressively, taking possibilities in street junctions and generally filled with more road rage as you angrily gesticulate with fellow drivers. Could all this be linked to that tasty salad?

T. gondii is a fascinating protozoan parasite which, like numerous same creatures, needs to move between several different emcee species in order to fully develop and photocopy. As such, it appears to have evolved cunning means to see transmission between legions most likely. For speciman, surveys have found that once rats intermediate hosts are polluted they display less forethought towards cats the final stage hosts and so the parasite is more likely to be passed on.

An increasing number of studies intimate humen known to be infected with these parasites could be more susceptible to schizophrenia, bipolar disorder, aggression and even increased suicide. Survey have even intimated “you think youre” two to three times more likely to have a car clang if your blood tests positive for the parasite. This is particularly stunning when it has been was expected that 30% -5 0 %~ ATAGEND of the worldwide person may carry the parasite.

Not so cute when you know what theyre carrying. Shutterstock

Chicken or egg ?

Very often criticisms of these studies come down to a chicken and egg inquiry. Connect doesnt required mean causality. Are those aggressive, fast-driving people or those with behavioural modes more likely to catch the parasites, or does the parasite cause these behavioural traits? Many of the studies were done retrospectively rather than looking at people behaviour before and after they grew infected with the parasites. So for now, we cant was sure whether your road rage certainly was linked to your salad.

What we do know is that there are plenty of examples in wildlife where parasites can manipulate the sex, increment, maturation, habitat and behaviour of their legions. “Hairs-breadth” worms, for instance, ended their lifecycle in a flow or torrent and appear to make their multitudes crickets attracted to irrigate.

The effects of the parasite dont stop there, either. The hapless crickets can provide fish with alternative solutions food generator to their usual diet of aquatic invertebrates and, for parts of the year, can form a substantial part of their food. So manipulating parasites can be important to insisting healthy ecosystems.

Some ant species polluted by trematode flukes are manipulated in a way that establishes them cling to the crowns of blades of grass, which means theyre more likely to be chewed by sheep. This permits the fluke to complete its life cycle in the sheep.

Chestburster. mardeltaxa/ Flickr, CC BY-NC-SA

A type of barnacle parasite known as a rhizocephalan, which gobbles its crab host from the inside out, is known to feminise its male legions by castrating them. Scientists have suggested they are then more likely to look after the parasite sac that abounds through their abdomens, often like a female would tend to her eggs.

Switching on genes

Through advances in molecular biology, we are increasingly works out how these parasites can change behaviour by altering gene show the method genes can be turned on or off. For instance, work in our laboratory at the University of Portsmouth is trying to uncover existing mechanisms that permits a newly discovered species of trematode parasite making such a shrimp-like( amphipods) hosts more attracted to the light.

Trematodes: little blighters. Josef Reischig/ Wikimedia Commons, CC BY-SA

These amphipods would prefer to be hiding under seaweed on our shores, escaping their bird piranhas as the tide recedes. By chemically mapping the brains of polluted shrimp, scientists have discovered that parasites somehow adapted the shrimps’ serotonin, a humor neurotransmitter find throughout the animal kingdom. Our recent analyses have revealed that infected prawns have subtle modifications to their serotonin receptors and the enzymes that create serotonin.

Other contemplates have shown amphipods hosting similar parasites are over 20 periods more likely to be eaten compared to non-infected specimens. Again, this highlights the often-overlooked importance of brain-bending parasites in the natural order of food webs.

We often think we must have discovered all the species possible in well-studied spots such as the UK, but many mesmerizing new manipulating parasites are yet to be discovered on our doorsteps. Our knowledge of how these brain-bending parasites interact with human species will no doubt develop more strongly over the next decade.

Alex Ford, Reader in Biology, University of Portsmouth

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