mind CONTROLLING parasites
Parasitologists study parasites wherever they occur and whether they are viruses, bacteria, worms or insects. Parasites are organisms that use other species of plants and animals as hosts. The hosts provide the environment in which the parasite lives. In the history of life on earth, the parasitic lifestyle has been incredibly successful; in fact, the number of species of parasites exceeds the number of free-living species. It is no wonder that parasitology is a diverse field. Parasitology is a dynamic field because the relationships between parasites and their hosts constantly are changing.
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If Tom & Jerry taught us anything, it's that cats and rodents typically don't get along. In fact, rats inherently know the smell of cat and run from it like their lives depend on it (because, well, it does).
Sneaking Medicine into the Brain :
infected stickleback
A kingfisher (a waterbird) catching a stickleback fish
Euhaplorchis (Dance for Me) californiensis:
Like several other parasites on this list, the parasitic worm Euhaplorchis californiensis has several hosts. The worm's life begins in the horn snails found in the salt-water marshes of Southern California. Inside of their sterilized hosts, the worms produce several generations of offspring, which then leave the aquatic snail in search of killifish. Once the parasite finds its new host, it latches onto the gills of the killifish, and then makes it way to the fish's brain cavity, where it forms a carpet-like layer over the fish's brain. Here it releases chemicals that mess with the fish's central nervous system. Infected killifish perform a complex dance routine involving the shimmy, the jerk, the flash and the surface. With these cool moves, the fish are 10 to 30 times more likely to get eaten by birds than uninfected fish. Inside of the birds, the fish breed and their eggs are pooped out, to be eaten by unsuspecting horn snails. |
How Parasites like Toxoplasma travel from Blood to Brain?
Just yesterday rresearchers from the University of Pennsylvania School of Veterinary Medicine and colleagues from across the country have identified how the parasite Toxoplasma Gondi makes its way into the Brain from blood stream. Using a powerful imaging technique that allowed the scientists to track the presence and movement of parasites in living tissues, the researchers found that Toxoplasma infects the brain's endothelial cells, which line blood vessels, reproduces inside of them, and then moves on to invade the central nervous system What are Endothelial cells? They form the inner lining of a blood vessel and provides an anticoagulant barrier between the vessel wall and blood. Its role is to act as a selective permeability barrier. Visualize Parasite Crossing the Blood-Brain barrier @ UPENN Here. Toxoplasma gondii:
(Observed using multiphoton microscope) The Penn Vet team observed the Toxo parasite ( labeled using red fluorescent protein) infecting and then reproducing inside the brain’s endothelial cells( labeled green using green flurescent protein) which line the blood vessels.
More about the Parasitic Flat Worm: Scientific name: Leucochloridium paradoxum Common name: green-banded broodsac. It is a parasitic flatworm (or "helminth") that uses gastropods (snails & slugs) as an intermediate host. It is typically found in Succinea that live in Europe and North America. Various birds consume these infected gastropods, becoming the definitive host for L. paradoxum to mature and release eggs in the rectum that are later found in the feces of the bird host. Study in Nature Microbology CDC About taxoplasmosis An infected stickleback heads for a warm bath. While its peers prefer to swim in lukewarm water at around 16 degrees Celsius, this individual likes it hotter. That's not because of a personal preference – instead, it is being steered by a parasite.
A tapeworm has lodged in its guts, and it needs warmer temperatures to grow as large as possible. The stickleback becomes little more than a living car that drives the worm to the heated pools that it prefers. The bird tapeworm Schistocephalus solidus, like many parasites, has a complicated life cycle. As its name suggests, it infects birds, and particularly those that live by water. It reproduces in its host's intestines and its eggs plop into the water along with the bird's droppings. There, they hatch into larvae that infect small crustaceans call copepods. These are then eaten by sticklebacks, which are, in turn, eaten by birds. Once inside its final host again, the tapeworm can mature into an adult and lay new eggs. To ensure that it completes its life cycle, the tapeworm manipulates the behaviour of its stickleback host. The fish becomes less averse to risks, more likely to swim alone, and less likely to flee from a predator. With such a laissez-faire attitude, it inevitably gets eaten by a bird.
But the tapeworm needs something else from the stickleback – time to grow. They have to get to a weight of 50 milligrams to be sure of successfully infecting a bird. Beyond that, the heavier they are, the more eggs they can lay. The fish, obviously, would prefer it if a smaller worm was writhing inside their bodies, rather than a large one. They don't often get their way; that much is obvious if you look at infected fish. The tapeworms can get so big that they outweigh their hosts, whose bellies are swollen and distended by their unwanted passengers. Tapeworms are just one of several parasites that do better in warmer conditions. |
