Intelligent design, parasite edition

An article on new discoveries about the behavior of plasmodium, the malaria-causing parasite that lives in mosquitoes, including one of my favorite examples of manipulative parasitic behavior:

Many parasites that need to live inside two different hosts during their life cycles also manipulate their hosts. A single-celled parasite called toxoplasma lives inside cats and then inside their prey, like rats. Research shows that infection with toxoplasma makes rats lose their fear of the odor of cats. "It's amazing how much manipulation is going on in parasites," Koella said.

Rats eat the cat poop with toxoplasma, thus causing them to be less afraid of cats, thus leading to their denouement as more cat poop containing toxoplasma.

But here's what the Kenyan and French researchers have discovered about mosquitoes and plasmodium:

In the late '90s, Koella documented how plasmodium, the cause of malaria, manipulated its mosquito host. When the mosquitoes first take up plasmodium in human blood, they become more cautious about finding another victim, making them less likely to be killed.

At this stage in the life cycle the parasite needs time to develop in the mosquito before it can be transmitted.

The mosquito's behavior changes when the parasite is ready to move on to a human. Koella found that mosquitoes carrying infective plasmodium become twice as likely to bite more than one person in a night, and they spend more time on each host drinking blood.

Applying these results to the question of whether plasmodium manipulate human hosts, they found that,

The parasite - a single-cell creature, plasmodium, carried by mosquitoes - makes infected humans smell more attractive to mosquitoes....

After the plasmodium enters the human body, it needs time to develop in the liver. The parasites then produce offspring that can invade blood cells, and eventually a few of these give rise to offspring, known as gametocytes, that can be taken up by a mosquito and survive....

After studying 12 sets of children, the scientists discovered a striking pattern. "Gametocyte-infected children attracted about twice as many mosquitoes as either uninfected ones or ones infected with non-transmissible stages," Koella said. "The results really jump out."

Fascinating. We're microscopically and macroscopically manipulated beings.