17. Halicephalobus gingivalis – Sometimes, being rare is a death sentence. While the odds are that you're never going to meet this parasite, the scarcity of it will make it that much harder for anyone to know what is killing you. While people try to figure it out, you may find that the nausea, the vomiting, the fever eventually may do you in.
16. Onchocerca volvulus – This parasitic worm is known for a few nasty symptoms. Itching, skin abnormalities, and blindness. Yep, this parasite can literally make you go blind. One can meet this parasite by being bitten repeatedly by black flies near rivers, and the only way to avoid it is to simply avoid being bitten by black flies. Yup, there is no vaccine. Have fun next time you go to the river!
15. Toxoplasma gondii – If you have mice, you might have to worry about this. Toxoplasma gondii is noted for forcing mice to present themselves to cats and get killed, so as to infect cats. This parasite can then transfer to humans, who are usually not at great risk… unless they are pregnant.