Schistosomes have a 2-host lifecycle: cercariae leave a snail host and penetrate definitive hosts including mammals and birds. Some avian schistosomes can also cause swimmer's itch when they accidentally penetrate into human skin and can not develop further! Greeting Cards Team: Dr. Chenhua Li (Lead, Ideas), Dr. Þórey Jónsdóttir (Illustrator, Ideas), Dr. Stephen Pollo (Writer, Researcher), Yuanzhe Wang (Digital Consultant).

Ticks, like the blacklegged tick Ixodes scapularis , have a complex multi-host lifecycle. They must feed on blood at each stage of their...

Eggs of  Ancylostoma duodenale in stool develop into infective larvae in warm, moist soil. The larvae penetrate the skin of the bottom of...

The malaria-causing parasite, Plasmodium , has a complex two-host lifecycle. In both hosts, the parasite must use and migrate through...