Malaria is the most destructive parasitic illness, by many accounts, but the second most is much less well-known.
Schistosomiasis [shis-tuh-soh-mahy-uh-sis] infects over 250 million people.
It is a common in areas with stagnant water where the where the parasitic flat-worms can enter even unbroken skin and take up residence in a host. The flat worms then produce thousands of eggs per day that can overwhelm the host’s organs. The disease itself is effectively treated with praziquantel but reinfection can occur quickly. This is a disease desperate for a vaccine.