Hookworms infect people mostly in countries where sanitation is poor and people often walk barefoot. Working on a mouse model, a research team has studied the secretion of the immune protein RELMalpha that is triggered in the body, following infection, to protect body tissue. When the researchers knocked out RELMalpha, the mice produced super-killer macrophages that attached to the hookworm in far greater numbers. These macrophages, however, provoked increased tissue damage and inflammation.