Infectious diseases know no borders, whether it's Ebola spreading fromGuinea to Liberia, measles in the Fraser Valley brought to Canada from the Philippines, or MERS claiming victims across the Middle East. These health crises are grim reminders that new and old infectious diseases often strike where and when we least expect them, in ways that confound us.

In isolated, largely indigenous communities like Chokisis, child malnutrition rates can reach 70 or 80 percent, severely hindering kids' ability to grow, learn, work, and lead healthy lives for years to come. These dubious distinctions make Guatemala a laboratory of sorts for innovations in the production and delivery of micronutrient-fortified food.

The World Health Organization declared a recent spread of polio to new countries to be an international public-health emergency, warning that it could undermine a lengthy and expensive eradication effort.