Sophia Jarvis, 4, of Berkeley, Calif., is one of the few children diagnosed with the polio-like disease, which left her arm paralyzed. She attended a press conference Monday at Stanford University with her dad, Jeff. Martha Mendoza/AP hide caption

itoggle caption Martha Mendoza/AP

Jockeys take their camels home after racing in Egypt's El Arish desert. The annual race draws competitors from around the Middle East, including Saudi Arabia, where camels carry the Middle East Respiratory Syndrome virus. Nasser Nouri/Xinhua /Landov hide caption

itoggle caption Nasser Nouri/Xinhua /Landov

New research finds a close connection between the flu that devastated the horse population in North America in the 1870s and the avian flu of that period. Hulton Archive/Getty Images hide caption

itoggle caption Hulton Archive/Getty Images

Hannah Rood, 3, receives an H1N1 vaccine at a clinic in San Pablo, California, during the 2009 swine flu epidemic. Justin Sullivan/Getty Images hide caption

itoggle caption Justin Sullivan/Getty Images

Small but costly: Dozens of mosquito species carry West Nile virus in the U.S. Darren McCollester/Getty Images hide caption

itoggle caption Darren McCollester/Getty Images

Mohonk Mountain House, a resort 90 miles north of New York City, is closed while crews sanitize the facilities after an outbreak of gastrointestinal illness. Jim Smith/AP hide caption

itoggle caption Jim Smith/AP

Palestinian girls read the Koran at a camp in Gaza City, June 2012. In poor countries, boys are 20 percent more likely than girls to enroll in school, UNICEF says. Mahmud Hams/AFP/Getty Images hide caption

itoggle caption Mahmud Hams/AFP/Getty Images

Young boys suspected of having Guinea worm infections wait for the parasite to emerge through the skin at a clinic in South Sudan. Louise Gubb/The Carter Center hide caption

itoggle caption Louise Gubb/The Carter Center

Yonta, 6, rests with her brother Leakhena, 4 months, under a mosquito bed net in the Pailin province of Cambodia, where deaths from malaria have decreased sharply in the past two decades. Paula Bronstein/Getty Images hide caption

itoggle caption Paula Bronstein/Getty Images

Timothy Webb and other advocates protest the cost of HIV drugs manufactured by the pharmaceutical company Gilead outside an AIDS conference in Atlanta in March. Gilead is making a new hepatitis C drug, Sovaldi. John Amis/AP Images for AIDS Healthcare Foundation hide caption

itoggle caption John Amis/AP Images for AIDS Healthcare Foundation

Sun, shopping and chikungunya? A nasty virus has sickened 10 people on the island of St. Martin in the past few months. Balalaika/iStockphoto hide caption

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A mother waits with her child at an HIV clinic in Nyagasambu, Rwanda, in February 2008. The clinic was built with a grant from the President's Emergency Plan for AIDS Relief initiative. Shashank Bengali/MCT /Landov hide caption

itoggle caption Shashank Bengali/MCT /Landov

There's no evidence that triclosan and other chemicals in antibacterial soaps do a better job than plain soap and water, the FDA says. Kiichiro Sato/AP hide caption

itoggle caption Kiichiro Sato/AP