Scans from patients with fungal meningitis show evidence of a stroke (left) and arachnoiditis. New England Journal of Medicine hide caption

itoggle caption New England Journal of Medicine

A young girl stands in the doorway of a home in Uttar Pradesh, India. The markings on the door show that a polio immunization team vaccinated children in the home. Alyce Henson/Courtesy of Rotary International hide caption

itoggle caption Alyce Henson/Courtesy of Rotary International

Histoplasma capsulatum is common in soil in the Midwest and Mid-Atlantic. So how did it get a rancher in Montana sick? CDC hide caption

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Hawah Alhassan, 5, contracted Guinea worm in a village near Tamale, Ghana, in 2007. The country eliminated the parasite in 2011. Wes Pope/MCT/Landov hide caption

itoggle caption Wes Pope/MCT/Landov

A nurse treats a cholera patient at the Juan Pablo Pina Hospital in San Cristobal, Dominican Republic, in August. Health officials say that the strain of cholera circulating in the country— the same one that first appeared in Haiti three years ago — has also caused outbreaks in Cuba and now Mexico. Erika Santelices/AFP/Getty Images hide caption

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Syrian opposition fighters sit on the front line in the city of Deir Ezzor on Oct. 13. Ongoing violence has ravaged the city since March 2011. AFP/Getty Images hide caption

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The botulism toxin comes from Clostridium botulinum bacteria, seen here in a colorized micrograph. James Cavallini/Science Source hide caption

itoggle caption James Cavallini/Science Source

Haitians protest against United Nations peacekeepers in Port-au-Prince in 2010. Hector Retamal/AFP/Getty Images hide caption

itoggle caption Hector Retamal/AFP/Getty Images

Avez, 2, is held by his mother, as he receives the polio vaccine in the Khyber Tribal Region in northwest Pakistan. Daniel Berehulak/Getty Images hide caption

itoggle caption Daniel Berehulak/Getty Images

A student gets vaccinated against pertussis at a Los Angeles middle school in 2012. The state required that students be immunized to halt an epidemic of whooping cough. Kevork Djansezian/Getty Images hide caption

itoggle caption Kevork Djansezian/Getty Images

A doctor takes an HIV test from an athlete during the 18th National Sports Festival in Lagos, Nigeria, last December. Sunday Alamba/AP hide caption

itoggle caption Sunday Alamba/AP

Inspector Mohammad Saleem Taqi takes a photo of sanitation workers as they clear out debris in sewers. The government feeds the photos into a map to track the city's effort to stop dengue fever. Beenish Ahmed/NPR hide caption

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