These are insect cells infected with the Guaico Culex virus. The different colors denote cells infected with different pieces of the virus. Only the brown-colored cells are infectious, because they contain the complete virus.
Michael Lindquist/Cell Press
Surgeon General Vivek Murthy looks at a sample of mosquitoes in Orlando, Fla., on Monday. With him is Department of Health and Human Services Secretary Sylvia Burwell and Orange County Mayor Teresa Jacobs.
By hanging a caged chicken near mosquito traps in bedrooms in three Ethiopian villages, researchers hoped to learn how the insects react to the scent of a fowl.
Kassahun Jaleta/Courtesy of Rickard Ignell
A common house mosquito (Culex pipiens) is about to sink her six-weaponed proboscis into a human arm. This type transmits West Nile virus by biting infected birds, then biting humans.
Sporadic dengue fever outbreaks in Florida in 2009 and 2010 spurred mosquito control efforts in Key West and Miami Beach, shown here. The same mosquito that carries dengue, Aedes aegypti,can transmit Zika.
Joe Raedle/Getty Images
A patient suffering from Guillain-Barre syndrome recovers in a hospital ward in San Salvador on Jan. 27. Researchers are trying to determine whether there is a link between the disorder, which can cause weakness and paralysis, and the mosquito-borne Zika virus.
Marvin Recinos /AFP/Getty Images
Dr. Margaret Chan is director-general of the World Health Organization. In her first major address on Zika, delivered Thursday in Geneva, she said: "Questions abound. We need to get some answers quickly."