Washington, Rajab 4, 1436, Apr 23, 2015, SPA -- The spread of a highly contagious type of avian influenza has prompted US health officials to take precautionary measures to prevent an outbreak in humans, the Centers for Disease Control and Prevention (CDC) and the United States Department of Agriculture (USDA) announced Wednesday, according to dpa. In Iowa, 5.3 million egg-laying hens were euthanized after tests confirmed an outbreak of the disease, the Des Moines Register reported. The influenza - also known as bird flu - kills more than 90 per cent of birds that become infected within 48 hours, the CDC reported. The disease affects both wild birds and farmed poultry. Since December, 16 US states have reported cases of H5N2 avian influenza, and the wider the spread, the higher the risk for humans, said Alicia Fry of the CDC. "Right now from everything we know it seems like the risk for human infection is very low, but we are really at the beginning of this," said Fry. "There is certainly a possibility [of human infection] considering the spread of infection among birds," she said. As with all influenza viruses, the CDC has taken the first steps needed to create a human vaccine, but at this point "haven't had a need to go further." We are cautiously optimistic, Fry said. The 16 states where cases of the H5N2 virus habe been reported in wild birds, captive wild birds, backyard poultry or commercial poultry are Arkansas, California, Iowa, Idaho, Kansas, Minnesota, Missouri, Montana, North Dakota, Nevada, Oregon, Utah, South Dakota, Washington, Wisconsin and Wyoming. Two cases have also been reported in Ontario, Canada. --SPA 03:08 LOCAL TIME 00:08 GMT www.spa.gov.sa/w