The US Department of Agriculture has eased its restrictions on poultry shipments out of Arizona and Nevada after officials decided that the outbreak of Exotic Newcastle Disease had successfully been contained.

The two states have not reported any new cases of the highly contagious avian virus since the initial findings earlier this year.

Exotic Newcastle Disease, which is harmless to humans and does not affect the safety of poultry meat and eggs, has also affected birds in California and Texas. The outbreak was first discovered in October in Southern California.

"In this interim rule, we are reducing the size of the quarantined areas in Nevada and Arizona based on the results of extensive surveillance and investigations conducted in those states," the USDA was quoted by Reuters as saying.