Health authorities and the United Nations have criticized the recent measures taken by some US states to impose mandatory quarantines on health workers returning from treating Ebola victims in West Africa, calling them extreme. Washington's top health official dealing with Ebola response warned against treating doctors and nurses who travel to West Africa as "pariahs". The United Nations condemned the restrictions imposed by some US states on health workers returning from Liberia, Guinea, and Sierra Leone, stating that these workers should not be stigmatized and should be supported. American soldiers returning from West Africa are also being isolated, even if they show no symptoms, to ensure the safety of themselves and their communities. The Army isolated a group of soldiers, including Major General Darryl Williams, upon their return to their base in Vicenza, Italy over the weekend. Williams stated that they are staying in a separate area on the base with no contact with the general population or their families. The US military is focused on building treatment units to assist health authorities in combating the Ebola epidemic, rather than interacting with Ebola patients. Dr. Jeff Duchin, Washington State epidemiologist and chairman of the public health committee of the Infectious Diseases Society of America, stated that up to 4,000 U.S. troops may be deployed on the mission and believes that isolation is not appropriate from a public health perspective. This decision goes against established military protocols and was made as the Obama administration tried to discourage quarantines imposed by some states on healthcare workers returning from Ebola-affected countries. US federal health officials have revised guidelines for medical workers returning from West Africa, with Dr. Thomas Frieden calling for isolation of those at highest risk for Ebola but stating that most returning workers will require daily monitoring without isolation. The CDC makes decisions based on science and experience. Frieden stated that guidelines and recommendations are adjusted as science and experience evolve. The new guidelines from the Obama administration are not compulsory, allowing states to implement stricter policies if desired. Some state officials have criticized federal restrictions on travelers from Ebola-affected countries as insufficient and have imposed their own measures. Australia recently imposed a visa ban on individuals from West African countries affected by Ebola, despite not having recorded any cases of the disease. Critics argue that the ban is politically motivated and may cause unnecessary fear and panic. Medical experts emphasize that Ebola is not easily transmitted and is not airborne, but rather spread through direct contact with bodily fluids. Mandatory quarantines have been criticized by various organizations as hindering efforts to combat the disease in West Africa. UN officials stress the importance of treating health workers returning from the region as heroes.