By Michelle Nichols and Umaru Fofana

MONROVIA/FREETOWN (Reuters) - Australia became the first developed country on Tuesday to shut its borders to citizens of the countries worst-hit by the West African Ebola outbreak, a move those states said stigmatized healthy people and would make it harder to fight the disease.

Australia's ban on visas for citizens of Sierra Leone, Liberia and Guinea followed decisions by the U.S. military to quarantine soldiers returning from an Ebola response mission and some U.S. states to isolate aid workers. The United Nations said such measures could discourage vital relief work, making it harder to stop the spread of the deadly virus.

"Anything that will dissuade foreign trained personnel from coming here to West Africa and joining us on the frontline to fight the fight would be very, very unfortunate," Anthony Banbury, head of the U.N. Ebola Emergency Response Mission (UNMEER), told Reuters in the Ghanaian capital Accra.

Liberia's President Ellen Johnson Sirleaf urged Australia to reconsider its travel ban.

"Anytime there's stigmatization, there's quarantine, there's exclusion of people, many of whom are just normal, then those of us who are fighting this epidemic, when we face that, we get very sad," she told a news conference.

Neighboring Sierra Leone called the Australian move draconian.

"It is discriminatory in that ... it is not (going) after Ebola but rather it is ... against the 24 million citizens of Sierra Leone, Liberia and Guinea," Information Minister Alpha Kanu told Reuters. "Certainly, it is not the right way to go."

The virus has killed almost 5,000 people since March, mostly in those three countries. Nine U.S. cases have prompted states such as New York and New Jersey to ignore federal advice and quarantine all health workers returning from the region.

A Texas nurse who caught Ebola in the United States while treating an infected Liberian patient left hospital on Tuesday after being declared free of the disease.

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"I'm so grateful to be well, a smiling Amber Vinson, 29, told reporters at Emory University Hospital before hugging the doctors and nurses who treated her for two weeks.

The arrival of the disease in the United States has prompted fierce debate there and in other developed countries about the best measures to prevent its spread.

The World Health Organization says overly restrictive quarantines and travel bans will put people off volunteering to go to Africa, where relief workers are needed to help improve a health system to deal with the disease.

"We desperately need international health workers ... They are really the key to this response,” WHO spokesman Tarik Jasarevic said.

World Bank chief Jim Yong Kim said the three worst hit countries needed 5,000 overseas health workers at any one time.

"Those health workers cannot work continuously: there needs to be a rotation. So we will need many thousands of health workers over the next months to a year in order to bring this epidemic under control," he said an African Union meeting in Ethiopia. "Right now, I am very much worried where we will find those health workers."

MASS PANIC

Even African countries with no Ebola cases have been angered by policies being implemented in richer countries.

"Western countries are creating mass panic which is unhelpful in containing a contagious disease like Ebola," said Ugandan government spokesman Ofwono Opondo.

"If they create mass panic ... this fear will eventually spread beyond ordinary people to health workers or people who transport the sick and then what will happen? Entire populations will be wiped out."

Eighty-two people who had contact with a toddler who died of Ebola in Mali last week are being monitored, the WHO said, but no new cases have been reported there.

Mali became the sixth West African country to report a case of the disease. Senegal and Nigeria both stopped the virus by tracking down people who had had contact with those who brought it into their country and monitoring them for symptoms.

American soldiers returning from West Africa are being isolated, even if they show no symptoms and are not believed to have been exposed to the virus.

Army said Chief of Staff General Raymond Odierno ordered the 21-day monitoring period "to ensure soldiers, family members and their surrounding communities are confident that we are taking all steps necessary to protect their health".

ADOPT AND ADAPT

Dr. Jeff Duchin, chairman of the public health committee of the Infectious Diseases Society of America, said the isolation was not a necessary step. "From a public health perspective, we would not feel that isolation is appropriate," he said.

The decision goes well beyond established military protocols and came as President Barack Obama's administration sought to discourage quarantines being imposed by some U.S. states.

Dr. Thomas Frieden, director of the U.S. Centers for Disease Control and Prevention (CDC), called for isolation of people at the highest risk for Ebola infection but said most returning medical workers would require monitoring without isolation.

"At CDC, we base our decisions on science and experience ... And as the science and experience changes, we adopt and adapt our guidelines and recommendations," Frieden said.

Australia has not recorded a case of Ebola despite a number of scares, and conservative Prime Minister Tony Abbott has so far resisted repeated requests to send medical personnel to help battle the outbreak on the ground.

Adam Kamradt-Scott, of the University of Sydney's Marie Bashir Institute for Infectious Diseases and Biosecurity, said the travel ban would do nothing to protect the country from Ebola while potentially having a negative public health impact by creating a climate of panic.

Medical professionals say Ebola is difficult to catch. It is spread through direct contact with bodily fluids from an infected person and not transmitted by asymptomatic people.

(Writing by Jeremy Laurence and Robin Pomeroy; Editing by Peter Graff)