* More than 100 being monitored in case they are infected
* Obama says sealing off West Africa would make situation worse
* GlaxoSmithKline says work on developing vaccine moving rapidly
* Canada to ship vials of experimental vaccine to WHO (.)
By Roberta Rampton
WASHINGTON, Oct 19 (Reuters) - With three cases of Ebola diagnosed in the United States and more than 100 people being monitored for possible infection, President Barack Obama said on Saturday that Americans "can't give in to hysteria or fear" about the spread of the virus.
While Obama administration and world health officials remained focused on tackling Ebola at its source in three West African countries, Texas state authorities said 14 people had been cleared from an Ebola watch list. Three weeks of monitoring for fever and other symptoms was expected to end for others in the next two days if they remained asymptomatic.
Those include Louise Troh in Dallas, fiancée of the now deceased Liberian Thomas Eric Duncan, who became the first U.S.-diagnosed Ebola case in late September while visiting her. Troh, her 13-year-old son and two Duncan relatives have been in mandatory quarantine in Dallas that ends on Sunday.
The Texas Department of State Health Services said in a statement that 145 people with "contacts and possible contacts" with the virus were being monitored.
In his weekly radio address, Obama made plain he does not plan to accede to demands from some U.S. lawmakers for a ban on travelers from Liberia, Sierra Leone and Guinea, the worst-hit countries, where more than 4,500 people have died since March in the worst Ebola outbreak on record.
"We can't just cut ourselves off from West Africa," Obama said. "Trying to seal off an entire region of the world, if that were even possible, could actually make the situation worse."
Obama, who has been criticized over his administration's handling of Ebola, held a flurry of meetings this week and on Friday appointed Ron Klain, an experienced Washington lawyer, to oversee efforts to contain the disease.
Republicans questioned why he did not pick a medical expert.
"I hope he (Klain) is successful in this. I think it's a step in the right direction, but I just question picking someone without any background in public health," Republican Rep. and House Foreign Affairs Committee chairman Ed Royce told CNN.
The World Health Organization has also been faulted for failing to do enough to halt the spread of the virus.
The WHO said it would publish a full review of its handling of the crisis once the outbreak was under control.
There is no cure or approved vaccine yet for Ebola but pharmaceutical companies have been working on experimental drugs. The virus is transmitted through an infected person's bodily fluids and is not airborne.
Canada said on Saturday it would ship 800 vials of its experimental Ebola vaccine, undergoing clinical trials, to the WHO in Geneva, starting on Monday. Iowa-based NewLink Genetics Corp holds the commercial license for the Canadian vaccine.
Britain's biggest drugmaker, GlaxoSmithKline, said work to develop a vaccine was moving at an "unprecedented rate" and the next phase, if successful, involving vaccinating frontline healthcare workers, would begin in early 2015.
Obama sought to put the extent of the disease in the United States in perspective. "What we're seeing now is not an 'outbreak' or an 'epidemic' of Ebola in America," he said. "This is a serious disease, but we can't give in to hysteria or fear."
A series of Ebola scares has hit the country since Duncan, who died on Oct. 8, was diagnosed. Americans' faith in the medical system and in its disease prevention ability was jolted by early missteps in his case.
In a public letter on Saturday night, Texas Health Resources Chief Executive Barclay Berdan acknowledged that the Texas Health Presbyterian Hospital where Duncan first went "made mistakes in handling this very difficult challenge," including initially not correctly diagnosing his symptoms.
Berdan said aggressive actions and changes since then ensured that the hospital was "a safe place" for patients and staff, and that outside experts would be consulted to determine how two nurses caring for Duncan became infected with Ebola.
Amber Vinson is at Atlanta's Emory University Hospital, while Nina Pham is being treated at the National Institutes of Health outside Washington.
People who had contact with them or Duncan are being monitored, while some 800 passengers who flew with Vinson on a trip she made to Ohio before being diagnosed, as well as those on subsequent flights on the same planes, have been contacted by Frontier Airlines, it said on Saturday.
Also being monitored are a lab worker at the hospital who is not ill but is in isolation at sea in her cabin on the Carnival Magic cruise ship owned by Carnival Corp. The worker had no contact with Duncan but may have come in contact with test samples. The ship was on its way back to Galveston, Texas.
The Ohio Department of Health strengthened its recommended Ebola quarantine protocols to limit travel by those required to have their health condition monitored locally or report it to officials. Ohio said its vigilance was meant to exceed CDC recommendations.
Obama has stressed that containing Ebola should include help for the worst-hit countries and Washington plans to deploy up to 4,000 military personnel to the region by late October. He is preparing to ask Congress for additional Ebola funding.
British Prime Minister David Cameron said on Saturday European Union leaders should raise the amount pledged to fight Ebola to 1 billion euros ($1.3 billion) and mobilize at least 2,000 workers to head to West Africa. A spokeswoman at Cameron's office said the EU commission and 28 member states had pledged a total of 500 million euros so far.
Additional reporting by Mohammad Zargham and Eric Beech in Washington, Frank McGurty in New York, Anna Driver in Dallas, Tom Miles in Geneva and Costas Pitas in London; Writing by Frances Kerry and Megan Davies; Editing by Grant McCool, Chris Michaud and Clarence Fernandez