Two American aid workers test positive for Ebola in worst outbreak ever recorded by: Randy Lubratich updated: Monday, July 28, 2014 Dr. Kent Brantly Nancy Writebol ‹ › MONROVIA, Liberia (AP) - Two American aid workers have tested positive for the Ebola virus while working to combat an outbreak of the deadly disease at a hospital in Liberia.An official with the relief group Samaritan's Purse says 33-year-old Dr. Kent Brantly is in stable but very serious condition. The second American is identified as Nancy Writebol, a worker with an allied aid group called Serving in Mission. Meantime, Liberia President Ellen Johnson Sirleaf has closed some border crossings and ordered strict quarantines of communities affected by the Ebola outbreak. The announcement late Sunday came a day after Sirleaf formed a new taskforce charged with containing the disease, which has killed 129 people in the country and more than 670 across the region. A top Liberian doctor died of Ebola over the weekend. Last week a Liberian official boarded an international flight to Nigeria and died of the disease in a Lagos hospital. Ebola is spread through contact with bodily fluids. Sirleaf said all entry points except for the international airport outside Monrovia and "key border crossings" would be closed, and new inspection procedures would be strictly observed.