MADRID (AP) -- Three more people were placed under quarantine for Ebola at a Madrid hospital where a Spanish nurse became infected, authorities said Tuesday. More than 50 other possible contacts were being monitored.

The nurse, who had cared for a Spanish priest who died of Ebola, was the first case of Ebola being transmitted outside of West Africa, where a months-long outbreak has killed at least 3,500 people and infected at least twice as many.

Her case highlighted the dangers that health care workers face caring for Ebola patients _ officials said she had changed a diaper for the priest and collected material from his room after he died. Dead Ebola victims are highly infectious and in West Africa their bodies are collected by workers in hazmat outfits.

News of the quarantines hit Spain's stock market Tuesday. Spain is one of Europe's biggest tourist destinations and stocks in tourism-related companies such as airlines and hotel chains fell on the Madrid stock exchange as investors feared the consequences of the Ebola case.

Shares in International Airlines Group, formed in early 2011 by the merger of British Airways and Iberia, dropped more than 6 percent, while those of NH Hotel Group and Melia Hotels were down 4 percent. The Ibex 35 stock market index was 1.7 percent lower.

The nurse's husband has shown no signs of having the disease but was hospitalized as a precaution, said Dr. Francisco Arnalich, head of internal medicine at the Carlos III hospital where all were under quarantine.

In addition, a second nurse who also treated the priest who died Sept. 25 was put into quarantine after experiencing diarrhea but she did not have a fever, the most common initial symptom for Ebola. And a Nigerian man who recently arrived in Spain was also under quarantine but tested negative for Ebola in his first test.

Public Health Director Mercedes Vinuesa told Parliament that authorities were drawing up a list of other people who may have had contact with the nurse. She has not been publicly identified but has no children.