Harris County officials on Sunday night announced one more presumptive positive case of the new coronavirus, bringing the region's total to 12.

The woman, who is between 60 and 70 years old, is from the unincorporated area of northwest Harris County, according to Harris County Public Health. She is associated with the same known group of people who traveled on a cruise in Egypt.

She has been quarantined, and her test will be sent to the Centers for Disease Control and Prevention for official confirmation, health authorities said.

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The new case is the latest to be confirmed in the Houston area. Earlier Sunday, Fort Bend County health officials announced three more residents who tested positive.

Officials said the three residents are all in good health and are being kept in isolation at their homes. Two patients were among the 17 Houston-area residents who returned in late February from the same Nile River cruise in Egypt, while one patient took the same cruise at a later date.

County officials gave the following descriptions of the infected patients: a man in his 70s who was hospitalized and discharged; a man in his 70s who had a one-day fever; and a woman in her 60s who had “mild symptoms, which have resolved.”

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Doctors at the Memorial Hermann Health System said Saturday that 11 health care workers were asked to self-quarantine due to contact they had about a week ago with an infected patient from the cruise.

To date, doctors have identified six infected patients in Fort Bend County and five in Harris County. All 11 were passengers on the same cruise line in Egypt. None has died.

The Fort Bend and Harris county health departments, as well as the Houston Health Department, asked Sunday for all residents who traveled on the cruise line M.S. A’sara between Feb. 12 and March 5 to self-quarantine for two weeks and contact one of the departments. The cruise line traveled to and from Aswan, Egypt.

Egyptian Health Minister Hala Zayed said Saturday that 45 people who traveled on the cruise ship have tested positive for the new coronavirus, according to the Associated Press. The group included 12 crew members and 33 tourists, who hailed from several countries.

County health officials advised residents to monitor for fever, cough and difficulty breathing for at least 14 days after returning from areas with an outbreak of COVID-19, the disease caused by the coronavirus. The areas with the most widespread infections include China’s Hubei province, northern Italy and parts of Iran and South Korea.

More than 500 cases of COVID-19 and at least 21 deaths from the virus have been confirmed in the U.S. as of Sunday afternoon, according to data compiled by researchers at Johns Hopkins University.

jacob.carpenter@chron.com