(Bloomberg) -- Craig Spencer, the New York City doctor whocontracted Ebola while caring for patients in Guinea, isimproving and remains in stable condition, health authoritiessaid.

Two of the three people Spencer had close contact with about thetime he fell ill last month have been released from quarantine,while one remains confined, city officials said yesterday in astatement.

One of those who had been under quarantine was releasedyesterday and “poses no public health threat and is showing nosymptoms,” health officials said in the statement. “This person’sdaily movements in New York City will no longer be restricted, andthe individual will be assessed twice each day by Health Departmentstaff.”

As part of a nationwide effort to stop or quickly identify newinfections, the city said it is monitoring 357 individuals. Mostare people who recently arrived in New Yorkfrom Ebola- affected countries. The group includesemergency medical workers who transported Spencer to BellevueHospital Center.

New York is one of five points of entry the U.S. has designatedfor travelers from nations with Ebolaoutbreaks. The U.S.Centers for Disease Control and Prevention has said that anyonecoming from those areas will be monitored for three weeks to checkif they develop symptoms.

Under Watch

The number of people under watch in New York will fluctuate ashealth officials learn more about possible exposures to the virus,new travelers arrive or depart, or as their monitoring period ends,city officials said.

New York, New Jersey and Illinois have said they will implementmandatory quarantines for anyone who arrives from Guinea, Liberiaand Sierra Leone, where the outbreak is concentrated, and is athigh risk of being infected. Pennsylvania, Maryland, Georgia andVirginia actively monitor people returning from the region.

The CDC recommended tighter screening procedures after a Dallashospital failed to identify an infected Liberian man when hearrived at the emergency room in September. The man, Thomas EricDuncan, was sent away from the hospital, only to return days laterin an ambulance. He died on Oct. 8, and two nurses who cared forhim were infected.

The Ebola outbreak has infected about 13,000 peopleand killed almost 5,000. There is no approved cure for the disease.Current standard care involves supporting the patient and usingantibiotics to fight secondary infections.

Spencer, 33, worked as a volunteer for Doctors Without Borders,an aid group that has sent medical professionals to fight theoutbreak at its source. He fell ill on Oct. 23, six days afterreturning to New York, and was rushed from his apartment innorthern Manhattan to Bellevue and put in a special isolationunit.

His treatment has included an experimental drug made by ChimerixInc., brincidofovir, as well as a blood transfusion fromanother Ebola survivor, which can boost virus-fightingantibodies in a patient.

--With assistance from Robert Langreth in New York.

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