HIPAA laws prevent disclosure of that information
...Thompson said medical privacy laws and his company’s contract with the State Department prevent him from revealing the figure....
They can’t discuss personal information ABOUT individual patients, but they CAN discuss number of people being treated and general locations.
I think the key, here, is in the “contract his company has with the State Dept” and the “State Dept preventing him from revealing the figure”.
No you can't discuss any information that has a high likelihood of identifying an individual patient. That means you can't mention age above (85 YO) lets say since so few people are that age it becomes an identifying characteristic. In this case the relatively few number of cases. The relatively few number of people that were in Ebola parts of Africa and then flown here, the fact that they were sent to various parts of the country. It wouldn't take a super sleuth to put names on these people.
That said HIPPA is a horrible law and should be repealed. It is only there to protect politicians, celebrities and PC groups dependent on health care. From a public health standpoint it's a nightmare.