With today’s announcement(Guardian link) that a healthcare worker at Texas Health Presbyterian hospital in Dallas has tested positive for Ebola, expect a renewal of the hysteria on cable news and the anti-science public.

it was confirmed that a close contact of the healthcare worker – who officials said was wearing full protective gear when he or she made contact with Duncan – has also been placed, “proactively”, in isolation [September 30].

While the announcement didn’t include much information, it’s enough to add to a provisional time line, and is higher quality data than what medical personnel in western Africa have been able to collect.
September 15 – Thomas Eric Duncan reportedly assists a gravely ill, young pregnant woman who died shortly thereafter (not verified if it was a day or several days).

September 20 – Duncan enters the US.  (Left Liberia Sept. 19th.)

September 24 – Duncan exhibits symptoms

September 25 [ED from 26 – see UPDATE below] – Duncan seeks medical attention at Texas Health Presbyterian.  Released when tests didn’t confirm several possible diagnoses which didn’t include Ebola.  

September 28 – Duncan taken to the hospital via ambulance and admitted.  (Family could not confirm that Duncan had had any contact with Ebola.)

September 30 – Duncan tests positive for Ebola.  A hospital statement detailed the steps taken by the hospital since the admission of Duncan, on 28 September, on his second visit. That would include the protocol for protection of health care workers, contact tracing and monitoring for symptoms, and isolation/quarantine for non-health care workers that had been in closest contact with Duncan before his hospital admission.

October 8 – Duncan dies (23 days from suspected infection date)

October 10 – Late evening, one of Duncan’s hospital health care workers reported low-grade fever.  Was tested for Ebola and placed in isolation (within 90 minutes).

October 12 – Hospital worker Ebola test positive.

Frieden told CBS the worker had treated Duncan multiple times after the Liberian man was diagnosed, and said that all those who had treated Duncan were now considered to be potentially exposed.

Let’s look at Spain:

September 22 –  Brother Manuel García Viejo was admitted to hospital in Madrid after being evacuated from Sierra Leone where he worked as a hospital medical director.

September 25 – Brother Manuel García Viejo dies.

September 30 – Teresa Romero Ramos, health care worker exhibited low grade fever.

October 6 – Positive Ebola test and admitted to hospital.  (October 7, second test confirmation.)

Health officials said the infected medical worker had been in contact once with Brother García Viejo while he was alive and with his clothes after he died.

Subsequent to hospital admission, Ramos developed additional symptoms:

The patient was suffering from diarrhoea, vomiting and coughing, the doctor said.

On October 8th, Ramos was able to give several short phone interviews.  By the next day (10/9), she had been intubated and her condition was reported to be deteriorating.

(Note: In August, Rev. Miguel Pajares was admitted to the same Madrid hospital after being diagnosed with Ebola in  Liberia.  He died  five days later.)

Days between earliest possible contact to suspected or known earliest symptoms.

Duncan: nine days (9/15 to 9/24).

Teresa Romero Ramos: eight days (9/22 to 9/30).  (From latest possible contact: five days; 9-25 to 9/30.)

Dallas hospital health care worker: ten days (9/30 to 10/10).

Disease stage of known/suspected victim/patient at time of earliest possible transmission

Liberian pregnant woman died within hours or up to four days later.

Brother Manuel García Viejo died three days later.

Thomas Duncan died eight days later.

The Liberian woman received no medical attention.  Duncan appears to have been admitted to hospital at an earlier stage in the progression of the disease than Viejo and likely received more aggressive medical care.

Piecing together these three cases, provides important data.  First, Duncan, Ramos, and the Dallas health care worker all came in contact with an extremely ill, late stage, Ebola victim.  Second, the shortest possible known time-frame from contact to low-grade fever symptom is five days, and the longest possible, documented time-frame from contact to low-grade fever is eight days.  There may be more certainty as to the date of Duncan’s contact with an Ebola victim, 9/15, but less certainty as to the date of the earliest possible symptom, low-grade fever.  By 9/24, nine days after contact, he experienced observable, but apparently not unduly worrisome, symptoms; those came two days later, day eleven..

In Ramos’ case and from news reports, the onset of observable symptoms was five to six days after recording a low-grade fever (Spanish health authorities deny any symptoms other than a low-grade fever when on October 6th, she was admitted to hospital, and a test returned a positive for Ebola.  From there her health deteriorated rapidly over the next three to four days.  Also note that Ramos’ was being monitored because she had been a health care worker for a known Ebola patient that had died, and yet, her low-grade fever and self-reported fatigue were dismissed for five to six days (depending on which published report is accurate).  Setting 9/22 (Day 1) as when Ramos was infected:

Day 8 – low grade fever and slight fatigue
Day 14 – additional symptoms, transported via ambulance to hospital, and tested positive for Ebola
Day 15 – second test returned positive for Ebola
Day 16 – 18 – health condition worsens

If 9/15 was Duncan’s Day 1:

Day ? – low-grade fever
Day 8 [ED from 9] – other symptoms
Day 11 – significant additional symptoms; evaluated by ER doctor/nurse
Day 13 – seriously ill, tested, and hospitalized.

It appears that Duncan became sicker faster than Ramos did.  Or he could have been infected earlier than the reported 9/15 or Ramos later than 9/22.

Ramos 9/25 infection date:

Day 5 – low grade fever and slight fatigue
Day 11 – additional symptoms, transported via ambulance to hospital, and tested positive for Ebola
Day 12 – second test returned positive for Ebola
Day 13-15 – health condition worsens

A 9/25 infection date for Ramos makes the time lines for her and Duncan more similar.  

From this, it’s more likely than not that the Dallas health care worker was infected between Duncan’s Day 15 through 20 or September 30 through October  5.  The period when all health care workers attending to Duncan were wearing hazmat type clothing.    

In the fourteen to fifteen days between Duncan’s contact with Ebola and diagnosis, none of those who he came in contact with have or are exhibiting any symptoms of Ebola and all are being monitored for low-grade fever.  Not those he was staying with when he was asymptomatic and symptomatic from 9/20 through 9/28.  Not hospital personnel that had contact with him on 9/26.  Not those that transported him to the hospital on 9/28 or hospital workers that cared from him from 9/28 to 9/29, although they would have been wearing some level of protective clothing.  

While it’s too soon to state with absolute certainty, the evidence is good that the Ebola incubation period from being infected to low-grade fever is approximately one week, plus/minus two days.  The isolation of the Dallas health care worker within as little as 90 minutes and no more than few hours of exhibiting a low-grade fever will provide the best evidence as to the possibility of Ebola being transmitted during the incubation phase.  That would be bolstered by any contacts Ramos had that were limited to her incubation phase.  Ramos’ case will add data to Duncan’s regarding how contagious Ebola is in the early symptomatic phase, first six days.  As it’s now fourteen or more days since Duncan had close and unprotected contact with others during that phase, evidence is mounting that it’s no more than weakly contagious, if at all, in the early symptomatic phase.  And quickly after that becomes highly contagious.  That’s essentially what public health officials have been saying, and it means that all of Duncan’s hospital care givers must be considered at high risk for having been infected.

The data on the effectiveness of treatment and of the treatment methods have some way to go before being proven.  The fatality rate of this epidemic is reported to be 50%; so, something is operating to spare half of those that test positive for Ebola.  It could be an individual’s ability to fight off the disease, adequate supplemental fluids in a critical phase of the disease, and/or new treatments such as ZMab or antibodies from the blood of Ebola survivors.

Today from The Guardian, Spanish Ebola Nurse Shows Signs of Improvement.

On Friday, health officials said they had secured an antibody cocktail known as ZMab to treat the nurse. She had previously been injected with antibodies extracted from the blood of Ebola survivors.
/…
Health official Fernando Simón said the presence of the virus in Teresa Romero Ramos’s blood appears to be diminishing. “We have high hopes that the infection is under control,” he said. However, given the seriousness of the virus he said it was impossible to determine whether she was out of danger.

Update [2014-10-13 12:11:54 by Marie2]: NYTimes reports that it was after 10:00 pm, September 25 and not the previously reported September 26th when Duncan first went to the hospital ER.

Update 2: 10/15/14 Nurse Pham, the first American Ebola patient diagnosed in the US, had contact with Duncan the first nine of ten days he was in isolation care at Texas Health Presbyterian Hospital, according to medical records obtained by AP. After running a fever on Friday, Oct. 10, she went to the hospital where she was placed in an isolation unit.