The patient, a 42-year-old male, is a Liberia citizen visiting his family members in the United States. He was sent to Texas Health Presbyterian in Dallas on ambulance on 28 September with high fever and vomiting. He was taken to isolation immediately and blood test confirmed ebola virus infection on 30 September.
Retrospectively, it was revealed that he first attended the same hospital on 26 September reporting low grade fever for two days. He was diagnosed to be a common viral infection and was sent home with antibiotics. According to the patient's family (a sister), the patient did inform a nurse at the hospital when the first time he attended the hospital on 26 September.
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| Progression of Ebola Symptoms (Source: http://www.huffingtonpost.com/2014/08/02/ebola-symptoms-infection-virus_n_5639456.html) |
Further on the contact tracing, the patient had his onset date on 24 September 2014 when he was in Dallas already. Prior to that, he was in Liberia and left Monrovia in Liberia on 19 September travelling through Brussels and Washington DC and arriving in Dallas on 20 September.
While in Liberia, the patient was a driver for shipping company. It was reported that he might have contracted the virus from the daughter of his landlord when he took her to the hospital on September 15. She was turned away and then died later at home with no exact date provided.
In other words, the patient might have developed symptoms on day 9 with initially mild flu-like symptoms then progress to systemic symptoms, notably vomiting and high fever before admitted to an isolation facility.
He should have become infectious and spreading the virus since 24 September. Contact tracing was focussed on his contacts between 24 to 28 September. As for his travelling on United Airlines flight 951 from Monrovia to Washington Dulles and flight 822 to Dallas/Fort Worth, spread was unlikely as he was asymptomatic at that time. It was also supported by information from CDC that he was not running a fever when his temperature was checked while boarding a plane in Monrovia.
According to CDC, a person shall be put under investigation (Person Under Investigation, PUI) if he/she has both consistent symptoms and risk factors as follows:
(a) Clinical criteria: fever and additional symptoms such as severe headache, muscle pain, vomiting, diarrhea, abdominal pain, or unexplained hemorrhage; AND
(b) Epidemiologic risk factors within the past 21 days before the onset of symptoms, such as contact with blood or other body fluids or human remains of a patient known to have or suspected to have EVD; residence in, or travel to, an area where EVD transmission is active; or direct handling of bats or non-human primates from disease-endemic areas.
Reference:
Bulluz, Julia. 15 Things you need to know about Ebola - A Dallas hospital failed to diagnose America's first-ever Ebola case. Vox. 2 October 2014. (http://www.vox.com/cards/ebola-facts-you-need-to-know/texas-hospital-diagnoses-the-first-case-of-ebola-in-the-us#E6660684)
CDC. Case definition for Ebola Virus Disease. (http://www.cdc.gov/vhf/ebola/hcp/case-definition.html)
Greg Botelho. U.S. Ebola patient: The travels and health travails of Thomas Eric Duncan. CNN. 3 October 2014. http://edition.cnn.com/2014/10/01/health/us-ebola-patient/index.html?iid=article_sidebar
