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Contact Tracing and the Second US Ebola Transmission

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Ebola is generally contained by contact tracing: finding anyone who had contact with any sick person and following up with them to be sure that they didn’t get infected. Usually this is done by taking their temperature twice a day or by having them self-monitor, taking their own temperature and reporting any fever to the relevant health group.[1] This continues for 21 days, the longest Ebola is known to incubate before showing symptoms.[2] If a contact shows signs of Ebola during this period, ideally they are isolated and treated. If all, or most, of contacts are traced and isolated successfully the disease will burn itself out. The current United Nations Mission for Ebola Emergency Response (UNMEER) goal is to successfully trace 70% of all contacts in West Africa.[3] In the US it is easier to find out who was where, so hopefully there will be at least that rate of success here.

Nigeria successfully used this method to contain an Ebola outbreak that was imported from Liberia via airplane.[4] The CDC has sent medical personnel to Nigeria to study their successful response.[5] Nigerian officials issued notifications to everyone exposed to Patrick Sawyer, who became ill on the plane.[6] Contacts in Nigeria did not have their movements restricted, but were instead contacted daily to check for symptoms and, if symptomatic, were then brought into isolation.[7] While Nigeria’s method was very successful, it is less restrictive than the WHO’s recommendations, which advise contacts to limit their movements.[8]

Anyone who had contact with the Ebola patient from the first sign of infection to time of cure or burial is ideally found. These contacts should be advised to “remain at home as much as possible, avoid crowded places, social gatherings, and . . . public transport” as well as reporting symptoms.[9] This helps limit the spread of Ebola from anyone who does eventually show signs of infection. While these guidelines were written with West Africa in mind their usefulness is universal. It’s probably not entirely necessary to limit movements of asymptomatic contacts, as Ebola isn’t believed to be contagious during the incubation period, but with such a deadly and infectious disease it’s wise to be cautious.

Contact tracing finds patients before they’re shedding large amounts of the virus in bodily fluids. This significantly reduces the risk of healthcare workers and those close to the patient becoming ill themselves.[10] As Ebola progresses in an infected individual the amount of virus in bodily fluids increases as does the expulsion of infectious bodily fluids: uncontrolled vomiting, diarrhea, and hemorrhaging spreads further than sweat or saliva. The WHO says that “[c]ontact tracing is . . . one of the most effective outbreak containment measures . . . “[11] In the 2000-2001 Uganda Ebola outbreak, previously the largest outbreak, patients quarantined after the onset of symptoms did not generate any additional contacts, something critical to stopping the disease.[12]

Yesterday, a great deal was made of Dr. Nancy Snyderman violating a voluntary quarantine to go out in a car to get carryout soup.[13] Dr. Snyderman is NBC’s chief medical correspondent.[14] She was among those with an NBC news team in West Africa when the team’s cameraman, Ashoka Mukpo, became ill with Ebola.[15] CDC Director Tom Friedan said that “If she was not sick, she was not putting others at risk.”[16] As a health professional she was still heavily criticized for leaving her home and the voluntary quarantine was made mandatory by the New Jersey Department of Health.[17][18] Too much was likely made of this quarantine breech, but coming right on its heels was the news that a second US healthcare worker was infected by Duncan and that she had been on a plane the evening before her morning discovery of infection.[19]

Obviously there was a difference in how the NBC crew was treated and how the infected healthcare workers who treated Duncan have been treated, with the former under mandatory quarantine and the latter allowed to move freely. The standard is that people who had high-risk exposure should be quarantined while the rest are monitored:[20] two Dallas paramedics and one paramedic intern were quarantined after high-risk exposure while transporting Duncan to the hospital.[21] As Texas Health Presbyterian Hospital said that the infected nurses were “following full CDC precautions” the CDC did not consider them high-risk contacts.[22] Either CDC procedures were not followed or the CDC procedures are not as effective as believed: one transmission is a coincidence but two seems to reveal a missing part of the picture regarding safe treatment of Ebola patients.

Training may be the important difference between a low-risk exposure and a high-risk one for healthcare workers. The CDC requested that nurses from the Emory University Hospital, which successfully treated Dr. Kent Brantley and nurse Nancy Writbol, to travel to Dallas and teach the healthcare workers there how to safely manage patient treatment and personal protective equipment (PPE) protocols.[23]

Until we see that healthcare workers are able to safely care for patients without becoming infected themselves perhaps they should not be categorized as “low-risk” contacts. Every contact who isn’t found increases the chances of another infection, and finding all contacts in Ohio (where the newest American patient visited) and from the plane is an additional burden. That the worker had a fever of 99.5 degrees Fahrenheit before boarding the plane does not automatically make it likely that she spread the disease.[24] It is, however, alarming that a healthcare professional would board a plane with a fever while under a fever watch instead of immediately reporting the symptom. CDC Director Frieden announced that “[w]e will, from this moment forward, ensure that no individual monitored for exposure undergoes travel in any way other than controlled movement.”[25]

Sources below the cut.

[1] WHO, Contact Tracing During An Outbreak of Ebola Virus Disease, September 2014, p.4 (hereinafter Contact Tracing); http://www.who.int/csr/resources/publications/ebola/contact-tracing-during-outbreak-of-ebola.pdf?ua=1

[2] Lisa Schnirring, Center for Infectious Disease Research and Policy, CDC to deploy Ebola response team to help hospitals; http://www.cidrap.umn.edu/news-perspective/2014/10/cdc-deploy-ebola-response-team-help-hospitals

[3] Id.

[4] Ventures, Ebola: US Borrows A Lead from Nigeria’s Response; http://www.ventures-africa.com/2014/10/ebola-us-borrows-a-leaf-from-nigerias-response/

[5] Id.

[6] Id.

[7] Clarence Roy-Macauly, Huffington Post, Nigeria Confirms New Ebola Cases, Boy Killed in Liberia Quarantine Zone; http://www.huffingtonpost.com/2014/08/22/nigeria-ebola-quarantine_n_5699062.html

[8] Contact Tracing, p.4

[9] Contact Tracing, p.4

[10] Partners In Health, Need to Know: How Contact Tracing Can Stop Ebola, http://www.pih.org/media/need-to-know-contact-tracing

[11] Contact Tracing, p.1

[12] Paolo Francesconi, et al, Emerging Infectious Diseases, Ebola Hemorrhagic Fever Transmission and Risk Factors of Contacts, Uganda, Emerg Infect Dis. Nov 2003, p.9; http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3035551/

[13] Erik Wemple, Washington Post, CDC boss addresses quarantine violation by NBC News doc Nancy Snyderman; http://www.washingtonpost.com/blogs/erik-wemple/wp/2014/10/14/cdc-boss-addresses-quarantine-violation-by-nbc-news-doc-nancy-snyderman/

[14] Patrick Kevin Day, LA Times, Media react to NBC News’ Dr. Nancy Snyderman violating ebola quarantine; http://www.latimes.com/entertainment/tv/showtracker/la-et-st-media-reacts-nbc-news-nancy-snyderman-ebola-violation-20141014-story.html

[15] Wemple, supra note 13.

[16] Id.

[17] Id.

[18] Day, supra note 14.

[19] CDC, CDC and Frontier Airlines Announce Passenger Notification Underway; http://www.cdc.gov/media/releases/2014/s1015-airline-notification.html

[20] International SOS, FAQ; https://www.internationalsos.com/ebola/index.cfm?content_id=410&

[21] Elahe Izadi, Washington Post, Investigating Ebola: How contact tracing will work in Texas; http://www.washingtonpost.com/news/to-your-health/wp/2014/09/30/investigating-ebola-in-the-u-s-how-contact-tracing-works/

[22] Abby Phillip, Lena H. Sun, and Brady Dennis, Washington Post, Second Ebola case confirmed. Texas health worker wore ‘full’ protective gear; http://www.washingtonpost.com/news/post-nation/wp/2014/10/12/dallas-health-care-worker-who-treated-thomas-eric-duncan-has-tested-positive-for-ebola/

[23] David Kroll, Forbes, Emory Nurses In Dallas To Provide PPE, Infection Control Training; http://www.forbes.com/sites/davidkroll/2014/10/14/emory-nurses-traveling-to-dallas-to-provide-ppe-infection-control-training/

[24] Mark Berman, Washington Post, Health-care worker with Ebola flew on commercial flight a day before being diagnosed; http://www.washingtonpost.com/news/post-nation/wp/2014/10/15/ebola-stricken-nurse-flew-on-a-passenger-plane-a-day-before-being-diagnosed/

[25] Id.



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