Thursday, October 30, 2014

Why is Ebola droplet spread controversial, when CDC, NIH and WHO have long acknowledged it?

From CDC regarding how one must handle laboratory specimens from someone with Ebola:
"Clinical specimens [such as blood or urine] from persons suspected of being infected with one of the agents listed in this summary (Ebola is listed as BSL-4 on page 251) should be submitted to a laboratory with a BSL-4 maximum containment facility."  (on page 238) "The recommendations for viruses assigned to BSL-4 containment are based on documented cases of severe and frequently fatal naturally occurring human infections and aerosol-transmitted laboratory infections" 
From CDC regarding air travel and Ebola:
When providing direct care to a sick traveler who came from a country with an Ebola outbreak, also wear surgical mask (to protect from splashes or sprays), face shield or goggles, and protective apron or gown... Give a surgical mask if a sick traveler is coughing or sneezing, if the sick person can tolerate wearing one.
From CDC regarding generation of aerosols in hospitals treating Ebola patients:
Aerosol Generating Procedures
Conduct the procedures in a private room and ideally in an Airborne Infection Isolation Room (AIIR) when feasible. Room doors should be kept closed during the procedure except when entering or leaving the room, and entry and exit should be minimized during and shortly after the procedure.
     HCP should wear appropriate PPE during aerosol generating procedures.
Conduct environmental surface cleaning following procedures (see section below on environmental infection control).
From CDC regarding the need to use Personal Protective Equipment (PPE) that can protect against aerosol and airborne virus:
...A PAPR with a full face shield, helmet, or headpiece. Any reusable helmet or headpiece must be covered with a single-use (disposable) hood that extends to the shoulders and fully covers the neck 
From WHO:
Theoretically, wet and bigger droplets from a heavily infected individual, who has respiratory symptoms caused by other conditions or who vomits violently, could transmit the virus – over a short distance – to another nearby person.

This could happen when virus-laden heavy droplets are directly propelled, by coughing or sneezing (which does not mean airborne transmission) onto the mucus membranes or skin with cuts or abrasions of another person.
BSL-4 agents "cause illness by spreading through the air (aerosol) or have an unknown cause [sic] of transmission" 

1 comment:

SatyaPranava said...

Good finds, but some discussion may be warranted here.

I can't believe we have to waste our time sifting for "smoking gun" evidence and arguing over various policies.

Go have a laugh at the factsheet provided by CDC re: the difference between infections spread via air and droplets.

I did a little scratch-out exercise yesterday during one of our meetings, where I scratched out language that was common to both, and then squigglied any statement that was incorrectly applied only to one, or factually incorrect and I found that the brochure said the following (I'm not really exaggerating and can scan a copy of the factsheet): infections spread by air are tuberculosis and chicken pox.

That was all that was left after a paragraph of rambling. The droplet paragraph wasn't much better.

So, so critical assessments re: your post here:

Re A)could be interpreted to be overgeneral (i.e. ebola could fall under the "documented cases of severe and frequently fatal naturally occurring human infections" part while they used an incorrect conjuction "and" instead of the disjunction "or." Thus, they would argue the "aerosol-transmitted laboratory infections" part does not pertain to ebola.

Another argument they could make here is that these refer to "laboratory" infections and thus, are not representative of the "real" world. But good find, nonetheless.

B) this is just horrible advice since surgical masks will only protect everyone else from what the wearer is usually presenting and will is like a barbed wire fence attempting to stop a swarm of bees. The giving one to the traveler makes sense, but not to the person "providing direct care." I"d be looking at N-99 or N-100 masks (vs the N-95s which may not filter all sub-micron viruses.

C) nothing to criticize here except save their claim that ebola is not aerosolized (yet). So this would be irrelevant (their weak argument might go) to ebola.

D) very good advice and should be implemented in health care settings in case of this risk.

E) the first paragraph is true, but irrelevant to droplets. The 2nd is just as true and doesn't quite apply to our aerosolization issue. And the CDC had already moved the goal posts in the past couple of weeks saying on a handout a few weeks ago that "ebola can not be spread through the air" (paraphrased, but might be exact), and then in the last two weeks began discussing droplets.

F) this is good, but still "overgeneral" argument could be made to absolve ebola (again not considering all the evidence).

Gosh what an important but unnecessary waste of time. It'd be so much easier if we didn't have to fight the CDC on airborne vs aerosolization vs droplets, etc.

Most people (incorrectly becasue of this really problematic word choice by the CDC and WHO) think the flu is airborne. Ebola is as airbone as the flu according to droplet & aerosolization processes.

Sorry for the ramble, but I thought you might be interested or wish to discuss.