Friday, October 31, 2014

Ebola: worldwide dissemination risk and response priorities/ The Lancet

This piece in the Lancet, authored by Cowling and Yu, discusses issues of Ebola dissemination and means to reduce spread to other countries.  Its final paragraph discusses what we do not yet know, but need to learn:
There are several important near-future research needs. Perhaps most urgent is a better understanding of the effectiveness of existing treatment options, including convalescent serum. In the medium term, it is hoped that new vaccines and drugs will be available quickly for human clinical trials and in exposed populations.8 The WHO Ebola Response team has neatly summarised the transmission dynamics and epidemiological characteristics including the reproductive number, incubation period, and case fatality risk in the current Ebola virus outbreak,1 but one important unknown is the proportion of infections that are asymptomatic or mildly symptomatic. If mild infections do occur and are infectious, disease control outside west Africa might be increasingly challenging. However, this scenario is thought to be unlikely.9 One particularly pressing need is for the reassessment of appropriate procedures for infection control, and the potential for the virus to spread via small particle aerosols10 in addition to via contact with infected patients or their bodily fluids. Infection of health-care personnel in west Africa is often attributed to the scarcity of appropriate protective equipment and supplies, or inadequate administrative controls.1112 However, the nosocomial cases in Dallas and Madrid have raised the concern that present protocols might not be sufficient to protect health-care personnel fully against infection, particularly if cases are managed in health-care facilities that are not fully prepared.
Readers note:  CDC improved its infection control PPE recommendations the evening of Oct 20, making them virtually equivalent or better than the SARS protocols. (SARS spread by the respiratory route.)  They now include respiratory droplet precautions. This piece was published online Oct. 21.  I believe the current CDC recommendations provide health-care personnel with as good protection as currently achievable using available PPE.


SatyaPranava said...

Agreed, and the key point here is "available" PPE. Though the minimum protections that they're recommending for hospitals is still quite below what is effective. They're quite close, though. The rest is in the details.

The CDC still has posted all over the hospitals donning instructions which have the wearer remove their gloves first AND THEN all their contaminated PPE. So even though you can put the right stuff on, it doesn't mean one is less likely to come out of it without exposure.

yousaf said...

I guess you've seen this in the Lancet also:

Meryl Nass, M.D. said...

People are using 2 or 3 pairs of gloves simultaneously, and removing each pair at a different point. Gloves are considered the likely source of heaviest contamination, so disinfection with bleach, alcohol, soap/water is recommended before removing outer layer, as is done in surgery: inside out, to prevent contamination of deeper layers of gloves.

Dr. Yousaf Butt said...

The CDC poster used to be about Ebola -- now it is about germs in the first part (where it talks about sneezing): 6ft range now.

Then in the second part (Ebola) it says no airborne transmission BUT DOES NOT MENTION SNEEZING!!!


SatyaPranava said...

I agree, Meryl. But these documents were put out when CDC was only recommending one pair of gloves (no mention of 2 or 3 pairs).

Peronsally, I want my staff in three pairs for anyone giving care to an active case, with the bottom most layer being a puncture-resistant surgical type glove that goes up the arm. There's even been talk about using a bovine insemination type glove (Which goes all the way up the shoulder). But I'm not sure that will fly.

Meryl Nass, M.D. said...

The first CDC poster came out on Oct. 24. The new PPE guidelines (effective for droplets) came out Oct 20. The new poster came out today.

I imagine it will all become congruent after the election.

Dr. Yousaf Butt said...

The CDC in their Ebola transmission Q&A is being misleading and disingenuous: they say --

"There is no evidence indicating that Ebola virus is spread by coughing or sneezing."

BUT -- there is no evidence against it either and it very likely can be!

WTF!? Why are they doing this?

SatyaPranava said...

If we're giving them the benefit of the doubt, then the answer might be that they're trying to quell fear ("fearbola" as one government advisor commented) by convincing the public that something as serious as Ebola cannot be transmitted in the same way that the flu (which can also be transmitted via droplets, and is not "airborne") or TB is.

If this is the case, the problem with this policy is that it's now outdated and confusing--they now state that Ebola can be spread via droplets, but can't become "airborne."

I explained earlier (possibly in another thread) that the CDC's (and WHO's) use of the term "airborne" is misleading in that the distinction between "airborne" (as they use and explain it) and "aerosolized" droplet transmission only exists for largest and heaviest droplets and only for about 1 second, maximum)!

This is the time it takes those heavy droplets to fall to the floor or a surface (and then be a "fomite" contaminant) or for the smaller droplets to evaporate while the germ inside the former droplemt becomes...wait for it..."airborne."

Hence my understanding of the Brosseau & Jones commentary in CIDRAP

The truth is that we don't know in each case how it's transmitted, as these categories are sometimes works of intellectual distinction, being relevant in the human intellectual mind much more than the more fluid world of the virus.