Tuesday, October 14, 2014
Ebola and the vectors of transmission
There has been a lot of news and opinions the last couple days about the nurse in Dallas who has been infected with the Ebola virus.
The outbreak in West Africa where her patient contracted his virus is currently the largest by a huge margin since Ebola was first identified in 1976. Prior to this the deaths were limited to smaller villages, and the total deaths would be around 10. This time it's above 4,400, and increasing. Current thoughts are that the number of infected is at or above 10,000, and rising at a current rate of 1,000 per week.
Consider that the mortality rate in those who are diagnosed is around 70%. We're talking 700 deaths per week, and it could increase through November. These are all stats from the CDC and Doctors Without Borders.
There is one major train of thought in the current outbreak as to the contagion, and another that has few numbers supporting it, but has not been ruled out by the majority.
The predominant theory as to why this one is exponentially larger is it's origins in cities, rather than the small villages, which were largely isolated. This coupled with their inability to handle the isolation requirements to protect workers at the hospital. This is supported by the fact that the alpha case, Patient Zero, was treated at a small hospital in a city, undiagnosed for a day. Of the 4 doctors that initially treated him, 3 died of the disease. All the phlebotomists also died who drew blood from him.
The alternate thought is that is found a way to mutate, to develop other vectors of transmission. An example given is that it has a respiratory/ventalitory means of transmitting the disease.
In understand the issue, and assessing the potential for threat, one needs to know the virus.
In order for a virus to transmit to others by their breathing, it is necessary for the virus to be present in the infected person's throat, large and small bronchi, or the lungs. Currently the Ebola virus have not been found in that area on those infected. The protein coating each virus has been identified as having the ability to adapt in blood, to disguise it's self and fool immune systems, allowing it to multiply.
So how did this nurse, in full contamination regalia, become infected? I can think of a hundred ways, everything from a near-microscopic hole in her gloves, to a small tear in her sleeves, on and on.
Here's where Ebola is scary: the concentration of virus per unit of blood. HIV, smallpox, the viral load in the blood. The higher, the worse in any virus. Comparing HIV, Smallpox and Ebola, the first two shrink to microscopic images, compared to Ebola. Over a million times greater concentration of virus per unit.
This means, if I can speculate, back in the day I and many, many other had direct exposure to HIV. Treated a lot of them, at some point I'm sure I got blood on my skin, saliva, etc. I never got it. Were it Ebola, I'd not be here.
The really scary part is scientists are hedging their bets on how fast it is mutating. The fact is, we don't know where this current outbreak is going, and how many it will kill. Or if it can successfully spread to a northern climate.
I guess we'll find out. Just an evening's thoughts.
Oh, and Ebola and The Vectors of Transmission might be a good name for a rock band.....