Frankly I don’t believe they know if you are only contagious after showing symptoms. They are acting like they know things they don’t to instill confidence - whether it’s true or not.
True. Like one poster said the virus is replicating at an astonishing rate in your bloodstream long before you show symptoms. It's just that the amount of the viral pathogen in your blood must reach a certain threshold before you're symptomatic. Nobody really knows exactly what that pathogen level must be to be contagious.
After scientists cashed in their reputation over global warming they now have a total credibility problem, and for good reason.
15% of ebola patients never get the fever, one of the earliest symptoms. Also:
Of particular concern is the frequent presence of EBOV in saliva early during the course of disease, where it could be transmitted to others through intimate contact and from sharing food, especially given the custom, in many parts of Africa, of eating with the hands from a common plate.
http://jid.oxfordjournals.org/content/196/Supplement_2/S142.full
If human skin itself contains the receptors required for the Ebola virus to easily bind to a host, aren’t carriers always contagious? Human skin is not a barrier, the virus passes right through it. Both directions... Once a significant population of the virus comes into contact with the host, that’s pretty much it. That is the horrific aspect of the virus here where airborne or not, on contact transmission is almost a given.
The attitude you explain is de rigueur in almost all engineering and management circles nowadays. I work in the medical device manufacturing field and this type of attitude is rampant.