"As far as we know, it is still that example of the two people sitting by me as being at greatest risk, or someone who might touch the table where I have just put some droplets, or some environmental factor which is carrying these droplets to another person, " he added.

BBC: Scientists home in on mystery bug

While carrying its mining operations, the company says it is committed to achieving a high standard of environmental care.

CNN: South Africa dune mining whips up sandstorm