The five others have yet to be identified -- so there is a possibility of an unknown virus at work.
The company said it spotted the "unknown virus" earlier this week and took desktop computers, email and web servers offline as it cleaned up.
This outbreak, on top of another death last month in Saudi Arabia from a previously unknown virus, a cousin of the Severe Acute Respiratory Syndrome (SARS), has set global health agencies on edge.
Much still remains unknown about the virus, including how people are getting infected, but scientists say it contains genetic markers that could help it infect humans.
When the avian flu first surfaced in 1997, the big unknown was whether the virus could be transmitted from human to human.
While the source of the virus remains unknown, further surveillance will help in understanding its transmission, said Liang Wannian, director general of the health emergency division of China's National Health and Family Planning Commission.
According to Reuters, the World Health Organization (WHO) originally issued an international alert in late September saying a virus previously unknown in humans had infected a Qatari man who had recently been in Saudi Arabia, where another man with the same virus had died.
FORBES: Is a New SARS-like Virus Spreading in the Middle East?
He said an FBI agent told him that his company was the victim of a new virus and an unknown perpetrator.
The alarming statements by the WHO and other UN agencies last week may in part have been prompted by a widespread feeling that health authorities in Asia failed to act quickly enough last year to contain the SARS virus, a hitherto unknown human infection.
How the virus might be able to do this was, however, unknown.
Custom Trojans are as hard for signature based anti-virus to catch as the dreaded zero-day threats which exploit previously unknown vulnerabilities.
FORBES: Modern malware requires modern methodologies to block
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