Drugmaker GlaxoSmithKline temporarily closed a North Carolina factory on Tuesday after testing at a cooling tower found bacteria that causes deadly Legionnaire's disease.
The Legionella bacteria were discovered during routine inspections at the site in Zebulon, N.C., the company said.
The shutdown is not expected to disrupt supplies of medicines made at the factory, which include GSK's $7 billion-a-year inhaled respiratory drug Advair. Advair is also made at two other sites in Ware, England, and Evreux, France.
GSK said the shutdown was a precautionary measure and the Zebulon site would reopen when the situation was remedied. The tower is a stand-alone structure that does not come in contact with any products.
"The cooling towers will be cleaned and retested before the site goes back into operation. GSK is taking these precautions to ensure the health and safety of our employees, as well as the safety and integrity of our products," the group said in a statement.
Spokeswoman Jenni Brewer Ligday said 600 workers were sent home or told not to come in while the towers were being cleaned.
City and state officials said the discovery did not warrant a public health alert and that no threat was posed to city drinking water, according to a report in the Charlotte News and Observer newspaper.
The Zebulon plant manufactures around 30 different GSK drugs in all, including malaria drug Malarone, HIV treatment Combivir and Requip for Parkinson's disease, but its biggest product line is Advair, for asthma and chronic lung disease.
GSK is also planning to produce its next-generation dry powder inhaled respiratory drugs, such as Breo and Anoro, at Zebulon, although for the moment these are only being made in Ware.
Legionella bacteria are found naturally in warm water and thrive in environments such as hot tubs, cooling towers, water tanks, large plumbing systems and fountains, according to the U.S. Centers for Disease Control and Prevention.
Legionnaire's disease, a severe kind of pneumonia, is contracted by breathing in mist containing the bacteria. It is not contagious, according to the CDC.
Last week, New York City's Department of Health ordered the inspection and cleaning of all cooling towers in the city in response to an outbreak of Legionnaire's' disease that has claimed 12 lives.