BOSTON, Sept. 13 (UPI) -- Two elderly Massachusetts residents have become the latest to die from the West Nile virus, state health officials said Friday.
In Illinois, meanwhile, two additional deaths were reported, bringing the state total to 16, the highest in the nation.
The deaths of an 87-year-old South Boston woman and an 81-year-old Weymouth man were the first in Massachusetts this year to be linked to the virus that has killed more than 50 nationwide.
The woman was only diagnosed with the virus Thursday, according to Roseanne Pawelec of the Massachusetts Department of Public Health.
She said the Sept. 6 death of the Weymouth man was confirmed Friday to be due to West Nile.
According to the MDPH, there have been 49 West Nile virus-related deaths across the United States this year, including the two new Massachusetts cases.
The federal Centers for Disease Control and Prevention put the national death toll at 54, with 1,295 people having contracted the disease.
In Massachusetts, 11 cases have been diagnosed this year.
In Illinois, the latest deaths were an 86-year-old Chicago-area woman and a 68-year-old man from the Decatur, Ill., area. Also, 12 more people tested positive for the disease, bringing the state's total to 358.
In a radio interview in Waterbury, Vt., Thursday, Sen. Patrick J. Leahy, D-Vt., questioned whether the spread of the virus to more than 30 states might be a result of biological terrorism.
"I think we have to ask ourselves: Is it a coincidence that we are seeing such an increase in West Nile virus, or is that something that is being tested as a biological weapon against us?" Leahy said.
Leahy said there are "some people, credibly, who feel that it is a test of our defenses and is a biological weapon or somebody doing this for commercial purposes."
According to the New York Times, law enforcement and public health officials dismissed the theory.
"Our research up until this point has not indicated that this is anything other than a natural evolution" of a virus that follows the migratory patterns of mosquitoes and birds, said Rhonda Smith, a CDC spokeswoman.
The virus first appeared in North America in New York City in 1999 and has spread this year to as far as California. It is mainly an infection of birds, but humans can be infected if bitten by mosquitoes that have bitten diseased birds.
Health officials have said that additional cases can be expected until there is a hard freeze.