The Pentagon has been asked to examine whether ticks and other insects were experimented on as potential biological weapons, after a US politician demanded the US military give answers.
Chris Smith, a Republican congressman for New Jersey, tabled a vote – passed last week – which compels the Pentagon inspector general to investigate.
Mr Smith asked that the Pentagon report back on "whether the department of defence experimented with ticks and other insects regarding its use as a biological weapon between the years of 1950 and 1975."
He wanted to know who ordered the programme, whether there was ever an accidental release of diseased ticks, and whether the programme has contributed to the increase of Lyme disease.
"My amendment tasks the DOD inspector general to ask the hard questions and report back," he said.
Mr Smith said that he was inspired to add the amendment to the annual defence bill by "a number of books and articles suggesting that significant research had been done at US government facilities including Fort Detrick, Maryland and Plum Island, New York to turn ticks and other insects into bioweapons."
Some theorists have suggested that bioweapon specialists packed ticks with pathogens that could cause severe disabilities, disease and death among potential enemies to the US.
Experts have dismissed the idea as a conspiracy theory.
But Mr Smith, co-chair of the House Lyme disease caucus, has been a strong advocate for further research into the disease.
Each year, approximately 30,000 cases of Lyme disease are reported to Centers for Disease Control and Prevention (CDC) by state health departments. The disease, spread by ticks, appears to be on the rise: in 1997 there were 12,800 confirmed cases, rising to 29,500 in 2017 – the most recent year for which data is available.
Earlier this year Mr Smith introduced the "Ticks: Identify, Control, and Knockout Act'' (TICK Act), a bill to come up with a national strategy to fight Lyme disease. If passed, the measure would authorize an additional $180 million to boost funding for Lyme disease research, prevention and treatment programmes.
The CDC currently spends about $11 million on Lyme disease research.
Mr Smith's tick amendment is not certain to make it into the final defence spending measure. Both the House and Senate have passed their own versions, and representatives from both the House and Senate will meet in conference committee to reconcile the two bills.