Doctors in the United States are so busy vaccinating people against smallpox that they might not notice an actual outbreak, it has been claimed.
There is no known cure for smallpox
A survey of public health departments shows over half have cut back on routine work as they press ahead with the vaccination programme.
In December, US President George W Bush announced plans to vaccinate 500,000 key workers against the disease.
By the middle of the year, 10 million people are scheduled to be vaccinated.
However, a survey by the National Association of County and City Health Officials (NACCHO) shows that the workload has forced four out of five of them to delay or scrap projects aimed at responding to bioterror attacks.
The survey, published in New Scientist magazine, shows 59% of authorities have had to cut back on routine work.
Ironically, if authorities are to have a hope of fighting the spread of smallpox in the event of an outbreak they need to identify any cases early.
"There's a certain irony," said Pat Libbey, head of NACCHO.
"The most important determinant for how well we manage any smallpox outbreak is how fast we detect and respond to it."
Mr Libbey recently gave evidence to the US Senate on this issue.
He warned that the workload could leave some communities open to other diseases, such as influenza or even the West Nile virus.
Addressing the health sub-committee, he said: "We are gravely concerned that, if diversion of general public health resources to smallpox vaccination continues and grows, our communities will become more vulnerable to ongoing public health threats such as influenza, childhood diseases, West Nile virus, contaminated drinking water, food-borne illness, and chronic diseases."
Meanwhile, the magazine also claims that the US government is struggling to meet its vaccination targets.
The report states: "As New Scientist went to press fewer than 5,000 had been vaccinated in just 27 states."
It suggests that a combination of money not reaching the frontline and individuals concerned about the possible side-effects are to blame.
In January, the Environmental Protection Agency announced plans to establish early warning systems designed to detect smallpox, anthrax and other deadly airborne germs across the US.
This will involve fitting monitoring stations with filters to detect biological agents.