Michael Silverman, a clinician at the University of Toronto, noticed that some of the Akwio children had open sores on their arms and legs.
, it seemed like a combination of two diseases, syphilis and yaws.
The former, caused by bacteria known as Treponema pallidum pallidum, produces open sores.
But it is spread through sexual contact and forms sores around the genitals.
Another strain, T. p. pertenue, causes yaws, which is spread by skin contact rather than sex and produces sores on the limbs.
But the Guyana disease was not quite like yaws either.
That disease causes raspberrylike eruptions, not the open sores the doctors saw.
"I thought, 'This is bizarre,' " says Silverman
The following year, Silverman
colleagues proved that the disease was caused by a form of Treponema, which infected about 5% of the children in the tribe.
They began treating them with penicillin.
Just before boarding a flight for his 2005 mission, Silverman got a call from Kristin Harper, a graduate student at Emory University in Atlanta, Georgia.
To get the DNA samples, Silverman
dipped swabs into sores, preserved them in alcohol, and sent them to Harper, who extracted fragments of Treponema DNA.
Months later, Silverman
got a call from Harper.
"You bring in the Europeans who only touch skin when they have sex, and it takes off as a venereal disease," Silverman
One reason the data are so sparse is the challenging work conditions in the jungles of Guyana, where Silverman
preserved samples in unrefrigerated alcohol--far from the ideal way to keep DNA from degrading.
But that may not be possible, as Silverman
colleagues have not been able to get any more DNA from the Guyanese strain.
On subsequent missions, they failed to find anyone infected with it.
It appears that they have eradicated the disease.
"We're still looking for one more case," says Silverman