A new way to identify malaria in the bone marrow of ancient human remains may help scientists track the disease’s spread back to its first appearance in people.
This is the first time researchers have been able to establish a diagnostic, human skeletal profile for the disease, which is transmitted by mosquitoes and continues to infect millions of people each year.
The findings suggest the method, which works effectively on bones resistant to previous forms of testing, may also be applicable to other diseases.
Malaria in archaeological bones
“The data set we build with this will be revolutionary for establishing the epidemiological curve for malaria in ancient societies,” says Jamie Inwood, an archaeology graduate student at Yale University who led the research team.
“By understanding how this parasite reacted to societal shifts in the past, we can aid in predicting its future behavior. We can understand the way it has evolved.”
Researchers spent several years identifying chemical and spectral indicators for malaria in archaeological bones. Specifically, they looked for the polymer hemozoin, which is produced by the parasite that causes malaria.
The technique is more effective than other methods of analysis, such as pathogen aDNA extraction, which often produce inconclusive results and is difficult to conduct when poor preservation conditions are a factor.
Infants and toddlers
However, the aDNA method did help Inwood find an archaeological site to test her new technique.
Previous research led by University of Arizona archaeologist David Soren had arranged for aDNA testing of human remains from 550 AD at Lugnano in Teverina, Italy.
Soren provided Inwood with bone samples from the site—from roughly 100 infants and toddlers in a cemetery within a destroyed Roman villa. The bones were interred with heavy roof tiles to weigh them down.
“Researchers from the University of Arizona had found burial practices that were throwbacks to pagan rituals,” Inwood says. “It was suspected there must have been an epidemic in the community that caused fever or fits.”
Femur and humerus bone samples from the site contained black, crystalline hemozoin clumps in the bone marrow. Researchers scraped the hemozoin from the marrow and used X-ray defraction to identify it.
Hemozoin “dances” under the microscope, Inwood says.
Later this spring, Inwood will return to Lugnano in Teverina for a ceremony with Soren and local officials to honor the memory of the deceased and acknowledge the new information. Understanding the past is essential to the continuing human struggle against malaria around the world, Inwood says.
“There is a constant evolution of this disease, because of changes in human populations and changes in the medicines we use to treat it,” says Roderick McIntosh, professor of anthropology.
“Knowing the history of the mechanisms by which malaria evolves is a very good thing. We want to put together enough data for a timeline of malaria in humans.”
Source: Yale University