Malaria in Roman times

Even today, Malaria is one of the greatest medical challenges worldwide, still killing hundreds of thousands of people every year. In the past, people have adapted to the threat of malaria in various ways. One of these are genetic adaptations that evolved as survival mechanisms.
Malaria was not eradicated on the Italian island of Sardinia until the 1950s[1]. Until now, it has been assumed that the disease was only endemic on the island since the Middle Ages (500-1500 CE).

However, researchers have now studied the history of malaria on Sardinia in far greater depth[2]. Since antique DNA (aDNA) of malaria is very difficult to extract, they studied thalassemia and other genetic adaptations instead. Thalassemias are genetic diseases that interrupt the development of red blood cells. These diseases, however, have the advantage that many people affected lead a relatively healthy life and are bad hosts for malaria parasites. They are therefore partially immune against infections with malaria. Even today, such thalassemias occur relatively frequently in former malaria regions, such as the Mediterranean.

The researchers studied a thalassemia allele called cod39 β-thalassemia, which is dominant on Sardinia. They were therefore able to prove that, contrary to what has been known until now, malaria was probably already endemic on Sardinia in the Roman period, long before the Middle Ages.

The decisive evidence of this supposition has been provided by the 2,000 year old (circa 300 BC to 100 AD) remains of a Roman, in which the cod39 allele could be proven. “This is the very first documented case of the genetic adaptation to malaria on Sardinia,” Claudia Vigano, lead-researcher, says. “We also discovered that the person was genetically a Sardinian in all probability and not an immigrant from another area.”

[1] Eugenia Tognotti: Program to Eradicate Malaria in Sardinia, 1946–1950 in Emerging Infectious Diseases - 2009. See here.
[2] Viganó et al: 2,000 Year old β-thalassemia case in Sardinia suggests malaria was endemic by the Roman period in American Journal of Physical Anthropology - 2017

No comments:

Post a Comment