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Bubonic plague: highly dangerous plague pathogen much older than previously thought


Dangerous infectious disease: So far the oldest genome of bubonic plague decoded

The plague claimed millions of lives, especially in the Middle Ages. Even today, epidemics continue to occur in some regions of the world. The most common form of plague is bubonic plague. Researchers have now found that this infectious disease exists much longer than previously thought.

One of the most devastating epidemics in human history

The plague is one of the most devastating epidemics in human history. Especially in the Middle Ages, the "Black Death" claimed millions of lives. Even today, epidemics continue to occur in some regions. An international research team headed by the Max Planck Institute for Human History in Jena has now found evidence that this infectious disease has existed significantly longer than previously thought.

Emergence of bubonic plague in the Bronze Age

As the Max Planck Institute (MPI) announced for human history, the researchers have reconstructed two Yersinia pestis genomes that indicate the Bronze Age origin of bubonic plague.

According to the information, the now identified strain was discovered in two skeletons from a double burial in the Samara region in what is now Russia. The burial took place around 3,800 years ago.

It is the oldest known strain to date that has the genes that are characteristic of bubonic plague.

And according to the researchers, he is the ancestor of today's tribes, which triggered the Justinian plague, the black death and the plague epidemics of the 19th century in China.

Cause of some of the deadliest pandemics

The plague caused by the Yersinia pestis bacterium was the cause of some of the deadliest pandemics in human history, including the Justinian plague, black death, and the major epidemics that swept through China and later the rest of the world in the late 19th century.

The disease continues to threaten populations around the world, so last year Madagascar had an outbreak of pes with several thousand people killed and many killed.

Other countries have also been affected in recent years. According to the World Health Organization (WHO), there were 3,248 cases worldwide between 2010 and 2015, including 584 deaths.

"The currently three most endemic countries are the Democratic Republic of the Congo, Madagascar and Peru," the organization reported on its website last year.

The origin and age of the disease have not been adequately researched

As the MPI writes, the origin and age of the disease have not been adequately researched, despite their historical and current significance.

It is particularly unclear when and where Yersinia pestis acquired the genes that allow the pathogen to use fleas as carriers.

Recent studies of Yersinia pestis genomes from earlier eras have identified an extinct variant of the pathogen and dated the late Neolithic and the early Bronze Age.

However, its genomes do not have the genetic characteristics that make the pest pathogen particularly efficient - namely the ability to survive in fleas, which is the main mode of transmission of the disease to humans and other mammals.

The aim of the study now published in the journal "Nature Communications" was therefore to analyze further Yersinia pestis genomes from these epochs in order to find out when and where these crucial adjustments took place.

Probably 1,000 years older

Using data obtained from previous sequencing of Yersinia pestis strains, the team of scientists calculated the age of the newly identified lineage to be around 4,000 years.

This shifts the presumed age of bubonic plague further by 1,000 years.

"The line that produced our Yersinia pestis isolates probably originated around 4,000 years ago and had all the genetic properties necessary for the efficient transmission of pest in rodents, humans and other mammals," explains lead author Maria Spyrou from the Max Planck Institute for human history.

Two plague lines could be circulating at the same time

Although previous studies have identified a single line of Yersinia pestis during the Bronze Age throughout Eurasia, the current study suggests that at least two plague lines circulated at the same time and that they may have different transmission and contagion potentials.

"Whether the lineages were equally widespread in human populations and the extent to which human activities have contributed to their spread are questions that need further investigation," explains study leader Johannes Krause from the Max Planck Institute for the History of Humanity.

He added: "Other Bronze Age and Iron Age plague genomes could help identify key events that have contributed to the spread of one of humanity's most notorious pathogens." (Ad)

Author and source information

Video: An Introduction to Infectious Diseases. The Dynamic World of Infectious Disease Part 124 (August 2020).