Measles first spread to humans from cattle more than 2,500 years ago, reveals research that could shed light on the current Covid-19 pandemic
- Measles virus spread to humans in the sixth century BC during the rise of cities
- Scientists sequenced DNA of a measles strain taken from an 100-year-old lung
- Experts say the research could help clarify the emergence of viral pandemics
Measles first spread to humans from cattle more than 2,500 years ago, likely during the rise of the first large cities, scientists claim.
The measles virus, measles morbillivirus, diverged from a closely related cattle-infecting virus in approximately the sixth century BC – around 1,400 years earlier than current estimates.
The highly-contagious virus emerged at roughly the same time that large urban centres were starting to spring up throughout Eurasia and South and East Asia, the experts say.
The discovery is based on a genome of measles extracted from lung tissue, more than a century old, taken from a patient in Berlin in 1912.
The team of researchers sequenced the DNA of the unfortunate patient’s measles strain and looked backwards to assess when the virus likely arose in human populations.
After comparing the sequencing data to a more recent viral genome, the research team estimated an emergence date of 528 BC, during the Iron Age.
Formalin-fixed lung of 1912 measles patient, from which researchers extracted a genome for their study. The team sequenced the genome and looked backwards to assess when the virus likely arose in human populations, dating this at around the sixth century BC
Similar research methods could reveal more about how and when zoonotic diseases – those that pass from animals to humans – emerged, including Covid-19.
The current global health pandemic is caused by the SARS-CoV-2 strain of coronavirus, which is thought to have been transmitted from bats to humans via an ‘intermediary animal’ in China.
Understanding the emergence and evolution of human pathogens plays a pivotal role in predicting the trajectories of outbreaks, according to scientists.
Many infectious diseases arose after the Stone Age revolution, when hunter gatherers turned to farming.
‘Although it is broadly accepted this also applies to measles, the exact date of emergence for this disease is controversial,’ said study author Dr Sebastien Calvignac-Spencer, an epidemiologist at the Robert Koch Institute in Berlin, whose research has published in Science.
A measles rash. Measles belongs to a group of diseases called morbilliviruses. They are found in various mammals – and are adept at jumping from one host species to another
Autopsy report for 1912 measles case archived by the Berlin Museum of Medical History of the Charité. To get a better fix on the origins of measles, researchers reconstructed the measles virus genome using lung samples collected from a 1912 measles case
Measles: a highly contagious disease
Measles belongs to a group of diseases called morbilliviruses.
They are found in various mammals – and are adept at jumping from one host species to another.
The common ancestor of measles was a virus that jumped into humans after cattle were domesticated.
It is known non-human morbilliviruses can easily adapt to enter human cells.
There are fears relatives of measles could jump from animals to us today.
Despite immunisation programmes incidence has recently been on the rise from 2017 compared with 2018.
In 2018 there were 9.8 million cases of measles and 142,000 deaths, according to estimates from the World Health Organisation (WHO) and the US Centers for Diseases Control and Prevention.
In 2017, there were 7.6 million cases of measles and 124,000 deaths.
‘The results paint a new portrait of the evolutionary history of the measles virus.
‘They support a scenario where a bovine virus ancestor circulated among cattle for thousands of years, before jumping to humans once settlements began to surge in size in the late first millennium BC.
‘Our analyses show the measles virus potentially arose as early as the sixth century BC, possibly coinciding with the rise of large cities.’
The earliest clear clinical description of measles is often attributed to the legendary Persian doctor Al-Razi, or Rhazes, who ran a hospital in Bagdhad in the tenth century AD.
‘But Rhazes was extremely familiar with all available medical literature at his time and made use of earlier sources,’ said Dr Calvignac-Spencer.
‘Indian medical texts possibly describe measles several centuries before Rhazes.’
The measles virus is a prime target for both health authorities and scientists seeking to define the evolutionary paths of common human pathogens.
Researchers had long suspected that the measles virus emerged when the now-eradicated ‘rinderpest’ virus – German for ‘cattle-plague’ – spilled over from cattle into human populations.
This was previously thought to have happened around the end of the ninth century AD.
To learn more on the origins of measles, Dr Calvignac-Spencer and colleagues reconstructed the measles virus genome using lung samples collected from a 1912 measles case, housed at the Berlin Museum of Medical History of the Charité.
Specimens in the basement of the museum in Berlin, which features a variety of special exhibitions on medical science and history
The lung specimen encased in formaldehyde, also known as formalin, to preserve the proteins and vital structures within the tissue
They then compared sequencing data to a 1960 measles genome, 127 modern measles genomes and genomes from rinderpest and another cattle virus named PPRV.
Using a series of evolutionary and molecular clock models, the researchers traced the emergence of measles in humans between the years 1,174 BC and 165 BC, with a mean estimate of 528 BC.
The authors speculate a scenario where a bovine virus ancestor circulated among cattle for thousands of years, before jumping to humans once settlements began to surge in size in the late first millennium BC.
Virologists Professor Simon Ho of the University of Sydney and Dr Sebastian Duchene of the University of Melbourne, who were not involved in the study, said the research could better explain how pathogens jump from animals to humans.
Researchers at the Chinese Academy of Sciences, the People’s Liberation Army and Institut Pasteur of Shanghai came to the conclusion that SARS-CoV-2 (pictured) may have come from bats
‘Dating analyses of pathogens have come under the spotlight in the ongoing pandemic,’ they write in an accompanying piece in Science.
‘Further genomic data from historical and ancient samples, along with more comprehensive and intensive surveys of viruses harboured in wildlife, will lead to continued refinements of the time scales of emergence and evolution of human pathogens.
‘In turn, these refinements will improve our understanding of the circumstances under which pathogens emerge in their hosts and the mechanisms by which they do so.’
Since the emergence of SARS-CoV-2 in Wuhan, China late last year there’s been much uncertainty surrounding the virus’s origin.
A previous report from scientists said the virus is 96 per cent identical to one found in bats, although this is yet to be officially confirmed as the source.
While it was initially assumed that the virus passed to humans in a Wuhan wet market, a scaled, more recent studies have pointed to an anteater-like animal called a pangolin being the intermediary animal.
Pangolins are consumed as food in China and are also used in traditional medicine.
Professor Ho said the human SARS-CoV-2 virus split from its closest known relative – another coronavirus from a horseshoe bat – about 30 to 40 years ago, but the jump to humans most likely happened more recently.
‘Had the coronavirus jumped from its animal host to a human much earlier than November or December last year, it probably would have been detected,’ he said.
Scientists in China believe SARS-CoV-2 came from bats
The human COVID-19 SARS-CoV-2 virus split from its closest known relative – another coronavirus from a horseshoe bat (pictured) – about 30 to 40 years ago, according to University of Sydney Professor Simon Hothe jump to humans most likely happened more recently
Researchers at the Chinese Academy of Sciences, the People’s Liberation Army and Institut Pasteur of Shanghai came to the conclusion that the coronavirus may have come from bats.
In a statement, the team said: ‘The Wuhan coronavirus’ natural host could be bats… but between bats and humans there may be an unknown intermediate.
Research published in the Lancet also determined bats as the most probable original host of the virus after samples were taken from the lungs of nine patients in Wuhan.
The team suggested that bats passed the disease on to an ‘intermediate’ host which was at the Huanan seafood market in Wuhan before being passed on to the ‘terminal host’ — humans.
Authorities have pointed the blame on food markets in Wuhan, the Chinese city at the centre of the outbreak that scientists are scrambling to contain.
Rodents and bats among other animals are slaughtered and sold in traditional ‘wet markets’, which tourists flock to see the ‘real’ side of the country.
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