The history and global spread of malaria over the past 5,500 years have been pieced together by researchers, who have identified trade, warfare, and colonialism as major factors in its dispersal. Malaria, a deadly infectious disease caused by single-celled parasites transmitted through the bite of infected Anopheles mosquitoes, continues to pose a threat to nearly half of the world’s population despite efforts to control and eradicate it. The World Health Organization estimates that malaria is responsible for nearly 250 million people get infected with malaria and over 600,000 die from it every year.
Aside from its huge impact on today’s world, malaria has played a major role in the evolutionary history of humans. “Even though it’s mostly found in tropical areas now, just 100 years ago the disease was present in half of the world’s land, including parts of the northern USA, southern Canada, Scandinavia, and Siberia,” says Megan Michel, the lead author and a doctoral researcher at the Max Planck-Harvard Research Center for the a research collaboration between the Max Planck Institute for Evolutionary Anthropology (MPI-EVA) and the Initiative for the Science of the Human Past at Har.Harvard University explains that genetic variants linked to devastating blood disorders like sickle cell disease are believed to have persisted in human populations because they provide partial resistance to malaria infection. The origins and spread of the deadliest malaria parasites, Plasmodium falciparum and Plasmodium vivax, are still not well understood despite their evolutionary impact. Malaria infections do not leave clear visible traces in human skeletal remains, and historical texts provide limited information. However, recent advances in ancient DNA analysis have provided new insights.Recent advances in the field of ancient DNA have shown that human teeth can retain evidence of pathogens found in a person’s blood at the time of their death. This provides a unique chance to study diseases that are typically not visible in the archaeological record.
In order to investigate the mysterious history of malaria, a group of researchers from 80 institutions and 21 countries worked together to analyze ancient Plasmodium genome-wide data from 36 individuals who were infected with malaria over a 5,500-year period on five different continents. These ancient cases of malaria offer an unprecedented opportunity to understand the global spread of the disease and its historical impact.
Research on the spread of malaria in the Americas has been a topic of interest for scientists, as the disease is endemic in tropical regions. One of the focuses of the research has been the P. vivax malaria species, which is adapted to survive in temperate climates. There has been speculation about whether this species arrived in the Americas via the Bering Strait during the peopling of the continent, or if it arrived later with European colonization. To better understand the journey of these parasites into the Americas, a team of researchers analyzed ancient DNA from a malaria-infected individual found in Laguna de los Cóndores, a high-altitude site in the cloud forests of the region. This analysis aimed to track the biomolecular breadcrumbs of the malaria parasites and shed light on their arrival in the Americas.In the eastern Andes of Peru, researchers conducted genomic analysis and found a striking similarity between the Laguna de los Cóndores P. vivax strain and ancient European P. vivax. This suggests that European colonizers likely brought this species to the Americas within the first century after contact. Coauthor Evelyn Guevara, a postdoctoral researcher at the University of Helsinki and the MPI, explains that infectious diseases, including malaria, had a devastating impact on Indigenous peoples during the colonial period due to factors such as warfare, enslavement, and population displacement. In some places, mortality rates reached as high as 90 percent.-EVA.
The team also found genetic connections between the Laguna de los Cóndores strain and modern Peruvian P. vivax populations 400 to 500 years later. “Our data indicates that malaria quickly spread to a relatively remote region and our evidence also suggests that the pathogen established an endemic focus there, leading to the development of parasites that continue to infect people in Peru today,” says Eirini Skourtanioti, postdoctoral researcher at MPI-EVA and MHAAM.
Malaria Spreading in Europe
Colonialism’s role in The Americas have seen a rise in malaria, and a team found that military activities influenced the spread of the disease in Europe. In Mechelen, Belgium, the cemetery near St. Rombout’s Gothic cathedral was next to the first permanent military hospital in early modern Europe (1567-1715 CE). Analysis of ancient human and pathogen DNA revealed that cases of P. vivax malaria were found in the local population buried before the military hospital was built, while cases of the more severe P. falciparum malaria were found in those buried after its construction. This suggests a shift in the type of malaria over time.Co-author Federica Pierini, a postdoctoral researcher at the MPI-EVA, noted an increase in malaria cases among non-local male individuals from the military hospital. The cases were attributed to the P. falciparum species, which was previously thought to only thrive in Mediterranean climates but was found in individuals from diverse Mediterranean origins. These individuals were likely soldiers recruited from northern Italy, Spain, and other Mediterranean regions to fight in the Hapsburg Army of Flanders during the 80 Years’ War.We’ve discovered that the movement of large groups of troops played a significant role in the spread of malaria during that time, similar to the cases of what is now known as airport malaria in temperate Europe,” says Alexander Herbig, Group Leader of Computational Pathogenomics at the MPI-EVA. “In our interconnected world, travelers infected with Plasmodium parasites bring them back to areas where malaria has been eliminated, and mosquitoes capable of transmitting these parasites can even cause ongoing local transmission. While the landscape of malaria infection in Europe looks very different now compared to 500 years ago, we can draw parallels in the way the disease spreads.The article discusses how human movement impacts the risk of malaria. It highlights a surprising discovery of the earliest known case of P. falciparum malaria at the high Himalayan site of Chokhopani in Nepal. This discovery was unexpected as the site is located far above the habitat range for the malaria parasite and the Anopheles mosquito. The region around Chokhopani is described as cold and dry, making it an unlikely location for malaria to thrive.The individual was a local male with genetic adaptations for high altitude living, and was likely engaged in long-distance trade based on archaeological evidence at Chokhopani and nearby sites. The researchers are puzzled by how the individual acquired malaria at such a high altitude, where neither the parasite nor the mosquitoes capable of transmitting malaria can survive. This raises a key question for them to explore.Mark Aldenderfer, a Distinguished Professor Emeritus at the University of California, Merced, and co-author of the article, mentions that despite being remote and hard to reach, the Kali Gandaki River Valley actually served as a pathway connecting people from the Tibetan Plateau with the Indian subcontinent. His excavations in the area have uncovered evidence of long-distance trade connections, such as copper artifacts found in the burial chambers of Chokhopani. This proves that the ancient residents of Mustang were involved in larger trading networks that included northern India. The low-lying, poorly drained regions of Nepal are not very far away from here.The team speculates that the man may have traveled to a malaria-endemic region with lower altitude, possibly for trade or other reasons, before returning to Chokhopani, where he was buried. The detailed information obtained from ancient DNA provides insights into how infectious diseases like malaria spread in the past, shaping our current disease landscape.
Historical and future perspectives of a constantly evolving disease
Today, the human encounter with malaria is at a turning point. Due to advancements in mosquito control and dedicated public health initiatives, malaria has become less prevalent in regions like Nepal and the Indian Terai, where it was once endemic.In the 2010s, malaria deaths hit a record low. However, the rise of drug-resistant parasites and insecticide-resistant vectors could undo years of progress. Climate change and environmental damage are also putting new areas at risk for malaria. Researchers believe that studying ancient DNA could help us better understand and fight this public health challenge.
“We can now study the ancient diversity of parasites in regions like Europe, where malaria has been eradicated,” explained senior author Johannes Krause, Director of Archaeogenetics at the Max PlThe Max Planck Institute for Evolutionary Anthropology states that the spread of malaria in the past through mobility and population displacement correlates with the vulnerability of malaria-free countries and regions to reintroduction today, due to modern globalization. The institute hopes that studying ancient diseases like malaria will offer new insights into understanding these organisms that still affect our world today.
