One morning in the spring of 1993. A family from the Navajo Nation parked their car at a service station in New Mexico and called 911.
Their son, a 19-year-old marathon runner, suddenly had trouble breathing. He was taken by ambulance to a local hospital where he died. The doctors looked confused – how could such a young and healthy person die suddenly?
It soon became apparent that the marathon runner’s death was not an isolated incident. He organized the funeral for his fiancée, who died of a similar respiratory illness a few days ago.
Every time reports of a new disease outbreak hit the headlines, they were often accompanied by speculation. There are more virus particles on Earth than there are stars in the universe, and there are 10 times more bacterial cells in our bodies than mammalian cells.
Overall, there are an estimated one trillion microbial species on our planet, but only 1,513 bacteria, 219 viruses, 300 parasites, 70 protozoa, and 200 fungi are currently known to cause human disease. The rest is waiting to be discovered.
How common are mysterious disease outbreaks?
“Clearly there are outbreaks that have been a mystery,” said Stephen Morse, a professor of epidemiology at Columbia University Irving Medical Center in New York City.
In the 1993 case of the Navajo couple, local medical investigators noticed that others had experienced unexplained symptoms in the preceding months. These cases all occurred in the Four Corners Aboriginal community in the southwestern United States.
As more cases emerge, the race begins to catch the “culprits.” It was not until two months later that “hantavirus pulmonary syndrome” was identified as the culprit. This is an infectious disease caused by a novel hantavirus that commonly infects rodents.
Even today, such delayed discovery is very common. “There are still many infections that are undiagnosed acute respiratory distress syndrome and similar conditions, such as hantavirus pulmonary syndrome that was not initially detected but was later discovered through backtracking,” Morse said.
Many disease outbreaks initially go unnoticed and unreported. Ultimately, Morse said, it may be that one specialist is particularly interested in a certain infection, leading to an increase in reporting.
“In other places, there are outbreaks that go unnoticed because there are no technical facilities, because they are in remote areas, because there is no motivation.”
As we all know, this is happening with COVID-19. In December 2019, the World Health Organization received an alert of a cluster of pneumonia cases in Wuhan, China, but the cause was unknown.
Within a month, Chinese authorities formalized the virus’s identity by sharing its genetic sequence with the rest of the world. However, some research suggests that the virus actually began circulating among humans as early as October 2019.
Once an outbreak is brought to people’s attention, the next step is actually to find the pathogen behind it.
What are the current causes of respiratory diseases in China?
On November 13, 2023, China’s National Health Commission reported a surge in the incidence of respiratory diseases in the country, especially among children. More reports followed, describing overcrowded pediatric wards, hospitals packed with sick children and undiagnosed clusters of pneumonia.
Chinese officials told the WHO they had not identified any new pathogens, but attributed the cause to a combination of respiratory syncytial virus (RSV) and regular winter illnesses such as influenza. Some neighboring countries, such as India, are cautious about whether this is the full story, and WHO continues to monitor the situation.
How is a mysterious disease solved?
During the 1993 outbreak, researchers identified the virus causing the infection using polymerase chain reaction (PCR), a cutting-edge technology at the time.
Using specific DNA sequences of known hantaviruses, the scientists succeeded in finding this group of previously undiscovered hantaviruses.
Photo Credit: Getty Images / BBC News
Outbreaks of hantavirus pulmonary syndrome, caused by Sinnoble virus, are now linked to El Niño, a phenomenon that even leads to increased rainfall and an increase in the virus’ rodent hosts.
“This is really the first time molecular testing has been used to identify the pathogen (of infection),” Morse said.
Today, PCR has become the standard method for identifying pathogens, but it also has shortcomings. Because the technique requires sequences that are closely related to the pathogen you are looking for, it can be difficult to get answers without intuition about the possible causes of an outbreak.
During the Four Corners outbreak, scientists had learned that those infected had antibodies to other hantaviruses, so they used this approach.
However, other, more advanced methods of searching for unknown pathogens are emerging that do not require specific information.
A recently developed PCR method means it is possible to identify new pathogens in a wider grouping. Not only can you look for close relatives of known viruses, but you can also find other viruses in the same family.
Another approach is next-generation sequencing, which can help scientists discover microorganisms that are completely unknown to the scientific community. This technique was used to discover a new arenavirus in a study of a group of transplant patients who died after receiving an organ from the same donor.
“In many laboratories in high-income countries or with adequate resources, you can look at a sample and identify sequences that look like pathogen sequences, whether they’re viruses or bacteria… without having to know in advance what’s in it,” Morse said. “
Are the causes of certain disease outbreaks never identified?
In 2010, an unknown bleeding disorder began spreading in northern Uganda. “I personally remember this because I was the co-director of Project Predict,” Morse said.
He said there was a delay when researchers from the infection surveillance program arrived to take samples. But when they took samples, they found that some of the samples were positive for the yellow fever virus.
“So it’s basically classified as a yellow fever outbreak, but there are infected people who have negative samples. So it’s probably yellow fever, but we don’t know for sure,” he said.
Morse cited this as an example of many epidemics that remain mysteries to this day.
So when a mysterious disease outbreak makes global headlines, in most cases scientists may already be able to figure out the cause behind it pretty well — but only in areas where they have the resources.
This article“BBC News Chinese”Reprinted with permission, original textPosted here
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2023-12-13 08:00:14
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