Zoonotic disease spilloverOr the transmission of the disease from animals to humans was a problem. In 1947, the World Health Organization established a global network of hospitals. Detect pandemic threats
Through a process called Syndrome surveillance
.. This process relies on a standardized symptom checklist to look for signs of a possible emerging or re-emerging infectious disease among a population of patients with symptoms that cannot be easily diagnosed.
This clinical strategy is for infected individuals Sentinel Hospital And medical authorities Influential and lasting Enough to sound the alarm.
There is only one problem: the outbreak has already happened by the time someone is sick and appears in the hospital.in the case of Virus that causes SARS-CoV-2, COVID-19, It probably spread long before it was detected. This time, the clinical strategy alone failed.
The spread of zoonotic diseases is more than one
A more aggressive approach is currently gaining attention in the world of pandemic prevention: viral evolution.This theory suggests that Animal virus becomes a dangerous human virus Due to frequent zoonotic spillovers, it gradually increases over time.
This is not a one-time transaction. It may be necessary for “intermediate” animals such as civets, pangolins, and pigs to mutate the virus so that people can jump first. However, the ultimate host that allows the variant to be fully adapted to humans can be humans themselves.
The theory of virus evolution is COVID-19 variant..In fact, an international team of scientists has suggested that there is likely to be undetected human-to-human transmission after an animal-to-human jump. Origin of SARS-CoV-2..
When the outbreak of new zoonotic diseases such as Ebola first gained worldwide attention in the 1970s, research on the extent of disease transmission was dependent. Antibody assay, A blood test to identify someone who is already infected.Antibody monitoring, also known as Serum survey, Test blood samples in the target population to determine the number of infected people. Serum tests can help determine if a disease such as Ebola is circulating undetected.
Ebola antibody 5% of people tested in Liberia in 1982, Decades before the 2014 West African epidemic. These results support the theory of virus evolution. It takes time, and sometimes a lot of time, to endanger animal viruses and infect them among humans.
What this means is that scientists have the opportunity to intervene.
Measurement of spillover of zoonotic diseases
One way to take advantage of lead times for animal viruses to fully adapt to humans is long-term repetitive monitoring.settings of Pandemic threat warning system With this strategy in mind Detect pre-pandemic virus Before they do harm to humans. And the best place to get started is directly from the source.
My team Virologist Shi Zhengli A study of the Wuhan Institute of Virology to develop a human antibody assay to test the very distant part of SARS-CoV-2 found in bats. A small 2015 serum survey in Yunnan, China, established evidence of zoonotic spillover. 3% of research participants living near bats Carrying a coronavirus like this SARS makes the antibody positive. However, there was one unexpected result. None of the previously infected study participants reported any adverse health effects. Early spreads of the SARS coronavirus, such as the first SARS outbreak in 2003 and the Middle East Respiratory Syndrome (MERS) in 2012, caused high levels of illness and death. This didn’t do that.
Researchers conducted larger studies in southern China between 2015 and 2017. This is a bat habitat known to carry coronaviruses such as SARS. Original 2003 SARS Pandemic And one Most closely related to SARS-CoV-2..
Less than 1% of participants in this study tested antibody positive. This means that you were previously infected with a coronavirus like SARS. Again, none of them have reported any adverse health effects. However, Syndrome Surveillance (the same strategy used in sentry hospitals) has revealed even more surprises. 5% of community participants Symptoms consistent with SARS have been reported over the past year.
This study did more than provide the biological evidence needed to establish a proof of concept for measuring zoonoses spillover. The pandemic threat warning system also detected signals of infectious diseases such as SARS that blood tests could not yet detect. It may even have detected an early variant of SARS-CoV-2.
If the monitoring protocol had been implemented, these results would have triggered a search for community members that could have been part of an undetected outbreak. But without an established plan, the signal was lost.
From prediction to monitoring and gene sequencing
Most of the pandemic prevention funding and efforts over the last two decades have focused on the discovery of wildlife pathogens and the prediction of pandemics before animal viruses infect humans. However, this approach does not predict major outbreaks of zoonotic diseases, including the 2009 H1N1 influenza, 2012 MERS, the 2014 West African Ebola epidemic, and the current COVID-19 pandemic. ..
However, due to predictive modeling Global “hotspot” The place where spillover of zoonotic diseases is most likely to occur.
Long-term, regular monitoring of these “hotspots” can detect spillover signals and changes that occur over time. These may include an increase in antibody-positive individuals, an increase in the level of illness, and changes in the vitality of infected people. As with other prophylactic disease surveillance, if a signal is detected, an outbreak investigation will follow. People identified as Symptoms that cannot be easily diagnosed Gene sequencing can then be used to screen and characterize and identify new viruses.
This is exactly what Duke University’s Greg Gray and his team did in their search. Undiscovered coronavirus In the Sarawak region of Malaysia, it is known as the “hotspot” for spillovers of zoonotic diseases. Eight of the 301 samples collected from patients with pneumonia hospitalized between 2017 and 2018 were found to carry canine coronavirus, which was previously unseen in humans. Complete viral genomic sequencing not only suggested that it had recently popped out of the animal host, but also had the same mutation that made both SARS and SARS-CoV-2 very fatal.
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Don’t miss the next pandemic warning signal
Fortunately, monitoring infrastructure already exists in global “hotspots”. NS Organizational connectivity for community disease surveillance The program links six regional disease surveillance networks in 28 countries. They were pioneers of “participant surveillance” and contributed to preventive efforts in collaboration with communities at high risk of both early spillover of zoonotic diseases and the most serious health outcomes.
For example, Cambodia, a country at risk of pandemic bird flu, has set up a free national hotline for community members to report animal diseases directly to the Ministry of Health in real time. Such an on-site boot approach is the key to timely and coordinated public health measures to prevent an outbreak before it becomes a pandemic.
It is easy to miss warning signals when global and local priorities are tentative. The same mistake does not have to happen again.
This article will be republished from conversation, A non-profit news site aimed at sharing ideas from academic experts. It was written by: Maureen Miller, Columbia University..
Maureen Miller was funded by USAID, which was used to develop the pandemic threat monitoring and warning system described in this article.