Episode Summary

Dr. Wun-Ju Shieh worked as a pathologist and infectious diseases expert with the CDC from 1995-2020. He recounts his experiences conducting high risk autopsies on the frontlines of outbreaks, including Ebola, H1N1 influenza, mpox and SARS-CoV-1 and 2. He also addresses key questions about factors contributing to the (re)emergence and spread of pathogens and discusses whether outbreaks are becoming more frequent or simply more widely publicized.

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Ashley's Biggest Takeaways

  • Pathologists are a group of medical doctors serving behind the line of the daily hospital activities.
  • Pathology service can be divided into atomic pathology and clinical pathology. The field covers all the laboratory diagnostic work in the hospital, and clinical microbiology or medical microbiology is actually a subdivision within the clinical pathology service.
  • Usually, a pathologist working in a hospital will examine and dissect tissue specimens from surgery or biopsy.
  • The pathologist also performs autopsies as requested to determine or confirm the cause of death.
  • Serving as first a clinician in Taiwan, and then a pathologist in the U.S., has provided Sheih with the unique experience of evaluating patients from both the outside-in and the inside-out!
  • Even when a major outbreak of a known etiologic agent is taking place, confirmatory diagnosis is necessary for subsequent quarantine, control and prevention of the outbreak.
  • During major disease outbreaks, other pathogens do not go away, and we must simultaneously facilitate their timely diagnosis to ensure effective patient treatment and care.
  • SARS-CoV-2 appears to be transmitted more easily than SARS-CoV-1. One possible explanation for this is that the amount of viral load appears to be the highest in the upper respiratory tract of those with COVID-19, shortly after the symptoms develop. This indicates that people with COVID-19 may be transmitting the virus early in infection, just as their symptoms are developing … or even before they appear or without symptoms.
  • SARS-CoV-1 viral loads peak much later in the illness.
  • Asymptomatic transmission is rarely seen with SARS-CoV-1 infection.
  •  Almost 99% of SARS-CoV-1 patients developed prominent fever when they started to carry infectivity. Temperature monitoring was therefore, very effective at detecting sick patients and facilitating prompt quarantining procedures, which effectively contained/minimized transmission of the virus.
  • This was not as effective for SARS-CoV-2, despite early attempts at temperature monitoring.
  • SARS-CoV-2 was much harder to contain both because of the milder display of host symptoms and the demonstration of higher viral transmissibility.


  • Outbreak: An outbreak is defined as a sudden rise in the numbers of cases of a disease more than normally expected in a given community or geographic area.
  • Epidemic: An outbreak is declared an epidemic when the disease spreads rapidly to many people locally.
  • Pandemic: A pandemic is an outbreak of disease across several countries or continents across the globe.
  • Endemic: An endemic is a disease outbreak that is consistently present, but only limited to a certain geopolitical area.

Featured Quotes:

“I was working at CDC, Centers for Disease Control, which is a public health institute, and not a hospital. So my duty and daily activities are somewhat different from the hospital pathologist.”

“In conjunction with the clinical and epidemiologic information, I will interpret all these test results, including molecular testing and electromicroscopy—if they’re performed—to generate a report with final diagnosis.”

“In a nutshell, I was utilizing pathologic, microbiologic, immunologic and molecular techniques to help investigate major outbreaks and difficult cases with unknown etiology of infection.”

“A pathologist is like a ninja, or a shadow warrior—highly skilled but usually working in the dark, behind the frontlines. We don’t get as much credit or visibility for what we do, but our work is essential for patient care in the hospital and for public health as well.”

“I used to be a hospital clinician, so I certainly saw a lot of patients. And like many of my colleagues, I did have severe cases or fatal cases—patients who died of certain infections. But back then, I couldn’t find the etiologic pathogens using the available laboratory methods. In Taiwan and many other Asian countries, the autopsy rating is, in general, very low because people don’t usually accept that type of procedure because of the culture or religious reasons.”

“If my patient unfortunately passed away, and if I could not find the etiologic agent, that case would bother me because I couldn’t help the patient.”

“When I was a clinician, I looked at the disease from outside-in. Later, I became a pathologist with my training in the U.S., and it was the reverse. When performing an autopsy, I was looking at things from the inside-out. Meaning, I was examining their tissue samples from histology and all those pathologic methods, and then trying to correlate with their clinical course.”

“It's very rewarding for me and such a good learning experience for my professional career to see things from both sides.”

“I got a chance to perform a partial autopsy in Vietnam on an anesthesiologist who contracted an infection from the index case [of SARS-CoV-1] at the emergency room when he was intubating the patient, and unfortunately died of the infection later.”   

“The knowledge and experience from studying SARS-CoV-1, I think, paved a faster and concrete way to the identification of SARS-CoV-2.”

“Back in 2003, after the SARS-CoV-1 outbreak, we performed many subsequent studies on animal models. We collaborated with NIH and other academic institutes, and we learned a lot in terms of the pathogenesis and pathology of SARS-CoV-1. And again, some of that information was very useful.”

“There are multiple reasons why we are seeing more pandemics caused by emerging and reemerging pathogens over the past 40 years or so. Evidence suggests that the risk of pandemics has increased because of many factors, such as increased global travel and integration, urbanization, change in land use, deforestation, global warming, greater exploitation of natural environments. And all these play some roles in terms of the so-called emerging outbreaks."

“When [pathogens] spread from a local area to a larger area geopolitical area or even globally, they become pandemic.”

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Mark O. Martin