Hunting a haunting virus

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As scary stories go, this one ranks high on Dr. Jeff Duchin’s list. The year was 1993, and he was serving as an Epidemic Intelligence Service (EIS) officer for the Centers for Disease Control and Prevention (CDC). Dubbed CDC’s Disease Detectives, EIS officers are often first on the scene when a public health emergency occurs, helping public health officials investigate and control infectious disease outbreaks or other events that endanger health and safety.

The reports from the Four Corners region of New Mexico and Arizona were tragic and ominous. Astute Indian Health Service physicians in the region had noticed a cluster of five young, healthy people who had all died after developing a “flu-like illness” that rapidly progressed to shock and acute respiratory failure, drowning its victims as fluid overtook their lungs and their blood pressure plummeted.

Dr. Duchin’s job as a member of the initial three-person CDC team was to work with the physicians and public health authorities in New Mexico to find the reason for the illnesses and stop the spread.

Read on to learn about the surprising cause and how they found it.

You were given a tough task to discover the cause of a mysterious and deadly illness. What clues did you have, and what did you look for?

Determining the cause was a large CDC team effort. The day we landed in Albuquerque, our team went directly to meet with colleagues from the Indian Health Service, the University of New Mexico (where patients had been treated), and the New Mexico Department of Health to review what was known about the cases and possible causes. We considered a wide range of possibilities, focusing in on severe viral and bacterial respiratory infections (like a novel strain of influenza or plague) and toxin exposure, although nothing fit the picture.

I was assigned to gather everything that was known about the clinical manifestations of the illness, while others collected specimens from patients and others conducted risk factor studies, where they tried to connect people’s behaviors, or risk factors, to the illness. And there were public information needs as well.

Community members were scared, and inaccurate rumors were rampant. How did you respond?

I was outraged to witness the unnecessary discrimination and bias against Native Americans because of this outbreak. Media reports inappropriately characterized the outbreak “Navajo flu” because the early cases were found on the Navajo reservation. Children were turned away from school and adults shunned, even though the disease is not unique to the Navajo people and does not transmit from person-to-person. We tried to correct misperceptions even as we were investigating the cause of the disease.

What turned out to be the cause?

When we began the investigation, we thought perhaps this illness was caused by a new hemorrhagic fever virus like the Hantaviruses seen in Asia and Europe. However, our suspicions were not very strong because these viruses were not known to cause human illness in North America. We sent blood samples from people who had the illness back to the CDC Viral Special Pathogens lab. They did excellent work, and ultimately found that antibodies from the blood samples reacted to Hantavirus samples in the lab. Their conclusion was that the culprit was likely a Hantavirus, one that had never been recognized before.

How did the investigation tie the disease back to mice?

We know that other Hantaviruses are carried by rodents. So our CDC field team did large scale rodent trapping and testing, which allowed us to pin the deer mouse as the main carrier of the virus. Epidemiologic studies established that proximity to deer mouse habitat and/or excreta increased the risk for infection.

How did you tell the public?

Public Health officials in New Mexico and at CDC put out messages explaining how the Hantavirus is acquired, how to prevent infection, that it does not spread from person-to-person, and clarifying that Navajo and other Native Americans played no role whatsoever in spreading the infection.

Are we at risk for Hantavirus in the Northwest? And what can we do to protect ourselves?

People in the Northwest have gotten Hantavirus. The deer mouse is common in Washington state, primarily in rural and wooded areas.

People get Hantavirus infection (HPS) when they breathe in Hantaviruses. This can happen when rodent urine and droppings that contain a Hantavirus are stirred up into the air. People can also become infected when they touch mouse or rat urine, droppings or nesting materials that contain the virus and then touch their eyes, nose or mouth. They can also get HPS from a mouse or rat bite, but that’s uncommon.

Activities that can put people at risk for HPS:

  • Not protecting yourself from exposure while cleaning up mouse and rat urine, droppings, and nests.
  • Cleaning a shed or cabin that has been closed for some time.
  • Working in areas where mice and rats may live (such as barns).

For more information on Hantavirus and how to protect yourself, visit the Public Health – Seattle & King County website.

And for a more extensive account of the investigation, read this Washington Post article.

Today, Dr. Duchin hunts diseases of all kinds as the Health Officer for Public Health – Seattle & King County.