How epidemiologists respond to outbreaks across the globe

by John Thompson
Office of University Communications

Western Washington University Assistant Professor of Health and Human Development Steve Bennett is an epidemiologist who has responded to outbreaks across the globe, from South Sudan (see image) to tracking HIV in Kenya and the spread of food-borne illness in Minnesota. Western Today recently chatted with Bennett about how epidemiologists track down and mitigate outbreaks such as the coronavirus, and what each of us can do to limit its spread.

Western Today: There are all kinds of terms associated with the spread of new infectious diseases that we read in the news or see in books or films, such as "outbreak," "pandemic," and "epidemic." Are there any differences between these terms or are they generally interchangeable?

SB: ‘Outbreak’ and ‘Epidemic’ are basically the same though there are sometimes differences in connotation in their usage. Functionally they simply mean an excess of incidence of disease based on history and current knowledge. Essentially we see more of 'Disease A' at a certain time or certain place or within a certain population than we would expect. “Pandemic” is where we have an epidemic that has crossed borders and regions and has essentially become ‘global’ rather than regional. ‘Endemic’ is another term you may see here. It’s a situation where certain disease occur regularly in populations and we generally expect them. Common cold viruses would be considered endemic; we expect them every year to show up at certain levels.

Western Today: Whereas biochemists are more involved with the direct production of vaccines and study of the viruses themselves, epidemiologists are all about crunching data to determine patterns and insight on how to fight the spread of a disease. In a very broad way, can you explain what you do and how your work informs public health policy?

SB: Epidemiologists are able to work in an interdisciplinary manner in order to determine the source of outbreaks as well as the best mitigation strategies. Based on determining who is at risk and why, epidemiologists can advise policy makers on the best strategies in order to lessen the burden of disease.

Personally I have worked in various capacities as an epidemiologist. In Minnesota I worked in food borne disease outbreaks as well as researched the spread of tick-borne disease to determine how pathogens interact and which animal hosts may be larger sources of disease transmission. I also worked in Kenya and South Sudan on various health issues including Guinea worm disease eradication in South Sudan.

My current work is focused on LGBTQ health in Kenya as well as locally. Specifically in Kenya, I am looking at how the global focus on HIV maybe be eclipsing many more pressing health issues for LBTQ-identifying individuals. My research will help guide how international funding is focused and how small community groups working on LGBTQ health in Kenya will be more empowered to address what they deem to be priority issues.

Western Today: How do epidemiologists typically respond when an outbreak is first reported, such as in Wuhan this winter?

SB: It depends on the disease and various factors. The first response tends to be focused on identifying and defining cases. A case definition needs to be determined (i.e., what do we consider to be the important variables to deem someone a ‘positive’ case - based on exposure/symptoms/testing). Defining a case can be tricky at the beginning, especially if we don’t have testing available. Thus we end up with determinations such as ‘suspected cases’ ‘probable cases’ and ‘confirmed cases.' With most infectious diseases, lab testing is required to call a case ‘confirmed.'

Field epidemiologists will then work to interview cases and any contacts they may have had and work to ensure the proper mitigation measures are taken.

Western Today: What has been particularly confounding from an epidemiological standpoint with the novel coronavirus as opposed to other outbreaks, such as SARS, and why did it manage to make the leap to the rest of the world whereas others have been contained?

SB: Various factors took place to allow this novel coronavirus to spread including a lack of transparency at the beginning about what was happening in China and a lack of response from various governments including our own once we knew the possible threat. Beyond human response issues, this virus has transmission dynamics different from SARS or MERS. This current pathogen seems especially infectious and difficult to control, much more in the way that influenza is, though our mitigation efforts through social distancing seems to be helping.

Once we know more about this virus and its transmission dynamics we will be able to better understand how infectious it is and specifically how people are becoming infected. It seems person-to-person contact through air droplets is the main route of transmission, but there is some evidence other forms of transmission could possibly be at play, such as surfaces, etc.

Western Today: What is going to be the key moving forward to limit the damage of this outbreak, and from the standpoint of your expertise, what needs to happen in the future to prevent the next one from starting?

SB: Continuation of social isolation and the mitigation efforts we are doing need to continue until this wave of the virus is over. To be clear, once our current isolation efforts end, we will most likely see another wave of the virus coming through. Once functional treatment protocols are found, and hopefully a vaccine, then things can ease up.

I’m seeing some people oddly lamenting that this virus suddenly doesn’t seem as dire as they thought - and that they aren’t seeing the massive amounts of death that were predicted. I want to state plainly that the reason for that is the social isolation people are doing. If we were not following public health protocols this would be exponentially worse. When public health works, you either don’t know anything is happening (like our lives on a daily basis) or you may feel like we are doing too much (like some peoples responses to social isolation and our economic impact).

Western Today: What is the single most important thing each of us can be doing to Flatten the Curve?

Stay home. Listen to public health recommendations and public health professionals. I also would generally recommend not reading ‘think pieces’ or ‘advice pieces’ that are not written by public health professionals. The internet is a source of so much misinformation so be careful what you are consuming.


Steve Bennett has taught at Western since 2017; he received his doctorate from the University of Minnesota in Environmental Health and infectious Disease in 2017. For more information about his research, contact him at



Thursday, March 26, 2020