What is upstream vs downstream in public health?

Dark blue tortuous lines tapering upward with a blue boar with its upper part

Those who know public health know Prof. Irving Zola‘s “upstream vs downstream” parable. Irving Zola is a medical sociologist. His friend, John McKinlay, describes Zola’s parable in his 2019 article titled “A case for re-focusing upstream: The political economy of illness”1.

The “Upstream boat” sails through this upstream path.

Following is the reproduction of the parable;

” I am standing by the shore of a swiftly flowing river, and I hear the cry of a drowning man. So I jump into the river, put my arms around him, pull him to shore, and apply artificial respiration. When he begins to breathe, there is another cry for help. So I jump into the river, reach him, pull him to shore, apply artificial respiration, and then just as he begins to breathe, another cry for help. So back into the river again; another cry!

Again and again, without end, goes the sequence.

You know I am so busy jumping in, pulling them to shore, doing the same, that I have no time to see who the hell is upstream pushing them all in”.

This public health metaphor classic forces us to re-focusing our attention on the highest impact interventions. It becomes an effective tool within the Social Determinants of Health framework.

Graphical presentations of Zola’s parable

Progressive organizations employ this parable to make their mission clearer to everyone. Following are two examples of such graphics;

Sudbury and Districts public health in Ontario, Canada

The following graphic appears on the website, which belongs to the public health Sudbury and Districts in the Ontario province. It vividly explains Zola’s parable.

Irving Zola’s “Upstream-downstream parable”; Source: Sudbury and Districts public health

National Collaborating Center for Determinants of Health (NCCDH)

Moving upstream; Source: NCCDH website;

The above NCCDH infographic travels a little further; It divides the stream into three;

  • Downstream
  • Midstream
  • Upstream

Stream-specific interventions

Downstream interventions

Let us begin with downstream determinants and their interventions. According to Zola’s parable, he saves lives one by one. So, the focus is on the individual – one unit. We can add one family also here.

We create strong scaffolds to save individuals from drowning. It also requires a lot of resources to search and bring those in danger to the shore.
We strive here to change the effects of the causes: by treating an illness, screening for it etc. Most of the healthcare budget spends on such activities: To improve service delivery and equitable access to services. However, these efforts do not remove the causes that fall them into the water.

Some examples:

The below is from Pamela M. Lantz’s 2019 article in the Milbank Quarterly.

Downstream interventionsMidstream and upstream interventions
Supportive housing to chronically homeless peopleEfforts to increase affordable housing in neighbourhoods, cities, and national levels.
Patient-centred interventions to improve health literacyBroad education system reforms to improve health literacy

Midstream interventions

The midstream approaches focus on improving working and living conditions and promoting healthy behaviours. According to the NCCDH, these changes occur at local, community and organizational levels. Unlike in the downstream interventions, here we attempt to change the causes of illnesses.

Upstream interventions

In contrast to the above two, the upstream interventions create positive environments that impact midstream and downstream conditions and interventions. Without upstream approaches, other interventions become unsustainable. These types of interventions either change or reform macro-level national and global policies.

In other words, the upstream interventions address “causes of the causes” and are also called “social determinants of health”.

With the help of Irving Zola’s river story parable, we can visualize the causes, causes of the causes, and the appropriate best return of investments.


  1. John B McKinlay (2019): A Case of Re-focusing Upstream: The Political Economy of Illness; IAPHS Occasional Classics, November 19 2019; https://iaphs.org/wp-content/uploads/2019/11/IAPHS-McKinlay-Article.pdf

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Author: Prasantha De Silva

A specialist in Community Medicine board-certified in Sri Lanka and a research analyst in Canada

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