Epidemics require specific condition to spread disease

Macrae: Without any one of these three ingredients, epidemics fizzle.

Robert Macrae. (Submitted photo)

Epidemics such as the Biblical plagues, Black Death, cholera, smallpox, syphilis, influenza, louse-borne typhus, HIV, SARS, and now COVID-19 are not inevitable.

Epidemics require (1) a virulent pathogen, (2) a susceptible host, and (3) environmental conditions suited to the spread of disease.

Without any one of these three ingredients, epidemics fizzle.

There is little we can do to prevent the evolution of virulent pathogens. Relatively harmless pathogens limited to single hosts regularly, but unpredictably mutate into aggressive strains able to spread and sicken less resistant hosts.

There is more we can do to protect susceptible hosts and much more we can do to limit environmental conditions that favour disease transmission. As COVID-19 winds down, it would be wise to plan how to reduce the risk of future epidemics because, as we are being reminded, prevention costs far less than cure.

Our understanding of epidemics is vastly improved. Today, few believe epidemics to be the punishment of angry deities or the product of vengeful sorcery.

Our understanding of microbiology, epidemiology, and immunology is better than even during the 2003 SARS epidemic when precious time was lost identifying the causal agent and its genetic sequence.

During the SARS epidemic, there was only one person testing samples in the entire province of Ontario using a clunkier, costlier procedure unable to process nearly the volume of tests run daily across Canada for COVID-19.

Past epidemics occurred when large numbers of impoverished people lived in crowded, unsanitary conditions where basic services such as clean water and sewage were scarce to non-existent.

For example, London during the Industrial Revolution, when exhausted, under-paid, over-worked labourers were packed into filthy tenements with cellars overflowing with sewage that saturated the ground, poisoned the water, fouled the air, and precipitated London’s Great Stink and tens of thousands of avoidable deaths.

Lesson one is eliminate poverty.

If this sounds ridiculously idealistic, dream bigger. Eliminating poverty is neither impossible nor impractical and a far better investment than assault rifles, intercontinental ballistic missiles, stealth fighter jets, nuclear aircraft carriers, or Star Wars defence systems.

Eliminating poverty requires a fraction of what we spend on the military and returns an infinitely preferable outcome.

Ontario, during the Kathleen Wynne era, experimented with guaranteed basic incomes. She proved they were cost-effective compared with the patchwork of existing social services programs and they enabled recipients to escape the poverty cycle.

In addition to poverty, war nurtures perfect conditions for epidemics.

There were many more deaths caused by louse-borne typhus, typhoid, cholera, and dysentery than by combat during the Crimean, American Civil, Boer, and Great Wars.

Lesson two is eliminate war.

Lesson three is eliminate environmental conditions suited to the spread of disease. This topic embraces more than I can discuss in this article, but here’s a preview.

In his recent book, LIU professor Bill Schutt discusses desertification in Texas and California where researchers gauged soil moisture to assess drought. They determined 2012-2014 to be the most arid period in the past 1,200 years.

Schutt reports, “Across China, Syria, and central Africa, regions that only recently experienced dry seasons are becoming deserts. People in Kenya, Somalia, and Ethiopia, three of the poorest countries in the world, are suffering through the worst drought in 60 years.

In parts of Sudan rainfall has fallen by 30 percent over the past 40 years.

The Sahara is encroaching into farmland at one mile per year. Famine and diminishing access to fresh water are now daily realities for more than 12 million Africans. According to the United Nations Environmental Programme, many conflicts in Africa are driven by climate change and environmental degradation.”

In concluding this article, there is a relationship between poverty, war, environmental degradation, especially climate change, and epidemics.

In our plans to reduce the risk of future epidemics, it would be ridiculously unwise to ignore this relationship.

Robert M. Macrae, Castlegar.

Climate changeOpinion

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