by Lawrence J. Winship for the Gazette
Hundreds of years ago, the flowering bulb markets of Holland were overcome by tulip mania. Buyers bid up highly desired varieties to astronomical prices, paying enormous sums for rarity and flamboyance. Fortunes were made and lost. One of the most sought-after varieties was the Semper Augustus, with striking streaks of white in its red petals — strange, magnificent, and deadly to other tulips.
Not until 1928 was it shown that the dramatic white streaks in the Semper Augustus tulips were caused by a viral infection, spread by aphids, and ultimately lethal to all infected tulips and lilies. But so highly desired and valuable were these infected plants that it took years before government stepped in to protect the bulb industry.
Authorities first regulated ownership of “broken” (infected) tulips and finally outlawed them altogether. Fancy ruffled tulips available today are genetically stable copies produced by standard breeding. Virus-infected, broken tulips live on only in isolated licensed private and academic collections.
We find ourselves now in the grip of another, much more serious, social upheaval also caused by a virus, SARS-CoV-2, the causative agent of COVID-19. Might we learn something useful from the rise and fall of tulip mania?
Broken tulips came about because hundreds of aphid species continually brought the virus into the tulip fields from a worldwide population of wild viruses, causing millions of dollars of damage each year. Elimination of the wild viruses is impossible, so control is focused on the vector (aphids), and plants are sprayed with mineral oil and pyrethroids.
Similarly, SARS-CoV-2 also appears to have arisen from an extensive reservoir of coronaviruses in wild animal populations, perhaps bats. Once a virus strain has passed from the wild population to people and begun human transmission, controlling the vector — us! — becomes much more difficult, requiring sharp government action.
As animals, we do have mechanisms for acquired resistance that plants do not have — most importantly, antibodies circulating in our blood. For those diseases where we have managed to limit epidemic spread and mortality, it has been through a combination of testing, contact tracing, isolation and inoculation with effective vaccines. Advanced molecular biology and anti-viral drugs offer some hope and there are a significant number of success stories.
Yet lately the challenges have been coming fast and furious. Influenza viruses occur widely in animals. For example, bird flu (especially H5N1) kills millions of poultry, and has a 60% death rate in humans, but fortunately human-to-human transmission is so far rare. Influenza vaccines offer limited but real and important protection to seasonal flu.
Still, influenza kills 250,000-500,000 people worldwide each year. Coronaviruses had long been with us in benign forms, then SARS-CoV-1 came to us in 2003 from cave-dwelling horseshoe bats via civets with a small outbreak (8,098 people infected) but a high death rate (about 9%).
We will of course fight viral outbreaks in every way possible, and vaccination and public health measures are crucial. But why so many new viruses in the past few decades, and how have so many become epidemics and pandemics? Could the answer lie in our changing relationship to the natural world?
We push out into forests and grasslands with logging, farming and denser settlements. We’re in ever closer contact with wild populations, displacing them from their habitats, mixing our domesticated animals with wild stocks. Closer contact increases the probability of transfer.
Across the earth, various cultures hunt, catch and kill almost any wild creature, sometimes for food, often in the belief, ironically, that some part of the animal will cure disease. Our current scourge, SARS-Cov2, is likely a relative of a coronavirus found in wild bat populations, and would have stayed there but for pangolins, or scaly anteaters — captured in the wild by the millions, and sold and killed in “wet” markets (which also sold bats in close proximity) to harvest “curative” scales.
We insist by our behavior that we should be able to travel anywhere in the world, at high speeds — an ideal trait for a viral vector. And most of us live in densely packed cities — viral paradise.
What’s the object lesson from tulip mania? Desire inflamed by commerce spells disaster.
We’re in peril because of our unchecked wants and our belief that we can purchase and consume anything, heedless of consequence. If we were small bands of nomads catching and eating whatever we could, the occasional viral transfer might limit our numbers, but not cause global extinction.
Connected and powerful as we are, we have set the stage for a viral (or bacterial for that matter) firestorm.
Maybe medical technology can save us. Or, perhaps we need a global shift to a plant-based diet. Plant viruses are benign to us — so far. Humans must kill and eat to survive. If we stick to eating plants, along with some animal products from small, local populations, perhaps we will.
Lawrence J. Winship is emeritus professor of botany at Hampshire College.
Earth Matters, written by staff and associates of the Hitchcock Center for the Environment at 845 West St., Amherst, appears every other week in the Daily Hampshire Gazette. For more information, call 413-256-6006, or write to us.Click here to return to full list of Earth Matters articles.