The Craziest Scientific Theory About What Causes Flu Pandemics

For centuries, influenza presented a deadly puzzle—it was a disease without any apparent cause that could kill millions almost instantly. Desperate for an explanation, some scientists concluded that flu viruses came from outer space. They even had evidence.

Although influenza has afflicted humans for thousands of years, medical historians believe the first true pandemic occurred in 1580, spreading northward from the Mediterranean to the Baltic region. A 16th century British physician wrote an account of the outbreak, observing that it was of such fierceness, "that in the space of six weeks it afflicted almost all the nations of Europe, of whom hardly the twentieth person was free of the disease, and anyone who was so became an object of wonder to others in the place. Its sudden ending after a month, as if it had been prohibited, was as marvelous as its sudden onset."

Influenza was different from previous epidemics. The disease would emerge rapidly, appear to simultaneously afflict people across entire continents, and then just as suddenly disappear. "Influenza has the qualities of suddenness, swiftness, transitoriness," wrote British physician Charles Creighton in 1894. "A wave of influenza comes up unexpectedly from a particular point of the compass, passes quickly over many degrees of latitude and longitude, lasting a few weeks at any given place, disappears in the distance, and does not return again perhaps for a whole generation." Or, to quote the more colorful prose of a 19th century French physician:

"Influenza, without cradle of origin, born no one Origin knows where, passing like a cloud which obeys the unknown caprice of the night, traverses at the same time or in the course of a few days the distance between towns situated at the four corners of the earth."

Pattern Recognition

The Craziest Scientific Theory About What Causes Flu Pandemics

Scholars and scientists, convinced that there was a hidden pattern to the outbreaks, began recording the dates of natural phenomena that could possibly offer clues to influenza's origins.

Prior to the emergence of germ theory, diseases were widely believed to be caused by miasma—poisonous vapors, containing particles of foul smelling, decaying matter. Poor sanitation was often singled out as the cause.

The investigators of influenza had their own take on miasma theory. Some argued that earthquakes and volcanoes periodically released toxic fumes from deep beneath the surface of the Earth. Others attributed the disease to electrical activity in the atmosphere that periodically produced excessive amounts of ozone.

And then there was outer space. Astrologers had long interpreted comets to be harbingers of doom, such as epidemics. What if there were some truth underlying this superstition? Perhaps comets or meteors that periodically encountered the Earth were the source of the illness. The term "influenza" is believed to be derived from the Italian phrase, "influenza coeli," meaning "influence of the heavens or stars."

The more that astronomers learned about the nature of space beyond Earth's atmosphere, the more appealing the theory became in some circles. By 1890, you could read articles and letters such as this one, which appeared in England's Daily Telegraph, during an outbreak that killed one million people worldwide:

You state that no solution as to the cause of the present influenza epidemic in Europe has been suggested, which, as you mention, attacks equally those on ships at sea as well as residents on land. I venture to put forward, upon the authority of Richard A. Proctor, a possible cause. In his interesting work, "The Expanse of Heaven," he describes how the Earth is "pelted with star dust, stoned with meteor balls." No less than 146,000 millions of meteoric bodies falling each year upon the Earth; how in their rapid velocity through the air they lose their solidity and reach the earth in the form of meteoric dust; that in the month of November a glass covered with pure glycerin exposed to a strong wind receives a number of black angular particles, which, being submitted to chemical action, produce yellow chloride of iron.

He then proceeds to ask whether this supply of meteoric dust is necessary to the wellbeing of the inhabitants of the earth and whether an unusual excess might not be injurious. Following which he says, "It has been suggested that some of the pestilences which history records were produced by meteoric influences. Some of the plagues were so sudden in their origin, lasted so short a time and had such singular features as to suggest the idea of extra-terrestrial influence. Amongst these may be mentioned the sweating sickness of the 15th and 10th centuries, which was not only characterized by the peculiarities in question, but by its recurrence thrice in 46 years, and has suggested the action of a recurrent cause like the return of meteoric clusters circling around the sun."

Space Invaders

Even as researchers made dramatic advances in understanding influenza, the idea of extraterrestrial infection persisted into the 20th century.

In the late 1970s, early 1980s, Dr. Edgar Hope-Simpson, a British epidemiologist, suggested that the influenza virus might lie dormant in people, waiting to be "reactivated" by yearly variations in solar radiation: "The apparent traveling of influenza would thus be dependent on the annual motions of an extra-terrestrial influence and be, with a few exceptions, independent of human travel."

But the most outspoken proponent of the "influenza from space" theory was the famous physicist and science fiction author Fred Hoyle. In the mid-1970s, Hoyle and his colleague, N. Chandra Wickramasing, had become advocates of "panspermia"—the idea that life begins in space, where it is then seeded across the cosmos.

Today, astronomers and astrobiologists increasingly suspect that comets and ice-laden meteorites crashing into the primordial Earth probably provided most of the planet's water—and perhaps much of the organic material—necessary for life. But Hoyle and Wickramasing took this idea much, much further. They argued that large comets were incubators—providing warm, liquid interiors where organic molecules could assemble into primitive microorganisms, while safely shielded from the extreme ultraviolet radiation in space.

But wait, Hoyle reasoned— if comets could scatter life on Earth, couldn't they also seed the atmosphere with viruses as they passed by our planet? Hoyle and Wickramasing rejected the idea that influenza was an infectious disease and turned back the scientific clock, adding a celestial spin to miasma theory.

The Craziest Scientific Theory About What Causes Flu Pandemics

Their article, "Does Epidemic Disease Come From Space?," appeared in the November 17, 1977 issue of New Scientist:

Reports of the sudden spread of plagues and pestilences punctuate the history of many countries. The most recent such disaster was the 1918-19 influenza pandemic in which 30 million people died. Different epidemics, scattered throughout history, bear little or no resemblance one to another. But they all share a common property of afflicting entire cities, countries or even widely separated parts of the Earth in a matter of days or weeks…..Such swiftness of transmission is hard to understand….before the advent of air travel, when movement of people across the Earth was a slow and tedious process.

We contend that primary cometary dust infection is the most lethal, and that secondary person-to-person transmissions have a progressively reduced virulence, so resulting in a declining incidence of the disease over a limited period. Primary infections of a human population could occur directly by contact with infected meteoritic dust, or indirectly by meteoritic infection passing to other creatures such as mosquitoes, rats and lice which act as intermediaries.

The factors governing the actual pattern of global incidence for any particular extraterrestrial invasion could be complex. If bacteria or viruses are dispersed in a diffuse cloud of small particles, the incidence of disease may well be global. On the other hand, a smaller disintegrating aggregate of infective grain clumps falling over a limited area of the Earth's surface could provide a geographically more localized invasion….Our suggestion, if correct, would have profound biological, medical and sociological implications. A continual microbiological vigil of the stratosphere may well be necessary to eliminate the havoc which will ensue from extraterrestrial invasions in the future.

Hoyle was not a biologist, let alone an epidemiologist—and his theories were smacked down by most of the scientific community. Still, he stood by his theory, tinkering with it over the years. In 1990, Hoyle and Wickramasing declared that they had collected strong statistical evidence of a relationship between sunspots and influenza pandemics.

As the New York Times reported:

Periods of maximum sunspot activity and influenza pandemics both appear to occur in cycles of approximately 11 years, they say, and since at least 1761, these cycles have often coincided.

The sun is currently at or near its periodic peak of activity, they note, and ''it is tempting to connect the recent flu epidemic in Britain with a maximum or imminent maximum of solar activity.''

Sir Fred and Dr. Wickramasinghe theorize that electrically charged influenza virus molecules floating through extraterrestrial space might be driven into the earth's atmosphere by the intense solar wind created during peak sunspot activity.

Dr. Joseph Hirman, manager of solar forecasting at the National Oceanic and Atmospheric Administration's solar observatory...was ''surprised'' that they would suggest a correlation between disease and sunspots.''You can correlate anything with anything you like,'' he said, ''but sooner or later, the correlation will disappear.''

Down to Earth

Today, we know that the virulence of influenza is the product of an unpredictable viral chain reaction composed of humans, birds, pigs and other animals. As strains of the virus are exchanged between species, subtle changes in its genetic material can occur. The mutations can be more significant if, say, a flu virus from a bird and a virus from a human combine inside a pig, producing a new, more virulent strain.

But, we're still looking for patterns, even if our gaze isn't directed up at space. Earlier this year, a study conducted at the University of Arizona pinpointed how the virus evolves at different rates in different species.

"We now have a really clear family tree of theses viruses in all those hosts—including birds, humans, horses, pigs—and once you have that, it changes the picture of how this virus evolved," says Michael Worobey, a professor of ecology and evolutionary biology, who co-led the study. "If you don't account for the fact that the virus evolves at a different rate in each host species, you can get nonsense—nonsensical results about when and from where pandemic viruses emerged. Once you resolve the evolutionary trees for these viruses correctly, everything snaps into place and makes much more sense."

Comets and sunspots not required.