Pandemic Influenza: 1510 – 2010
1890 Influenza cartoon of the
My first clue on the existence of specific influenza pandemics before 1918 came a few years ago while
reading some local newspapers on the Spanish Flu itself. The papers were warning people that this was not
an ordinary flu year, it would be like 1893! The papers referred to 1893 in the same way that we refer to
1918 today. Since then I’ve been intrigued by the 1889-1893 ‘Russian flu’. Yet the Spanish flu of 1918 so
dominates publications on influenza pandemics that it has not been easy to find information.
So how do we identify a historic pandemic flu from seasonal flu or a bad cold virus? Morens,
Taubenberger, Folkers, and Fauci (2010) have outlined three basic criteria: 1) the standard influenza
symptoms (fever, chest congestion, fatigue, body aches, and cough), 2) explosive transmission and
directional movement along trade routes, and 3) high morbidity but low mortality. Influenza pandemics kill
many people by infecting huge numbers so that a low mortality rate still amounts to many fatalities.
Historically the fatalities have been among the very young and very old, pregnant women, and the
chronically ill (Morens & Taubenberger, 2010a).
The first recognized pandemic occurred in July and August of 1510 when an outbreak of “gasping
oppression” appeared nearly everywhere at once. It was described as a “‘gasping oppression’ with cough,
fever, and a sensation of constriction of the heart and lungs”, leaving an impression strong enough for
people to write of it decades later (Morens et al, 2010). At least seven contemporary and nearcontemporary reports exist of the 1510 pandemic (Morens, North & Taubenberger, 2010). The 1510
outbreak had a high morbidity but low mortality, killing primarily children and those who had been overbleed (Morens et al, 2010). Francesco Muralto, who lived through the 1510 pandemic, estimated that it
killed about ten people in a thousand per day, or about 1% which is comparable to the Spanish flu. Yet, we
do have to remember that Muralto was a lawyer and politician not a physician so his estimates of mortality
may not be very accurate (Morens, North & Taubenberger, 2010)..
The figure below outlines 15 pandemics in the last 500 years. In this first pandemic and many that
followed, influenza occurred during the summer. The frequency of pandemics varies widely from as short
as 6 years to 149 years. Not one human pandemic has been recognized in the 17th century, though equine
(horse) influenza was identified in 1648. Within the 149 year gap are many local epidemics, some of them
quite severe.
Fig. 1 Influenza pandemics from 1510-2010. (Morens, Taubenberger, Folker, & Fauci, 2010. Placed in
public domain)
These pandemics have gone by many contemporary names. Physician Daniel Sennet (1572-1637) reported
that the “names applied to [the 1580 pandemic disease] included febrile catarrh, suffocating fever, epidemic
catarrh, coughing epidemic, [and] contagious headache. The Germans called [it] ‘the chirp’, the sheep
cough, and the sheep disease, [and] the chicken malady, because sick persons were suffering [as with] the
coryza of chickens.” (Morens & Taubenberger, 2010a). Human cases of influenza associated with the great
equine influenza panzootic of 1872 were said to have “epizooty” or “zooty”. Le Grippe (the grip) seems to
have become a common name for influenza from the time of the Russian flu (1889-1893). Le Grippe is
commonly found on death certificates in the early 20th century (at least in my area). For about the last
century, pandemics have been known by their reputed city or country of origin: Russian flu (1889-93),
Spanish flu (1918), Hong Kong flu (1968-69) and despite great efforts Mexican flu/swine flu (2009). The
politics of naming flu pandemics came to the fore like never before in 2009 as neither Mexico or swine
producers wanted the flu named after them.
Today we recognize that influenza is primarily evolves in wild birds and then circulates among domestic
poultry, humans and swine. Historically influenza was once known primarily as an infection of horses that
frequently spread to humans and dogs. Canine infections have frequently been documented, most recently
in 2009, but appear to have been historically dead-end hosts. However, there is now an equine influenza
H3N8 virus that has adapted to dogs where it its evolving by antigenic drift. Multiple lineages of the now
dog virus are spreading internationally (Morens & Taubenberger, 2010a).
Equine influenza (H3N8) has circulated among humans in at least the 19th century. People born before
1893 produced antibody activity against equine influenza decades later. Human susceptibility to equine
influenza has also been confirmed experimentally (Morens & Taubenberger, 2010a). Horse epizootics have
correlated with influenza-like illness in humans in 1299, 1328, 1404, 1647-48, and 1657-1658. Between
1688 and 1888, Moren and Taubenberger (2010a) counted 112 human epidemics or horse epizootics in
Europe. Of these outbreaks, only 20 were human only epidemics, 25 were horse only epizootics, and 67
were horse and human outbreaks. In the Americas over the same 200 year period, influenza-like illness was
documented in only 56 years (half that of Europe) with humans and horses in 21 years, humans only 20
years and horses only in 10 years. Morens and Taubenberger (2010a) noted that in all but two years (1776
and 1780) when both horses and humans were infected, equine influenza proceeded the human outbreak by
about 3 weeks. Before 1700 it was widely accepted that flu epidemics began with horses and ended with
humans. By the mid-19th century it was beginning to be noted that horse outbreaks occurred in four-year
cycles, probably due to herd immunity generated by previous epizootics. While human seasonal influenza
was a winter phenomenon as it is today, when major human epidemics coincided with horse epizootics the
human infections occurred in the spring and summer along with the horse outbreak (Morens &
Taubenberger, 2010a).
Host switching between humans and swine has been documented in the twentieth century, most notably in
2009, but Morens and Taubenberger could not find evidence of swine influenza before 1918. Morens and
Taubenberger (2010a) suggest that swine have replaced horses as the “secondary extra-human mammalian
reservoir”. As swine are susceptible to both avian and human influenza A strains, they are a likely mixing
host that could produce an antigenic shift with pandemic potential.
Avian influenza in domestic poultry has garnered a lot of attention for the last decade. Although the few
human infections contracted directly from domestic poultry have produced high mortality rates, there is
little historical evidence that avian influenza from domestic poultry has directly produced human
pandemics even though the pandemic-causing genes ultimately originate in avian influenza from wild
birds. The avian epizootic of 1872 that occurred simultaneously with the equine influenza epizootic of 1872
is the best lead for finding an avian influenza capable of causing a mammalian panzootic (Morens &
Taubenberger, 2010b).
If influenza has shown us anything over the last 500 years it is that its unpredictable, expect the
unexpected. Its host-switching abilities make it likely it will retain the ability to blind side us.