How many current pandemics?
The word 'pandemic' is not entirely defined on narrow public health criteria. (Likewise, an economic depression has no technical definition.) In an important sense it is a word of history, a word to describe significant health events of the past that had substantial diffusion beyond any particular locality.
Since the World Health Organisation (WHO) came into being after World War 2, however, current events could be called official pandemics while they were happening, even in their early stages. This labelling is a necessarily inconsistent process, with 2003 SARS1 not being officially classed as a pandemic, while 2009 H1N1 Swine Flu (for which New Zealand was an early player) was so categorised.
Wikipedia's list of epidemics is useful here, not because it is authoritative, but because it represents a good indication of which health events we know most about, and how we rated them.
An event seems more likely to be labelled a pandemic if it is due to a new contagion, or a resurfacing after many years of an old and feared contagion. Thus the 2009 Swine Flu had the potential to become the 'Second H1N1 Influenza Pandemic', with the first being the 1918 'Black Flu' (inappropriately called by many the 'Spanish Flu'). With hindsight the 2009 event may have been insufficiently consequential to justify the moniker 'pandemic'; though it was undoubtedly 'pan'. Perhaps the 2009 experience led to a delay in calling Covid19 a pandemic in 2020?
There is a case for calling the 2019 Measles outbreak a pandemic, given that Measles had been such a significant contagious disease in the Pacific in the nineteenth century (including an epidemic in New Zealand in the 1850s), and in the Americas before that. For 1919, Wikipedia lists five entries for Measles in 2019, including New Zealand (also Samoa, Philippines, Malaysia, Congo); I was in Canada in April and May 2019, and the same outbreak was happening there and in the United States, though to a lesser extent.
There is also a strong case for calling SARS1 a pandemic, given that it was serious, it did travel worldwide, and the virus was more lethal than the present SARS2 pandemic virus. Interestingly, the 1889-90 'Russian Flu' pandemic may have actually been coronavirus OC43 – a virus that "currently causes only mild cold-like symptoms in humans"; SARS0 if you will. (Refer to one pandemic we might have missed, from The Conversation. Also refer to Our Coronavirus Predicament Isn’t All That New Bloomberg 16 May 2020, and What four coronaviruses from history can tell us about Covid19 New Scientist 29 April 2020).
Of the pandemics listed in Wikipedia, one – other than Covid19 – has not been deemed to have ended; that's HIV/AIDS.
Not listed in Wikipedia is Dengue Fever. Frank Snowden in the penultimate chapter of Epidemics and Society (2019) refers to the "global pandemic of dengue fever that began in 1950 and has continued unabated", which began little noticed at the beginning of an "age of hubris" in which western scientists convinced themselves that the problem of infectious diseases had been solved. Dengue is particularly interesting in that it has become more dangerous over time, not less. And it alerts us to an ongoing problem in public health science and elsewhere – that the 'hubris' referred to was a largely Euro-western phenomenon, that could downplay events outside of Europe and North America. And – as in the case of Covid19 – hubris with racial undertones continues to downplay the Europeanness of the pandemic.
So that's three current pandemics so far: Dengue, HIV/AIDS, and Covid19. There is, I would argue, a fourth.
We often talk about not seeing "the elephant in the room". If we look at the Wikipedia list of epidemics, the elephant is an absence rather than a presence. Between the years 747 and 1346 CE, there is nothing. That's a period of 600 years, more than half a millennium. Further, there is no obvious reason why the contributors to Wikipedia should have a blind spot about this period, a period that represents the substance of the medieval era, the Middle Ages in Europe; there are plenty of disease outbreaks listed before 750, including Smallpox in Japan. Nor can we argue that the medieval period has been neglected by historians; rather it represents a substantial field of historical literature, and not only for European history.
For many of us the word 'medieval' conjures up pictures of disease. There is one main reason for that image; 'plague', misleadingly labelled 'bubonic plague' which is the best-known variation of Plague. (The other two variations 'septicaemic plague' and 'pneumonic plague' are more fatal.) Plague is an infection from the Yersinia pestis bacterium.
Before commenting further on Plague, it is important to take stock, and acknowledge that the period from 750 to 1300 was almost certainly one of the most healthy epochs in the history of humankind. It gives context to the 'Black Death' that followed.
The problems of the fourteenth century began well before the arrival of Plague. A cooling climate and overpopulation brought famine to Europe in the early decades of that century. And, in the west of Europe, the 100 Years War between England and France began in the 1830s. The Battle of Crecy was fought in 1346, two years before Plague arrived in England.
From my studies of history, I knew about the First Plague Pandemic (about years 550 to 750 CE) and the Second Plague Pandemic, which until the beginning of this year I would have dated 1340 to 1720 CE.
In 1994, I was shocked when the news came out of an outbreak of Plague (bubonic and pneumonic) in Surat, a city in the Indian state of Gujarat. I had previously assumed that Plague had been eliminated if not eradicated. (Further, the story was sufficiently played down in the media that, I expect, most New Zealanders born before 1980 have little memory of that episode in the history of disease.)
Early this century I became aware that Plague had visited California, Sydney, and yes – Auckland – in 1900; this awareness came from reading a newspaper cutting in Mokau's museum, and also from watching a science documentary which mentioned endemic Plague in California. Plague is indeed endemic in the southwest of the United States, where there are a few human cases of bubonic Plague most years. The American experience shows that Plague is essentially a disease of rodents; fleas carrying Yersinia pestis jump to unaffected hosts mainly when there is a rodent epidemic die-off. Snowden (Epidemics and Society, p.41) reminds us that "underground disasters unknown to humans take place" among wild rodents such as "marmots, prairie dogs, chipmunks and squirrels in their burrows". "Plague is best understood as a disease of animals by which humans are afflicted by accident".
Snowden adds (p.52): "Pneumonic plague … spreads rapidly, is readily aerosolized, and is nearly 100 percent lethal. Furthermore, it begins with mild flulike symptoms that delay recourse to diagnosis and treatment, and it frequently runs its course within the human body in less than seventy-two hours. The opportunity to deploy curative strategies is therefore exceptionally brief. This situation is rendered even more critical by the recent appearance of antibiotic-resistant strains of Yersinia pestis."
(Almost certainly, antibiotic resistance will prove to be the single most important public health crisis this century. Excessive fear of exposure to microbes in the 2020s may prove to be an important aggravating factor to this coming crisis. We may be especially setting up our young children to not acquire basic resistance to common seasonal pathogens.)
This year I learned much more about Plague. In January I was reading a biography of Jane Franklin (after whom an Auckland street and an Auckland district are named). She was an inveterate traveller for most of her life, for most of the nineteenth century. I was surprised to read of references to Plague outbreaks in Istanbul (Turkey), and how that city was often best avoided by travellers.
But it was only after the Covid19 lockdown started that I did some systematic enquiry into Plague, discovering that there was/is a whole Third Plague Pandemic, conventionally dated 1855 to 1960. Also, I discovered that Plague had been significant in and around the (Turkish) Ottoman Empire (which included most of southeast Europe) for around 200 years from the seventeenth to the nineteenth centuries. (This included a final Plague visitation to Malta in 1813; Malta was then part of the British Empire, indeed an important British military base.)
It seems that the correct dating for the Second Plague Pandemic is 1330s to 1856, half a millennium in duration. While substantially a European event, its origin around the 1330s appears to have been Mongolia. It overlapped the Third Plague Pandemic.
For the most part, the Third Plague Pandemic was classic bubonic Plague. It started in China's southern Yunnan province, and festered in southeast China for many years until breaking out as a major epidemic in British Hong Kong in 1894. It was during the Hong Kong outbreak that the Plague pathogen (Yersinia pestis) was identified; and it was not until the twentyfirst century that the first and second Plague pandemics were confirmed to have in fact been Plague.
The British were very cruel in Hong Kong, literally pursuing a scorched earth policy that was inspired by the 1666 Great Fire of London. (It didn't work; the affected rats fled to other parts of the city, and the people burned out of their crowded homes had to move to even more crowded accommodations.)
Reading the 1900 NZ Herald article (see list of links, below), it is clear that Plague was then regarded as "a dirt disease, cultivated through living in insanitary surroundings under conditions of poverty and filth". (Rats were coming to be seen as co-victims of Plague, as shown in the Mokau story. While the diagnosis of Plague as a "dirt disease" has been disabused, rats – seen as the principal villain for most of the twentieth century – now tend to be regarded mainly as co-victims.)
The Third Plague Pandemic was transmitted across the world from Hong Kong, literally through ships carrying rats harbouring infected fleas. Most outbreaks (outside of China) in the Third Pandemic were initiated by infected ship rats; all the ports of the world already had substantial populations of rattus rattus; the 'ship rat', the 'black rat'.
The first and most important new Plague site was Bombay (Mumbai) in British India. The British repeated their Hong Kong policy, treating Plague with fire to cleanse the soil. (Much of the problem is that the experience of the London Plague of 1665 was misleading. The link to rats and fleas was much stronger in the Third Pandemic than in the Black Death Pandemic. Further, because during the Black Death the Plague was transmitted mainly from people to people rather than via rats, that pandemic showed little socio-economic discrimination.) The full understanding of the role of rats and fleas had to wait until the 1908 publication of the Indian Plague Commission (Snowden p.337); while valid for the Indian event, the new explanation arguably overstated rats as the principal vector for local transmission of Plague.
The Third Plague Pandemic reached the European ports of Oporto (1899) and Glasgow (1900). It reached Honolulu, San Francisco and Sydney (via New Caledonia) in 1900. (Recent reports in relation to Glasgow suggest rats were relatively unimportant there. For a reasonably comprehensive list of Third Pandemic sites, see the Wikipedia entry.) San Francisco suffered several outbreaks over the next two decades, with Los Angeles experiencing an outbreak of pneumonic Plague in 1924 (refer "Plague in the City of Angels", in The Pandemic Century, by Mark Honigsbaum). The final pre-death stages of pneumonic Plague – the Black Death – were similar to the final stages of the 1918 Black Flu; a form of pneumonia that turned live people a kind of dark purple colour. Indeed, given the then recent history of Plague in New Zealand and the United States, many thought the Black Flu was the Plague.
For more about Plague in Auckland, Sydney and Glasgow, at the end of this article is a reference list of links to stories about the Plague in 1900.
Given that the First Plague Pandemic lasted two centuries, and the Second Plague Pandemic lasted five, I would argue we are still in the Third Plague Pandemic. Indeed, following a few quiet decades – 1960s to 1980s – outbreaks of Plague have become more prevalent, with Madagascar and Peru having had significant outbreaks this century. The sites of recent outbreaks are in the same places that had important outbreaks in the early years of the Third Plague Pandemic.
The first two Plague Pandemics had substantial impacts on subsequent global history. (One of the most important events during the First Plague Pandemic was the rise of Islam, and its accompanying first Jihad of expansion into North Africa and Spain.) New Zealand's own favourite historian, Jamie Belich, at Oxford University studied the Black Death and its impact on subsequent global history (see his chapter 'The Black Death and the Spread of Europe', in The Prospect of Global History, 2016). If I am right, and the Third Plague Pandemic has not yet finished, then Plague Three may also prove to be one of the most important turning points in world history.
Dangers in the wake of Covid19
My review of Plague history reminds us that public health is about far more than 'one epidemic at a time'. Our responses – and over-responses – to one pandemic event may influence, for better or worse, our experiences of future epidemics and pandemics.
While we know that vaccines are important, we also know that certain amounts of acquired immunity gained through the rough and tumble of normal childhood life is important. The highest-impact pandemics have occurred in populations with minimal incidental immunity. The 1918 Black Flu was most lethal to people with less exposure to an earlier less malign Flu wave, and in the United States to people with less exposed to common urban pathogens. Before that, the Black Death was particularly lethal to a population in Europe that had been through centuries with comparatively little contagious disease. And, as most of us know, diseases like Measles (and Smallpox from which New Zealand was largely spared) are specially lethal to populations without prior exposure.
We also need to appreciate that infectious diseases occur in social contexts and environments, and that the outcomes of outbreaks are contingent on the ways we interpret these events. In the case of Covid19 – like the Black Death (Plague 2), a disease of Europe that happened to begin in Asia – we should look to historically acquired attitudes towards Asia to understand why Europe took too long to understand what was happening to it; and to understand why Europe and many Europeans are in denial about this.
One aspect of this denial is the talk in ethnic European countries about the possibility of a future 'second wave' of Covid19. Actually, the second wave of this pandemic began in Europe in the third week of February 2020. The second wave of Covid19 is the pandemic. The first Asian wave – like its predecessor SARS1 – could have ended in the same way as SARS1. The difference between SARS1 and SARS2 was the European 'second wave' that turned a major regional epidemic into a substantial pandemic. (Europe, North America and Australia did get cases in the first wave. These were largely resolved before the Covid19 second wave began in late February.) While there may prove to be a Covid19 third wave next northern hemisphere winter, it is the second European wave that is now changing the world; especially the world of Europe and the Americas. We do ourselves – and especially Asia – a disservice when we conflate the Asian event with the European event, as a way of absolving Europe.
Mark Honigsbaum noted "the key role played by environmental, social, and cultural factors in changing patterns of disease prevalence and emergence." "Recalling Dubos’s insights into the ecology of pathogens, [he] argue[s] that most cases of disease emergence can be traced to the disturbance of ecological equilibriums or alterations to the environments in which pathogens habitually reside. … Thanks to global trade and travel, novel viruses and their vectors are continually crossing borders and international time zones, and in each place they encounter different mixes of ecological and immunological conditions."
In 2020 we are narrowly focussed on Covid19; perhaps rightfully so. Nevertheless, humanity is (arguably) experiencing four public health pandemics; the others are: Dengue, HIV/AIDS, and Plague. There will be other others. The pressures we place on our economic environments, with economic growth treated as our only alleviant to poverty, will continue to create spaces for familiar and unfamiliar pathogens to play.
The Bubonic Plague, New Zealand Herald, Volume XXXVII, Issue 11263, 5 Jan 1900, Page 5
A Plague of Rats, by Rhonda Bartle
Migratory' Rats, Otago Daily Times, 7 Jul 1900, Page 8
Health Notes, Rats and Rat-borne Diseases, Evening Post, 19 Feb 1927, Page 15
Plague, NZ Ministry of Health
A timeline of epidemics in New Zealand, 1817–2020, Te Ara [pdf, doesn't mention the 2019 Measles outbreak, but indicates 9 Plague deaths]
Tales from the Crypt: Bubonic plague scare in Auckland, Matthew Gray, Western Leader, 15 Jun 2016
After centuries in the dock, rats are cleared of causing the Black Death, Stuff, Henry Bodkin, 17 Jan 2018
A life without antibiotics and the bubonic plague, Stuff, Roger Hanson, 25 Aug 2017
Plague's ground zero: when the Black Death hit Sydney, Stuff, Julie Power, Feb 09 2019
Bubonic plague Sydney: How a city survived the black death in 1900, Gillian McNally, The Daily Telegraph 3 Sep 2015
Rats 'wrongly blamed' for 1900 Glasgow plague outbreak, Kenneth Macdonald, BBC Scotland, 2 Jan 2019
Glasgow's bubonic plague outbreak in 1900, Gillian Sharpe, BBC Scotland, 31 Aug 2013
Peru suffers deadly outbreak of bubonic and pneumonic plague, Telegraph, 3 Aug 2010
Black Death plague mapped: Where is the deadly disease still found today? Express, 12 Oct 2017
Plague: Global cases down significantly, Madagascar accounts for majority, Outbreak News Today, 4 Jan 2020