Parsing pandemics: the bacteriologists and the ecologists are still at odds, but at least they're talking.

Waltner-Toews, David

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Plague Ports: The Global Urban Impact of Bubonic Plague, 1894-1901

Myron Echenberg

New York University Press

347 pages, softcover

ISBN 9780814722336

SARS Unmasked: Risk Communication of Pandemics and Influenza in Canada

Michael G. Tyshenko, with assistance from Cathy Paterson

McGill-Queen's University Press

451 pages, softcover

ISBN 9780773536180

THE FIRST RECORDED PLAGUE PANDEMIC--Plague of Justinian--started in Egypt in about 541 CE, and over the next 200 years killed between a quarter and a half of Europe's population. The second plague pandemic, sometimes called the Black Death, started in Asia in the 1300s, came in repeated epidemic waves across Europe and, over several hundred years, killed some 75 million people.

The third pandemic emerged at the dawn of the age of modern medical science, in 1894, and trailed off in the mid 20th century, leaving in its wake some 15 million dead. Plague Ports: The Global Urban Impact of Bubonic Plague, 1894-1901, Myron Echenberg's comparative study of how different countries dealt with the disease, follows the early years of this third pandemic.

Like Maurice Ravel's orchestral masterpiece Bolero, Plague Ports begins with an insistent theme that gradually, through repetition, each one adding more instruments, builds to an insistent crescendo. Plague Ports follows the disease methodically from Hong Kong (1894) to Bombay (1896), Alexandria and Porto (1899), Buenos Aires and Rio de Janeiro (1899/1900), Honolulu and San Francisco (1900), and the British Empire ports of Sydney (1900) and Capetown (1901). In following the spread of the disease, Echenberg highlights, again and again, themes and conflicts that continue to characterize the practice of public health.

Conflicts among those with different perspectives on the practice of medicine (which depends on expert practitioners) and public health (which depends on good public policy) have complicated efforts to manage almost every epidemic. In 1894, the battle was between the new "germ theory" scientists such as Louis Pasteur, Robert Koch and their followers, and the miasmatists, those who held that disease was caused by bad air, or bad water, or bad soil. Some of the miasmatists, aligned with the sanitarian movement, saw the germ theory as just another excuse for governments to avoid spending money on public health infrastructure such as garbage disposal and provision of clean drinking water.

It did not help the germ-focused contagionists that their exquisite theory came with no new treatments, nor did it help that their successes were closely aligned with a kind of colonial triumphalism that relegated traditional knowledge to the realm of ignorant superstition. Although the physician and bacteriologist Alexandre Yersin identified the bacterium that causes the disease (hence its name, Yersinia pestis), treatments based on natural antibacterial substances that were part of ancient Chinese, Greek and Egyptian remedies were not actively studied and not incorporated into the anti-plague campaigns. Commercially produced antibiotics such as penicillin did not enter the western medical kit until several decades into the 20th century.

The best response that the contagionists could come up with were vaccines. Vaccination works if you have a very good vaccine, and if you target all those people who will be exposed to the infectious agent. A plague vaccine was developed by Waldemar Haffkine, a Jewish Ukrainian bacteriologist who was working in India when the plague entered Bombay. When tested in a Bombay prison population, it prevented death in half those who got the disease and appeared to reduce the probability of getting the disease in the first place. The vaccine, then, while not perfect, certainly showed enough promise that it was widely adopted not just in Bombay, but also in subsequent outbreaks.

As Echenberg explains in his opening chapter, however, the plague was, and remains, a true zoonosis--that is, it is a disease of other vertebrate animals that can be transmitted to people. People only get sick when they are exposed to the animal source; with rare exceptions, it is not transmitted from one person to another. When not killing and stirring up panic among people, the plague circulates in wild rodents, transmitted from one animal to another by fleas. In this population of rodents, referred to as a disease reservoir, the bacterium does not cause disease. The flea sucks up infected blood from one animal, the bacteria multiply and plug up its gut, and the frantic, starving flea leaps from animal to animal, trying to get more blood, regurgitating bacteria as it goes. One could say with some justification that the plague is a disease of fleas, which they get from rodents. Some species of fleas are much more efficient at transmitting the bacteria than others. To get into the human population, the bacteria have to get from the wild reservoir into a population of rodents that live closely with people.

Usually these are urban rats living in overcrowded communities. These rats actually do get seriously sick and die, often in large numbers. The fleas then leap from the dead rats on to people, bringing the disease with them. Die-offs in rats preceding human epidemics of plague were well known in the 19th century, but the transmission of the disease from rats to people via certain species of fleas was a contentious proposition. Without an understanding of this disease ecology, there was no scientific way to determine who should get vaccinated.

Because the disease is spread by certain species of infected rat fleas, it made sense that it spread from port to port via the rats on the ships. But because the method of transmission was not known, quarantine and control measures were targeted at people, rather than at rats and fleas. As Echenberg demonstrates, in outbreak after outbreak, because the communities affected were generally poor, crowded and filled with new immigrants or visible ethnic groups, disease control measures very quickly took on racial overtones.

Plague Ports thus highlights the counterpoint between those who have championed the social determinants of disease and those who argue for a biomedical approach. The social determinants of disease, in their most enlightened fashion, are strong arguments for equitable distribution of wealth and access to services and fostering strong social networks, as these are all associated with health status. Such arguments played a part in Sun Yat-sen's fight for regime change in China and the struggle for independence in India, as were used by those who campaigned for better housing, water supplies, garbage cleanup, "slum clearance" and sewer systems (the so-called sanitarians).

Invoking political and social causes of disease is a dangerous undertaking. In the third plague pandemic, commercial interests in several port cities resisted quarantine laws because they would interfere with trade, and hence--so the argument might be framed in the 21st century--these public health restrictions would decrease wealth, increase unemployment, increase poverty and foster disease. Governor Henry T. Gage of California, in order to protect commercial interests, recommended a law in 1901 "making it a felony for anybody to write or publish allegations of the presence of plague anywhere in California without a prior determination" by the board of health (which the governor controlled).

We now have good evidence that the strongest social support networks are often those based on religion or ethnicity. In non-pandemic times, and in mono-racial societies, this seems to work just fine. But in the panic of uncertainty and a new disease, or in the multi-racial post-colonial world, this makes immigrants, ethnic groups and disempowered, poor, visible populations (such as the blacks in South Africa or the Chinese in San Francisco) easy targets for ethnic cleansing and programs for "neighbourhood beautification" (slum clearance by fire).

Given this political volatility and danger, it is no wonder that the new contagionists and biomedical scientists at the turn of the last century focused on the technical aspects of the disease, which were seen to provide neutral, objective evidence and sound advice. Indeed, the 20th century was a triumph of biomedical science, giving us new drugs and vaccines and eradicating or nearly eradicating some of the most serious infectious disease scourges that have historically plagued humanity. It was only a matter of time before biotechnology, vaccines and drugs would save us from malaria and HIV/AIDS, starvation and obesity. Who really needed to understand ecology, human behaviour, history--all those soft sciences?

Severe acute respiratory syndrome (SARS) has suggested that perhaps we have stood on the aircraft carrier and pronounced victory prematurely. SARS is a disease of animal origin, but not a true zoonosis. That is, once it made the initial jump to people, the virus adapted and no further exposure to animals was required for the disease to spread. The SAILS coronavirus made the jump from animals (fruit bats, and then to civets) to people, adapted and spread like a brush fire. Its origins are embedded in regional ecology, bat migrations, rapid urbanization, food preferences, cultural histories, viral genetics, liberal trade policies, travel, scrambles for wealth, all that soft stuff. Bursting out of China in 2003, the virus SARS navigated easily past government denials and international travel, burned through Toronto's healthcare system, elicited a hue and cry about economic consequences of the way the disease was managed (not the disease itself), and then, suddenly, completely, disappeared. By 2010, the most significant scientific reports were confirming that fruit bats were the reservoir for the SARS coronavirus, and not the much maligned civet, which served as an amplifying host.

In almost all respects, the same themes played out in the SARS pandemic, but at a much faster pace--hours and days rather than months and years--as for the bubonic plague: the disjunction between the new bioscientists, who could describe the genome of the virus in record time, with great certainty, but could provide no particular advice on how to manage the disease in the midst of uncertainty and rapid change; the ethnic targeting; the conflicts between those who saw the tragic human costs of the disease and those who saw the catastrophic economic impacts of the travel advisories (the mayor of Toronto, when hearing of the World Health Organization's advice to the world to avoid Toronto asking "who are these people?"); tensions between individual rights and collective responsibilities raised by quarantines; and constantly shifting public advisories, policies and regulations, depending on which groups had the loudest voices, the most convincing evidence, the most power.

If Plague Ports, with its repeated themes of clashing cultures and ideas, brought to mind Ravel, then SARS Unmasked: Risk Communication of Pandemics and Influenza in Canada evoked in me Albert Camus's The Plague, with its call to be unheralded healers in the midst of uncontrollable terror.

This association is odd, because Plague Ports is the quieter, more thoughtfully reflective book. SARS Unmasked is a cacophony of voices and statistics, still reeling in the stunned aftermath of the visitation of the SARS pandemic to Toronto in 2003. Perhaps Camus comes to mind because SARS Unmasked reignites that vague sense of panic that many of us felt in the spring of 2003. And the book swings rather wildly from policy analysis to blow-by-blow description. Michael Tyshenko, the main author, is a specialist in science policy and risk communication at the University of Ottawa. Several chapters by Cathy Paterson, a nurse clinician in one of the hospitals hit hardest by the outbreak in Toronto, are immediate and personal. We go from reading a detailed text with figures and scientific technical language only to be pulled aside in an elevator by Paterson and told harrowing tales of the front lines.

Her memories stoked up my own: unreadable pink sheets handed out at the airport; fearful fellow train passengers coming back to Toronto from the annual general meeting of The Writers' Union of Canada in Ottawa wondering if they should wear masks; rumours from my colleagues about chaotic communications and squabbles over jurisdiction and data ownership; Dr. Sheela Basrur, Toronto's Medical Officer of Health, a reassuring voice facing the camera; a government healthcare worker who left an envelope in my office for safekeeping (in case something unspecified happened), detailing complaints about how the outbreak was being handled.

I hoped this book would help me understand what was really going on. SARS Unmasked does indeed provide much information that is useful in assessing risk communications under conditions of public panic; in the end, however, I was left unsatisfied. There is more information than wisdom here, including a detailed SARS timeline in Canada, the properties of coronaviruses and the "social amplification of risk."

The second part of the book, somewhat puzzlingly, includes a chapter on avian influenza and demonstrates a shaky understanding of the economic and social drivers of poultry production and trade. In fact, Tyshenko undercuts his own analytical approach by using tables of cumulative cases of avian influenza (rather than new cases), which he had earlier argued (rightly I think) amplify negative interpretations of data and promote alarm. His uncritical use of words such as "unprecedented" to describe avian influenza does little to give one confidence of a dispassionate consideration.

All things considered, I would recommend Plague Ports as a slow reflective read on long winter evenings. SARS Unmasked, on the other hand, has sufficient raw material in it that I would recommend it as a reference text for students in public health and risk communication.

We are learning, slowly, from our history. The tendency to binary thinking (it is either the bacterium or the environment, either healthcare delivery or economic policies) and a lack of understanding of the ecology of diseases and how that ecology links to economic and social policies is beginning to change. Recent fears related to the emergence of infectious diseases such as H5N1 avian influenza, and the SARS and H1N1 pandemics, are pulling integrated and ecosystemic approaches to ecological resilience, social organization and health from the margins into the mainstream.

At the heart of every pandemic is a denial of our biological selves, a secret human dream that we are fundamentally different from rats and chickens and fleas. At the basis of every successful program to contain or eliminate pandemic diseases is the acknowledgement that we are more than rats and chickens and fleas. We have our biological selves, but biology is not necessarily destiny. We are all part of the same complex social-ecological system, and that system is mutable. The challenge facing public health workers in the 21st century is how to take that understanding and translate it into action.

David Waltner-Toews is a professor in the Department of Population Medicine at the Ontario Veterinary College in the University of Guelph, founding president of Veterinarians without Borders Canada and a founding member of the Canadian Community of Practice in Ecosystem Approaches to Human Health. He is a specialist in the epidemiology of zoonoses and the author of The Chickens Fight Back: Pandemic Panics and Deadly Diseases that Jump from Animals to Humans (Greystone, 2007).