By: Connie Ngo,
on 1/22/2016
Though caused by microscopic agents, infectious diseases have played an outsized role in human history. They have shaped societies, lent us words and metaphors, and turned the tide of wars. Humans have eliminated some diseases, but others continue to plague us. In this quiz, find out if confusion is contagious or if you’re immune to the challenge.
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By: Joe Couling,
on 8/28/2015
This summer intrepid travelers everywhere are strapping on backpacks, dousing themselves in mosquito spray, and getting their inoculations -- ready to embark on journeys that will take them into contact with some of the most virulent viruses and nastiest bacteria on the planet. Even those of us who aren’t going off the beaten track may end up in close quarters with microbes we’d rather not befriend. Explore some of the most common infectious diseases around the globe and how to identify them in this infographic.
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By: Alice,
on 8/14/2014
Until the current epidemic, Ebola was largely regarded as not a Western problem. Although fearsome, Ebola seemed contained to remote corners of Africa, far from major international airports. We are now learning the hard way that Ebola is not—and indeed was never—just someone else’s problem. Yes, this outbreak is different: it originated in West Africa, at the border of three countries, where the transportation infrastructure was better developed, and was well under way before it was recognized. But we should have understood that we are “all in this together” for Ebola, as for any, infectious disease.
Understanding that we were profoundly wrong about Ebola can help us to see ethical considerations that should shape how we go forward. Here, I have space just to outline two: reciprocity and fairness.
In the aftermath of the global SARS epidemic that spread to Canada, the Joint Centre for Bioethics at the University of Toronto produced a touchstone document for pandemic planning, Stand on Guard for Thee, which highlights reciprocity as a value. When health care workers take risks to protect us all, we owe them special concern if they are harmed. Dr. Bruce Ribner, speaking on ABC, described Emory University Hospital as willing to take two US health care workers who became infected abroad because they believed these workers deserved the best available treatment for the risks they took for humanitarian ends. Calls to ban the return of US workers—or treatment in the United States of other infected front-line workers—forget that contagious diseases do not occur in a vacuum. Even Ann Coulter recognized, in her own unwitting way, that we owe support to first responders for the burdens they undertake for us all when she excoriated Dr. Kent Brantly for humanitarian work abroad rather than in the United States.
We too often fail to recognize that all the health care and public health workers at risk in the Ebola epidemic—and many have died—are owed duties of special concern. Yet unlike health care workers at Emory, health care workers on the front lines in Africa must make do with limited equipment under circumstances in which it is very difficult for them to be safe, according to a recent Wall Street Journal article. As we go forward we must remember the importance of providing adequately for these workers and for workers in the next predictable epidemics — not just for Americans who are able to return to the US for care. Supporting these workers means providing immediate care for those who fall ill, as well as ongoing care for them and their families if they die or are not longer able to work. But this is not all; health care workers on the front lines can be supported by efforts to minimize disease spread—for example conducting burials to minimize risks of infection from the dead—as well as unceasing attention to the development of public health infrastructures so that risks can be swiftly identified and contained and care can be delivered as safely as possible.
Fairness requires treating others as we would like to be treated ourselves. A way of thinking about what is fair is to ask what we would want done if we did not know our position under the circumstances at hand. In a classic of political philosophy, A Theory of Justice, John Rawls suggested the thought experiment of asking what principles of justice we would be willing to accept for a society in which we were to live, if we didn’t know anything about ourselves except that we would be somewhere in that society. Infectious disease confronts us all with an actual possibility of the Rawlsian thought experiment. We are all enmeshed in a web of infectious organisms, potential vectors to one another and hence potential victims, too. We never know at any given point in time whether we will be victim, vector, or both. It’s as though we were all on a giant airplane, not knowing who might cough, or spit, or bleed, what to whom, and when. So we need to ask what would be fair under these brute facts of human interconnectedness.
At a minimum, we need to ask what would be fair about the allocation of Ebola treatments, both before and if they become validated and more widely available. Ethical issues such as informed consent and exploitation of vulnerable populations in testing of experimental medicines certainly matter but should not obscure that fairness does, too, whether we view the medications as experimental or last-ditch treatment. Should limited supplies be administered to the worst off? Are these the sickest, most impoverished, or those subjected to the greatest risks, especially risks of injustice? Or, should limited supplies be directed where they might do the most good—where health care workers are deeply fearful and abandoning patients, or where we need to encourage people who have been exposed to be monitored and isolated if needed?
These questions of fairness occur in the broader context of medicine development and distribution. ZMAPP (the experimental monoclonal antibody administered on a compassionate use basis to the two Americans) was jointly developed by the US government, the Public Health Agency of Canada, and a few very small companies. Ebola has not drawn a great deal of drug development attention; indeed, infectious diseases more generally have not drawn their fair share of attention from Big Pharma, as least as measured by the global burden of disease.
WHO has declared the Ebola epidemic an international emergency and is convening ethics experts to consider such questions as whether and how the experimental treatment administered to the two Americans should be made available to others. I expect that the values of reciprocity and fairness will surface in these discussions. Let us hope they do, and that their import is remembered beyond the immediate emergency.
Headline Image credit: Ebola virus virion. Created by CDC microbiologist Cynthia Goldsmith, this colorized transmission electron micrograph (TEM) revealed some of the ultrastructural morphology displayed by an Ebola virus virion. Centers for Disease Control and Prevention’s Public Health Image Library, #10816 . Public domain via Wikimedia Commons.
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By: Alice,
on 3/28/2014
It is almost impossible to read a daily newspaper or listen to news reports from television and radio without hearing about an outbreak of an infectious disease. On 13 March 2014, the New York City Department of Health investigated a measles outbreak. Sixteen cases including nine pediatric cases were detected, probably caused by a failure to vaccinate the victims. On 12 February, an outbreak of a common microbial pathogen known as C.difficile occurred in several hospitals in Great Britain. This pathogen induces severe cases of gastrointestinal distress including diarrhea, fever, and stomach cramps. One of the main problems with a number of microbial pathogens like C.difficile is that they have become completely resistant to many known drugs.
How did this occur? Antibiotics, complex substances produced by certain types of microbes that destroy other microbes, were hailed as miracle drugs when the first one (penicillin) was discovered more than 70 years ago by Alexander Flemming. Although over 70 useful antibiotics have been discovered since penicillin, many can no longer be used because microbial pathogens have become resistant to them through evolution. In fact, over two million people in the United States become infected with antibiotic resistant pathogens every year, leading to 23,000 deaths according to the Centers for Disease Control and Prevention (CDC). New non-antibiotic drugs are always being sought to treat infectious diseases (mostly microbial because viral diseases are not susceptible to antibiotics). One such new discovery is a commonly used pain medication called Carprofen which inhibits antibiotic resistant pathogens. Thus, the “war against” infectious diseases remains an ongoing focus of medical research.
Of course there are many other pathogens (both microbial and viral) besides those mentioned above that assault us and our body defenses constantly. They include pneumonia, dysentery, tuberculosis, tetanus, diphtheria, scarlet fever, ulcers, typhoid, meningitis, plague, cholera (bacterial), polio, HIV (AIDS), rabies, influenza, measles, mumps, the common cold, yellow fever, and chicken pox (viral). Nevertheless, all of us are not equally “susceptible” to each infectious disease — a poorly understood term that determines why some of us get one disease but not another, or why some diseases occur in the winter while others occur in the summer.
This brings us to an important concept, namely, that there is no way to be free of microbes that inhabit every “nook and cranny” of our bodies. Of the approximately ten million cells that make up the human body, there are billions of microbes that come along with them. Most microbes that inhabit our bodies are necessary for our existence. Together they make up what is called the “microbiome” consisting of a diverse group of microbes that help keep each of us healthy. Most of them are found in the gastrointestinal tract where they aid digestion; synthesize vitamins and other necessary biochemicals our cells cannot make; attack and destroy pathogens; and stimulate our immune system to act in the same way.
Nevertheless, with this constant assault, one might wonder how it is possible we have survived for so long. There are a number of other variables besides the “microbiome’ that are responsible and that are still poorly understood. These include an ability of a host (us) to coexist with a pathogen (we keep them at bay or limit their spread internally like tuberculosis), an ability to mount a furious immunological attack on the pathogen to destroy them, or an innate ability to remain “healthy” (a vague term that really signifies the fact that all of our metabolic systems are operating optimally most of the time like digestion, excretion, blood circulation, neurological or brain function, and healthy gums and teeth among other systems).
Where does this innate ability come from? Simply put, genetic phenomena (both in microbes and in humans). These traits are not only inherited under the control of genes but their functions are also controlled by such genes. Different pathogens have different sets of genes which act to produce a specific disease in a susceptible host. However, it is also why individual hosts (humans) are more or less resistant to such infectious diseases.
How does the body interact with these “foreign” entities? The immune system must protect the body from attack by pathogens and also from the formation of abnormal cells which could turn cancerous. Two types of immune responses exist. One is under the control of antibodies (proteins which circulate in the blood stream) that resist and inactivate invading pathogens by binding to them. The other is mediated by a certain type of white blood cell called a lymphocyte that destroys abnormal (potentially cancerous) cells and viral infected cells. Together, with other white blood cells, they present a formidable defense against infection and abnormality.
It takes time for an immune response by antibodies to develop during a pathogenic invasion because there are many components involved in the activity. They are usually divided into primary and secondary responses. The primary response represents the first contact with the antigen which after a period of time results in an increased production of specific antibodies that react only to that antigen (which by the way are also produced by certain lymphocytes called “B” or plasma cells). Once the infection is controlled, antibody levels fall considerably. If, however, another infection occurs in the future by the same pathogen, a much more vigorous response will result (called the secondary response) producing a much faster development and a higher level of antibodies. Why is the secondary response so much faster and vigorous? This phenomenon is due to a remarkable property of the immune system in which the primary response is “remembered” after its decrease by the preservation of “memory” “B” lymphocytes that circulate until the secondary response occurs, no matter how long it takes.
William Firshein is the Daniel Ayers Professor of Biology, Emeritus and author of The Infectious Microbe. He chaired the Biology Department at Wesleyan University for six years and published over 75 original research papers in the field of Molecular Microbiology of Pathogens. He was the recipient of several million dollars of grant support from various public and private research agencies and taught over 6,000 graduate and undergraduate students during his 48 year career.
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The post The never-ending assault by microbes appeared first on OUPblog.
