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By Janet R. Gilsdorf

Every April, when the robins sing and the trees erupt in leaves, I think of Brad — of the curtain wafting through his open window, of the sounds of his iron lung from within, of the heartache of his family. Brad and I grew up at a time when worried mothers barred their children from swimming pools, the circus, and the Fourth of July parade for fear of paralysis. It was constantly on everyone’s minds, cast a shadow over all summertime activities. In spite of the caution, Brad got polio — bad polio, which further terrorized our mothers. It still haunts me. If, somehow, he had managed to avoid the virus for a couple years until the Salk vaccine arrived, none of that — the iron lung, the shriveled limbs, the sling to hold up his head — would have happened.

In 1954, many children in my town, myself included, became “Polio Pioneers” because our parents made us participate in the massive clinical trial of the Salk vaccine. Some of us received the shot of killed virus, others received a placebo. We were proud, albeit scared, to get those jabs, to be part of a big, important experiment. Our moms and dads would have done anything to rid the country of that dreaded disease.

Because the vaccine is so effective, mothers today aren’t terrified of polio. Children in our neighborhoods aren’t growing up in iron lungs or shuffling to school in leg braces. We seem so safe. But our world is smaller than it used to be. The oceans along our coasts can’t stop a pestilence from reaching us from abroad. A polio virus infecting a child in Pakistan, Nigeria, or Afghanistan can hop a plane to New York or Los Angeles or Frankfurt or London, find an unimmunized child, and spread to other unimmunized people. Our earth is not yet free of polio.

Germs are like things that go bump in the night. They can’t been seen, they lurk in familiar places, they are sometimes very harmful, and they instill great fear—some justified, some not.

Fear of measles, like fear of polio, is justified. In the old days, one in twenty children with measles developed pneumonia, one or two in a thousand died. The vaccine changed all that in the developed world. But, measles continues to rage in underdeveloped countries. In a race for very high contagiousness, the measles virus ties the chickenpox virus (which causes another vaccine-preventable childhood infection). Both viruses can catch a breeze and fly. Or they may linger in still air for over an hour. They, too, ride airplanes. This year alone, outbreaks of measles started by imported cases have occurred in New York, California, Massachusetts, Washington, Texas, British Columbia, Italy, Germany, and Netherlands.

Fear of whooping cough (aka pertussis) is also justified. In the pediatric hospital where I work, two young children have died of this infection in the past several years and many others have suffered from the disease, which used to be called “the one-hundred day cough.” It lasts a long time and antibiotic treatment does nothing to shorten the course. Young children with pertussis may quit breathing, have seizures, or bleed into their eyes. It spreads like invisible smoke around high schools and places where people gather … and cough on each other.

On the other hand, fear of vaccines — immunizations against measles, polio, chickenpox, or whooping cough — is hard to understand. In the grand scheme of things, any of these serious infections is a much greater threat than the minimal side effects of a vaccine to prevent them. Just ask the mothers of the children who died of pertussis in my hospital. It’s true that the absolute risk of these infections in resource rich areas is small. But, for even rare infections, a 0.01% risk of disease translates into hundreds of healthy children who don’t have to be sick, or worse yet die, of a preventable infection.

In spite of the great success of vaccines, they aren’t perfect. Perfection is a tall order. Still we can do better. Fortunately, because of the work of my medical and scientific colleagues, new vaccines under development hold promise to be more effective with fewer doses, to provide increased durability of vaccine-induced immunity, and to be even freer of their already rare side effects. And, we’re creating vaccines against respiratory syncytial virus, Staphylococcus aureus, group A Streptococcus, herpes virus, and HIV, to name a few.

Brad would be proud of how far we have come in protecting our children from the horrible affliction that crippled him. He’d also be furious at our failure to vaccinate all our children. Every single one of them. He’d tell us that no child should ever be sacrificed to the ravages of polio or measles or chicken pox or whooping cough.

Janet R. Gilsdorf, MD is the Robert P. Kelch Research Professor of Pediatrics at the University of Michigan Medical School and pediatric infectious diseases physician at C. S. Mott Children’s Hospital, Ann Arbor. She is also professor of epidemiology at the University of Michigan and President-elect of the Pediatric Infectious Diseases Society. Her research focuses on developing new vaccines against Haemophilus influenzae, a bacterium that causes ear infections in children and bronchitis in older adults. She is the author of Inside/Outside: A Physician’s Journey with Breast Cancer and the novel Ten Days.

To raise awareness of World Immunization Week, the editors of Clinical Infectious Diseases, The Journal of Infectious Diseases, Open Forum Infectious Diseases, and Journal of the Pediatric Infectious Diseases Society have highlighted recent, topical articles, which have been made freely available throughout the observance week in a World Immunization Week Virtual Issue. Oxford University Press publishes The Journal of Infectious Diseases, Clinical Infectious Diseases, and Open Forum Infectious Diseases on behalf of the HIV Medicine Association and the Infectious Diseases Society of America (IDSA), and Journal of the Pediatric Infectious Diseases Society on behalf of the Pediatric Infectious Diseases Society (PIDS).

The Journal of the Pediatric Infectious Diseases Society (JPIDS), the official journal of the Pediatric Infectious Diseases Society, is dedicated to perinatal, childhood, and adolescent infectious diseases. The journal is a high-quality source of original research articles, clinical trial reports, guidelines, and topical reviews, with particular attention to the interests and needs of the global pediatric infectious diseases communities.

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Image credit: Vaccination. © Sage78 via iStockphoto.

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By William Firshein

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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One snowy morning in early February, I was sitting on a runway in Cincinnati, Ohio, waiting for the plane to be de-iced before take off, checking emails on my phone. Amongst the mundane messages one leapt out: from Christine McNab of the Measles and Rubella Initiative, the subject line read, "Proposal to travel to the DR Congo/ Illustrate." Through this small device in my hand, I was whisked from the icy Mid-West to Africa, to communities devastated by measles, to children dying in the thousands from this preventable disease. The proposal was very compelling, to visit these communities to talk with families and the immunization workers who travel across the country, often on foot, to distribute the vaccine. And then to draw. To create posters and maybe a book and a video, to communicate the toll of measles and show the ways we can prevent deaths and eliminate this disease.