Infectious disease may be an unavoidable fact of life, but there are many strategies available to help us protect ourselves from infection and to treat a disease once it has developed.
Some are simple steps that individuals can take; others are national or global methods of detection, prevention, and treatment. All are critical to keeping communities, nations, and global populations healthy and secure.
Medicines have existed in human society probably as long as sickness itself. However, with the advent of the modern pharmaceutical industry, biochemical approaches to preventing and treating disease have acquired a new level of prominence in the evolving relationship between microbes and their human hosts.
A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism and is often made from weakened or killed forms of the microbe or its toxins. The agent stimulates the body’s immune system to recognize it as foreign, destroy it, and ”remember” it, so that the immune system can more easily identify and destroy any of these microorganisms that it encounters later. The body’s immune system responds to vaccines as if they contain an actual pathogen, even though the vaccine itself is not capable of causing disease. Because vaccines are widely used in the United States, many once-common diseases—polio, measles, diphtheria, whooping cough, mumps, tetanus, and certain forms of meningitis—are now rare or well controlled.
Vaccinated people produce antibodies that neutralize a disease-causing virus or bacterium. They are much
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IV Prevention and Treatment Infectious disease may relationship between microbes and their human hosts. be an unavoidable fact of life, but there are many Vaccines A vaccine is a biological preparation that strategies available to help us improves immunity to a particular disease. A vaccine protect ourselves from infection typically contains an agent that resembles a disease- and to treat a disease once it has causing microorganism and is often made from weakened or killed forms of the microbe or its toxins. developed. The agent stimulates the body’s immune system to recognize it as foreign, destroy it, and ”remember” Some are simple steps that individuals can take; it, so that the immune system can more easily others are national or global methods of detection, identify and destroy any of these microorganisms prevention, and treatment. All are critical to keeping that it encounters later. The body’s immune system communities, nations, and global populations responds to vaccines as if they contain an actual healthy and secure. pathogen, even though the vaccine itself is not capable of causing disease. Because vaccines Vaccines and Medicines are widely used in the United States, many once- common diseases—polio, measles, diphtheria, Medicines have existed in human society probably whooping cough, mumps, tetanus, and certain forms as long as sickness itself. However, with the advent of meningitis—are now rare or well controlled. of the modern pharmaceutical industry, biochemical approaches to preventing and treating disease have Vaccinated people produce antibodies that neutralize acquired a new level of prominence in the evolving a disease-causing virus or bacterium. They are much 34
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less likely to become infected and transmit those disappear, is key to curing an infection and germs to others. Even people who have not been preventing the development of resistant bacteria. vaccinated may be protected by the immunity of the “herd,” because the vaccinated people around Antibiotics don’t work against viral infections such them are not getting sick or transmitting the infection. as colds or the ﬂu. In those cases, antiviral drugs, The higher the proportion of vaccinated people in a which ﬁght infection either by inhibiting a virus’s community, the lower the likelihood that a susceptible ability to reproduce or by strengthening the body’s person will come into contact with an infectious immune response to the infection, are used. There individual—leading to greater herd immunity. are several different classes of drugs in the antiviral family, and each is used for speciﬁc kinds of viral infections. (Unlike antibacterial drugs, which may In the past, thimerosal, a preservative that contains cover a wide spectrum of pathogens, antiviral mercury, was used in some vaccines and other medications are used to treat a narrower range of products. Use of this product became the subject organisms.) Antiviral drugs are now available to of controversy, with some arguing that the treat a number of viruses, including inﬂuenza, HIV, substance caused autism in children. Extensive, herpes, and hepatitis B. Like bacteria, viruses mutate independent research has presented no convincing over time and develop resistance to antiviral drugs. evidence of harm associated with the low levels of thimerosal present in vaccines. Since 2001, thimerosal has New Treatments not been routinely used as a Modern medicine needs new preservative in recommended kinds of antibiotics and antivirals childhood vaccines. to treat drug-resistant infections. But the pipeline of new drugs is drying up. For example, nearly Antibiotics and Antivirals 40 years elapsed between Antibiotics are powerful introduction of the two newest medicines that ﬁght bacterial molecular classes of antibiotics: infections. They either kill ﬂuoroquinolones (such as Cipro) bacteria or stop them from in 1962 and the oxazolidinones reproducing, allowing the body’s (such as Zyvox) in 2000. natural defenses to eliminate the pathogens. Used properly, Major pharmaceutical companies antibiotics can save lives. But have limited interest in dedicating growing antibiotic resistance is resources to the antibiotics curbing the effectiveness of these market because these short- drugs. Taking an antibiotic as course drugs are not as proﬁtable directed, even after symptoms 35
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as drugs that treat chronic conditions and lifestyle- discovery and clinical development of new therapies related ailments, such as high blood pressure or high to treat infectious diseases are bringing together cholesterol. Antibiotic research and development is philanthropists, medical research foundations, also expensive, risky, and time consuming. Return on industry leaders, and other key stakeholders to forge that investment can be unpredictable, considering that effective collaborations. resistance to antibiotics develops over time, eventually making them less effective. Microbe Awareness New antiviral drugs are also in short supply. These Daily habits provide some of the strongest defenses medicines have been much more difﬁcult to develop against infectious diseases. Among the sensible than antibacterial drugs because antivirals can actions you can take: damage host cells where the viruses reside. Today, there are more antiviral drugs for HIV than for • Keep immunizations up to date. any other viral disease, transforming an infection • Wash your hands often. Washing with regular soap that was once considered a death sentence into a and rinsing with running water, followed by thorough manageable chronic condition. But novel drugs are drying, is considered the most important way to needed to combat other epidemic viral infections, prevent disease transmission. Routine consumer use such as inﬂuenza and hepatitis B and C. of residue-producing antibacterial products, such as those containing the chemical triclosan, have Several programs have been developed to stimulate not been proven to confer health beneﬁts and may research and development of new vaccines and actually contribute to antibiotic resistance. medicines. The U.S. Department of Health and Human Services recently formed the Biomedical Advanced Research and Development Authority, which provides an integrated, systematic approach to the development and purchase of the vaccines, drugs, therapies, and diagnostic tools necessary for public health medical emergencies. The Cures Acceleration Network provision of the Patient Protection and Affordable Care Act, signed into law by President Obama in March 2010, is designed to move research discoveries through to safe and effective therapies by awarding grants through the National Institutes of Health to biotech companies, universities, and patient advocacy groups. And nonproﬁt organizations dedicated to accelerating the 36
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• Prepare and handle food carefully. (See “How to Government Policies Protect Yourself” in the Foodborne Pathogens section on page 16.) Keeping our nation safe from disease outbreaks • Use antibiotics only for infections caused by depends on effective and well-coordinated programs bacteria. Viral infections cannot be treated with that monitor public health. What are some of the key antibiotics. Your doctor may prescribe an antiviral efforts at work in the United States? medication if your condition warrants it. Public Health Capacity • Report to your doctor any rapidly worsening The mission of public health is to safeguard and infection or any infection that does not get better improve the health of the community as a whole. after taking a course of antibiotics, if prescribed. Effectively responding to infectious disease threats • Be careful around all wild animals and unfamiliar therefore requires a robust public health system. In domestic animals. After any animal bite, cleanse the the United States, public health wound with soap and water and consult a clinician surveillance for infectious for further evaluation. Enjoy wild animals with your diseases is conducted through eyes, not by touching them. a variety of agencies. Health care providers and others report • Avoid insect bites whenever possible by using cases of notiﬁable infectious insect repellent and wearing long-sleeved shirts, diseases (as deﬁned by local long pants, and a hat outdoors. and state health codes) to state • Protect yourself by using safe sex practices. health departments. State health You and your partner should be tested for sexually department ofﬁcials, in turn, transmitted diseases, including HIV, if there has been verify disease reports, monitor any risk of exposure. Consistently and correctly use disease incidence, identify condoms when having sex with a partner of unknown possible outbreaks, and forward status. Avoid sex with an injecting drug user. their ﬁndings to the CDC. • Stay alert to disease threats when traveling or The CDC and other federal visiting underdeveloped countries. Seek advice agencies, including the Food from a reliable source, such as the WHO or the and Drug Administration, the CDC, if you are going to areas of moderate-to-high U.S. Department of Agriculture, disease risk. and the U.S. Department of CDC headquarters in Atlanta, Georgia. Defense, independently gather • Acquire healthy habits such as eating well, getting and analyze information for enough sleep, exercising, and avoiding tobacco and disease surveillance. illegal drug use. 37
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Public health advocates have called for improved surveillance to better monitor infectious diseases across the country. Among their recommendations: a national electronic infectious diseases reporting system; innovative methods of disease surveillance (such as automated laboratory reporting of infectious disease or systematic gathering of informal reports of disease from the Internet); and fortifying the entire public health system, which historically has been underfunded compared to biomedical research. Syndromic surveillance—the near- or real-time monitoring of nonspeciﬁc pre-diagnostic signs of disease outbreaks—is an innovative surveillance method that is being explored by some cities and states with assistance from the federal government as a means of providing early warning of infectious of foods. Monitoring the entire food production disease outbreaks. Syndromic surveillance rests process can pinpoint hazards and control points on the idea that, following large-scale exposure to where contamination can be prevented, limited, infectious disease in an epidemic or bioterrorist or eliminated. A formal method for evaluating attack, people will ﬁrst develop symptoms, stay risk control is called the Hazard Analysis Critical away from work or school, and attempt to treat Control Point, or HACCP (pronounced “has-sip”) themselves before seeing a doctor. These systems system. First developed by NASA to ensure that the therefore monitor school and work absenteeism, food eaten by astronauts was safe, HACCP safety sales of over-the-counter medications, illness- principles are now being applied to a widening related 9-1-1 calls, and other patterns that suggest an range of foods, including meat, poultry, seafood, outbreak. However, most surveillance still focuses fruit juices, and other products. on tracking reported infections. In recent years the U.S. Government Accountability Ofﬁce, food safety advocates, and legislators have Food Safety documented problems resulting from the fragmented Foodborne diseases are largely preventable—but nature of the nation’s food safety system. At least the goal requires vigilance in every step from a dozen federal agencies, implementing at least the farm to the table. Good agricultural and 30 different laws, have roles in overseeing the manufacturing practices can reduce the spread of safety of the nation’s food supply. Advocates have microbes among animals and prevent contamination 38
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recommended that all food safety activities be a critical component to responding to infectious consolidated into a single federal agency with a disease worldwide. Among the strongest measures uniﬁed mission. promoting worldwide infectious disease surveillance are the WHO’s revised International Health Regulations, which entered into force in 2007. International Cooperation These require WHO member states to report certain diseases and outbreaks that may represent public National borders offer trivial impediment health emergencies of international concern to the to infectious disease threats. In the highly WHO and to strengthen their capacities for public interconnected and readily traversed global village health surveillance, diagnosis, and response. In of our time, one nation’s problem soon becomes addition, the CDC’s Division of Global Migration every nation’s problem. Therefore, many of the and Quarantine, an integrated and comprehensive strategies described above must be implemented partnership of local, national, and global health worldwide, not just nationally, in order to have a authorities, works to prevent, detect, and contain true impact. infectious diseases in countries of origin and at U.S. ports of entry. Global Surveillance Just as national surveillance is critical to controlling Technological advances in disease surveillance and outbreaks within a nation, global surveillance is detection such as regional syndromic surveillance, bioinformatics, and rapid diagnostic methods, have strengthened infectious disease control and prevention efforts. The global response to SARS, for example, was triggered by a report posted to the Program for Monitoring Emerging Diseases— or ProMED Mail—a global electronic reporting system for outbreaks of emerging infectious diseases and toxins. Other networks are beginning to listen in on what scientists call “viral chatter”—the seemingly commonplace transmission of animal viruses to humans in parts of the world where the two populations overlap, such as live-animal markets or urban areas carved out of tropical rainforests. By identifying viruses, bacteria, and parasites in animals where they naturally live, and monitoring 39
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those organisms as they move from animals into diarrhea, children in poor countries are not; for each people, it may be possible to prevent deadly child who dies from pneumonia in an industrialized new infections of animal origin from entering country, more than 2,000 children die from the and racing through human populations. The One infection in developing countries. Health Initiative, a worldwide movement to forge collaborations among physicians, veterinarians, Many factors inﬂuence whether poor nations can and other related disciplines, is an example of obtain affordable drugs of good quality. Most drug efforts to improve communication about human research and development is not geared toward and animal diseases. the needs of people in poor countries because they are not a large market. As a result, a large percentage of the money spent worldwide on health Public Health in Developing Nations care research is dedicated to problems affecting a The gaps in life expectancy between the richest small percentage of the world’s population. Social and poorest countries now exceed 40 years—in and political challenges to the distribution of large measure owing to the toll of infectious medicines are factors as well. Efforts are being made diseases. Safe water supplies, sewage treatment and by foundations, pharmaceutical companies, and disposal, improved food safety, and vaccination other organizations to overcome these challenges, programs are urgently needed in developing providing funding, research, and donations of nations. A major barrier to achieving these medications. The tragedy of global infectious disease improvements is the underlying weakness of public is not only that so many lives are lost or damaged, health systems in resource-poor countries, including it’s that so many of these infections could be a shortage of health care workers, which hinders prevented or treated effectively with low-cost drugs. efforts to immunize, treat, and monitor the status of patients. Poor nations also lack disease surveillance programs and up-to-date laboratories, which are essential in the mission to ﬁnd, diagnose, and contain infectious diseases. Distribution of Medicines Life-saving vaccines and medications are not distributed equitably around the world. More than half of those suffering from HIV/AIDS who need drug treatment are not receiving it. Only 2 percent of people with multidrug-resistant TB receive the right medications. And while children in wealthy countries are routinely immunized with vaccines Two health workers give a child polio vaccine during a vaccination that protect against childhood pneumonia and campaign in the Democratic Republic of the Congo. 40