Emerging and Re-emerging Infectious Diseases
Emily S. Read, BS, RN & Swati Thakur, MD
“Although optimists once imagined
that serious infectious disease (ID) threats would now be conquered, newly
emerging infectious diseases such as severe acute respiratory syndrome (SARS),
reemerging diseases such as West Nile Virus, and even deliberately disseminated
infectious diseases such as anthrax bioterrorism, continue to appear throughout
the world (Fauci, Touchette, & Folkers, 2005).” Infectious diseases can be defined as those
diseases, which are caused by microorganism or their toxic secretions that
penetrate the natural barriers in the body and multiply within to cause
disease. It has been reported that death
and lost years of healthy life from these diseases has declined over the past
ten years. However, the global public
health impact from these microorganisms remains considerable. Infectious diseases continue to be the third
leading cause of death in the
As aforementioned, death is not the only negative consequence of infectious diseases. Infectious microorganisms also affect lost years of healthy life. “Infectious diseases lead to compromised health and disability, accounting for nearly 30% of all disability-adjusted life years (DALYs) worldwide (1 disability-adjusted life year is 1 lost year of healthy life) (Fauci, Touchette, & Folkers, 2005).” Terrible disability and death from infectious diseases in not a new phenomenon, however. Deadly microorganisms have been plaguing human civilizations throughout time.
A Look throughout History
Before civilizations were established, infectious diseases were probably rare. Populations were not limited by illness, but instead by available resources such as food and water. The primary reasons for the lack of infectious diseases at this time can be noted as: the nomadic existence of the population at that time, the absence of domesticated animals such as cows and horses limited infectious diseases, and finally, most infections during this time were the result of trauma and not epidemics (Bayer Pharmaceuticals Corporation, n.d.). This nomadic life began to change, eventually, as people started liver closer together. The loss of larger wild mammals due to prolific hunting may have caused this gathering of people. These early civilizations relied heavily on domesticated animals and cultivated plants for their food. “The development of agriculture fostered (and was dependent upon) the cooperation of large numbers of families who lived close to each other. The development of agriculture also resulted in poorer, carbohydrate-rich diets with consequent under nutrition and less individual resistance to infections (Bayer Pharmaceuticals Corporation, n.d.).” Close proximity of these people is believed to be the cause for the emergence of infectious diseases. Infectious diseases became one of the major limitations for population size.
Growing civilizations probably caused the first extensive spread of infectious diseases. People began to focus on crop cultivation. Villages, town, and then cities were established to meet this growing need for food. A major problem, and reason for the spread of infectious disease, was the fact that people and animals began to live in the same buildings. Individuals became exposed to such diseases as influenza, tuberculosis, and parasitic infections. This contact was either through direct contact (particles in the air, polluted water, or contaminated food) or through indirect contact (through insect vectors carrying the disease) (Bayer Pharmaceuticals Corporation, n.d.).
As the cities grew, so did the start of trade. Local and distant settlements were established to fit the growing need of the population. As the traders and newly formed armies visited town after town, they brought with them infectious diseases. These individuals were known as human carrier. They might have been ill themselves or asymptomatic hosts. As these human carriers of disease traveled from town to town, the people of different towns, who had no built up immunity to the new, exotic illnesses, became sick. Epidemics and pandemics began to occur. An epidemic is a sudden outbreak of disease in excess of what is expected and a pandemic is a sudden geographically widespread outbreak of disease (Bayer Pharmaceuticals Corporation, n.d.).
Over 200 years ago, the process of industrialization began to take place. This led to a great social transformation. People living in the cities were forced to contend with industrial wastes and polluted air and water. Slums began to arise in the cities and became the focal points for poverty and the spread of disease. It is noted that epidemics of such diseases as, smallpox, typhus, typhoid, diphtheria, measles, and yellow fever in urban settings were well documented (Museum of Natural History Publication, 1996). “Urban population centers, with their extremely high mortality, were not able to maintain their population bases by the reproductive capacity of those living in the city. Mortality outstripped fertility, requiring immigration to maintain the size of the population (Museum of Natural History Publication, 1996).”
The First Epidemics – A Chronological Look
430 BC – The plague of Athens – This plague resulted from 200,000 inhabitants and villagers escaping into Athens when in danger of the Spartans. A mysterious infectious agent, believed to be spread from Ethiopia via Egypt, killed one third of this population and ended the Golden Age of Athens (Bayer Pharmaceuticals Corporation, n.d).
166 AD – The Antoine Plague – This particular epidemic was carried to Rome from Syria by troops returning home to Rome. Believed to be smallpox, bubonic plague, and possibly measles, this epidemic devastated the Roman Empire by killing four to seven million people throughout Europe. The probably led to the social and political upheaval of the people and the resulting collapse of the Roman Empire (Bayer Pharmaceuticals Corporation, n.d).
Circa 160 AD – Barbarian Boils – This plague, believed to be bubonic plague, was brought by invaders from the north and led to the collapse of the Han Empire in China (Bayer Pharmaceuticals Corporation, n.d).
1346-1350 – Bubonic plague – This pandemic began in China and spread along the trade routes through South Russia to the Crimea, which was besieged at the time. The plague, nicknamed Black Death, killed more than one third of the population of Europe at that time (Bayer Pharmaceuticals Corporation, n.d. & PRAVDA, 2005).
1492 – Columbus – Influenza, smallpox, tuberculosis, and gonorrhea all emerged when Columbus sailed to the Caribbean. The local population had no immunity to these diseases and consequently, eight million people on the Island of Hispaniola died. African slaves, introducing additional diseases to the new world, such as malaria and yellow fever, replaced the population. These new diseases proceeded to kill many of the European settlers (Bayer Pharmaceuticals Corporation, n.d). There is some speculation that Columbus brought the sexually transmitted infection, syphilis, back to Europe. “The origin of the disease in Europe has been the cause of debate for centuries. Experts estimate that recently found bones, which show signs of syphilis, are aged between 1296 and 1445. That suggests syphilis was already present in England before Columbus discovered the New World in 1492 (GMT, 2001).”
1542 – Black Death – This pandemic started in Egypt and spread all over Europe, killing 40% of the population of Constantinople in its wake (Bayer Pharmaceuticals Corporation, n.d). This plague killed 10,000 people per day. Several European regions, one of which was Italy, become largely depopulated at this time (PRAVDA, 2005).
1600’s, 1700’s, 1800’s, & 1900’s – Ongoing epidemics – These centuries saw epidemics throughout the world of malaria, yellow fever, dysentery, worm infestations, influenza, poliomyelitis, acquired immune deficiency syndrome, chlamydia, and plague to name a few. In 1918-1919, a terrible Spanish flu spread globally. It is estimated that this fast killer killed between 20 million and 50 million people globally (Bayer Pharmaceuticals Corporation, n.d, & PRAVDA, 2005). Influenza outbreaks also occurred in both 1957 and again in 1968.
2003 – SARS – The recent severe acute respiratory syndrome epidemic in Asia and some parts of Canada resulted in devastating economic setback to these involved countries and caused considerable harm to the tourist industry (PRAVDA, 2005).
Infectious Disease Spread through Bioterrorism
“Terrorism is the use of force or violence against persons or property in violation of the criminal laws of the United States for purposes of intimidation, coercion or ransom. Terrorists often use threats to create fear among the public, to try to convince citizens that their government is powerless to prevent terrorism, and to get immediate publicity for their causes (Federal Emergency Management Agency, 2005).” Microbial agents such as bacteria or toxins may be used as weapons in terrorist acts. When this occurs, it is known as bioterrorism. These biological agents can be dispersed through the air as aerosols or airborne particles. Terrorists may use bioterrorism to contaminate food or water causing illness and possibly death. Common biological agents, which may be utilized in this capacity, include, smallpox, plague, diphtheria, anthrax, ricin, tularemia, botulism, shigella, cholera, Q fever, E. coli 0157, salmonella, plague, and viral hemorrhagic fevers (Centers for Disease Control and Prevention (CDC)a, 2004). Much time, effort, and funding is being utilized by the United States and globally to prepare for such a disaster as a bioterrorism attack.
In 2001, Bacillus anthracis was sent as tiny white spores through the mail system in the United States. Twenty-two people were infected with anthrax, five of which died of the pulmonary disease. This is not the first case of bioterrorism, and sadly, will probably not be the last.
Bioterrorism – A Chronological Look
1340 – In northern France, catapults were used to hurl dead horses and other animals into the castle of Thun L’Eveque in Hainault. A truce was negotiated thereafter because the defenders could not endure “the stink in the air” (NOVA Online, 2002).
1346 – “As Tartars launched a siege of Kaffa, a port on the Crimean peninsula in the Black Sea, they suffered an outbreak of plague. Before abandoning their attack, they sent the infected bodies of their comrades over the walls of the city. Fleeing residents carried the disease to Italy, furthering the second major epidemic of “Black Death” in Europe (NOVA Online, 2002).”
1763 – At Fort Pitt, on the Pennsylvania frontier, British General Jeffery Amherst ordered that blankets be taken from persons infected with smallpox and given to the Delaware Indians at a peace-making parley (NOVA Online, 2002).
1936 – Japanese scientists used many Chinese human subjects to test the lethality of numerous disease causing agents, including, typhoid, plague, cholera, and anthrax. It is thought that as many as 10,000 individuals were killed (NOVA Online, 2002).
1979 – During this year, a peculiar outbreak of anthrax killed nearly 70 people in a Soviet city called Sverdlovsk. The Soviet Government blamed contaminated meat but the United States intelligence suspected that the dissemination of anthrax was linked to secret weapons work at a nearby army laboratory (NOVA Online, 2002).
1984 – Followers of the Indian guru Bagwan Shree Rajneesh, living on a compound in rural Oregon, spread Salmonella over salad bars in restaurants throughout their county. The cult was attempting to make the local citizens sick and thus, prevent them from voting in an upcoming election. Over 750 people reported cases of food poisoning, of which, 45 required a hospital stay (NOVA Online, 2002).
1995 – “The apocalyptic religious sect Aum Shinrikyo released sarin gas in a Tokyo subway, killing 12 commutes and injuring thousands. The cult also had enlisted Ph.D. scientists to launch biological attacks. Between 1993 and 1995, Aum Shinrikyo tried as many as 10 times to spray botulinum toxin and anthrax in downtown Tokyo (NOVA Online, 2002).”
2001 – Just one week after the terrible September 11th, terrorist attack, letters containing anthrax spores were sent to Tom Brokaw at NBC News in New York, the New York Post, and Senator Tom Daschle in Washington, D.C. Twenty-two individuals were made sick by the spores, five of which died of inhalation anthrax (NOVA Online, 2002).
Major Emerging and Re-emerging Infectious Diseases
Human Immunodeficiency Virus/Acquired Immune Deficiency Syndrome (HIV/AIDS) –
Greater than 20 million deaths have occurred throughout the world from HIV/AIDS. Currently, this terrible virus is the leading cause of death among persons 15-59 years old. In the United States, there is an estimated one million persons infected with HIV, and approximately 40,000 new infections occur each year (Fauci, Touchette, & Folkers, 1996). At first this disease was thought to only affect homosexual men. Today we can see that trend dramatically changing, with heterosexual women having the highest incidence. The mortality from acquired immune deficiency syndrome is exceptionally high (Prescott, Harley, & Klein, 2005).
“The social, economic, and human toll exacted by malaria globally is widespread and profound. Each year, acute malaria occurs in greater than 300 million people and results in over one million deaths worldwide. Most of these deaths occur in young children who live in sub-Saharan Africa (Fauci, Touchette, & Folkers, 2005).” Malarial disease is caused by a parasite that enters the bloodstream through the bite of an infected mosquito (Prescott, Harley, & Klein, 2005).
Mycobacterium tuberculosis (TB) is an ancient microbe, which is re-emerging at an alarming pace. It is estimated that this bacterium has infected one third of the world’s population. Eight million new cases of tuberculosis develop each year on a global scale. The death toll from this disease is greater than two million persons per year (Fauci, Touchette, & Folkers, 2005). A major reason for this re-emergence of tuberculosis pertains to a co-infection with HIV and TB. Some researchers believe that TB accelerates the clinical course of HIV (Fauci, Touchette, & Folkers, 2005). Multi-drug resistant tuberculosis is increasing in many countries throughout the world.
Annually, influenza, a respiratory virus (many different strains), develops in 20% of all U.S. citizens. Greater than 200,000 people are hospitalized each year with the “flu.” Influenza is generally self-limiting but the elderly, very young, persons with chronic illness, and immunocompromised people are at risk for mortality from influenza (Fauci, Touchette, & Folkers, 2005). Throughout the world, influenza infection affects three to five million people yearly. Of these individuals, 250,000 to 500,000 die.
Avian influenza is a major threat to today’s population. In Southeast Asia, at least 55 people have been infected with the influenza strain of H5N1 and 42 have died since January of 2004 (Fauci, Touchette, & Folkers, 2005). This strain is highly pathogenic and has killed millions of birds and poultry. Currently, there are very few suspected cases of a human-to-human transmission of this strain. If this virus were to mutate however, and take on those characteristics which would allow for a human-to-human transmission, a pandemic such as the Spanish Flu of 1918 may be repeated, with the potential to kill millions (Fauci, Touchette, & Folker, 2005).
West Nile Virus –
This virus, spread by mosquitoes, has long been endemic in such areas as Africa, West Asia, Europe, and the Middle East. In 1999, West Nile Virus made its first appearance in the United States, becoming visible in the New York City area. During this time, 62 people were infected with seven deaths occurring. Since that time, West Nile Virus has continued to spread throughout most of the United States (Fauci, Touchette, & Folkers, 2005). West Nile Virus probably came to the United States by crossing the Atlantic Ocean in an infected bird, mosquito, or human traveler (Prescott, Harley, & Klein, 2005).
In 2002, the worldwide epidemic of SARS began in China. From 2002 to 2003, SARS, a coronavirus, infected more than 8,500 individuals, killing 800 people in 27 different countries. “The global spread proceeded with unprecedented speed, overwhelming many hospitals and some public health systems in a matter of weeks. This led to the World Health Organization’s (WHO) declaration of a global alert and travel advisory to mainland China, Hong Kong, Singapore, Hanoi, and Toronto (Prescott, Harley, & Klein, 2005).” The impact of this devastated the economies of those countries affected.
Viral Hemorrhagic Fevers –
Several distinct families of viruses cause this group of illnesses. Viral hemorrhagic fevers (VHFs) involve a severe multisystem failure. Multiple organ systems in the body are affected when a person has VHF. Some of the diseases caused by these viruses include, Ebola hemorrhagic fever, hantavirus pulmonary syndrome, Lassa fever, Marburg hemorrhagic fever, and Rift Valley fever (CDCb, 2004). These viruses can be found throughout the world. For the past few years, there have been small outbreaks of Ebola Hemorrhagic Fever in Africa. In 2004, there was an outbreak in South Sudan involving 20 cases and five deaths. As of April 2005, an outbreak of Marburg hemorrhagic fever has infected over 230 individuals, killing over 210 of them in Angola.
Antibiotic-resistant Microorganism –
In recent years, the emergence of methicillin-resistant Staphylococcus aureus (MRSA) has risen from 2% in 1975, to 14% in 1987, and to over 40% in 1999 (Prescott, Harley, & Klein, 2005). Organisms such as vancomycin-resistant enterococcus (VRE) are also gaining in prevalence. In 1998, almost 25% of enterococci-related hospital acquired infections were due to VRE (Prescott, Harley, & Klein, 2005). This phenomenon is frightening due to the fact that these drug-resistant organisms are mutating faster than humans can defend against them.
New variant CJD (vCJD) is a very rare, neuro-degenerative, fatal brain disorder in humans. This disease is caused by prion proteins entering the body through consumption of infected cattle products (CDCc, 2004). “As of December 1, 2003, a total of 153 cases of vCJD had been reported in the world: 143 from the United Kingdom, six from France, and one each from Canada, Ireland, Italy, and the United States (CDCc, 2004).”
Public Health Achievements
Childhood vaccinations have mainly eliminated such diseases as polio, diphtheria, measles, mumps, and pertussis. Organizations such as the WHO, the United Nations Children’s Fund (UNICEF), CDC, and Rotary International have played key roles in the eradication of polio. In the US, political campaigns have contributed successfully to vaccination initiatives, requiring children to be vaccinated against deadly diseases upon school entry (Koplan & McPheeters, 2004).
Stricter policy for the mandate of clean air and water has led to a decrease in the spread of infectious disease. In the United States, there has been a decrease in dysenteric diseases and Legionnaires’ disease because of these stricter mandates to promote clean water. “Public policy has sought to control infectious disease throughout history, including attempts to ban spitting in the streets around the turn of the century and imposing restaurant inspections to ensure sanitary conditions in food preparation (Koplan & McPheeters, 2004). The benefits to fighting back against the spread of infectious disease include, the fact that lives are saved, the tremendous cost reduction, improved health and decreased suffering and disability, the promotion of worldwide political stability, and finally, the heightened awareness and potential response to bioterrorism.
Possible Reasons for the Emergence and Re-emergence of Infectious Disease – A Listing
Addressing the Crises: Key Organizations and Programs Designed to Fight the Spread of Infectious Disease
· National Immunization Program: VCP (Vaccination of Children Program) – Created by Omnibus Budget Reconciliation Act (OBRA) in 1993, and implemented in 1994; VCP is a critical element of former President Clinton’s Child Immunization Initiative (CII). Under this program, federally purchased vaccines are provided to those children between 0-18 years of age who are enrolled in Medicaid, do not have health insurance, or are American Indian or Alaskan natives (CDC, 2001). For those children whose health insurance does not cover immunization, they can receive vaccinations at rural or federally qualified health center. It is operational in all 50 states, and between 1994 and 1998, a total of 43,884 provider sites became enrolled in the program. Operational responsibility of this program lies with the National Immunization Program at the CDC. Successful implementation requires close collaboration with Health Care Finance Administration center for Medicaid, Infant and Children Program, and managed care organizations. Vaccine preventable diseases in children are diphtheria, haemophilus influenza type b, hepatitis A and B, measles, mumps, pertussis, polio, rubella, tetanus, and varicella. Vaccines for people >65 years are also available for diphtheria, influenza, pneumococcus, and tetanus (CDC, 2001).
· The Global Fund was created to finance a dramatic turn-around in the fight against such diseases as AIDS, malaria, and TB (Global Fund, n.d.). This organization has collected $3 billion in US funds in 128 countries to support strong interventions against these three top killers.
· The United Nations Children’s Fund (UNICEF) “works with governments and partners to scale up routine immunization services to make full immunization a part of every child’s life. UNICEF is a co-founder of the Global Alliance for Vaccines and Immunization (GAVI), a partnership dedicated to strengthening immunization systems and increasing access to new and under-used vaccines. Working through GAVI, UNICEF and other partners have expanded the access of millions of children in the world’s poorest nations to needed vaccines, including hepatitis B, Hib (which protects against some forms of meningitis and pneumonia) and yellow fever (UNICEF, n.d.).”
Infectious diseases are tremendously dangerous because of the negative affects on the global economy and the deleterious affects on quality of life throughout the world. The World Health Organization, working in collaboration with UNICEF, the CDC, and other key organizations, has been successful in combating many diseases, however. In the past, these organizations played a major role in the global eradication of smallpox. Similar efforts are being made today toward achieving global eradication of other diseases like polio, guinea worms, and measles. In United States alone, as a result of the ongoing efforts, the crude death rate from infectious diseases has dropped and caused an increase in the life expectancy (Global Health, n.d.). This control has occurred due to advances in public health such as improved sanitation, improved hygiene, and vaccination programs (Global Health, n.d.). Technological advances such as, serological testing, viral isolation, tissue culture, and molecular diagnostic techniques have been used to detect and characterize infectious agents. Due to some of these variables, our ability to create newer and more effective antibiotics has been established. Focused public attention and enhanced technology has improved our capacity to track, prevent, and treat diseases. However, there is still a need to further local, national, and international cooperation and coordination to effectively fight these emerging and re-emerging infectious diseases.
Improving laboratories facilities, training additional personnel, establishing reliable and efficient communication networks, and building a strong public health infrastructure may bring about improvement in surveillance and disease control/response (University of Chicago Press, n.d.). The application of genomics, proteomics, synthetic chemistry and robotics, molecular and genetic epidemiology, and information technology will be critical to the success of any disease control program. A challenge will lie in the development of new, safe, and effective vaccines like recombinant protein vaccinations designed to fight the three main killers worldwide: HIV/AIDS, malaria, and tuberculosis. Sequencing the genome of the various pathogenic organisms will help us in making selective vaccines and antimicrobial agents. Therefore, in order to effectively meet the challenge of infectious diseases in the future, both scientific and technological advances will be critical (University of Chicago Press, n.d.). In addition, Public Health on all levels, must keep a watchful eye on infectious diseases in order to prevent the devastation caused by pandemics.
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