Chapter 13 Infectious Disease Prevention and Control

Multisystem Approach to Control

Communicable diseases represent an imbalance in the harmonious relationship between the human host and the environment. This state of imbalance provides the infectious agent an opportunity to cause illness and death in the human population.

Control and Prevention of Parasitic Infections (nurse role)

Correct diagnosis by nurses and other health care workers allows the provision of early and appropriate treatment and client education for preventing and controlling parasitic infections. Diagnosis of parasitic diseases is based on history, including travel, characteristic clinical signs and symptoms, and the use of appropriate laboratory tests to confirm the clinical diagnosis. Knowing what specimens to collect, how and when to collect, and what laboratory techniques to use are all important in establishing a correct diagnosis.

Healthy people 2020 Measles

Healthy People 2020 calls for the reduction, elimination or maintained elimination of vaccine-preventable diseases including the reduction of indigenous measles cases. Efforts to meet this goal will require (1) rapid detection of cases and implementation of appropriate outbreak control measures, (2) achievement and maintenance of high levels of vaccination coverage among preschool-age children in all geographic regions, (3) continued implementation and enforcement of the two-dose schedule among young adults, (4) the determination of the source of all outbreaks and sporadic infections (5) cooperation among countries in measles control efforts.

Prevent the spread of disease

EX: Identify and treat new case/testing and counseling (HIV, Syph, Influenza) Administer TB test Quarantine (rabies) Prophylaxis treatment for Risk of exposure (needle exchange, condom distribution)

Modes of Transmission

Infectious diseases can be transmitted horizontally or vertically.

Reduce Complications and disabilities through treatment and Rehab

Outreach for TB clients education Home Health services

VectorBorne Diseases

Vectorborne diseases refer to illnesses for which the infectious agent is transmitted by a carrier, or vector, which is usually an arthropod (mosquito, tick, fly), either biologically or mechanically. With biological transmission, the vector is necessary for the developmental stage of the infectious agent. Examples include the mosquitoes that carry WNV and the fleas that transmit plague. Lyme disease (Borrelia burgdorferi), Rocky Mountain spotted fever (Rickettsia rickettsii), ehrlichiosis (Ehrlichiae), and anaplasmosis (Anaplasma phagocytophilum), formerly known as human granulocytic ehrlichiosis.

The transmission of communicable diseases depends on the successful interaction of the :

Infectious agent, the host, and the environment.: These three factors make up the epidemiologic triangle At present, the potential results of such disturbance require attention as advances in science and technology, destruction of natural habitats, explosive population growth, political instability, and a worldwide transportation network combine to alter the balance among the environment, people, and the agents that produce disease.

Prevention and Control Programs

Infectious disease can be prevented and controlled. The goal of prevention and control programs is to reduce the prevalence of a disease to a level at which it no longer poses a major public health problem. In some cases, diseases may even be eliminated or eradicated.

Resistance

is the ability of the host to withstand infection, and it may involve natural or acquired immunity.

Infection

refers to the entry, development, and multiplication of the infectious agent in the susceptible host.

Host Factor

A human or animal host can harbor an infectious agent. The characteristics of the host that may influence the spread of disease are host resistance, immunity, herd immunity, and infectiousness of the host.

avian flu

Also in 1997, the first reported outbreak of avian flu affecting humans occurred in Hong Kong.

"Essential Services" under which these roles fall are presented by core function.

Assessment, policy development, assurance

Nurses role in vaccine Preventable Diseases

Because many children receive their immunizations at public health departments, nurses play a major role in increasing immunization coverage of infants and toddlers. Nurses track children known to be at risk for underimmunization and call or send reminders to their parents. They help avoid missed immunization opportunities by checking the immunization status of every young child encountered, whether or not the clinic or home visit is related to immunization. In addition, they organize immunization outreach activities in the community; provide answers to parents' questions and concerns about immunization; and educate parents about why immunizations are needed, inappropriate contraindications to immunization, and the importance of completing the immunization schedule on time.

Parasitic Opportunistic Infections

Opportunistic infections (OIs) are infections that occur more frequently or more severely in individuals immunocompromised by HIV infection. Before the introduction of routine prophylactic treatment and potent-combination, highly active antiretroviral therapies (ARTs) in the 1990s, OIs were the leading cause of illness and death in this group. Toxoplasma gondii is a coccidial organism harbored by cats infected by eating other infected animals

In 2011 FoodNet reported 18,964 laboratory-diagnosed cases of infection, the majority caused by

Salmonella, Campylobacter, and Shigella

Salmonellosis

Salmonellosis is a bacterial disease characterized by sudden onset of headache, abdominal pain, diarrhea, nausea, sometimes vomiting, and almost always fever. Onset is typically within 48 hours of ingestion, but the clinical signs are impossible to distinguish from other causes of gastrointestinal distress. Diarrhea and lack of appetite may persist for several days, and dehydration may be severe. Although morbidity can be significant, death is uncommon except among infants, older adults, and the debilitated.

SARS

Severe acute respiratory syndrome (SARS) was first recognized in China in February 2003 and, as if in a bestselling thriller, this newly emerging infectious disease quickly achieved pandemic proportions. . A large number of individuals infected by SARS could be traced back to unrecognized cases in hospitals, suggesting that prompt identification and isolation of symptomatic people is the key to interrupting transmission.

Factors that Can Influence the Emergence of New Infectious Diseases

Societal events - Economic impoverishment, war or civil conflict, population growth and migration, urban decay Health care - New medical devices, organ or tissue transplantation, drugs causing immunosuppression, widespread use of antibiotics Food production - Globalization of food supplies, changes in food processing and packaging Human behavior - Sexual behavior, drug use, travel, diet, outdoor recreation, use of childcare facilities Environmental -Deforestation/reforestation, changes in water ecosystems, flood/drought, famine, global changes (e.g., warming) Public health - Curtailment or reduction in prevention programs, inadequate communicable disease infrastructure surveillance, lack of trained personnel (epidemiologists, laboratory scientists, vector and rodent control specialists) Microbial adaptation - Changes in virulence and toxin production, development of drug resistance, microbes as co-factors in chronic diseases

Prevent the occurrence of Disease

Universal Precautions : PPE Vaccines Monitoring immunization records Community outreach

Vectors

are arthropods such as ticks and mosquitoes or other invertebrates such as snails that transmit the infectious agent by biting or depositing the infective material near the host. Vectors may be necessary to the life cycle of the organism (e.g., mosquitoes and malaria) or may act as mechanical transmitters (e.g., flies and food).

Emerging infectious diseases

are those in which the incidence has actually increased in the past several decades or has the potential to increase in the near future. These emerging diseases may include new or known infectious diseases.

health care-associated infections (HAIs)

are, as the name implies, those transmitted during hospitalization or developed within a hospital or other health care setting. They may involve clients, health care workers, visitors, or anyone who has contact with a hospital or doctor's office. Invasive diagnostic and surgical procedures, broad-spectrum antibiotics, and immunosuppressive drugs, along with the original underlying illness, leave hospitalized clients particularly vulnerable to exposure to virulent infectious agents from other clients and indigenous hospital flora from health care staff. In this setting, the simple act of performing hand hygiene before approaching every client becomes critical.

Surveillance

gathers the "who, when, where, and what"; these elements are then used to answer "why." A good surveillance system systematically collects, organizes, and analyzes current, accurate, and complete data for a defined disease condition. The resulting information is promptly released to those who need it for effective planning, implementation, and evaluation of disease prevention and control programs.

Infectious Diseases

have not vanished, and they remain a continuing cause for concern. They remain the leading cause of death for children and adolescents worldwide and the second-leading cause overall, killing an estimated 8 million people a year (WHO, 2013). In the United States, the downward trend in mortality from infectious diseases seen since 1900—with the exception of the 1918 influenza pandemic—reversed itself in the 1980s, with the emergence of new entities such as HIV disease and the increasing development of antibiotic resistance. Respiratory diseases in the form of pneumonias and influenza remain among the 10 leading causes of death, and new strains such as novel influenza A H1N1 and avian influenza A H5N1 test our disease control abilities and consume resources. Previously unknown causal connections between infectious organisms and chronic diseases have been recognized, such as Helicobacter pylori and peptic ulcer disease, and human papillomaviruses (HPVs) and cervical cancer. Also, in the twenty-first century, infectious diseases have become a means of terrorism, as illustrated by the anthrax letters of 2001.

Healthcare Infection Control Practices and Advisory Committee

is charged with providing guidance on hospital infection control and developing strategies for surveillance, prevention and control of HAIs.

Pandemic

refers to an epidemic occurring worldwide and affecting large populations. HIV disease is both epidemic and pandemic, as the number of cases continues to grow across various regions of the world as well as in the United States. SARS and novel influenza A H1N1 are both emerging infectious diseases and responsible for recent pandemics.

Natural immunity

refers to species-determined, innate resistance to an infectious agent. For example, opossums rarely contract rabies.

Infectiousness

is a measure of the potential ability of an infected host to transmit the infection to other hosts. It reflects the relative ease with which the infectious agent is transmitted to others.

List of Reportable Diseases

"A notifiable disease is one for which regular, frequent, and timely information regarding individual cases is considered necessary for the prevention and control of the disease" (CDC, 2013b). Requirements for disease reporting in the United States are mandated by state rather than federal law and, as such, vary slightly from state to state. State health departments, on a voluntary basis, report cases of selected diseases to the CDC through the National Notifiable Diseases Surveillance System (NNDSS)

Tertiary Prevention

though many infections are acute, with either recovery or death occurring in the short term, some exhibit chronic courses (AIDS/HIV stage III) or disabling sequelae (leprosy/Hansen's disease). Tertiary prevention works to reduce complications and disabilities through treatment and rehabilitation. To reduce complications and disabilities through treatment and rehabilitation: • Pneumocystis pneumonia (PCP) chemoprophylaxis for people with AIDS/HIV stage III • Regular inspection of hands and feet as well as protective footwear and gloves to avoid trauma and infection for leprosy clients who have lost sensation in those areas

Assessment

(1) Monitor health/identify problems and (2) Diagnose and investigate health problems. Examples include surveillance, investigation, and identification of reportable communicable disease cases.

policy Development

(3) Inform, educate, and empower and (4) Mobilize community partnerships. Examples include evaluating immunization status, explaining the reason for immunizations and how to comply with the immunization schedule, organizing community partners to provide immunizations and documentation through a registry, and mounting a community campaign to inform the community of the importance of age-appropriate immunization.

WHO Five Keys to Safer Food

1. Keep food clean. 2. Separate raw and cooked food. 3. Cook thoroughly. 4. Keep food at safe temperatures. 5. Use safe water and raw materials.

Ten Basic Data Elements of Surveillance

1. Mortality registration 2. Morbidity reporting 3. Epidemic reporting 4. Epidemic field investigation 5. Laboratory reporting 6. Individual case investigation 7. Surveys 8. Utilization of biological agents and drugs 9. Distribution of animal reservoirs and vectors 10. Demographic and environmental data

assurance

5) Enforce laws and regulations and (6) Link to services and provide care. Examples include assuring compliance with communicable disease control laws through treatment or prophylaxis for exposure to reportable diseases; excluding diseased students from daycare or school; linking individuals without insurance to follow-up care for communicable disease treatment or exposure.

Prevention and Control of Tickborne Diseases

A vaccine for Lyme disease, recommended for use by persons living in high-risk areas, was licensed in 1998; however, in 2002 the manufacturer withdrew it from the commercial market because of low demand and sales. Measures for preventing exposure to ticks include reducing tick populations, avoiding tick-infested areas, wearing protective clothing when outdoors (long sleeves and long pants tucked into socks), using repellants, and immediately inspecting for and removing ticks when returning indoors. The CDC reports that landscaping modifications such as removing brush and leaf litter or creating a buffer zone of wood chips or gravel between yard and forest may reduce exposure to ticks as well as appropriate pesticide application to lawns. Ticks require a prolonged period of attachment (6 to 48 hours) before they start blood-feeding on the host; prompt tick discovery and removal can help prevent transmission of disease.

Zoonoses

A zoonosis is an infection transmitted from a vertebrate animal to a human under natural conditions. The agents that cause zoonoses do not need humans to maintain their life cycles; infected humans have simply managed somehow to get in their way. Means of transmission include animal bites (bats and rabies), inhalation (rodent excrement and hantavirus), ingestion (milk and listeriosis), direct contact (rabbit carcasses and tularemia), and arthropod intermediates. This last transmission route means that many vector borne diseases are also zoonoses.

MRSA

Although MRSA is still largely a health care-associated infection, community-associated disease is becoming more common with outbreaks frequently associated with school athletic programs and prison populations.

Examples of Emerging Infectious Diseases

Borrelia burgdorferi Cryptosporidium Ebola-Marburg Escherichia coli 0157:H7 Hantavirus Human immunodeficiency virus (HIV-1) Human papillomavirus (HPV)

Malaria

Caused by the bloodborne parasite Plasmodium, malaria is a potentially fatal disease characterized by regular cycles of fever and chills. Transmission is through the bite of an infected Anopheles mosquito. The word malaria is based on an association between the illness and the "bad air" of the marshes where the mosquitoes breed. Malaria is an old disease that appears in recorded history in 2700 BC China. Malaria prevention depends on protection against mosquitoes and appropriate chemoprophylaxis. Drug resistance is an increasing problem in combating malaria. Of the four Plasmodium species causing human malaria, P. ovale and P. vivax result in disease that can progress to relapsing malaria and P. vivax is increasingly drug resistant. P. falciparum causes the most serious malarial infection and is highly drug resistant.

The Role of Safe Food Preparation

Common errors include (1) cross-contamination of food during preparation, (2) insufficient cooking or reheating temperatures, (3) holding cooked food or storing food at temperatures that promote growth of pathogens and/or formation of toxins, and (4) poor personal hygiene.

Rocky Mountain Spotted Fever

Contrary to its name, Rocky Mountain spotted fever (RMSF) is seldom seen in the Rocky Mountains and most commonly occurs in the southeast, Oklahoma, Kansas, and Missouri. The infectious agent is R. rickettsii. The tick vector varies according to geographic region. The dog tick, Dermacentor variabilis, is the vector in the eastern and southern United States. RMSF is not transmitted from person to person.

Intestinal Parasitic Infections

Enterobiasis (pinworm) is the most common helminthic infection in the United States. Pinworm infection is seen most often among school-aged children and is most prevalent in crowded and institutional settings. Transmission is via consumption of infected eggs found in soil contaminated by human feces. Pinworms resemble small pieces of white thread and can be seen with the naked eye. Diagnosis is usually accomplished by pressing cellophane tape to the perianal region early in the morning. Treatment with oral vermicides and concurrent disinfection is highly effective

Enterohemorrhagic Escherichia coli (EHEC or E. coli 0157:H7)

Escherichia coli 0157:H7 belongs to the enterohemorrhagic category of E. coli serotypes producing a strong cytotoxin called a Shiga toxin and are collectively known as Shiga toxin-producing E. coli (STEC). E. coli serotypes in this group can cause a potentially fatal hemorrhagic colitis. This pathogen was first widely described in humans in 1992 following the investigation of two outbreaks of illness associated with consumption of hamburger from a fast-food restaurant chain. Transmission is through ingestion of food contaminated by infected feces. Ruminants, particularly cattle, are the most important reservoir, although humans may also serve as a source for person-to-person transmission.

West Nile Virus

In 1999 the first Western Hemisphere activity of West Nile virus (WNV), a mosquito-transmitted illness that can affect livestock, birds, and humans, occurred in New York City. By 2002 WNV, thought to be carried by infected birds and possibly mosquitoes in cargo containers, had spread across the United States as far west as California and was reported in Canada and Central America as well.

Disease Development

Exposure to an infectious agent does not always lead to an infection. Similarly, infection does not always lead to disease. Infection depends on the infective dose, the infectivity of the infectious agent and the immunocompetence of the host. It is important to differentiate infection and disease, as clearly illustrated by the HIV disease epidemic.

H1N1

First reported from Mexico and rapidly acquired by travelers to that country, H1N1 spread quickly across the world, causing the WHO to declare a pandemic and stimulate the race for a vaccine. While H1N1 did not become the major killer it was feared to, it did disproportionately result in hospitalizations and deaths in younger and middle-aged adults.

Small Pox

Formerly a disease found worldwide, smallpox has been considered eradicated since 1979. The last known natural case in the United States was in 1949. The last known case of smallpox worldwide occurred in Somalia in 1977. The United States stopped routinely immunizing for smallpox in 1982. The only documented existing virus sources are located in freezers at the CDC in Atlanta and at a research institute in Novosibirsk, Russia.

Agent Factors

Four major categories of agents cause most infections and infectious disease: bacteria (e.g., Salmonella and E. coli), fungi (e.g., Aspergillus spp. and Candida spp.), parasites (e.g., helminthes and protozoa), and viruses (e.g., hepatitis A and B and HIV). Less commonly seen is the prion, a transmissible agent that causes abnormal folding of normal cellular prion proteins in the brain, resulting in a family of rare progressive neurodegenerative disorders that affect both humans and animals.

Disease Spectrum

Persons with infectious diseases may exhibit a broad spectrum of disease that ranges from subclinical infection to severe and fatal disease. Those with subclinical or inapparent infections are important from the public health point of view because they are a source of infection but may not be receiving care like those with clinical disease. They should be targeted for early diagnosis and treatment.

A Multisystem Approach to Communicable Disease Control

Goal: Improve host resistance to infectious agents and other environmental hazards Ex: Hygiene, nutrition, and physical fitness; increased immunization coverage; provision of drugs for prevention and treatment; stress control and improved mental health Goal: Improve safety of the environment Ex: Sanitation, clean water and air; proper cooking and storage of food; control of vectors and animal reservoir hosts Goal: Improve public health systems EX:Increased access to health care; appropriate health education; improved surveillance systems Goal: Facilitate social and political change to ensure better health for all people Ex: Individual, organizational, and community action; legislation

VRSA

In 1997 vancomycin-resistant Staphylococcus aureus (VRSA) was first reported; previously, vancomycin had been considered the only effective antibiotic against methicillin-resistant S. aureus (MRSA).

Primary Prevention

In prevention and control of infectious disease, primary prevention seeks to reduce the incidence of disease by preventing occurrence, and this effort is often assisted by the government. federally supplied vaccines and "no shots, no school" immunization laws, are population based because of public health mandates. Nurses deliver childhood immunizations in public and community health settings, check immunization records in daycare facilities, and monitor immunization records in schools. Primary Prevention To prevent the occurrence of disease: • Responsible sexual behavior • Malaria chemoprophylaxis • Tetanus boosters, flu shots • Rabies pre-exposure immunization • Safe food-handling practices in the home • Repellants for preventing vector borne disease • Following childhood immunizations recommendations, and "no shots, no school" laws • Regulated and inspected municipal water supplies • Bloodborne pathogen regulations • Restaurant inspections • Federal regulations protecting American cattle from exposure to bovine spongiform encephalopathy (BSE)

Foodborne and Waterborne Diseases

In recent years attention has focused on stories related to foodborne illness associated with peanut butter, cookie dough, spinach, lettuce, tomatoes, chili peppers, strawberries, raspberries, oysters, uncooked eggs, poultry and hamburger, raw milk, unpasteurized apple cider, and so forth. Food infection results from bacterial, viral, or parasitic infection of food by pathogens such as Salmonella, Campylobacter, hepatitis A, Toxoplasma, and Trichinella. Food intoxication is caused by toxins produced by bacterial growth, chemical contaminants (heavy metals), and a variety of disease-producing substances found naturally in certain foods such as mushrooms and some seafood. Examples of food intoxications are botulism, mercury poisoning, and paralytic shellfish poisoning.

Diseases of Travelers

Individuals traveling outside the United States need to be aware of and take precautions against potential diseases to which they may be exposed. Which diseases and what precautions to take depend on the individual's health status, the destination, the reason for travel, and the length of travel. Persons who plan to travel in remote regions for an extended period may need to consider rare diseases and take special precautions that would not apply to the average traveler. Consultation with public health officials can provide specific health information and recommendations for a given situation. Nurses often staff public health travel clinics and provide this information based on CDC recommendations.

Influenza

Influenza is a viral respiratory tract infection often indistinguishable from the common cold or other respiratory diseases. Transmission is airborne and through direct contact with infected droplets. Unlike many viruses that do not survive long in the environment, the flu virus is thought to exist for many hours in dried mucus. Outbreaks are common in the winter and early spring in areas where people gather indoors such as in schools and nursing homes. Gastrointestinal and respiratory symptoms are common. There are three types of influenza viruses: A, B, and C.

Measles

Measles is an acute, highly contagious disease that, although considered a childhood illness, may be seen in the United States in adolescents and young adults. Symptoms include fever, sneezing and coughing, conjunctivitis, small white spots on the inside of the cheek (Koplik's spots), and a red, blotchy rash beginning several days after the respiratory signs. Measles is caused by the rubeola virus and is transmitted by inhalation of infected aerosol droplets or by direct contact with infected nasal or throat secretions or with articles freshly contaminated with the same nasal or throat secretions. A very contagious nature, combined with the fact that people are most contagious before they are aware they are infected, makes measles a disease that can spread rapidly through the population. Infection with measles confers lifelong immunity

Pertussis

Pertussis (whooping cough) begins as a mild upper respiratory tract infection progressing to an irritating cough that within 1 to 2 weeks may become paroxysmal (a series of repeated violent coughs). The repeated coughs occur without intervening breaths and can be followed by a characteristic inspiratory "whoop." Pertussis is caused by the bacterium Bordetella pertussis and is transmitted via an airborne route through contact with infected droplets. It is highly contagious and considered endemic in the United States. Vaccination against pertussis, delivered in combination with diphtheria and tetanus, is a part of the routine childhood immunization schedule. Treatment of infected individuals with antibiotics such as erythromycin may shorten the period of communicability but does not relieve symptoms unless given early in the course of the infection. Nonetheless, vaccination with DTaP and Tdap continues to be recommended as the single most effective strategy in reducing illness and death from pertussis.

Parasitic Diseases

Parasites are organisms that depend on a host to survive. Endoparasites, those that live within the body, are classified into four major groups: nematodes (roundworms), cestodes (tapeworms), trematodes (flukes), protozoa (single-celled animals). Nematodes, cestodes, and trematodes are all referred to as helminths along with acanthocephalins or thorny-headed worms, which are not as commonly involved in human infections. Parasites that remain on the surface of a host's body to feed rather than within it such as ticks, fleas, lice, and mites that attach or burrow into the skin are called ectoparasites. Many parasitic infections are vector borne and/or zoonotic.

Lyme Disease

Parents in Lyme, CT, concerned about the unusual incidence of juvenile rheumatoid arthritis in their children, were the first to bring attention to this tick borne infection that now bears their town's name. The causative agent, the spirochete B. burgdorferi, was identified in 1982. Lyme disease is transmitted by ixodid ticks that are associated with white-tailed deer (Odocoileus virginianus) and the white-footed mouse (Peromyscus leucopus). Lyme disease usually occurs in summer during tick season and it has been reported throughout the United States, with 95% of cases concentrated in rural and suburban areas of the northeast, mid-Atlantic and north-central states, particularly Wisconsin and Minnesota.

Role of Nurses in Prevention

Prevention is at the center of public health, and nurses perform much of this work. Examples include immunizations for vaccine-preventable disease, especially childhood immunization and the monitoring of immunization status in clinic, daycare, school, and home settings. Nurses work in communicable disease surveillance and control, teach and monitor bloodborne pathogen control, and advise on prevention of vector borne diseases. They teach methods for responsible sexual behavior, screen for sexually transmitted infection, and provide HIV disease counseling and testing. They screen for TB, identify TB contacts, and deliver directly observed TB treatment in the community.

Tularemia

Sometimes referred to as "rabbit fever" or "deer fly fever," tularemia is a zoonotic disease caused by the bacterial agent F. tularensis which is carried commonly by wild animals, especially rabbits, as well as muskrats, voles, beavers, some domestic animals, and some ticks, mosquitoes, and flies. Tularemia may be transmitted by the bite of an infected arthropod; contact of eyes, skin, or mucous membranes with infected tissues, blood, or water; ingestion of inadequately cooked infected meat or contaminated water; inhalation of contaminated dust; and handling of contaminated pelts and paws. Hunters handling rabbit and rodent carcasses, lawn care workers, and those working outside in rural areas may be at higher risk. Tularemia is not transmitted from person to person

Environment Factor

The environment refers to everything that is external to the human host, including physical, biological, social, and cultural factors. These environmental factors facilitate the transmission of an infectious agent from an infected host to other susceptible hosts. Reduction in communicable disease risk can be achieved by altering these environmental factors. Using mosquito nets and repellants to avoid bug bites, installing sewage systems to prevent fecal contamination of water supplies, and washing utensils after contact with raw meat to reduce bacterial contamination are all examples of altering the environment to prevent disease.

Secondary Prevention

The goal of secondary prevention is to prevent the spread of infection and/or disease once it occurs. Activities center on rapid identification of potential contacts to a reported case. Contacts may be (1) identified as new cases and treated, or (2) determined to be possibly exposed but not diseased and appropriately treated with prophylaxis. Public health disease control laws also assist in secondary prevention because they require investigation and prevention measures for individuals affected by a communicable disease report or outbreak To prevent the spread of disease: • Immunoglobulin after hepatitis A exposure • Immunization and chemoprophylaxis as appropriate in meningococcal outbreak • Rabies postexposure immunization • Tuberculosis screening for health care workers • Sexually transmitted disease (STD) partner notification • Human immunodeficiency virus (HIV) testing and treatment • Quarantine

Rubella

The rubella (German measles) virus causes a mild febrile disease with enlarged lymph nodes and a fine, pink rash that is often difficult to distinguish from measles or scarlet fever. In contrast to measles, rubella is only a moderately contagious illness. Transmission is through inhalation of or direct contact with infected droplets from the respiratory secretions of infected persons. Children may show few or no constitutional symptoms, whereas adults usually experience several days of low-grade fever, headache, malaise, runny nose, and conjunctivitis before the rash appears. Many infections occur without a rash

Ebola and Marburg

The viral hemorrhagic fevers (HF) Ebola and Marburg, unknown to most people 30 years ago, have become the premise of movies and novels, and recently the cause of widespread international concern. While earlier reported Ebola virus outbreaks largely occurred in Central Africa and were limited and quickly contained, an outbreak of Ebola virus that began in the spring of 2014 in Guinea, West Africa resisted containment and in spite of international assistance, spread rapidly through neighboring Liberia and Sierra Leone. Although caused by different viruses within the Filoviridae family, Ebola and Marburg hemorrhagic fevers (HF) have similar clinical presentations. The reservoir host of Ebola viruses remains unknown but there is an association with nonhuman primates, and evidence is also beginning to point toward a bat reservoir The reservoir host of Marburg virus is the African fruit bat, Rousettusa egyptiacus

Universal Precautions

This strategy requires that blood and body fluids from all clients be handled as if infected with HIV or other bloodborne pathogens. When in a situation where potential contact with blood or other body fluids exists, health care workers must always perform hand hygiene and wear gloves, masks, protective clothing, and other indicated personal protective barriers. Needles and sharp instruments must be used and disposed of properly The CDC also made recommendations for preventing transmission of HIV and hepatitis B during medical, surgical, and dental procedures

Diarrheal Diseases

Travelers often suffer from diarrhea, so much so that colorful names, such as Montezuma's revenge, turista, and Colorado quickstep, exist in our vocabulary to describe these bouts of intestinal upset. Some of these diarrheas do not have infectious causes; they result from stress, fatigue, schedule changes, and eating unfamiliar foods. Acute infectious diarrheas are usually of viral or bacterial origin. E. coli probably causes more cases of traveler's diarrhea than all other infective agents combined.

Foodborne and Waterborne Diseases

Trichinosis, tapeworms, and fluke infections, as well as bacterial infections, result from eating raw or undercooked meats. Raw vegetables may act as a source of bacterial, viral, helminthic, or protozoal infection if they have been grown with or washed in contaminated water. Fruits that can be peeled immediately before eating, such as bananas, are less likely to be a source of infection. Dairy products should be pasteurized and appropriately refrigerated. Water in many areas of the world is not potable (safe to drink), and drinking this water can lead to infection with a variety of protozoal, viral, and bacterial agents including amoebae, Giardia, Cryptosporidium, hepatitis, cholera, and various coliform bacteria.

Vaccine-Preventable Diseases

Vaccines are one of the most effective methods of preventing and controlling communicable diseases. The smallpox vaccine, which left distinctive scars on so many shoulders, is no longer in general use because the smallpox virus has been declared eradicated from the world's population. Diseases such as polio, diphtheria, pertussis, and measles, which previously occurred in epidemic proportions, are now controlled by routine childhood immunization. They have not, however, been eradicated, so children need to be immunized against them. In the United States, "no shots, no school" legislation has resulted in the immunization of most children by the time they enter school.

Waterborne Disease Outbreaks and Pathogens

Waterborne pathogens usually enter water supplies through animal or human fecal contamination and frequently cause enteric disease. They include viruses, bacteria, and protozoans. Hepatitis A virus is probably the most publicized waterborne viral agent, although other viruses may also be transmitted by this route (enteroviruses, rotaviruses, and paramyxoviruses). The most important waterborne bacterial diseases are cholera, typhoid fever, and bacillary dysentery. However, other Salmonella spp. as well as Shigella, Vibrio, and Campylobacter species and various coliform bacteria including E. coli 0157:H7 may be transmitted in the same manner. Recently, since added to surveillance in 2001, Legionella spp. have frequently been implicated in waterborne disease outbreaks (WBDOs) in the United States.

A CDC Framework for Preventing Infectious Disease: Sustaining the Essentials and Innovating for the Future

a plan for preventing and controlling infectious threats through a "strengthened, adaptable, and multi-purpose U.S. public health system." Reflecting technological advances of the past decade, the plan places a heavy emphasis on the role of technology in surveillance, detection, and control. Three elements for action are identified: (1) Strengthen public health fundamentals, including infectious disease surveillance, laboratory detection, and epidemiologic investigation; (2) Identify and implement high-impact public health interventions to reduce infectious diseases; and (3) Develop and advance policies to prevent, detect, and control infectious diseases. It also discusses linkages between infectious and chronic disease; lists a timeline of disease threats, emerging pathogens, and unusual health events worldwide from 2000-2011; and identifies infectious disease issues of special concern: (1) antimicrobial resistance, (2) chronic viral hepatitis, (3) food safety, (4) health care-associated infections, (5) HIV/AIDS, (6) respiratory infections, (7) safe water, and (8) zoonotic and vectorborne diseases

Worldwide, infectious diseases are the leading killer of children and young adults and are responsible for almost half of all deaths in developing countries. Of these infectious disease deaths, 90% result from six causes:

acute respiratory infections, diarrheal diseases, malaria, and measles among children; and TB and HIV infection among adults. TB alone is estimated to kill a million people a year and malaria another 625,000

foodborne infections

again have made headlines as E. coli-infected spinach sickened and killed individuals across the United States. In 2008, tomatoes were blamed for a nationwide outbreak of salmonellosis but were ruled innocent when the green chilies that accompanied them in salsa were found to be the actual culprit.

the transmission of infectious disease through the food supply

became a newsworthy concern when the consumption of improperly cooked hamburgers and unpasteurized apple juice contaminated with a highly toxic strain of E. coli (E. coli 0157:H7) caused illness and death in children across the country. In 1996 multiple states reported outbreaks of diarrheal disease traced to imported fresh berries; the implicated organism in these outbreaks, Cyclosporacayetanensis (a coccidian parasite), was first diagnosed in humans in 1977

Plague

is a vector borne disease transmitted by rodent fleas carrying the bacterium Y. pestis. Portrayed vividly in the Bible and events throughout history, plague is believed responsible for the epidemic of Black Death that killed over a quarter of the population of Europe during the Middle Ages. The disease is endemic in much of South Asia, parts of South America, and the western United States, but the majority of outbreaks and cases today are reported from Africa, especially from the Democratic Republic of the Congo. Plague arrived in the United States as a consequence of a pandemic that began in China during the late 1800s and spread to the West Coast via shipboard rats.

Anthrax

is an acute disease caused by the spore-forming bacterium B. anthracis. It is thought that anthrax may have caused the biblical fifth and sixth plagues of Exodus as well as the Black Bane of Europe in the 1600s. is a clever organism that perpetuates itself by forming spores. When animals dying from anthrax suffer terminal hemorrhage and infected blood comes into contact with the air, the bacillus organism sporulates. These spores are highly resistant to disinfection and environmental destruction and may remain in contaminated soil for many years. may manifest in one of three syndromes: cutaneous, gastrointestinal, and respiratory or inhalational. Cutaneous anthrax, the form most commonly seen, occurs when spores come in contact with abraded skin surfaces. Gastrointestinal anthrax is considered rare and occurs from eating undercooked, contaminated meat. Inhalational anthrax is also considered rare, typically seen in occupations with exposure to hide tanning or bone processing. Initially, symptoms are mild and nonspecific and may include fever, malaise, mild cough, or chest pain. Any threat of anthrax should be reported to the Federal Bureau of Investigation and to local and state health departments. Anthrax is sensitive to a variety of antibiotics including the penicillins, chloramphenicol, doxycycline, and the fluoroquinolones

Disease

is one of the possible outcomes of infection and it may indicate a physiological dysfunction or pathologic reaction. An individual who tests positive for HIV is infected, but if that person shows no clinical signs, the individual is not diseased. Similarly, if an individual tests positive for HIV and also exhibits clinical signs consistent with AIDS (HIV stage III), that individual is both infected and diseased.

eradication

is removing a disease worldwide by ending all transmission of infection through the complete extermination of the infectious agent.

Communicable period

is the interval during which an infectious agent may be transferred directly or indirectly from an infected person to another person. The period of communicability for influenza is 3 to 5 days after the clinical onset of symptoms. Hepatitis B-infected persons are infectious many weeks before the onset of the first symptoms and remain infective during the acute phase and chronic carrier state, which may persist for life.

vertical transmission

is the passing of the infection from parent to offspring via sperm, placenta, milk, or contact in the vaginal canal at birth. Examples of vertical transmission are transplacental transmission of HIV and syphilis.

horizontal transmission

is the person-to-person spread of infection through one or more of the following four routes: direct/indirect contact, common vehicle, airborne, or vector borne. Most sexually transmitted infections are spread by direct sexual contact. Enterobiasis, or pinworm infection, can be acquired through direct contact or indirect contact with contaminated objects such as toys, clothing, and bedding.

Acquired immunity

is the resistance acquired by a host as a result of previous natural exposure to an infectious agent. Having measles once protects against future infection. Acquired immunity may be induced by active or passive immunization.

incubation period

is the time interval between invasion by an infectious agent and the first appearance of signs and symptoms of the disease. The incubation periods of infectious diseases vary from between 2 and 4 hours for staphylococcal food poisoning to between 10 and 15 years for AIDS (HIV stage III).

Elimination

is to remove a disease from a large geographic area such as a country or region of the world.

Agents of Bioterrorism

ix infectious agents are considered of highest concern: -anthrax (Bacillus anthracis), -plague (Yersinia pestis), -smallpox (variola major), -botulism (Clostridium botulinum), -tularemia (Francisella tularensis) -selected hemorrhagic viruses (filoviruses such as Ebola and Marburg; arenaviruses such as Lassa fever, Junin virus, and related viruses).

Passive Immunization

refers to immunization through the transfer of a specific antibody from an immunized individual to a nonimmunized individual, such as the transfer of antibody from mother to infant or by administration of an antibody-containing preparation (immunoglobulin or antiserum). Passive immunity from immunoglobulin is almost immediate but short lived. It is often induced as a stopgap measure until active immunity has time to develop after vaccination. Examples of commonly used immunoglobulins include those for hepatitis A, rabies, and tetanus.

Endemic

refers to the constant presence of a disease within a geographic area or a population. Pertussis is endemic in the United States.

Herd immunity

refers to the immunity of a group or community. It is the resistance of a group of people to invasion and spread of an infectious agent. Herd immunity is based on the resistance of a high proportion of individual members of a group to infection.

Active Immunization

refers to the immunization of an individual by administration of an antigen (infectious agent or vaccine) and is usually characterized by the presence of an antibody produced by the individual host. Vaccinating children against childhood diseases is an example of inducing active immunity.

Epidemic

refers to the occurrence of disease in a community or region in excess of normal expectancy. Although people tend to associate large numbers with epidemics, even one case can be termed epidemic if the disease is considered previously eliminated from that area. For example, one case of polio, a disease considered eliminated from the United States, would be considered epidemic.

Common Vehicle

refers to transportation of the infectious agent from an infected host to a susceptible host via food, water, milk, blood, serum, saliva, or plasma. Hepatitis A can be transmitted through contaminated food and water, and hepatitis B through contaminated blood. Legionellosis and TB are both spread via contaminated droplets in the air

image Healthy People 2020 Selected Objectives Related to Infectious Diseases

• IID-1: Reduce, eliminate, or maintain elimination of cases of vaccine-preventable diseases. • IID-12: Increase the percentage of children and adults who are vaccinated against seasonal influenza. • FS-1: Reduce infections caused by key pathogens transmitted commonly through food. • HAI-2 Reduce invasive health care-associated methicillin-resistant Staphylococcal aureus (MRSA) infections.

Six Characteristics of an Infectious Agent

• Infectivity: The ability to enter and multiply in the host • Pathogenicity: The ability to produce a specific clinical reaction after infection occurs • Virulence: The ability to produce a severe pathological reaction • Toxicity: The ability to produce a poisonous reaction • Invasiveness: The ability to penetrate and spread throughout a tissue • Antigenicity: The ability to stimulate an immunological response