Ch 26: Infectious Disease
Transmission of communicable diseases
COMMUNICABLE DISEASE: diseases of human or animal origin caused by an infectious agent and resulting from transmission of that agent from an infected person, animal, or inanimate source to a susceptible host. Not all communicable diseases are communicated from host to host (example: tetanus = inanimate source to person, but then can not be passed from one person to another). AGENT FACTOR: causative factor, such as a biological or chemical agent, invading a susceptible host through an environment favorable to produce disease. Four main categories of infectious agents can cause disease: bacteria, fungi, parasites, and viruses. Six characteristics of infectious agent: **infectivity - ability to enter & multiply in the host **pathogenicity - ability to produce specific clinical reaction after infection occurs. **Virulence - ability to produce severe pathological reaction **toxicity - ability to produce poisonous reaction **invasiveness - ability to penetrate and spread throughout a tissue **antigenicity - ability to stimulate an immunological response HOST FACTOR: living organism, human or animal, in which an infectious agent can exist under natural conditions. Characteristics of host: **resistance - ability of the host to withstand infection, which may involve natural or acquired immunity. **natural immunity - species-determined, innate resistance to an infectious agent. **acquired immunity - resistance acquired by a host as a result of previous natural exposure to an infectious agent. **active immunization - immunization by administration of an antigen (infectious agent or vaccine) and is usually characterized by the presence of an antibody produced by the individual host. (example: childhood vaccinations against disease). **passive immunization - immunization through the transfer of a specific antibody form an immunized individual to an nonimmunized individual (example: transfer of antibody from mother to infant. Also: Hepatitis A, Rabies, and Tetanus are induced as stopgaps until active immunity as time to develop after vaccinations. **herd immunity - immunity of a group or community, resistance of people to invasion and spread of an infectious agent. **infectiousness - measure of potential ability of infected host to transmit infection to other hosts. ENVIRONMENT FACTOR: all of those factors internal and external to the client that constitute the context in which the client lives and that influence and are influenced by the host and agent-host interactions. The sum of all external conditions affecting the life, development, and survival of an organism. (Example: using nets & sprays against mosquitos, or, installing sewage systems.)
Disease development
DISEASE: an indication of a physiological dysfunction or a pathological reaction to an infection. INFECTION: the state produced by the invasion of a host by an infectious agent. Such infection may or may not produce clinical signs. INCUBATION PERIOD: time interval beginning with the invasion by an infectious agent and continuing until the organism multiplies to sufficient numbers to produce a host reaction and clinical symptoms. COMMUNICABLE PERIOD: the time, or times when an infectious agent may be transferred from an infected source directly or indirectly to a new host.
Foodborne & Waterborne diseases
FOODBORNE DISEASE: (also known as food poisoning). can be categorized as either a food infection or food intoxication. **Food infection: result from bacterial, viral, or parasitic infection of food. Includes Salmonellosis, hepatitis A, Trichinosis. **Food intoxication: results from 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 seafood. Includes: botulism, mercury poisoning, paralytic shellfish poisoning. WATERBORNE DISEASE: pathogens enter water supplies hrough animal or human fecal contamination and often cause enteric disease. Include: viruses, bacteria, protozoans. Hep A is probably the best known waterborne viral agent. Bacterial waterborne agents are typhoid fever, cholera, bacillary dysentery.
Disease spectrum
ENDEMIC: the constant presence of an infectious disease within a specific geographic area. EPIDEMIC: the occurrence of an infectious agent or disease within a specific geographic area in greater numbers than would normally be expected. PANDEMIC: a worldwide outbreak of an epidemic disease.
Role of nurse in prevention & control
Role of nurse in prevention Multisystem approach to control
Universal precautions
Strategy to prevent exposure to pathogens transmitted though blood and other body fluids by requiring blood and body fluids from all clients to be handled as if they were infected with such pathogens.
Nosocomial infections
Infections acquired during hospitalization or developed within a hospital setting. May involve clients, health care workers, visitors, or anyone who has contact with a hospital.
Agents of bioterrorism
Antrax: acute disease caused by the spore-forming bacterium, Bacillus anthracis. Small pox: acute contagious febrile disease caused by a pox virus and characterized by skin eruption with pustules, sloughing, and scar formation.
Vaccines & Vaccine Preventable diseases
Measles: acute, highly contagious disease. Often seen in the US in adolescents and young adults. Fever, sneezing, coughing, conjunctivitis, small white spots on inside of cheeks, and red blotchy rash several days after respiratory signs begin. 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. Rubella: (german measles) virus causes mild febrile disease characterized by enlarged lymph nodes and a fine, pink rash that is often difficult to distinguish from measles or scarlet fever. It is only moderately contagious. Transmitted thru inhalation of or direct contact with infected droplets from the respiratory secretions of infected persons. Pertussis: (whooping cough) begins as mile upper respirator infection hat progresses to an irritating cough and in 1-2 weeks may become paroxysmal (series of repeated violent coughs). Caused by bacterium Bordetella pertussis and is transmitted via an airborne route through contact with infected droplets. It is highly contagious and is considered endemic in the US. Influenza: viral respiratory infection often indistinguishable from the common cold or other respiratory disease. Transmission is airborne and through direct contact with infected droplets. The flu virus can survive many hours in dried mucus. Three types of flu virus: A, B, C. Type A - usually responsible for large epidemics Type B - more regionalized Type C - less common and result in mild illness
Parasitic diseases
More prevalent in tropical climates and countries with inadequate prevention and control methods. Intestinal parasitic infections, Parasitic opportunistic infections, Control and prevention of parasitic infections. Parasitic dx are more prevalent in devel. Counries than US bc tropical climate and inadequate prevention and control measures. Enterobiasis (pinworm) is most common helminthic infection in the US with estim 42 million cases/year. Mostly seen in children and most prevalent in crowded and institutional settings. Dx accomplished by pressing cellophane tape to the perianal region early in the morning. Tx w ora vermicides cure rate 99-100%. Effective drug tx is avail. For intestinal parasitic infections (thrichomonas, giardia lamblia, cryptosporidium and toxoplasma).
Prevention and control of communicable diseases
Primary prevention: to prevent the occurrence of disease *teach responsible sexual behavior, safe food handling *Malaria chemoprophylaxis *tetanus boosters, flu shots *repellants for vector borne diseases *childhood immunizations *rabies pre-exposure immunization *regulated municipal water supplies *blood-borne pathogen regulations *restaurant inspections *Federal inspection of cattle from Bovine (BSE) Secondary prevention: to prevent the spread of disease *rabies post-exposure immunization *Hep A post-exposure immunoglobulin *meningococcal outbreak chemoprophylaxis and immunization *TB screening for healthcare workers *STD partner notification *HIV testing and treatment *quarantine Tertiary prevention: to reduce complications and disabilities through treatment and rehabilitation. *PCP - pneumonia, chemoprophylaxis for people with AIDS *Inspection of hands and feet for leprosy clients who have lost sensation in those areas
Emerging infectious diseases & factors
Those in which the incidence has actually increased in the past two decades or has the potential to increase in the near future. May include new or known infectious diseases. HANTAVIRUS - pulmonary syndrome,1993, in Arizona and New Mexico, appeared to target healthy young Native Americans. Attributed to rodent-borne virus. HIV / AIDS - existed in isolated parts of Africa, and emerged into rest of the world. TB - after years of decline, it has resurged as a result of infection secondary to HIV / AIDS and the development of multidrug resistance. WNV (West Nile Virus) - birds, mosquitos - affected humans and horses. Arrived in US in 1999 and by 2002, more than 3000 cases with more than 180 deaths were recorded.
Diseases of travelers
Those traveling outside the U.S. need to be aware of and take precautions against diseases they may be exposed to; may return to the U.S. with an "unplanned souvenir"; health professionals taking client history need to consider recent travel by the client. Malaria, Foodborne and waterborne diseases, Diarrheal diseases. ***NOTE**** In the US, infectious diseases account for 25% of all physician visits per year. In the US, number one infectious disease is Lyme disease In the world, number one infectious disease is malaria.
Modes of transmission
VERTICAL TRANSMISSION: passing the infection from parent to offspring via sperm, placenta, milk, or contact in the vaginal canal at birth. HORIZONTAL TRANSMISSION: person-to-person spread of infection through one or more of the following routes - direct, indirect contact, common vehicle, airborne, or vector borne. COMMON VEHICLE: transportation of the infectious agent from an infected host to a susceptible host via water, food, milk, blood serum, or plasma. VECTORS: nonhuman organisms, often insects, that either mechanically or biologically play a role in the transmission of an infectious agent from source to host.
Surveillance of communicable diseases
When conducting surveillance of communicable diseases, gather: Who, When, Where, What A good system systematically collects, organizes, and analyzes current, accurate, and complete data for a defined disease condition. Prompt release of the data is used for planning, implementation, and evaluation of disease prevention an control programs. Surveillance for Agents of Bioterrorism: (basic 10 elements) 1 mortality registration 2 morbidity reporting 3 epidemic reporting 4 epidemic field investigation 5 laboratory reporting 6 individual case investigation 7 surveys 8 distribution of animal reservoirs and vectors 9 demographic and environmental data List of reportable disease: US requires states to mandate reporting of disease (rather than federal law) - so the list of reportable diseases varies by state. Select cases are reported by states to the CDC (NNDSS - National Notifiable Diseases Surveillance System), which are collected and reported weekly in the Morbidity and Mortality Weekly Report, and annually by the CDC.
Zoonoses
an infection transmitted from a vertebrate animal to a human under natural conditions. The agents that cause zoonosis do not need humans to maintain their life cycles, infected humans have simply managed to get in their way. Animal bites, inhalation, ingestion, direct contact, and arthropod intermediates. Rabies (hydrophobia) One of the most feared of human dx rabies has the highest case fatality rate of any known human infection. In the 1970's three cases of presumed rabies recovery were reported. During 2004, one rabies pt in the US recovered and remains the only pt in the US recovered and remains the only rabies pt to have survived w/out the admin of rabies vaccinatin. Today, the major arriers of rabies n the US are not dogs, but wild animals, rabbits, raccoons, skunks, foxes, coyotes and bats. Recommendations for providing post exposure prophylaxis tx are provided by the advisory committee for recommen. On immun. Practices and are avail. Through local public health .
Vector borne diseases
illnesses for which the infectious agent is transmitted by a carrier, or vector, usually an arthropod (mosquito, tick, fly), either biologically or mechanically. Biological transmission - vector is necessary for the infectious agent to develop. example: mosquitoes carry malaria. Mechanical transmission - insect contacts innfectious agent with legs or mouth parts and carries it to the host. example: flys, roaches, rodents, contaminate food or cooking utensils.
