Communicable Diseases and Infection Control

Week Ten ➔​ For over 10 years, Saskatchewan has had the highest annual rate of new HIV and hepatitis C (HCV) diagnoses in the country. The province now has one of the fastest growing rates of syphilis infections in Canada. It has become increasingly important that CHN's possess...

Week Ten ➔​ For over 10 years, Saskatchewan has had the highest annual rate of new HIV and hepatitis C (HCV) diagnoses in the country. The province now has one of the fastest growing rates of syphilis infections in Canada. It has become increasingly important that CHN's possess a foundational understanding of the current epidemiology of sexually transmitted and blood borne infections (STBBI) in Saskatchewan; including how that are transmitted and clinically managed. The rising rates have resulted in an urgent need to educate health care providers on how to recognize, test, treat and manage STBBIs. Chapter Sixteen ➔​ Emerging infectious diseases may include new or known infectious diseases. Consider the following examples: ◆​ (1) Ebola virus is a virus with a frightening mortality rate that is highly contagious; ◆​ (2) HIV and AIDS are associated with a rising number of previously rare opportunistic infections such as cryptosporidiosis, toxoplasmosis, and Pneumocystis pneumonia; ◆​ (3) West Nile virus (WNV) and Zika are viruses that are new to Canada and transmitted mainly by infected mosquitoes; ◆​ (4) anthrax is an acute disease caused by the spore-forming bacterium Bacillus anthracis that is highly resistant to disinfection and environmental destruction and may remain in contaminated soil for many years; ◆​ (5) avian influenza virus is a contagious viral infection that most often affects birds but can infect mammals; ◆​ (6) the H1N1 flu virus is a strain of influenza virus that is transmissible to humans (who have developed little or no immunity to it) and could result in an influenza pandemic; ◆​ (7) Middle East respiratory syndrome (MERS) is a viral respiratory illness that is new to humans—it was first reported in Saudi Arabia in 2012; and ◆​ (8) cryptococcal disease is a rare but treatable fungal infection that has emerged on Vancouver Island, British Columbia. ➔​ A communicable disease is a contagious disease of human or animal origin caused by an infectious agent. Its transmission depends on the successful interaction of the infectious agent, the host, and the environment, the factors that make up the epidemiological triangle. ➔​ The goal of elimination is to remove a disease from a large geographical area such as a country or region fof the world. Eradication is the permanent elimination of a disease worldwide. ➔​ Resistance is the ability of the host to withstand infection, and it may involve natural or acquired immunity. ➔​ Natural immunity refers to species-determined, innate resistance to an infectious agent. For example, coyotes in Saskatchewan rarely contract rabies, because that species has developed a natural immunity to rabies. ➔​ 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. ➔​ Active immunization refers to the immunization of an individual by the administration of an antigen (infectious agent or vaccine [a preparation of killed microorganisms, living attenuated organisms, or living fully virulent organisms]) to stimulate an active response by the host’s immunological system, which is usually characterized by the presence of antibodies produced by the individual host, therefore providing complete protection against the specific disease. ➔​ Passive immunization refers to immunization through the transfer of a specific antibody from an immunized individual to a non immunized individual, such as the transfer of antibodies from mother to infant or the administration of an antibody-containing preparation (immune globulin or antiserum). Passive immunity from immune globulin 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 immune globulins include those for hepatitis A, rabies, and tetanus. ➔​ Vertical transmission is the passing of an 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 or indirect contact, common vehicle, airborne, or vector borne. ➔​ Common vehicle refers to the transportation of the infectious agent from an infected host to a susceptible host via food, water, milk, blood, serum, saliva, or plasma. ➔​ Incubation period is the time interval between the 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. ➔​ Communicable period is the interval during which an infectious agent may be transferred directly or indirectly from an infected person to another person. ➔​ Endemic refers to the constant presence of a disease in a particular population or geographical area. For example, pertussis is endemic in the United States. ➔​ Epidemic refers to the occurrence of a greater number of cases of a disease, an injury, or other condition than expected in a particular area or group  ➔​ Pandemic refers to an epidemic occurring in a geographically widespread area or in a large population. HIV/AIDS is both epidemic and pandemic because the number of cases is growing rapidly across various regions of the world. PowerPoint Historical Perspectives ➔​ In 1900, communicable diseases were the leading cause of death in Canada. ➔​ By 2000, improved nutrition and sanitation, vaccines, and antibiotics had put an end to the epidemics that once ravaged entire populations. ➔​ Organisms once susceptible to antibiotics are becoming increasingly drug resistant. ➔​ New killers are emerging, and old familiar diseases are taking on different, more virulent characteristics. ➔​ Those diseases with an increased incidence in the past two decades or with the potential to increase in the near future. They can include newer or known infectious diseases. ➔​ COVID-19, Ebola, Human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS), West Nile virus, Anthrax, Avian influenza, H1N1 influenza, Cryptococcal disease, Legionnaires disease, Toxic shock syndrome, Hantavirus pulmonary syndrome, Necrotizing fasciitis. SDOH ➔​ There are associations between the determinants of health and communicable and infectious diseases, for example: Low income is linked to increased rates of sexually transmitted infections (STIs), Low literacy levels are a barrier to receiving effective care for STIs. Communicable Diseases ➔​ Prevention and control programs seek to reduce the prevalence of a disease to a level at which it no longer poses a public health problem. ➔​ Elimination: The removal of the disease from a large geographic area, such as a country or region of the world. ➔​ Eradication:The permanent elimination of a disease worldwide ➔​ Transmission of communicable diseases depends on the successful interaction of three factors, together known as the epidemiological triangle: The host, The infectious agent, the environment. Changes in any of these three factors may result in disease transmission. ➔​ Agent factor: Four main categories of infectious agents that can cause infection or disease: Bacteria, Fungi, Parasites, Viruses. ➔​ Host factor: A human or animal host may harbour an infectious agent. ➔​ Four host factors influence the spread of disease: ◆​ Resistance: The ability of the host to withstand infection. ◆​ Immunity: A resistance to an infectious agent ◆​ Herd immunity: The resistance of a group of people to invasion and spread of an infectious agent. ◆​ Infectiousness: A measure of the potential ability of an infected host to transmit the infection to other hosts. ➔​ Environment factor: All that is external to the human host: physical, biological, social, and cultural factors. Environmental factors aid the transmission of an infectious agent from an infected host to other susceptible hosts. Changing environmental factors can reduce communicable disease risk. ➔​ Vertical transmission:Passing an infection from parent to offspring through sperm, placenta, milk, or contact in the vaginal canal at birth. ➔​ Horizontal transmission:Person-to-person spread of infection. Can happen in four ways: Direct or indirect contact, Common vehicle, Airborne, Vector-borne. ➔​ Infection: The entry, development, and multiplication of the infectious agent in the susceptible host. ➔​ Disease:One of the possible outcomes of infection; may indicate a physiological dysfunction or pathological reaction. ➔​ Incubation period:The time interval between invasion by an infectious agent and the first appearance of signs and symptoms of the disease. ➔​ Communicable period: The time interval during which an infectious agent may be transferred directly or indirectly from an infected person to another person. ➔​ Disease Spectrum: People with infectious diseases may exhibit a broad spectrum of disease that ranges from subclinical infection to severe and fatal disease. At the community level, the disease may occur in endemic, epidemic, or pandemic proportion. ◆​ Endemic: Constantly present in a given geographic area or population ◆​ Epidemic:An occurrence of disease in a community or region that is greater than normally expected. ◆​ Pandemic: A worldwide epidemic affecting large populations (e.g., COVID-19, SARS) Surveillance of Communicable Diseases  ➔​ Surveillance: Systematically collecting, organizing, and analyzing current, accurate, and complete data for a defined disease condition. This information is promptly provided to those who need it. ➔​ All provinces and territories in Canada are required to report communicable diseases. The Public Health Agency of Canada maintains a list of Nationally Notifiable Infectious Diseases that must be reported. ➔​ Primary prevention seeks to reduce the incidence of disease through health promotion and education. ➔​ Secondary prevention seeks to reduce the prevalence of disease or to diminish morbidity through early diagnosis and treatment. ➔​ Tertiary prevention seeks to reduce complications and disabilities related to disease through treatment and through mental and physical rehabilitation. ➔​ Prevention is at the centre of public and community health. Examples of community health nurse (CHN) roles: Education, Immunization, Screening. Vaccine Preventable Diseases ➔​ Vaccines are one of the most effective methods of preventing and controlling communicable diseases. Many diseases (e.g., polio, diphtheria, pertussis, and measles) are controlled by vaccines but have not been eradicated. ➔​ In Canada, most children are immunized by the time they enter school. ➔​ Although immunization is strongly recommended, it is not generally compulsory. ➔​ In Canada, only three provinces have legislated vaccination policies that apply to children about to enroll in school: Ontario and New Brunswick require immunization for DTP, measles, mumps, and rubella, Manitoba requires a measles vaccine. However, the legislation includes an exemption clause which allows parents to request exemption from the vaccine on medical, religious, or personal grounds. ➔​ It is important to be alert for communicable disease cases in regions where the following apply: ◆​ Groups obtain exemption from immunization on religious or health belief grounds ◆​ Immunization is incomplete ◆​ International visitors are frequent ◆​ Prompt outbreak control is essential among susceptible populations. ➔​ Influenza (“flu”): A viral respiratory infection often indistinguishable from the common cold or other respiratory diseases.The most important factors to note about influenza: Its epidemic nature, The mortality resulting from pulmonary complications, especially in older persons. ◆​ There are three types of influenza viruses: A, B, and C. Types B and C are fairly stable, but type A is constantly changing. ◆​ Flu vaccines are prepared each year on the basis of the best possible prediction of what type and variant of virus will be most prevalent that year. ◆​ Immunization is necessary annually and is given in the fall before the flu season begins. ➔​ Smallpox: Smallpox has been considered eradicated since 1979. The last known natural death from smallpox occurred in 1977. The only documented existing virus sources are located in freezers at the Centers for Disease Control and Prevention (CDC) in Atlanta and a research institute in Russia. It is important to be familiar with the clinical and epidemiological features of smallpox because There is a potential for bioterrorism, Many health care providers have never seen this disease, It is important to know how smallpox is differentiated from chickenpox. Non-Vaccine Preventable Diseases ➔​ Non-vaccine-preventable diseases: Diseases that cannot be prevented by vaccination (e.g., tuberculosis [TB]). ➔​ TB: Caused by Mycobacterium tuberculosis, Usually transmitted in airborne droplets, About 5% of those initially infected develop pulmonary TB, In 95% of those initially infected, the infection becomes latent and may be reactivated later in life. ◆​ R/f: Those who travel to and from countries where TB is endemic, First Nations peoples living in communities with a high prevalence of TB, Homeless people, Residents of some long-term care facilities or persons in correctional facilities, Health care workers, Persons with weakened immune systems (e.g., alcoholics, diabetics, those infected with HIV). ◆​ CHNs may do the following: Administer and interpret TB skin tests, Collect specimens, Monitor medications, Provide education and support when necessary, Familiarity with the current Canadian Tuberculosis Standards is paramount. STIs ➔​ In Canada, since 1997, the number of reported cases of STIs has increased: Chlamydia is the most common, Gonorrhea is the second most common, Syphilis is the least common. STIs have long-term health effects, so CHNs should be knowledgeable about them. ➔​ Chlamydia: Caused by the organism Chlamydia trachomatis, which causes infection of the urethra and cervix, Infections may be asymptomatic and, if untreated, result in severe morbidity.  ➔​ Gonorrhea:Caused by the bacterium Neisseria gonorrhoeae, Can result in inflammation of the urethra and cervix and dysuria, or it may result in no symptoms. ➔​ HIV infection: HIV infection and AIDS continue to have a significant political and social impact on society. In Canada, approximately 58,000 people were living with HIV/AIDS in 2006. ◆​ Transmission: HIV is transmitted through exposure to blood, semen, vaginal secretions, and breast milk. It is not spread through casual contact, such as coughing or sneezing. Screening has significantly reduced the risk of transmission of HIV by blood products and organ donations. ➔​ Public fears and an attitude of blame have led to discrimination against the two most commonly afflicted groups: homosexuals and intravenous drug users.Many of the opportunistic infections that affect people with AIDS are caused by microorganisms that are normally present in healthy people. The most common opportunistic diseases are Pneumocystis carinii pneumonia and oral candidiasis. Infectious Diseases ➔​ Infectious diseases can be spread by direct and indirect modes of transmission from host to host. The agent can be a virus, bacterium, parasite, or fungus. If untreated, these diseases are often fatal, so prevention is the best approach. ➔​ Hepatitis: Viral hepatitis refers to a group of infections that primarily affect the liver. These infections have similar clinical presentations but different causes and characteristics. ◆​ Hepatitis A virus (HAV): Most often transmitted through the fecal-oral route. Sources may be water, food, or sexual contact. The clinical course of HAV ranges from mild to severe and often requires prolonged convalescence. The virus level in the feces appears to peak 1 to 2 weeks before symptoms appear, making individuals highly contagious before they realize they are ill. HAV is one of the most frequently reported vaccine-preventable diseases. ​ R/f: Travellers to countries with high rates of HAV infection, Children in areas of high rates, Injection drug users, Men having sex with men, Persons with clotting disease or chronic liver disease. ➔​ Hepatitis B virus (HBV): HBV is found mostly in the following groups: Users of injection drugs, Persons with STIs or multiple sex partners, Immigrants and refugees (and their descendants) from areas with high endemic rates of HBV, Health care workers, Hemodialysis patients, Inmates of long-term correctional institutions, Young adults (especially homeless adolescents). ◆​ The number of new cases of HBV has decreased with the use of the HBV vaccine. HBV infection can be prevented by: Immunization, Prevention of nosocomial occupational exposure, Prevention of exposure via sex or injection drug use. ➔​ Hepatitis C virus (HCV): Transmitted when blood or body fluids of the infected person enter an uninfected person. “The silent stalker”—up to 70% of newly infected people experience no symptoms, and it may take up to 30 years for symptoms to appear. ◆​ Primary prevention: Screening of blood products and donor organs and tissue. Risk-reduction counselling and services (including a sexual and injection drug use history). Infection-control practices. ◆​ Secondary prevention strategies: Testing of high-risk individuals, including those who seek HIV testing and counselling. Appropriate medical follow-up of infected patients. ◆​ HCV testing should be offered to the following: Those who received blood or an organ transplant before 1992., Health care workers who have been exposed to blood or body fluids, Children born to HCV-positive women, Those who have ever injected drugs or been on dialysis. Water + Food Borne Diseases ➔​ Water-borne diseases: Water-borne pathogens usually enter water supplies through animal or human fecal contamination and frequently cause enteric disease. Pathogens include viruses, bacteria, and protozoa. ➔​ Hepatitis A is the most widely publicized water-borne viral agent. The most important water-borne bacterial diseases are: Cholera, Typhoid fever, Bacillary dysentery Other Salmonella types, Shigella, Vibrio, and various coliform bacteria (e.g., E. coli) may also be transmitted by water. ➔​ Food-borne illness (food poisoning): Often categorized as food infection or food intoxication. Results from toxins produced by bacterial growth, chemical contaminants (e.g., heavy metals), or disease-producing substances found naturally in certain foods, such as some types of mushrooms and seafood. Food infections are usually associated with incubation periods of 12 hours to several days after ingestion of the infected food. Food intoxications become obvious within minutes to hours after ingestion. Much food-borne illness can be prevented through effective food preparation, handling, and storage. ➔​ Salmonellosis: A bacterial food-borne illness. Although morbidity can be significant, death is uncommon except among infants, older persons, and the debilitated. The rate of infection is highest among infants and small children. It is estimated that only a small proportion of cases are recognized clinically and that only 1% of clinical cases are reported. The yearly number of Salmonella infections may be in the millions.  ◆​ Transmission route: eating inadequately cooked food that: Comes from an infected animal, Is contaminated by feces of an infected animal or person, Meat, poultry, and eggs are the foods most often associated with salmonellosis outbreaks. Outbreaks occur commonly in restaurants, hospitals, nursing homes, and children’s institutions (e.g., schools, daycares). ➔​ Escherichia coli 0157:H7: First described in humans in 1992 after two outbreaks of illness were associated with eating undercooked hamburgers from a fast-food restaurant chain. Infection causes bloody diarrhea, abdominal cramps, and, infrequently, fever. Hamburger appears to be involved in outbreaks. The best protection is to cook food thoroughly. Vector Borne Diseases ➔​ Vectors: Nonhuman organisms, often insects, that either mechanically or biologically play a role in the transmission of an infectious agent from source to host. ◆​ Biological transmission – the vector is necessary for the developmental stage of the infectious agent. ◆​ Mechanical transmission – occurs when an insect simply contacts the infectious agent with its legs or mouth and carries it to the host. ➔​ Vector-borne diseases encountered in some parts of Canada are those associated with ticks: Lyme disease, Rocky Mountain spotted fever (less common). ➔​ Measures for preventing exposure to ticks:Reducing tick populations, Avoiding tick-infested areas, Wearing protective clothing when outdoors, Using repellents, Immediately inspecting for and removing ticks when returning indoors. ➔​ CHNs who work with large immigrant populations or with international travellers may encounter malaria and dengue fever, both carried by mosquitoes. West Nile virus is an example of an endemic mosquito-borne virus. Diseases of Travellers ➔​ Malaria: A potentially fatal disease characterized by regular cycles of fever and chills.Caused by the blood-borne parasite Plasmodium, transmitted through the bite of an infected mosquito. ◆​ Worldwide, malaria is the most prevalent vector-borne disease, No vaccine is available, Prevention depends on protection against mosquitoes and appropriate chemoprophylaxis, Malaria is gaining drug resistance, so decisions about antimalarial medications must be tailored to the individual. ➔​ Diarrheal diseases: Much food-borne disease can be avoided in other countries if the traveller eats thoroughly cooked foods prepared with reasonable hygiene. Water in many areas is not potable. Drinking unsafe water can lead to a variety of infections. Only boiled water, bottled water, or water purified with iodine or chlorine compounds should be consumed. ➔​ Zoonosis: An infection transmitted under natural conditions from a vertebrate animal to a human. Means of transmission: Animal bites, Inhalation, Ingestion, Direct contact, Arthropod intermediates. ◆​ Rabies: A well-known zoonosis, A significant public health problem worldwide, Causes as many as 55,000 human deaths a year, mostly in developing regions such as Asia and Africa. Rabies is rare in Canadians since the availability of a vaccination for pets in the mid-1900s. The best protection against rabies is vaccinating domestic dogs, cats, cattle, and horses. Even if there is no suspicion of rabies, a physician should be contacted because tetanus or antibiotic prophylaxis may be indicated. If an individual is bitten: Clean the wound thoroughly with soap and water., Consult a physician immediately, Suspect rabies if the bite is from a wild animal or an unprovoked attack from a domestic animal. Parasitic Diseases ➔​ Parasitic diseases are more common in developing countries than in Canada because of The tropical climate in many of the countries, their often-inadequate prevention and control measures. ➔​ Parasites are classified into four groups: Nematodes (roundworms), Cestodes (tapeworms), Trematodes (flukes), Protozoa (single-celled animals). ➔​ Some common parasites that cause infections that a CHN might encounter: Enterobius (pinworm), Giardia lamblia, Trichuris trichiura (whipworm), Ascaris lumbricoides (roundworm), Taenia solium (pork tapeworm). ➔​ Diagnosis of parasitic diseases is based on history of travel, characteristic clinical signs and symptoms, and laboratory tests. Effective drug treatment is available for most parasitic diseases. CHNs play a key role in the prevention, diagnosis, and control of parasitic infections. The CHNs Role in Providing Preventative Care ➔​ Primary Prevention: Consists mainly of activities to keep people healthy before the onset of disease, for example: Assessing for risky behaviours, Providing relevant intervention through education on how to avoid infection, mostly through healthy behaviours. ➔​ In questioning patients at risk of acquiring STIs, the CHN should do the following: Obtain a sexual and injection drug use history for patients and their partners., Identify the total number of partners AND the number of contacts with these partners, Be clear that this information is confidential. Based on the sexual history and risk assessment, the CHN can  identify specific education and counselling needs. Nursing action focuses on education and contracting with patients to change behaviour. ➔​ Community outreach: Because of the illegal nature of injectable drugs and the poverty associated with HIV, many people at risk do not seek health care, CHNs go into communities where those at risk live, to provide risk-reduction education, counselling, and referral. ➔​ Community education: CHNs may provide educational sessions about STIs to community groups, These sessions are most effective when delivered in settings where groups regularly meet, such as churches, schools, or businesses. Topics covered: Symptoms of HIV and other STIs, Modes of transmission, Ways to prevent infection, Available community resources. ➔​ Evaluation: Based on behaviour change toward safer behaviour, The best indicator of success is measuring the incidence and prevalence of the diseases. ➔​ Secondary Prevention: Screening for diseases to ensure early identification and treatment, Follow-up with contacts to prevent further spread, CHNs should recommend that persons who have engaged in high-risk behaviour be tested for HIV. ◆​ The Canadian Guidelines on Sexually Transmitted Infections identify at-risk persons who should be offered HIV testing. ◆​ The STI guidelines outline the pre- and post-counselling needed for persons with negative and positive antibody test results. ◆​ Contact tracing (partner tracing): The process of identifying the relevant contacts of a person with an infectious or communicable disease to inform them of their exposure to that disease, Plans are made for the contact to seek follow-up care, An example of a population-level intervention aimed at controlling communicable diseases, Contact notification programs usually occur in conjunction with reportable disease requirements and are carried out by most health departments. ➔​ Tertiary Prevention: Can apply to many of the chronic STIs and to TB. For viral STIs, the focus is on managing symptoms and psychosocial support regarding future interpersonal relations.Directly observed therapy (DOT) programs for TB medication monitoring: ◆​ Aimed at the population level, to prevent antibiotic resistance in the community and ensure effective treatment at the individual level ◆​ If patients prematurely stop taking medication, the TB may become resistant. This can affect an entire community of susceptible people. The CHN observes and documents individual patients taking their TB drugs. ➔​ AIDS: Management in the home may include: Monitoring physical and emotional health status, Referring the family to additional care services for maintaining the patient in the home ➔​ Infection control education: Teaching caregivers about infection control in the home is vital, Standard and routine precaution procedures must be taught to caregivers in the home setting. All blood and articles soiled with body fluids must be handled as if they were infectious or contaminated by blood-borne pathogens. This should include the use of gloves, mask, goggles, and gown, when necessary.