HLTINF006 - SLG - Chapter 1.pdf

 HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control V1.0 N/A Initial creation V1.1 11th July 2023 Spelling 11 Jul 2023 | V1.1...

 HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control V1.0 N/A Initial creation V1.1 11th July 2023 Spelling 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 1 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Chapter 1 Infectious Diseases and Infectious Agents Introduction What is an infectious disease? The infection process The chain of infection Chapter summarise 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 2 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Lesson 1 of 5 Introduction  In this chapter, you will learn about: - Infectious diseases and types of pathogens, - The infection processes, - The chain of transmission for infections In order to prevent and control infections we first need to understand what they arg and how they occur. As a future healthcare worker, it is vital that you understand these principles, so that you can keep yourself, your colleagues, your friends and family, and your patients safe. After completing this chapter, you should be able to meet the following Learning Outcomes: Be able to explain the di erence between bacteria, viruses, fungus and parasites and how they can lead to infection. Be able to explain each of the 5 steps of the infection process. Be able to explain the 6 aspects of the chain of infection. Be able to list factors which might make a host more susceptible to infection. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 3 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Lesson 2 of 5 What is an Infectious Disease? A disease refers to any disorder in a human which produces symptoms and is not simply a direct result of physical injury. Many things can cause disease, for example cancer or a stroke, but not all are due to infection. Infectious diseases, or infections, are diseases (or illnesses) caused by the spread of pathogenic microorganisms, such as bacteria, viruses, fungi or parasites. Infectious diseases can be spread, directly or indirectly, from one person to another, or they may arise from animals or the environment, such as from food or water. An infection might be present yet cause no symptoms, or it can cause obvious symptoms. Infections can remain localised, for example in a wound, or they can spread through the blood or lymphatic vessels to become systemic throughout the body. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 4 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Infectious diseases are constantly circulating in the community. Some cause minimal harm to most people, like the common cold, herpes, or ringworm. Others can be life-threatening and life- changing, such as a COVID-19 infection in an elderly patient, a Hepatitis C or HIV infection in a young adult, or whooping cough to an infant. We should note here that infectious diseases can impact individuals differently, for example a young and healthy person might barely even notice a cold or COVID-19 infection, while this may be fatal to someone with a compromised immune system. An infectious agent is the pathogen responsible for causing the disease. Pathogens can pass from person to person,directly through touch or bodily fluids and wastg or indirectly via contaminated surfaces, air,food and drink. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 5 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control The major groups of infectious agents are called micro-organism which you will probably know by the common terms “bug or “germ. Micro-organisms are all around us. Millions of individual micro- organisms interact with human bodies on a regular basis and not all cause infection. Micro- organisms can be beneficial, harmless or harmful to humans. For examplg the beneficial bacteria present in the body’s intestines aids in the digestive process and overall health. However, some micro-organisms cause disease, we call these pathogenic micro-organism, or simply pathogens (note this is the same as saying infectious agent). There are four main groups of micro-organisms bacteria, viruses, fungi and parasites. Within each group there are various different types of micro-organisms which given the right conditions have the ability the cause disease. There are also larger organisms that cause disease, such as parasitic tapeworms, lice and scabies. We will look at each category in more detail now. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 6 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control  Quick vocab recap: Infectious diseases, or infections - Illnesses caused by the spread of pathogenic microorganisms Micro-organisms - a microscopic organism, especially a bacterium, virus, fungus Pathogenic micro-organisms, infectious agents, or pathogens - the substance responsible for causing a disease 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 7 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Bacteria Bacteria are single-celled microorganisms. Some live harmlessly on our skin, in our gut, ears, nose and throats, and more and more evidence indicates that many bacteria benefit our health and wellbeing. Other bacteria can be harmful to us and can lead to serious infections that can be deadly if untreated. Types of pathogenic bacterium Pathogenic bacterium are simply bacteria that cause disease. Remember that not all bacteria do this in humans. To help provide context for you here is a summary of the major types of bacterium and some examples from each. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 8 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control https://letstalkscience.ca/educational-resources/backgrounders/introduction-bacteria Spirochetes Spirochetes are thin, flexible spiral-shaped bacteria. They are f‘ree living’,which means they can live in mud and sediments and animals in the mouth or GI tract. Some unique examples of spirochetes includf Leptospira, which causes leptospirosis in animals and humans and is an example of a spirochete which can jump from animals to humans, Treponema pallidum, which causes syphilis through sexual transmission, Campylobacter jejuni,which causes bacteria diarrhoea,especially in children and is transmitted through ingestion of undercooked poultry or shellfish,and Helicobacter pylori, which can colonise the lining of the stomach and causes peptic ulcers. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 9 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Vibrios Vibrios are bacterium shaped like a curved rod or comma. Vibrios can live in anaerobic conditions, that is, without oxygen. Vibrio cholerae is a vibrios bacteria and causes Asiatic cholera, which, untreated, is one of the most rapidly fatal infectious diseases known. Aerobic rods and cocci Aerobic rods and cocci bacteria cause many human diseases, including: bordetella pertussis, which causes whooping cough (pertussis) and spreads from human to human, legionella pneumophila causes legionnaires disease, which lives in water and infects humans through aerosols. escherichia coli (E. coli) is found in water and food contaminated with human faecal matter and causes intestinal and urinary tract infections, and can also lead to neonatal meningitis. Pyogenic Cocci Pyogenic Cocci are spherical bacteria that cause suppurative (pus-producing) infections. These include Staphylococcus aureus, Streptococcus pyogenes and Streptococcus pneumoniae. Two species of ‘staph’ bacteria live in/on humans: Staphylococcus epidermidis, which normally lives on the skin and mucous membranes, and Staphylococcus aureus which primarily lives in the in nares but can be found in other places. S. epidermidis is rarely a harmful pathogen and probably benefits its host by retarding the growth of dermatophytic fungi. S. Aureus has the potential to cause disease, so we consider it a pathogen. Di erent strains can cause boils and pimples, wound infections, pneumonia, osteomyelitis, septicaemia, food intoxication, and toxic shock syndrome. It is also the leading cause of hospital acquired infections. 11 Jul 2023 | V1.1 key features Chapter such 1: Infectious as: and Infectious Agents Diseases Page 10 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Endospore-forming bacteria Some bacteria, for example Bacillus and Clostridium can form spores. These spores also called endospores are the dormant form of the bacteria, and are highly resistant to physical and chemical agents that would normally kill the vegetative form of the bacteria. In other words, they are very hard to kill. Bacterial spores are produced by bacteria as a method of surviving unfavourable conditions. They have a number of key features, such as: They can tolerate extreme dryness Some cannot be killed even in sub-zero temperatures; and Some can spread poisonous chemicals Bacterial spores are extremely resistant, can survive even after the bacteria has been killed, and are highly transmissible. Spores of tetanus, for example, can survive in the soil for many years. Examples include Bacillus anthracis, which causes anthrax, bacillus cereus, which causes food poisoning, clostridium botulinum, which causes botulism, and clostridium tetani, which causes tetanus. Actinomycetes and related bacteria Most actinomycetes (pronounced act-in-o-my-sites) and related bacteria and not considered pathogenic to humans. They are used to produce antibiotics and are the source of most tetracyclines, macrolides, and aminoglycosides. Mycobacterium are a relative of actinomycetes. Mycobacterium tuberculosis causes tuberculosis (TB) in humans, which is the leading cause of death from a single infectious disease worldwide. There are strains of multiple drug-resistant strains of tuberculosis. Corynebacterium are a diverse group of bacteria. Some genera are part of the normal microbiome of humans and can live in almost every anatomic site. The best-known species is Corynebacterium diphtheriae, which causes diphtheria. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 11 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Coccus Bacillus Vibrio 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 12 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Coccobacillus Spirillum Spirochete 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 13 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Actinomycetes and related bacteria It’s not uncommon for you to encounter a patient who has an infection you’ve never heard of. In these cases, a quick internet search can give you the basics you need to understand what to expect. Gonorrhoea Salmonella Gonorrhoea is caused by infection with Salmonella, also called Salmonellosis, is a the bacterium Neisseria gonorrhea and is disease caused by the bacteria Salmonella. spread by having unprotected vaginal, It is usually characterized by acute onset of anal or oral sex with an infected person. fever, abdominal pain, diarrhoea, nausea and It can be passed by fingers or hands from sometimes vomiting. the genitals to the eyes. Gonorrhoea can also be passed from an Staphylococcus infected mother to her baby during birth, which can cause eye infection (neonatal Staphylococcus aureus (S. aureus or conjunctivitis) and even blindness. “staph”) causes skin and soft tissue infections such as abscesses (boils), furuncles, and cellulitis. Although most staph infections are not serious, S. aureus can cause Shigellosis serious infections such as bloodstream infections, pneumonia, Shigellosis is caused by the or bone and joint infections. Excessive Shigella bacteria. Washing your hands use of antibiotics has led to drug- often with soap and running water can resistant strains of S. aureus (check out help protect you from infection. MDR pathogens). 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 14 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control  Spotlight: Multidrug Resistant Pathogens Unfortunately, some pathogenic bacteria mutated with new forms of virulence and new patterns of resistance to treatment with antibiotic medications. These microorganisms are called multidrug-resistant (MDR) pathogens. They can spread rapidly, especially in health care settings with vulnerable patients, so it makes hygiene procedures to prevent this of vital importance. One example of an MDR is Methicillin-resistant Staphylococcus aureus (MRSA). This Infection is caused by a type of staph bacteria that's become resistant to many of the antibiotics used to treat ordinary staph infections. Many MRSA infections are transmitted in hospitals or other health care settings as the inhabitants are particularly susceptible, especially when they are associated with invasive procedures, such as surgery or intubation. In these cases the infections are usually spread by health care workers touching people with unclean hands or people touching unclean surfaces. Another type of MRSA infection has occurred in the wider community among healthy people, and usually begins as a painful skin boil. It's usually spread by skin-to-skin contact. Viruses A virus is a very simple microorganism that infects cells and may cause diseaseViruses are the smallest microbes and exist only to reproduce. However, viruses can’t reproduce by themselves, they need a host organism, for example you, though they can also use bacteria, plants and animals. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 15 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control They reproduce by invading host cells and using the reproduction mechanisms of the cell to create more of its own genetic material. Once they have replicated, the virus particles leave the host cell by either budding or bursting out of the cell. Bursting out damages or destroys the host cell and is called lysis, this is a non-enveloped virus. Budding is the term used for a process whereby the new viral particle pushes against the host cell’s plasma membrane, which then envelops the virus and creates a viral envelope, making this an enveloped virus. This viral envelope protects the newly formed genetic material of the virus, which may help it avoid detection by the host’s immune system. Enveloped viruses can create persistent infections that are extremely hard to overcome through the natural immune processes of the human body, or by antiviral treatments. Examples include: Poxviruses such as orthopox, which causes smallpox, Herpesviruses such as varicella zoster, which causes chickenpox, Coronaviruses including SARS, MERS and COVID-19, and the common cold Paramyxoviridae including those that cause mumps, measles, and respiratory tract infections Retroviruses such as HIV, which causes AIDS Non-enveloped viruses are less resistant to external stressors such as disinfectants, heat and drying out. This makes them easier to control and eliminate: they do not last long outside of the host environment, and inside the host, they are susceptible to destruction from increased body temperature. Examples of non-enveloped viruses include: norovirus, which causes dysentery rhinovirus, which causes the common cold, and poliovirus, which causes polio 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 16 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control https://www.news-medical.net/health/What-is-a-Virus.aspx Figure 2 Non-enveloped and enveloped viruses goalfinder.com CC BY-NC-SA 2.0 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 17 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Fungi Fungi are any of a group of spore-producing organisms feeding on organic matter, including moulds, yeast, mushrooms, and toadstools. Fungi are a lifeform that lives just about everywhere, from the mould in your bathroom grout to mushrooms in the soil and ringworm on your cat or dog. They can grow and colonise many environments. There are two forms of fungus: Yeasts, which are single round cells 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 18 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Moulds, in which many cells form long, thin threads called hyphae Fungi infect the human body by two primary pathways through contact with the skin and inhalation of fungal spores. There are also two kinds of fungal infections: 1 Opportunistic: which take advantage of a weakened immune system 2 Primary: which occur in people with normal immune systems. People with weakened immune systems, for example people with a HIV infection or autoimmune disorders, or people using immunosuppression drugs or antibiotics, are particularly vulnerable to: Aspergillosis, an infection that can a ect the lungs, is caused by breathing in the 1 common Aspergilli fungus spore. Aspergillosis can be a serious infection and cause permanent damage to the lungs. Candidias: is an infection caused by several species of Candida, especially Candida 2 albicans. Candid albicans usually lives harmlessly on our skin but certain conditions can cause it to grow out of control. The most common candidiasis is a superficial infection of the vagina or mouth, also known as thrush. Women on the contraceptive pill and who have taken a course of antibiotics are susceptible to vaginal thrush. It can also be passed on through sexual intercoursg including oral sex,and men can be infected. Mucormycosis: can be caused by several fungi moulds that can be inhaled or enter 3 the body through a break in the skin. These moulds are common in the environment and include bread moulds. Inhaling the spore is the most common route into the body, and can cause rhinocerebral mucormycosis, which can be fatal, pulmonary mucormycosis, or if swallowed, can infect the digestive tract. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 19 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Fungal infections can be restricted to one area of the body, in which they are called localised, or can a ect many areas of the body, in which they are called systemic. Localised infections usually involve the skin and nails, vagina, mouth, or sinuses. Figure 3 Candida albicans David Arqueas CC4.0, Pulmonary aspergillosis by KGH CC by 3.0 Parasites A parasite is an organism that lives on or in an organism of another species (called a host) and gains its food from the host. There are three main classes of parasites that can cause disease in humans: 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 20 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Protozoa One-celled organisms that live in the human intestines. Transmission is usually via the faecal oral route. An amoeba is a protozoa. They can be free-living or parasitic (needing a living host to survive). Helminths (or worms) Large multi-celled organisms. Harmful parasites can reside in the intestines and other organs e.g. flat, round and thorny headed worms Ectoparasites For example mosquitoes, ticks, fleas, lice and mites. These can cause disease in their own rite e.g. scabies from mites Parasites can also transmit other infectious agents e.g. mosquitoes carry malaria, dengue and yellow fever. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 21 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control https://microbeonline.com/parasitic-infections-source-of-infection-mode- of-transmission-and-prevention/  Spoiler alert! We will discuss this in detail later, but did you know that when an infectious disease is transmitted through something like a mosquito, this is known as a vector borne disease? A great example of this is Malaria, mosquitoes transmit Malaria from one host to another, but are not the actual cause of the infection themselves. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 22 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Lesson 3 of 5 The Infection Process There are millions of micro-organisms around us, and on us, all the time. As previously discussed, most bacteria, viruses, fungi and parasites in the environment are harmless and are not pathogenic, that is they won’t cause an infection in a human. For example, Colonisation describes the process of an organism taking up residence on a host and then multiplying, but not causing harm to the individual. There are many bacteria which colonise our digestive tract, and actually help us digest food, but don’t cause harm to us. Sometimes, they can live in us for years, not causing any trouble, and then all of a sudden cause an infection that can be fatal, a great example of this is Tuberculosis. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 23 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control People colonised with a pathogen but who are not showing signs or symptoms are called carriers, or asymptomatic carriers. We will discuss this later, but for now, just know that it’s possible to carry a pathogen, and transmit the infection, but not experience any symptoms, just like we just discussed with Tuberculosis. When microbes lead to infection they follow a specific process. The infectious agent enters the body and multiplies resulting in an immune response and formation of symptoms. Disease occurs when the cells in the body are damaged by the infection and signs and symptoms of an illness manifest. Hopefully the host can fight o the infection and recover. For all this to occur,the infection process goes through five stages: 1 Incubation 2 Prodromal 3 Illness 4 Declive 5 Convalescence We will discuss each stage in turn. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 24 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Incubation stage The incubation stage includes the time from exposure to an infectious agent until the onset of symptoms. Viral or bacterial particles replicate during the incubation stage. Duration:The exact time frame of the incubation stage varies depending on the infection. For example the influenza virus incubates for 1–4 days but symptoms can appear as early as 2 days after the virus enters the body. Some other examples of incubation periods for infectious diseases are: Chicken pox: 10 - 21 days Measles: 10 - 12 days Mumps: 12 - 25 days Food poisoning: 30 minutes - 4 weeks (dependent on bacteria e.g Salmonella 12 – 72 hours) Influenz 1 - 4 days Hepatitis A: 2 - 7 weeks Hepatitis B: 8 weeks - 5 months Hepatitis C: 2 - 12 weeks Glandular fever (infectious mononucleosis): 4 - 6 weeks Whooping cough: 7 - 10 days COVID-19: 2 - 14 days 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 25 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Prodromal stage The prodromal stage refers to the period after incubation and before the characteristic symptoms of infection occur. People can also transmit infections during the prodromal stage. During this stage, the infectious agent continues replicating, which triggers the body’s immune response and mild, nonspecific symptoms, for example low-grade fever and fatigue. Duration: The duration of the prodromal stage varies depending on the type of infection. For example, the influenza virus has a short incubation period of about 2 days. As a result, the prodromal stage may overlap with the incubation stage and the onset of illness. Illness The third stage of infection is an illness or clinical disease. This stage includes the time when a person shows symptoms of an infectious disease. The symptoms of infection vary widely depending on the underlying cause. In general, people who have an active infection may experience: Fever Fatigue headaches swollen lymph nodes Duration: The exact time frame varies depending on the type of infection, the number of infectious microbes in the body, and the strength of a person’s immune system. For example the influenza virus symptoms can last up to 7-10 days. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 26 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Decline During the decline stage, the immune system mounts a successful defence against the pathogens, and the number of infectious particles decreases resulting in symptoms gradually improving. However, a person can develop secondary infections during this stage if the primary infection has weakened their immune system. During this stage, the virus can still be transmitted to other people. Convalescence The final stage of infection convalescence refers to the stage where symptoms resolve and a person can return to their normal functions. Depending on the severity of the infection, some people may have permanent damage even after the infection resolves. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 27 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Lesson 4 of 5 The Chain of Infection The infection process explains the steps required for an infection to occur. For an infection to spread, it must follow the chain of infection. Certain conditions must be met for a pathogen or infectious disease to spread from person to person. This process, called the chain of infection, can only occur when all six links in the chain are intact. By breaking this chain at any of the links, the spread of infection is stopped. We will discuss each step in the chain in turn. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 28 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Causative Agent Firstly, we need a causative agent, or the pathogen which begins the infection. As we have already learned this might be a bacteria, virus, fungus, or a parasite. There are many di erent pathogens that you might encounter as a healthcare professional. It is beyond the scope of this lesson to discuss all of them, but it is useful to practice looking up different diseases so you can quickly learn about them. Open the following resource and look up some common diseases that are of interested to you: https://www.healthdirect.gov.au/infectious-diseases. You may need to look up different diseases during your assessment for this unit, or in other units. Reservoir Next, we need a reservoir, which is the habitat of the infectious agent, where it would normally live, grow and multiply. Reservoirs include the environment (for example, water, soil, plants), animals (such as dogs, pigs, birds, horses, bats) and of course humans. The reservoir might not be the source from which the infectious agent is transferred to humans. For example, Clostridium botulinum naturally occurs in the soil, its reservoir, but the source of most botulism infections in humans is improperly preserved food containing C. botulinum spores. Humans are the most common reservoirs of human infectious diseases. Diseases that move from human to human without intermediaries include streptococcal infections, measles, mumps, and sexually transmitted diseases such as chlamydia and gonorrhoea. Animal reservoirs Zoonotic disease refers to infectious diseases that can transfer to humans under natural conditions from vertebrate animals. For example: The Hendra virus is named for being first identified as transferring from horses to humans in Hendra Queensland. It can infect humans through exposure to the body fluid, tissue or , excretions of infected horses. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 29 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Flying foxes carry lyssavirus that can jump to humans through contact with the saliva of infected bats, through a bite or scratch, and by getting saliva in eyes, nose, or mouth. Q fever is transmitted via aerosolisation of breathed in bird droppings. Brucella suis which causes brucellosi, is widespread in the feral pig population in Queensland. Brucellosis can infect humans through direct contact with tissues or body fluids from an infected animal or eating undercooked infected meat. Luckily, Hendra virus, Q fever, lyssavirus and brucellosis are not commonly transmissible between humans. However there are other zoonotic diseases which are easily transmissible from human to human ,including swine flu,bird flu and COVID-19. Environmental reservoirs Environmental reservoirs can include soils, water, and plants. Legionnaires’ disease is commonly caused by Legionella pneumophila in air conditioning cooling towers, whirlpool spas, showerheads and other bodies of water, and Legionella longbeachae found in soils and potting mix in Australia. Legionnaires’ disease is a dangerous form of pneumonia that can a ect people with compromised immune systems, the elderly, and people taking immunosuppressant drugs. It does not travel from human to human. Portal of exit The portal of exit is the pathway by which the pathogen b ( acteria,virus , fungi etc.) leaves the reservoir or host. The portal of exit is usually the same as the site where the infectious agent is localised. For example influenza and the common cold viruses commonly enter and exit the respiratory tract through mucosal excretions s ( neezes coughs blowing or wiping your nose). Other portals can include faeces, uring sweat, vomit , blood, saliva,semen and even skin flakes. There are also non-human portals, such as medical equipment not correctly sterilised and stored. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 30 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control https://universityhealthnews.com/daily/eyes-ears-nose-throat/how-far-does-a-sneeze-travel/ Mode of transmission The mode of transmission is how an infectious agent can be transferred to a susceptible host. In healthcare settings, the main modes of transmission of infectious agents are: Contact, Droplet, and Airborne The modes of transmission vary by type of organism. In some cases the same organism may be transmitted by more than one route (eg. norovirus ,influenza and respiratory syncytial virus (RSV) can be transmitted by contact and droplet routes). 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 31 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control We will summarise each type now, please note that this can be confusing the first time you learn ,so we have also made a summary at the end. Read though the following section and the summary and if you are still unsure come back and repeat. Contact transmission Contact is the most common mode of transmission, and usually involves transmission by touch or via contact with blood or body substances. Contact may be direct or indirect, and indirect can be further divided into vector borne and vehicle borne: Direct transmission occurs when there is physical contact in which body secretions or excretions are transferred from an infected host’s body to a susceptible new host. For example when you have influenza and you cough in your hand and then shake hands with someone else. Note that in this scenario an infected person directly delivers the infectious agent to another person by physical touch. Another example might be transmission from kissing or intercourse. Note that direct transmission occurs when there is the movement from one currently infected host to a new host, using physical contact. Remember this as it’s the key point here. Indirect transmission occurs when an infectious agent is transferred through a contaminated intermediary object or person, for example a healthcare worker’s hands transmitting infectious agents after touching an infected body site on one patient and not performing proper hand hygiene before touching another patient. Alternatively you might come into contact with fomites objects ( or materials which are likely to carry infection ,e.g. bedding ,used tissues ,or unclean equipment),or bodily fluids like faeces or saliva, and then touch a patient and transfer the infection. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 32 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Note in this case there isn’t direct physical contact between the original host and the new host, the infection is transferred through an intermediary. Because Indirect transmission occurs with an intermediary, we can split this into two categories, vector and vehicle borne transmission. Vector transmission occurs when a living organism carries the infectious agent on its body (mechanical) or as an infection host itself (biological), to a new host. As we learned earlier, a mosquito carrying Malaria is an example of vector borne transmission. The mosquito does not suffer the effects of the Malaria, it carries the virus as a sort of parasite. Vehicle transmission occurs when a substance (also called a fomite), such as soil, water, or air, carries an infectious agent to a new host. An example of this might be someone drinking water that contains bacteria which then cases gastroenteritis. Droplet transmission Droplet transmission usually occurs when an infected person coughs , sneezes or talks , and the infection is transferred with droplets. Droplets are infectious particles larger than 5 microns in size w ( hich might sound small but in the context of infectious agents it’s quite large). Respiratory droplets transmit infection when they travel directly from the respiratory tract of the infected person to susceptible mucosal surfaces (nasal, conjunctival or oral) of another person generally over short distances. Droplet distribution is limited by the force of expulsion and gravity and is usually no more than 1 metre. Likewise droplets fall to Earth quickly, they don’t float around for extended periods. https://link.springer.com/article/10.1007/s10867-020-09562-5 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 33 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Airborne transmission Airborne transmission occurs via particles which contain infectious agents which remain infective over time and distance. Small-particle aerosols o ( ften smaller than 5 microns) are created during breathin talkin coughing or sneezin and secondarily by evaporation of larger droplets in conditions of low humidity. Aerosols are tiny compared with droplets ,which is what allows them to han suspended in the air for so long and to float long distances making them harder to avoid. Aerosols containing infectious agents can be dispersed over long distances by air currents (e.g. ventilation or air conditioning systems) and inhaled by susceptible individuals who have not had any contact with the infectious person, or even been in the same room. These small particles can transmit infection into small airways of the respiratory tract. https://www.science.org/doi/10.1126/science.abd9149 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 34 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Recap So, in summary: Direct – movement from one host to another by direct physical contact between the two – e.g coughing into your hand and then shaking hands with another person. Indirect – movement from one host to another through an intermediary which makes contact with each party – e.g. coughing into your hand and then opening a door, which another person then places their hand over. Indirect vector borne – a living organism carries the infection from one host to another – e.g. a flea or mosquito moves from one host to another. Indirect vehicle borne – a substance carries the infection from one host to another- e.g. contaminated soil or water carriers the infection to the host. Droplet transmission One host transfers the infection to another through droplets containing the infectious agent - e.g. a cough or sneeze into the atmosphere which another person then inhales Airborne transmission One host transfers the infection to another through aerosols containing the infectious agent – e.g.someone sits in a chair and infectious particles attach to particles and then float until landing on a susceptible host 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 35 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Portal of entry The portal of entry is how the infectious agents get from the reservoir into the susceptible host. Any injury to the skin, including those made in a medical setting by needles, stents and catheters, can be a potential entry point for an infectious agent into the skin and the bloodstream. Other common portals of entry include the mouth, nose, eyes, ears, vagina, urethra and anus. Infectious agents can also be inhaled into the lungs, swallowed into the gastrointestinal tract, and absorbed through the mucous linings of the entries into the human body. The susceptible host The susceptible host is the person who becomes infected with the infectious agent. You don’t actually have to be weakened to become the susceptible host, even young, fit and healthy people can become infection. However, there are factors that can increase a person’s susceptibility. The susceptibility of the person for infectious diseases can depend on a variety of factors, such as: Age plays a role: infants and babies have immune systems that are not fully developed, and so are susceptible to picking up infections more easily than older children and teenagers. Also, younger infants may not be old enough to have had their inoculations. Older adults' immune systems are usually in decline, so they are more susceptible than younger adults to infectious diseases. Immune status is a very important factor, for example some people have compromised immune systems from autoimmune disorders or HIV infection. People taking immunosuppressants, or who are having chemotherapy, are all more likely to get sick from coming into contact with infectious agents. Co-morbidities can also make individuals more likely to succumb to infections. For examplg people with cystic fibrosis may have an increased susceptibility to and complications from cold and flu viruss, and bacterial lung infections. People with diabetes are seemingly more susceptible to many infections including gangreng due to nerve and circulation damage. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 36 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Medical devices and implants make an individual more susceptible to disease infection in the implantation site. Any device that provides and pathway in to or out of the body, such as a catheter, IV-line, colostomy bag or feeding tube (gastrostomy), can be a pathway for infectious agents to enter the body. Any implant of foreign material into the body brings a risk of transmission of bacteria, virus or fungi directly into organs or the bloodstream, including pacemakers, stents, breast implants and collagen lip injections if they are not correctly stored and handled in sterile environments. In healthcare settings, the most common susceptible hosts are patients and healthcare workers. Patients may be exposed to infectious agents from themselves such as bacteria residing within the skin, in the respiratory or gastrointestinal tract (endogenous infection), from other people, instruments and equipment, or their environment (exogenous infection). The level of risk relates to the healthcare setting (specifically the presence or absence of infectious agents), the type of healthcare procedures performed, adherence to hand hygiene, immunisation status and the susceptibility of the patient. Healthcare workers may be exposed to infectious agents from infected or colonised patients, instruments and equipment, or the environment. The level of risk relates to the type of clinical contact healthcare workers have with potentially infected or colonised patient groups, instruments or environments, adherence with standard and transmission-based precautions, and the health status of the healthcare worker (e.g. immunised or immunocompromised). Factors influencing healthcare associated infection https://www.safetyandquality.gov.au/sites/default/files/2021-10/break_the_chain_poster_- _october_2021.pdf 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 37 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Lesson 5 of 5 Chapter Summarise Well done for reaching the end of the chapter!Below we have summarised some key terms and concepts from the chapter,please make sure you have understood this before taking the quiz to check your knowledge. Remember the quiz does not count towards your final scorg and you can retake it as many times as you like Key terms: Terms Meaning Refers to any disorder in a human which produces Disease symptoms and is not simply a direct result of physical injury An illness caused by the spread of pathogenic Infectious disease, or infection microorganisms a microscopic organism, especially a bacterium, Micro-organisms virus, fungus, or parasite Pathogenic micro-organisms, infectious agents, or the substance responsible for causing a disease pathogens Bacteria single-celled microorganisms Spore or endospore dormant form of a bacteria 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 38 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Terms Meaning a very simple microorganism that infects cells and Virus may cause disease a replicated viral particle pushes against the host cell’s plasma membrane which then envelops the Enveloped Viruses virus and creates a viral envelope which protects the newly formed genetic material and may help it avoid detection by the host’s immune system a replicated viral particle uses cell lysis to burst out Non-Enveloped viruses of the host’s cell any of a group of spore-producing organisms Fungi feeding on organic matter, including moulds, yeast, mushrooms, and toadstools an organism that lives on or in an organism of Parasite another species (called a host) and gains its food from the host describes the process of an organism taking up Colonisation residence on a host and then multiplying, but not causing harm to the individual Key concepts: The infection process When microbes lead to infection, they follow a specific process called the infection process: 1 Incubation - the time from exposure to an infectious agent until the onset of symptons 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 39 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control 2 Prodromal - the period after incubation and before the characteristic symptoms of infection occur 3 Illness - the time when a person shows symptoms of an infectious disease Decline – the time when the immune system mounts a successful defence against the 4 pathogens and the number of infectious particles decreases resulting in symptoms gradually improving Convalescence – the time when symptoms resolve and a person can return to their 5 normal functions The chain of infection The steps that must occur in order for an infection to be transmitted 1 Causative agent - the pathogen which begins the infection 2 Reservoir - the habitat of the infectious agent, can be animal or environmental 3 Portal of exit - the pathway by which the pathogen exits the reservoir (or host) Means of transmission - how an infectious agent can be transferred to a susceptible 4 host, can be through contact, droplet or airborne modes 5 Portal of entry - how the infectious agent actually gets from the reservoir into the susceptible host 6 A susceptible host – the person who becomes ill with the infectious disease 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 40 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Modes of transmission Contact transmission 1. Direct – movement from one host to another by direct physical contact between the two. 2. Indirect – movement from one host to another through an intermediary which makes contact with each party Indirect vector borne – a living organism carries the infection from one host to another Indirect vehicle borne – a substance carries the infection from one host to another Droplet transmission - One host transfers the infection to another through droplets containing the infectious agent Airborne transmission - One host transfers the infection to another through aerosols containing the infectious agent Check your understanding Now that you have completed this Chapter, take this short quiz and see how well you’ve understood the content. This quiz does not count towards you mark for the unit; these quizzes are simply for you to gauge your learning.  Now that you have completed Chapter 1, answer these questions and see how well you’ve understood the content. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 41 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control 1 2 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 42 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control 3 4 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 43 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control 5 6 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 44 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control 7 8 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 45 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control 9 10 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 46 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control 11 12 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 47 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control 13 *Answers are on the following page. 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 48 © Industry Pathways operating as Australian Paramedical College | RTO 32513  HLTINF006 Apply Basic Principles and Practices of Infection Prevention and Control Answers: 1. Infectious agent 2. Lichens 3. Non-enveloped 4. False 5. Bacterial endospores are the dormant form of the bacteria 6. An enveloped virus uses a viral envelope to protect the newly formed genetic material of a reproduced virus, which helps it avoid detection by the host's immune system 7. False 8. Incubation, prodromal, illness, decline, convalescence 9. Prodromal 10. The steps required for an infection of occur 11. Contact transmission 12. Age, Immune status, Co-morbidities and Implanted medical devices 13. Reservoir 11 Jul 2023 | V1.1 Chapter 1: Infectious Diseases and Infectious Agents Page 49 © Industry Pathways operating as Australian Paramedical College | RTO 32513