Causes_and_Spread_of_Infection

Unit 265 Causes and spread of infection Outcome 1 1. Identify the difference between bacteria, viruses, fungi and parasites Bacteria Bacteria are organisms made up of one cell, but have the capability to divide, and can therefore multiply by themselves. They have a wide range of shapes ranging from spheres to rods and spirals. Bacteria exist everywhere, even inside the human body. Most of them are harmless and some are very useful eg gut bacteria produce vitamins and help people digest food, but some bacteria can cause disease. People have more bacteria cells in their bodies than human cells. Bacteria can cause food poisoning, which is why it is necessary to ensure food is cooked thoroughly and store certain foods in the fridge. Bacterial infections can be cured with antibiotics, but using them too often can stop antibiotics working as they build up a resistance. MRSA is a resistant form of bacteria found on the skin, which can cause infections after surgery. Viruses Viruses are simpler than bacteria and are made up of genetic codes of DNA or RNA, long molecules that carry genetic information and a protein shell. They cannot reproduce on their own and need to take over another cell, animal, plant or human. Some viruses eg bacteriophages, are useful and can kill the bacteria that is harmful in food. Most diseases are caused by a virus, like flu or a cold. Other diseases are chickenpox, measles, mumps, German measles and HIV which causes AIDS. If a person has a virus eg chickenpox, it usually makes them immune to having it again. Vaccination can also help build an immunity to prevent most viral infections. Viruses cannot be cured with antibiotics, but there are a few antiviral drugs which have been developed. They can be passed on by sneezing, coughing, or from coming into contact with someone who has a virus. Fungi Fungi are any of a group of unicellular, multicellular, or syncytial spore-producing organisms which unlike bacteria can grow in low moisture environments. Examples include mildew, moulds mushrooms toadstools and yeast. They obtain nourishment from dead organic matter. Out of about 70,000 species only some are edible to humans, but most are poisonous. They are used for commercial uses such as the manufacture of food and alcoholic beverages and antibiotics such as penicillin. They are the main decomposers of organic matter. Most fungi are saprobes, as they digest non-living things eg wood, leaves and dead animals. However some fungi are parasites and attack living things causing several human diseases. Parasites A parasite is an organism that lives on or in a host and gets its food from or at the expense of the host. There are three main classes of parasites that cause disease in humans, protozoa, helminths, and ectoparasites. Protozoa These are microscopic organisms that are able to multiply in humans. This factor contributes to their survival and also allows serious infections to develop from one organism. Transmission via the intestine is usually by a faecal or oral route eg contaminated food, water or person to person contact. Protozoa that live in the blood or tissue are transmitted by insect bites. Helminths These are large multicellular organisms that are usually visible to the human eye in their adult stages. They cannot multiply in humans. The three main human parasites are: • Flatworms, including tapeworms • Thorny-headed worms, that reside in the gastrointestinal tract • Roundworms, that reside in the gastrointestinal tract, blood, lymphatic system or subcutaneous tissues Ectoparasites This includes mosquitoes, tics, fleas, lice and mites that depend on blood from a human host for their survival. They are transmitters of many different pathogens and can cause death from the diseases they cause. 2. Identify common illnesses and infections caused by bacteria, viruses, fungi and parasites Bacteria Acute rheumatic fever This is a disease that can occur following an infection caused by the Group A streptococcus bacterium. If left untreated a throat infection can lead to inflammation in other parts of the body. Botulism Botulism is caused by nerve toxins made by Clostridium botulinum bacteria. People who develop botulism most commonly get it from eating food that is contaminated with the bacteria or its toxin. The toxin that causes botulism is one of the most powerful known poisons and small amounts can do lots of damage to nerves. Cholera Cholera is a diarrhoeal disease caused by infection of the intestine with the bacterium Vibrio cholerae. Gastroenteritis This is the inflammation of the stomach or intestines. It may be caused by bacteria such as campylobacter, salmonella and shigella Haemophilus Influenza type b (Hib) This is is an infection caused by the Haemophilus Influenzae type b bacteria which can cause meningitis Salmonella This is a gastroenteritis infection caused by eating contaminated food or coming into contact with another person infected with the salmonella bacteria. Tetanus This is caused by toxins produced from bacteria called Clostridium tetani . They are common in the environment and can be found in soil, dust and manure. The bacteria can contaminate wounds, where they produce the toxin which causes the symptoms of tetanus Toxic shock syndrome Toxic Shock Syndrome is an illness caused by a toxin produced by certain types of the bacterium known as Staphylococcus Tuberculosis This is a bacterial infection which can affect any part of the body, but most commonly the lungs. Whooping cough Whooping cough is a highly contagious respiratory infection caused by the bacteria Bordetella pertussis. Viruses Influenza This is a highly contagious virus that can infect the respiratory tract. Most flu in the UK is caused by the influenza A virus. Common cold There are more than 200 different viruses that cause colds and this is one of the reasons we get so many. The most common ones are rhinoviruses, but coronaviruses, adenoviruses and respiratory syncytial virus can cause colds as well. Herpes Herpes is an infection that is caused by a herpes simplex virus. Oral herpes causes cold sores around the mouth or face. Genital herpes affects the genitals, buttocks or anal area. Chickenpox This is a highly contagious disease caused by primary infection with varicella zoster virus. Chickenpox causes a distinctive rash and mild flu-like symptoms. Measles Measles is a highly infectious viral illness which causes fever and a red rash, but can lead to serious complications such as blindness and even death. HIV Human immunodeficiency virus, or HIV, is the virus that causes AIDS. It weakens a person’s ability to fight infections and cancer. Viral Meningitis Viral meningitis is more common than bacterial meningitis and, although rarely life-threatening, it can make people very unwell. It causes inflammation of the lining around the brain and spinal cord. German measles German measles is an illness caused by a virus and is also known as Rubella. It produces a red rash, swollen glands and cold like symptoms. Mumps Mumps is an infection caused by a virus. It mainly affects the salivary glands but sometimes other parts of the body are affected. Fungi Athletes’ foot Athlete's foot is a common infection caused by the tinea fungus. Symptoms include itching, burning and cracked, scaly skin between your toes. Candida Candida is the scientific name for yeast. It is a fungus that lives almost everywhere, including in your body. Usually, your immune system keeps yeast under control. If you are sick or taking antibiotics, it can multiply and cause an infection. Fungal meningitis This is caused by the Cryptococcus fungus. Infections in people are acquired by inhalation of small fungal cells spread on air currents. The organisms survive and spread only in people with weakened immune system. Aspergillis Aspergillis is caused by a mould called aspergillus that spreads through the air. It can cause serious pulmonary and bloodstream infections in people with weakened immune systems. It usually affects the lungs, but it can spread to almost anywhere in the body. Scalp itch Scalp itch is a fungal infection of the scalp and hair. Nail fungus Nail fungus is most common in adolescents and adults, especially among people who have frequent manicures. Sometimes a portion of the nail becomes thick and brittle. Other times, the fungi attack the cuticle and the growth spreads out from there. Ringworm Ringworm is an infection that is caused by a fungus and causes a ring like red rash on the skin. It is highly contagious and easily spread among people. Parasites Malaria This infectious disease is transmitted by a female mosquito. It takes approximately a week for the malaria infection to spread around the body, specifically the red blood cells. Symptoms are fever, headache and even hallucinations. Body lice Known as Pediculosis, body lice infestation is caused by blood-sucking lice and other parasitic insects Such as: • Pediculosis capitis or head lice is the most common form of body lice infestation and is normally seen in children 3-10 years • Pediculosis corporis is the infection of lice in the human body. • Pediculosis pubis is the infestation of lice in the pubic hair and private part of a person's body. Toxoplasmosis Toxoplasmosis is a disease caused by the parasite Toxoplasma Gondi. Most of them do not get sick, but the parasite causes serious problems for some people. These include people with weak immune systems and babies whose mothers become infected for the first time during pregnancy. Round worm Roundworms are worms that can infest the human digestive tract, specifically the small intestine. Bed bugs Bed bugs are parasitic insects that feed on human blood. They are mainly active at night and their preferred habitats are beds or other areas where people sleep. Tapeworms A tapeworm is a parasite that can live in a person's intestines (bowel). They are known medically as cestodes. Infection is caused by: • touching contaminated faeces (stools) and then placing their hands near their mouth • swallowing food or water containing traces of contaminated faeces • eating raw contaminated pork, beef or fish 3. Describe what is meant by “infection” and “colonisation” Infection This is an invasion of pathogen microorganisms into the body. These pathogens multiply and spread into bodily parts and tissues, which may produce subsequent damage and injury. This will progress to disease and even death through various different cellular or toxic processes. Colonisation Colonisation is the multiplication of microorganisms without tissue invasion or damage, Bacterial cells begin reproducing to form colonies. The person may not show any signs or symptoms of infection, but still has the potential to infect others. 4. Explain what is meant by “systemic infection” and “localised infection” Systemic infection Systematic infection means that the pathogens have spread throughout the body. This means that the bacteria have been able to invade the bloodstream or lymphatic system affecting a number of organs or tissues. Localised infection Localised infection is an infection that is limited to a specific part of the body and has local symptoms. The bacteria invade a specific point of the body and remain there multiplying until treated. 5. Identify poor practices that may lead to the spread of infection Poor practices include:  not washing hands  not wearing the appropriate PPE  not storing or cooking foods properly  not keeping equipment and surfaces clean  using personal items eg soap for several service users  not covering your mouth or nose when coughing or sneezing  waste not being disposed of in the correct manner eg yellow bags for clinical waste  bad personal hygiene Outcome 2 1, Explain the conditions needed for the growth of micro-organisms There are six factors required for the growth of microorganisms, they are: Suitable food Microorganisms have a wide range of nutrient requirements. Some can grow on inorganic material, but the bacteria that are responsible for food poisoning prefer high protein, high moisture and low acidic conditions. Suitable water Microorganisms require water for growth and multiplication and do not thrive well on dried foods. Most microbes will not grow in high sugar foods. Freezing food makes water unavailable to microorganisms. They will grow on any surface that contains moisture eg tea towels, dishcloths and mops. Temperature Micro-organisms vary in their temperature requirements. Some thrive at low temperatures eg. Listeria Monocytogenes, while others can live at higher temperatures. Bacterial spores can survive boiling. Each microorganism has its own temperature for growth. Below a minimum temperature the growth stops but it does not always die. Above a maximum temperature the microbe is likely to be destroyed. Bacteria cause food poisoning between 4 and 60oc. Oxygen Most microbes need oxygen for growth. A small group of bacteria are capable of growing with or without oxygen and are called facultative eg yeast. All moulds are aerobic (need oxygen) which is why they grow on the surface of food. PH conditions Bacteria prefer neutral or slightly acidic conditions. Moulds and yeast prefer quite acidic environments. Time Microorganisms can reproduce rapidly in the correct conditions, with bacteria being the fastest growing. Growth relates to the number or multiplication of microbes rather than their size. Micro-organisms need time to multiply enough to cause food poisoning or serious spoilage of food. 2. Explain the ways an infective agent might enter the body. There are four main routes through which infections can enter the body, they are:  Through the respiratory tract into the lungs eg coughs, colds and influenza  Through the skin. The skin acts as a protective barrier against infection. Anything that breaks the skin, including the mucus membranes of the nose and mouth, provides an entry point for infection.  The digestive tract. Food or drink that is infected with microorganisms is swallowed and will affect the stomach or bowels causing diarrhoea and vomiting.  Through the urinary or reproductive systems. The infection can stay localised or may enter into the blood stream. Sexually transmitted diseases such as HIV and the AIDS virus are carried in bodily fluids and can be transmitted in saliva, seminal fluid, or blood. 3. Identify common sources of infection. Common sources of infection are:  Not washing hands  Staff not wearing PPE  Person to person contact  Unclean equipment or surfaces  Airborne infection eg coughing or sneezing  Contaminated food that has not been stored or cooked properly  Bodily fluids eg urine or blood  Naturally occurring microorganisms 4. Explain how infective agents can be transmitted to a person. Infective agents can be transmitted to a person by:  Droplet contact eg coughing or sneezing  Direct physical contact eg touching an infected person  Contamination from soil or unclean surfaces  Airborne transmission eg bacteria or viruses travel on dust particles  Oral transmission eg ingesting contaminated food  Transmission of infection via a parasite eg malaria from a mosquito  Transmission of infection due to a medical procedure  Sexual transmission eg syphilis or AIDS  Vertical transmission. Transmission of a disease from a mother to the baby immediately before or after birth, through the placenta or breast milk eg AIDS 5. Identify the key factors that will make it more likely that infection will occur. Factors that will make it more likely for infection to occur are:  If a person has a weak immune system eg due to illness  Poor hygiene when dealing with wounds  Sharing personal items eg soap or towels  Not washing hands after assisting with personal care, before preparing food or administering medication  Not cooking and storing food at the correct temperature  An unclean environment or equipment  Not covering your mouth when coughing or sneezing  Not immunising against diseases eg flu  Not disposing of waste in the appropriate way  Not using PPE