Infections are caused by, bacteria, viruses, fungi and parasites free essay sample

Infection is the process where germs enter a susceptible area in the body, where they multiply, resulting in disease. Colonisation is where microbes are present on or in the body, where they grow and multiply without invading the surrounding tissues. An example of this is the bacteria that cause MRSA will often live harmlessly on the skin and in the nose of people without causing any harm at all to that individual. Localised infection is only confined to one certain part of the body and will only affect that specific area. If they are internal they can be very serious, such as appendicitis or endocarditis. An infected cut may also be another example of this; symptoms may include hot skin, pain, redness, swelling and a pussy discharge. These localised infections do not usually make you ill, but without the proper care they could cause a systemic infection. Systemic infections will affect the whole of the body by spreading through the bloodstream. Examples of this include tonsillitis, influenza, malaria and chicken pox. Symptoms of systemic infections include; fever, chills, weakness and aching joints. The chain of infection begins with a pathogen. The pathogen needs the right environment to enable them to grow. They need a route of transmission and a portal of entry. They then begin to multiply and make the host feel ill, then some of the pathogens will now exit the body and the chain begins again. Infections are caused by microbes which are found everywhere such as dust, homes, animals and humans. Some microbes are helpful to us and are called normal flora, others can be harmful and cause infections, and these are called pathogens. Normal flora being present is very important in preventing pathogens from colonising the body, because pathogens would rather grow where there are no other pathogens to compete with. Large numbers of flora discourage pathogens from multiplying, which helps us to stay healthy and be able to fight of any infection we are introduced to. Normal flora which lives in our intestines help for us to digest food and also protect our intestines from pathogens which are trying to invade. Normal flora found within the body and on the skin, will eat dead cells and pathogens. Lactobacillus acidophilus is the main friendly bacteria in the upper intestinal tract. It is important for the body as it helps to reduce the levels of harmful bacteria and yeast in the small intestine. It does this by crowding out any harmful microbes so they cannot grow. Lactobacillus acidophilus also produces lactose which is an enzyme that is important in the digestion of milk. Bifidobacterium bifidum and Bifidobacterium longum are the main friendly bacteria found in the large intestine. Bifidobacterium are important to protect the large intestine from invading bacteria and yeasts. They also manufacture B vitamins such as niacin, folic acid and pyridoxine and help the body to detoxify bile. Problems may arise when normal flora get into parts of the body where they will normally not be found. Such as if flora from the gut got into the vagina it could cause irritation and infection. Pathogenic microorganisms are described as transient; this is because they can be transferred from one person to another. All these organisms need are conditions which are suitable for growth and reproduction. Most pathogens that are associated with humans will grow rapidly at around body temperature whereas some pathogens such as listeria can multiply at lower temperatures meaning they can spoil food. Most pathogens use respiration for the production of energy, meaning they grow successfully in oxygen. Anaerobic pathogens are able to survive without any oxygen. An essential requirement for the growth of bacteria is moisture; most will die very quickly without it. This provides us with a useful infection control measure; we can stop pathogens from multiplying by keeping surfaces clean and dry. Some yeast, moulds and fungi can grow in dry conditions. Protein and carbohydrate are needed by most bacteria in order to grow. Bacteria can obtain their essential nutrients from foods such as meat, eggs, fish, cheese, milk and cooked rice. Many places within the human body have an abundance of suitable food such as the mouth. Most pathogens prefer to grow in pH neutral conditions; many of the cavities in the body are protected from an invasion by a high pH. An example of this is the stomach, which is very acidic and kills ingested pathogens. All bacteria need time to be able to multiply and it has been observed that generally bacteria divide into two every twenty minutes. Infections can be spread through many things, these include; food borne infection, person to person, water borne infection, airborne infection, insect borne infection and fomites. Contamination may happen at any stage of food production, from seed and soil to packaging and cooking. Meat may be contaminated by inadequate storage or poor hygiene. Cross contamination can happen through raw meat. Pathogens can still be present in food due to food that is insufficiently warm. Food should only be reheated once, and drinking water could also be contaminated, although there are hygiene controls to prevent this in the UK. Infections which are spread person-to-person may be airborne, through inhalation of infectious droplets. A lot of virus infections are obtained through inhalation of infectious droplets, the common cold virus is an example of this. A common way of spreading gastrointestinal infections is through the faecal-oral route, examples of this include typhoid, cholera, dysentery, hepatitis A and poliomyelitis which are all obtained through drinking water contaminated with for example human faeces. The pathogens which cause venereal diseases are vulnerable. They die rapidly when exposed to conditions outside of the body. For them to be able to spread, these pathogens need the most intimate of human contact. Infections can be passed on through direct inoculation. Intravenous drug users who share dirty needles with others risk getting hepatitis and HIV infection because of the direct inoculation of blood from someone who is infected. Airborne infections are one that is contracted due to the inhalation of microorganisms or spores suspended in the air on water droplets or dust particles. Airborne infection: Legionella Pneumophila causes Legionnaire’s disease which is found in many natural water sources but is commonly associated with poorly maintained air conditioning systems or rarely cleaned shower heads. Airborne droplets from these sources are the cause for Legionnaire’s disease. Pathogenic microorganisms which are directly transmitted when contaminated drinking water is consumed are waterborne diseases. Contaminated water can be the cause of diseases such as typhoid, cholera, dysentery, hepatitis A and poliomyelitis. Insets feed of animals that are infected and then transmit the infection to humans such as mosquitos. Many diseases are insect borne. The most important historically, is the plaque which was caused by Yersinia pestis and transmitted by rat fleas. Fomites are any inanimate object or substance which is capable of carry pathogens, such as door handles, mops, cloths and bedding. This is of particular importance for hospital hygiene. Microorganisms are classified into categories these are bacteria, viruses, fungi and parasites. Bacteria absorb nutrients through the cell walls and waste products are excreted in the same way. They have no nucleus or mitochondria. In many bacteria the cell wall is slimy to enable the cell to attach to surfaces. The flagellum helps with motility of each cell through the water and body tissues. The process called binary fission is where bacteria reproduce. Each bacterium splits into two to make two clone daughters, this process can occur around every ten minutes. Different types of bacteria include; bacilli (rod shaped), cocci (spherical), spirochetes (spiral shaped) and vibrios (curved). Bacteria are spread in different ways. These include; airborne by droplet infection through coughing or sneezing, direct contact by touching an infected person, indirect contact by toughing an object an infected individual has touched, touching foods with dirty hands and bodily fluids like saliva, blood and semen. Types of bacterial infection include; tuberculosis, salmonella, syphilis, legionnaire’s disease, clostridium difficile, methicillin resistant staphylococcus aureus (MRSA), campylobacter and tetanus. Each virus has genetic material inside a protein coat which is called the capsid, which is responsible for protecting the cell, attaching the virus to a cell and infecting the cell. After it is attached the virus will inject DNA/RNA into the cell, which replicates the virus and erupts from the cell into many viruses ready to invade new cells. In order for a virus to live and make more viruses they must have a host cell. Some viruses can live for many years inside their host cells without causing any harm. An example of this is a person infected with HIV can live without showing symptoms of AIDS for years, but they virus will still be able to spread to others. Viruses are spread by different things, these include carrier organisms such as mosquitoes and fleas, airborne infections such as coughs and sneezing, direct transfer of body fluids from one person to another such as saliva, sweat, nasal mucus, blood, semen and vaginal secretions, and surfaces on which body fluids have dried. Types of viral infections include; HIV/AIDS, colds/influenza, herpes, chicken pox, measles, Ebola and glandular fever. An example of how influenza may be spread is If an infected individual sneezes near you, you inhale the virus particle, and it attaches to the cells lining the sinuses in your nose. The virus then attacks the cells lining the sinuses and rapidly reproduces new viruses. The host’s cells will break and new viruses spread into your bloodstream and also into your lungs. Because the cells lining your sinuses are lost, fluid can flow into your nasal passages and give you a runny nose. The viruses in the fluid that drips down your throat attacks the cells lining your throat and give you a sore throat. Viruses in your bloodstream can attack the muscle cells and cause you to have muscle aches. Fungi are multi celled organisms that include yeast, mildew, moulds and mushrooms, which reproduce by budding. Budding is a process where a protrusion from a cell becomes free. They make spores that grow into fungi when conditions become favourable. Fungal infections like warm and moist conditions such as the mouth, armpits, vagina and other skin folds. Fungal infections can be spread by domestic animals such as dogs and cats and can also be spread by direct or indirect contact such as touching an infected person or from swimming baths and using contaminated towels. Types of fungal infections include thrush, athlete’s foot, ringworm, fungal nails and pityriasis versicolor. Individuals are at risk of fungal infections when they have recently taken a course of antibiotics, been taking oral steroids, have diabetes, obese, African-Caribbean and have a risk of fungal infections have a weakened immune system caused such as by cancer or AIDS. A parasite is a plant or animal which lives on or in another organism to enable them to gain its nourishment and continued survival. They survive by attaching themselves in various different ways to the body and will often lay eggs on the skin, hair or intestines. Types of parasite infections include fleas/lice, threadworms, scabies, tapeworm, giardia and malaria. Parasites can spread in different ways these include some like malaria are spread by insects, some such as giardia are drunk drinking water, some such as live and scabies are caught from direct contact and some are ingested in food such as threadworm and tapeworm. In this assignment I have explained how infections are caused by bacteria, viruses, fungi and parasites. I have also explained how pathogenic microorganisms grow and spread.