Task 3; Infectious Diseases Flashcards
Bacteria structure
Bacteria are prokaryotic, unicellular organisms. They don’t have membrane-bound organelles. Their DNA is contained in a single loop known as a nucleoid.
What per cent of bacteria is pathogenic
Not all bacteria cause disease, only 1% of bacteria is identified as pathogenic.
Bacteria can cause disease by:
- Secreting toxins (chemical change)
- Invading cells (physical change)
- Forming bacterial colonies to disrupt cell function
Disease caused by bacteria
include:
- bacteria name
- Disease
- Symptoms
- Treatment
- Vaccine
- prevention
Bacteria – Vibrio cholerae
Disease: cholera (a diarrheal infection)
Symptoms: diarrhoea, vomiting, leg cramps, dehydration
Treatment: Oral Rehydration Solution (ORS) mixture of salt and sugar with of water and drunk in large amounts. Other treatments include intravenous fluid replacement and antibiotics.
Vaccine: Vaxchora
Prevention: drink and use safe water; wash hands often with safe water; cook food well, peel fruits and vegetables and eat food hot; clean up kitchens safely.
Fungi structure
Eukaryotic, non-photosynthetic, heterotrophic organisms with a cell wall. Can be unicellular or multicellular
Fungi can cause disease by:
Fungi secrete digestive enzymes to break down organic matter, which can then be absorbed into the fungus. These substances usually cause disease.
Fungi commonly cause skin infections. These are caused by fungal species which live on the outside layer of skin and break down keratin tissue, producing by-products that cause inflammation and itchiness.
Disease caused by Fungi
include:
- bacteria name
- Disease
- Symptoms
- Treatment
- Vaccine
- prevention
Bacteria name: dermatophytosis
Disease: Tinea
Symptoms: darkening of the skin, peeling, red rashes, or scaly patches, blisters, cracking of the skin
Treatment: The treatment for ringworm is an antifungal medication
Vaccine: Ringvac
Prevention: maintain hygiene, keep skin dry, avoid sharing towels, avoid public swimming pools
Mode of transmission = direct contact, skin to skin contact, surfaces e.g. shower floor
The fungi live outside the layer of the human skin, where they produce chemicals that break down the keratin.
Examples of types of tinea include athlete’s foot, ringworm
Protozoa structure
Protozoa are eukaryotic, unicellular microorganisms that are larger than bacteria, they have internal membranes and have DNA inside the nucleus.
Disease caused by Protozoa
include:
- bacteria name
- Disease
- Symptoms
- Treatment
- Vaccine
- prevention
Protozoa – Plasmodium falciparum
Disease: Malaria (transmitted via Anopheles mosquito)
plasmodium floasts freely int he blood of an infected person, it feeds on haemoglobin in the RBC’s causing them to pop
Symptoms: fever, headache, chills, sweating; gastrointestinal (diarrhea, vomiting, nausea); pain in abdomen and muscles.
Treatment: prescription drugs to kill the parasite; antimalarial drugs are currently being researched and developed.
Vaccine: Mosquirix vaccine (RTS,S)
Prevention: avoid mosquito bites by using insect repellant; use mosquito net.
Protozoa can cause disease by:
Transmission of protozoa that live in a human’s intestine to another human typically occurs through a fecal-oral route (for example, contaminated food or water or person-to-person contact). Protozoa that live in the blood or tissue of humans are transmitted to other humans by an arthropod vector (for example, through the bite of a mosquito)
Disease caused by parasites
include:
- bacteria name
- Disease
- Symptoms
- Treatment
- Vaccine
- prevention
Bovicola ovis
Disease: sheep lice
Symptoms: excessive itching and unwarranted wool loss, damaged wool.
Treatment: shearing fleece to remove lice; pouring preparations containing medicated drugs.
Prevention: stock-proof fences to prevent sheep from straying and catching lice (known as biosecurity); isolating infected sheep; stock introduced in farm should be quarantined and inspected for lice.
Virus Structure
non-cellular entities (non-living), consisting of a single type of nucleic acid (RNA or DNA) encased in a protein coat.
Virus is a very small piece of genetic material encased in a shell called a capsid. Outside of a host, they are called virions with a protein coat (capsid) and inner nucleic acid (DNA or RNA).
Because they contain nucleic acid, they can mutate and evolve. They can also infect bacteria, and these are known as bacteriophages.
Disease caused by a virus
include:
- bacteria name
- Disease
- Symptoms
- Treatment
- Vaccine
- prevention
Virus – Severe Acute Respiratory Syndrome Coronavirus 2
Disease: coronavirus disease (COVID-19)
Symptoms: fever, dry cough, loss of taste and smell
Treatment: rest, drink lots of fluids, and eat nutritious foods; self-isolate and visit the doctor.
Prevention: wear mask, sanitise, cough into elbow, maintain safe distance, stay home if feeling unwell.
Vaccine: Moderna, Resvisir
prevention: social distancing, PPE
Virus can cause disease by:
The virion is the vector stage that is transmitted from host to host. Once a virus penetrates a host’s defences, they shed their capsid and release their nucleic acid into the host for replication by incorporating their DNA or RNA into the host’s genetic material.
Prions structure
They are the smallest known agents of disease comprising solely of protein and no genetic material.
Prions can cause disease by:
Protein’s that have been altered from their normal structure and can then alter other proteins to develop more prions
Prions cause neurodegenerative diseases by promoting abnormal folding of proteins in the host’s central nervous system.
Prion diseases are also called transmissible spongiform encephalopathies (TSEs)
the symptoms usually include spongiform changes associated with loss of neurons (brain damage) and the body’s inability to induce inflammatory responses.
Disease caused by a Prion
include:
- bacteria name
- Disease
- Symptoms
- Treatment
- Vaccine
- prevention
Prions – Bovine spongiform encephalopathy (BSE)
Disease: Mad cow disease (also Variant Creutzfeldt-Jakob disease through contaminated food – zoonic disease)
Symptoms: dementia, problems with coordination, psychosis, unresponsiveness, weight loss and drop in milk (for cattle), behavioural changes, trembling.
Treatment: no cure
Prevention: avoid feeding cattle rendered material from slaughtered animals and to isolate and destroy all infected animals.
Pathogen Adaptations
Adaptations allow pathogens to remain on or in their hosts for longer periods of time or facilitate transmission to other organisms
- Using Vectors to transition between hosts (e.g. mosquitos) are a vector for malaria and ticks for Lyme disease
- Flagella for movement
- Enzymes to break down and penetrates mucous membranes and chemical barriers
- Variations in antigens avoid host recognition e.g. flu
Direct transmission
Contact between reservoir or infected host and new host. This includes sexual contact, skin-to-skin contact or biting in animals. Infection through sneezing, coughing and breathing are also direct as droplets spread.
Indirect transmission
Requires an intermediate between one host and the next. Includes spread of disease through air and dust, in food and water, on surfaces and objects (fomites). Vectors, such as mosquitoes, also spread disease indirectly.
VEHICLE TRANSIMISSON
Spread of pathogens by contaminated food, air or
VECTOR TRANSMISSION
Spread through other organisms. A pathogen in a biological vector undergoes part of its life cycle in the vector (eg. Mosquitos transporting malaria). Mechanical vectors physically transfer the pathogen from one person to another without being infected themselves (e.g. flies)
Portal of entry
Portal of entry is often the same as portal of exit the pathogen must access the type of tissues where it can grow and reproduce.
Susceptible host
The susceptibility of the host relies on many factors, including their genetics, immunity to the pathogen, and overall health. If the host is suffering from malnutrition, for example, their susceptibility will be increased.
what are the three responses to pathogens
Physical barriers
Chemical barriers
Microbiological barriers
Physical barriers
Epithelial cells create a physical barrier that prevents pathogens from entering the organism. These cells line the skin, and the respiratory, gastrointestinal and urogenital tracts. They are joined tightly by specialized membrane proteins to form a continuous barrier against pathogens.
Additionally, adaptations include mucus-secreting membranes that trap invading organisms in mucus and membranes lined with cilia that sweep foreign bodies away (e.g. those that line the airways).
Chemical barriers
External chemicals barriers include lysozyme enzymes and toxic metabolites (i.e. lactic acid and fatty acids), which are found in secretions (i.e. tears, saliva and sweat). They have a protective function to destroy bacterial cell walls.
Stomach acid and digestive enzymes, while also used for food digestion, can also kill pathogens. In females, the lining of the vagina is coated in acidic secretions that serve several functions, including defence against pathogens.
Microbiological barriers
Microflora are found on the sin and in the mouth, nose, throat, lower part of the gastrointestinal tract and the urogenital tract. Microflora prevents growth and colonization of other bacteria because microflora compete with pathogenic bacteria for space and resources and produce chemicals that reduce the pH of the micro-environment.
Koch’s postulates
- It must be shown that the microorganism is ALWAYS preset in the diseased organism.
- The microorganism must be isolated and grown in pure culture.
- Microorganisms grown in pure culture when injected into a healthy organism without the disease, must produce the disease.
- Microorganisms isolated from the experimental organisms, grown in pure culture, and compared with the microorganisms in the original culture, must be IDENTICAL.
Robert Koch
Robert Koch developed many agar techniques including one to culture micro-organisms. He also demonstrates that specific micro-organisms are responsible for causing specific disease.
- Identified the bacteria responsible for causing anthrax
- Identified the bacterium responsible for causing tuberculosis and cholera