Communicable diseases: preventing and treating disease Flashcards
Describe natural active immunity
Immune system is activated and antibodies formed. Antigen is destroyed. T & B memory cells are produced, so a secondary immune response is produced if a second encounter. Body itself produces antibodies.
Describe natural passive immunity
Immune system of a new-born is not mature and cannot make antibodies to start with. Some antibodies cross the placenta when still a fetus, so has some immunity. The first milk of a mother called colostrum, is high in antibodies. Breast-fed baby will have the same number of antibodies as the mother in a few days. Lasts until the baby makes its own antibodies. Not made by the baby so passive.
Describe artificial passive immunity
Antibodies are formed in one individual, extracted and them injected into the bloodstream of another individual. This gives temporary immunity. e.g. tetanus caused by toxin Clostridium tetani. Causes muscle spasms so no breathing or swallowing. Injected with tetanus antibodies extracted from the blood of horses preventing the development of the disease.
Describe artificial active immunity
immune system is stimulated to make its own antibodies towards a dead pathogen, injected as a vaccine. The pathogen is made safe, injected into the blood, triggering a primary immune response. A secondary immune response is triggered if encountered again. These are safe vaccines, that do not cause disease.
How are pathogens made safe for vaccines?
Killed or inactivated bacteria and viruses.
Attenuated (weakened) strains of live bacteria or viruses.
Toxin molecules have been altered and detoxified.
Isolated antigens extracted from the pathogen.
Genetically engineered antigens.
What is an epidemic?
Communicable disease spreads rapidly to a lot of people at a local or national level.
What is a pandemic?
When the same disease spreads rapidly across a number of countries and continents.
What is herd immunity?
When a significant number of the population have been vaccinated, giving them immunity, and protecting those not vaccinated. There is minimal chance that an outbreak may appear.
Give examples of diseases that cannot be prevented by vaccination
Malaria: Plasmodium is very evasive. Spends time in erythrocytes, protected by self antigens from the immune system. Antigens reshuffle.
HIV: causes AIDS. Enters macrophages and T helper cells, to disable the immune system.
What are some common medications?
Painkillers, anti-inflammatories, anti-acid.
Give examples of medicines that cure people
Chemotherapy for cancer, antibiotics for bacteria, antifungals against fungi.
How are drugs designed today?
Scientists can use complex computer programmes, to build 3D models of key molecules in the body, and of pathogens and antigens. This allows models of drugs to be built, which can target particular areas.
Computers can search through libraries of chemicals, to isolate against a specific group pf a pathogen.
How has the analysis of genomes aided sources of medicine?
Enabled scientists to target novel drugs to attack any vulnerabilities. Many of the most commonly used drugs are still derived from, or based on, bioactive compounds discovered in plants, microorganisms etc.
Penecillin
Commercial extraction, originally from mould growing on melons. Antibiotic - first against many bacteria.
Docetaxel / paclitaxel
Yew trees.
Treatment of breast cancer.
