4.6 Immunology & Disease Flashcards
Define pathogenic
An organism that causes damage to its host
Define infectious
A disease that may be transmitted from one individual to another
Define a carrier
- shows no symptoms when infected
- can pass disease onto another
Define a disease reservoir
- where a pathogen is normally found
—> animals or humans, and could be a source of infection
Define an endemic
A disease which is always present at low levels in an area
Define fomities
- objects or materials that are likely to carry infection
—> clothes, utensils and furniture
Define an epidemic
Where there is a significant increase in the usual number of cases of a disease, associated with rapid spread
Define a pandemic
- epidemic occurring worldwide or over a very wide area, crossing international boundaries
- affects a large number of people
Define a vaccine
- uses non-pathogenic forms, products or antigens of microorganisms to stimulate an immune response
- gives protection against subsequent infection
Define antibiotics
- substances produced by microorganisms that affect the growth of other microorganisms
Define antibiotic resistance
- where a microorganism that should be affected by an antibiotic is no longer susceptible to it
Define a vector
A living organism that transfers a disease from one individual to another
Define a toxin
A chemical produced by a microorganism which causes damage to its host
Define antigenic types
- organisms with similar or the same antigens
- subgroups or strains of microbial species which may be used to trace infections
—> identified by antibodies
What are the origins of cholera?
- caused by gram negative bacteria
- only reproduce when inside human host
- endemic in parts of the world - people infected by contaminated food or water and become carriers that can contaminate other water supplies
How does cholera impact the body?
- toxin produced by the bacteria inside the small intestine impacts the chloride channel proteins called CFTR
- water and many ions are not absorbed into blood so patient has severe, watery diarrhoea which causes dehydration and dramatic loss of blood pressure
What are the methods to improve/treat cholera?
- prevented with good hygiene and sanitation
- a vaccine with either genetically engineered or inactive bacteria is an option to give temporary protection
- treatment once contracted can either be giving patients electrolytes, or bacteria treated with antibiotics
Describe the cause and spread of TB
- bacillus bacterium
- named for the dead and damaged cells in lungs of those infected
- spreads by aerosol transmission especially in crowded conditions
- seen a lot in HIV/AIDS patients since they have decreased immune system
Impact of TB
- affects lungs so patients develop chest pain and cough up blood
- bacteria may infect lymph nodes and give fever like symptoms
Treatment for TB
- long course of antibiotics
- BCG vaccine given to babies
Cause and impact of small pox
- caused by a DNA containing virus
- virus inhaled or transmitted in saliva
- enters small blood vessels in the skin, mouth and throat
- causes a rash and fluid filled blisters which leave scars
- some suffer blindness and limb deformities
Treatment for small pox
- fluids and drugs to control fever and pain
- antibiotics given to control secondary infection
- smallpox vaccine provides strong immune response and is very effective at preventing disease
- it is the only species humans have made deliberately extinct
Describe the origins of influenza
- many sub groups that affect many species
- new strain appears with new proteins on the virus surface, the immune system cannot provide protection which results in pandemics
- contains RNA as genetic material
Describe the structure of the influenza virus
- RNA in 8 strands
- virion surrounded by phospholipid envelope derived from the host cells surface membrane
- envelope contains 2 types of antigen;
—> haematglutinin (HA) has a role in entering host cell
—> neuraminidase (NA) has a role in leaving cell
How does the flu impact the body?
- attacks mucous membranes in upper respiratory tract, causing sore throat, cough and fever
Ways to reduce risk of flu infection
- hand washing
- binning used tissues
- annual vaccine
- quarantine
- antibiotics to prevent or treat secondary infections
What is meant by an antigenic type?
- different individuals of the same pathogenic species with different surface proteins, generating different antibodies
Describe antigenic drift
- no RNA proofreading enzymes so following each round of replication, each virion has a new mutation
- produces a gradual change in surface proteins
- particularly impacts HA which is why new vaccine needed annually
Describe antigenic shift
- different combos of NA and HA lead to diff virus types
- cause epidemics
Describe the origins of malaria
- caused by protoctistan Plasmodium
- transmitted by over 100 species of Anopheles mosquitos when they pierce skin to drink blood
- females are vectors but males are not
- occurs in habitats that support the Anopheles mosquitos
—> endemic in sub tropical regions, can be epidemic in wet seasons and regarded as pandemic
Describe the transmission of malaria
- when a mosquito takes blood it takes in the sexually reproducing stage of Plasmodium called gametocytes
- they produce zygotes which develop into an infective stage called sporozites
- sporozites migrate from the mosquito’s gut to its salivary glands
- when mosquito takes another feed, the sporozites are injected into the human and then travel to the liver and reproduce asexually, producing merozites
- merozites released into blood and infect red blood cells
- red blood cells burst and release more merozites released into - process repeats many times
- some merozites become gametes
Describe the treatment of malaria
- drugs do not attack Plasmodium when it’s inside cells so effectiveness is limited
—> use artemisinin and combo of other drugs as unlikely to be resistant to them all at the same time - unable to produce vaccine due to variety of antigenic types and mutations
Describe preventative measures for malaria based in mosquito behaviour
- sleep under nets
- pyrethroid insecticide on nets
- spray indoor walls with insecticide
- drain or cover stagnant water
- film of oil on water
Describe preventative measures for malaria - biological control
- fish introduced to water to eat larvae
- infect mosquitos w bacteria which blocks plasmodium development
- sterilise male mosquitos with x-rays - no offspring
