Diseases Flashcards
What is a pathogen?
An organism that causes damage to it’s host
What is infectious?
A disease that may be passed from one individual to another
What is a carrier?
An individual who shows no sign of infection but can pass the disease on to another
What is a disease reservoir?
Where the disease is normally found; in humans or another animal. Often outside of epidemics
What is an endemic?
A disease which is always present at low levels in an area
What is an epidemic?
A significant increase in the number of cases in an area, often spreading rapidly
What is a pandemic?
An epidemic spreading worldwide or across a large area
What is an antibiotic?
Substances produce by bacteria and fungi which interfere with the metabolism and growth of other bacteria
What is a vaccine?
A medicine using microbes or parts of microbes to elicit a protective immune system
What is antibiotic resistance?
Where a microbe which should be susceptible to an antibiotic is no longer affected by it
What is a vector?
A living organism which transfers a disease from one individual to another
What is a toxin?
A chemical produced by a microbe which causes damage to it’s host
What is an antigenic type?
Organisms with the same or very similar antigens on the surface. Often identified using antibodies
What is cholera?
- Caused by gram negative bacterium = Vibrio cholerae
- Comma shaped motile bacteria (with flagellum for movement)
- Fatal disease of human intestine which is an endemic
- Lives and multiples in the intestine
- Produces powerful endotoxin which causes inflammation in mucus membrane
- Many pathogens required
- Humans act as reservoirs and carries the bacteria
How is cholera spread? What are the symptoms? What is the treatment?
- Water contaminated by faeces containing the organism
- Contaminated food
- Diarrhoea
- Dehydration and loss of mineral salts
- Rehydration of salts and fluid
- Drugs = tetracyclines reduce duration of diarrhoea
- Vaccinations = last 3-6 months
- Education
What is tuberculosis?
- Caused by bacterium Mycobacterium tuberculosis (MTB)
- Transmitted in airborne droplets when people cough or sneeze
- Spreads quicker in crowded conditions
- Epidemic (growing due to poor health services, cramped living conditions etc.)
What are the symptoms? How to detect TB? What is the BCG vaccine?
- Usually attacks lymph nodes and lungs
- Coughing up blood, fatigue, fever, chills, chest pain, weight loss and shortness of breath
- The Heaf Test = purified protein extracted from TB bacterium, injected under skin, read after 2-3 days, redness or swelling indicated a positive reaction so no need for BCG, no reaction means not immune
- BCG is a freeze dried live bacterial vaccine prepared from an attenuated strain of M. bovis, used on children aged 10-14 and lasts 15 years
What are the symptoms of influenza virus? How is it spread?
- 2 day incubation period there are no symptoms
- Followed by 4 days of coughing and sneezing, headache, sore throat and fever
- Respiratory aerosols can be generated from the respiratory tract by various means - speaking to sneezing
What are the programmes to prevent spread of influenza? Are vaccines always effective?
- Annual vaccination programmes given to elderly and people at risk e.g asthmatics and pregnant women
- Vaccine is 70-80% effective - not 100% effective because of the emergence of new strains
- Vaccine only lasts 1 year
What is small pox? What are the symptoms? How is it transmitted?
- Caused by the Variella major virus
- Only organism ever to be made extinct (eradicated)
- Blisters covering the skin, fever, vomiting, severe pain
- Only found in humans
- Transmitted by direct contact or contacts with contaminated bedding etc.
Why was the eradication of smallpox so successful?
- Virus showed little antigenic variation
- Virus was very antigenic so vaccine was very effective
- People were keen to be vaccinated
- No other hosts other than humans, animals cannot form a second reservoir
What is Malaria? How is it transmitted? What are the symptoms?
- Parasitic disease caused by the Plasmodium spp, a protoctistan parasite
- Transmitted by a vector = a female Anopheles mosquito
- Endemic
- 1-2 weeks after being bitten, headache, coma, repeated vomiting, anaemia, pain in joints
How is malaria controlled?
- Hanging insecticide mosquito nets over beds
- Use insect repellant
- Wear long sleeves
- Drain standing water
- Spray water with insecticide
What are the drug treatments and vaccines?
- Take anti-malarial drugs before and during a trip to foreign country which has an endemic of malaria
- Artemether is an effective, fast acting drug but this is more expensive
- No effective vaccine because plasmodium frequently mutate resulting in many antigenic types
- Antibodies are only effective when the parasite is outside of the body cells
