communicable diseases Flashcards
1
Q
communicable diseases
A
- infectious
- caused by pathogens
2
Q
pathogens
A
microorganisms that cause disease:
- viruses - bacteria - protists - fungi
3
Q
viruses
A
- viruses are not cells and are not alive
- viruses comprise of genetic material and a protein coat
- the genetic material is not contained in a nucleus
- viruses lack cytoplasm
4
Q
HIV (human immunodeficiency virus)
A
- a retrovirus, so its genetic material is RNA and it has the enzyme reverse transcriptase (only found in retroviruses, catalyses the conversion of viral RNA to DNA)
- HIV can be transmitted through infected body fluids that contain the virus (sexually transmitted/transferred in infected blood/breast milk)
5
Q
prevention of HIV infection
A
- using a condom during sexual intercourse
- HIV-infected mother bottle feeding her baby rather than breast feeding
- screening blood so infected blood is not used in a blood transfusion
6
Q
HIV pathology
A
- the virus parasitises lymphocytes causing them to make new HIV
- HIV is released into the bloodstream by destroying the lymphocyte
- a HIV+ person may have a reduced WBC count -> weakened immune system -> more susceptible to diseases
- when the person reaches this stage, they are said to have AIDS (acquired immune deficiency syndrome)
- currently there is no cure but HIV+ people can be given anti-retroviral drugs that stop reverse transcriptase from functioning so that new HIV will not be made
7
Q
influenza (flu)
A
- caused by influenza virus
- spread in airborne droplets of sputum sneezed/coughed out of an infected person and inhaled by an uninfected person
- can be caught through contact
- symptoms: runny nose, fever, sneezing, coughing, sore throat
- vaccines using inactive/weakened virus can help immunocompromised individuals and to avoid pandemics
- antiviral drugs also available
8
Q
measles/rubeola
A
- caused by morbilivirus
- spread by direct contact/airborne mucus droplets
- symptoms: reddish blotchy rash that tends to start in the head/neck region, spreads over the face and then can cover the full surface of the skin & sensitivity to light
- no treatment, as the person will make a full recovery
- can be prevented by MMR vaccine (live weakened virus)
9
Q
tobacco mosaic disease
A
- attacks plants including tobacco plants
- the virus can be transmitted between plants by direct contact/via an insect/remnants in the soil
- transmission can be prevented by removing infected plants/crop rotation
- the virus can cause tobacco leaves to have light and dark green areas (mosaic) and become wrinkled
- plants can be infected with a milder strain of TMV which acts like a vaccine, preventing a more damaging strain
- the tobacco plant can be genetically modified to make it resistant to the disease
10
Q
bacterial disease prevention
A
- antibiotics (however resistance is becoming a problem)
- vaccination
11
Q
salmonella food poisoning
A
- ingesting food contaminated with salmonella bacterium
- the bacterium survives the low pH conditions of the stomach and reproduces in the small intestine where it causes inflammation
- symptoms: diarrhoea, vomiting, fever
- prevention: proper food preparation e.g. washing hands after handling raw meat, ensure frozen meat is fully defrosted before cooking, ensuring food is thoroughly cooked
- most people recover without treatment, but sometimes oral rehydration supplements are needed to replace lost electrolytes
12
Q
protists
A
- any eukaryote that isn’t an animal, plant or fungus
- single celled
- contains nucleus
13
Q
malaria
A
- cause by the protist, plasmodium
- spread by mosquitoes infected with the protist
- once a human has the protist, it enters the liver where it matures. It then moves into RBCs where it reproduces.
- the RBCs rupture, releasing the protists which then infect more RBCs
- reproduction happens in regular cycles leading to periodic fevers
- sleeping inside mosquito nets/using mosquito repellent can prevent them biting
- anti-malarial medication can be taken prior to going to malaria-infested areas to prevent infection by the protist
- Ways of interrupting the mosquito life cycle include:
- adding fish to the water that eat the larvae
- draining areas of stagnant water
- use of insecticides (however risk of resistance)
14
Q
aspergillosis
A
- a group of diseases caused by the Aspergillus fungus
- they produce a chemical which is a toxin and a carcinogen
- it can contaminate foods like nuts/bread where the fungus is growing
- the fungus produces large numbers of spores asexually which disperse into the air and are then breathed in
- prevention: reducing exposure to the growing fungus by regulating food storage in dry conditions which prevent fungal growth
- symptoms: fever, cough, chest pain, breathlessness
- treatment: steroids/antifungal medication (however some strains have developed resistance to the medication)
15
Q
development of new medicines
A
- medicine tested on animals - to ensure it is safe to test on humans
- medicine tested on few healthy people (phase 1) - to ensure it is safe and to identify the main side effects
- medicine tested on a few people (phase 2) - to make sure it works and to identify optimal dose
- medicine tested on many patients, usually done as a double blind test using a placebo (phase 3) - to look for less common side effects, double blind test to reduce bias, placebo to compare medicine against placebo effect
