4.3.1.2 Viral Diseases

Question 1

What type of pathogen is measles caused by?

Answer 1

virus

Question 2

How is measles transmitted?

Answer 2

• highly infectious
• transmission through the air - inhaling infected droplets from sneezes and coughs from an infected individual

Question 3

What are the symptoms of measles?

Answer 3

• symptoms initially begin with fever, swollen eyes, coughing and runny nose
• after few days red skin rash on face develops before spreading across body
• spots
• red eyes
• diarrhoea

Question 4

What can measles lead to?

Answer 4

• can lead to complications in children (which can be fatal) e.g. pneumonia (lung infection), encephalitis (brain infection), blindness, lifelong brain damage, deafness, death

Question 5

How is the spread of measles prevented?

Answer 5

• most young children vaccinated against measles due to measles being a serious illness and being fatal if complications arise and to reduce transmission - get MMR shot
• infected individuals should minimise contact to avoid spreading it further

Question 6

What is the treatment for measles?

Answer 6

• no specific treatment for this disease
• with appropriate rest and care the individual will recover
• additional medicines will need to be used to treat any complications arising from diseases

Question 7

What type of pathogen is HIV caused by?

Answer 7

HIV virus

Question 8

What affect does HIV have on the body?

Answer 8

• HIV attacks and destroys the infection fighting cells CD4 cells of the immune system
• loss of CD4 cells makes it difficult for body to fight infections and certain cancers
• HIV virus attacking immune systems means white blood cells can’t kill bacteria as easily

Question 9

What are the symptoms of HIV?

Answer 9

• initially causes flu-like illness
• fever
• headache
• rash
• rapid weight loss
• chronic diarrhoea

Question 10

How is HIV transmitted?

Answer 10

• spread through exchange of body fluids through sexual contact e.g. semen, pre-seminal fluids, rectal fluids, vaginal fluids
• exchange of body fluids which occurs when drug users exchange needles
• can also be spread through breast milk

Question 11

How can the spread of HIV be prevented/controlled?

Answer 11

• use condoms
• ensure you and any partners are STD tested
• don’t injects drugs/share needles
• screening blood when it is used in blood transfusions
• mothers with HIV bottle-feeding their children instead of breastfeeding
• if your are at high risk of HIV from sex or injecting drugs, taking HIV medicines daily, called pre-exposure prophylaxis (or PrEP) reduces risk of HIV infection

Question 12

What is the treatment for HIV?

Answer 12

• no cure for disease
• use of antiretroviral drugs to stop viruses replicating in body and to stop the development of AIDs (late stage of HIV)

Question 13

What happens if HIV is not successfully treated?

Answer 13

• if HIV not successfully controlled by antiretroviral drugs the HIV virus attacks the body’s immune system
• HIV virus attacking immune systems means white blood cells can’t kill bacteria as easily
• leads to late stage HIV or AID’s when body’s immune system so badly damaged can no longer deal with other infections or cancers

Question 14

What type of pathogen is TMV?

Answer 14

• virus
• a widespread plant pathogen which affects many species of plants inc. tomatoes

Question 15

What was the 1st virus to be discovered?

Answer 15

TMV

Question 16

How is TMV transmitted?

Answer 16

• direct between diseased and healthy plants
• indirect contact e.g. plants infected via plant wounds after human handling, via contaminated equipment
• virus can also contaminate seeds which grow into infected plants
• through vectors e.g. insects

Question 17

What are the symptoms of TMV?

Answer 17

• distinct ‘mosaic’ pattern of discolouration on surface of leaves which affects growth of plants due to lack of photosynthesis
• virus doesn’t usually cause plant to die, but can seriously stunt its growth

Question 18

What is the treatment for TMV?

Answer 18

no cure or treatment for TMV

Question 19

How can the spread of TMV be prevented/controlled?

Answer 19

• diseased plant should be dug up and burnt
• practice good field hygiene throughout entire growing season
• remove decaying leaves from plant and surrounding soil
• burn all parts of infected plant, never put them on compost heap or dig them into soil
• wash hands thoroughly and disinfect all gardening implements after handling infected plants
• regularly inspect plants for signs of TMV infection
• pest control
• TMV resistant strains

Question 20

How does TMV negatively affect the growth of a plant?

Answer 20

discolouration on leaf caused by TMV means there is less chlorophyll made so less photosynthesis takes place so less glucose/starch/protein so less glucose used for respiration so less energy released for growth reducing growth