Communicable Diseases: animal and plant diseases Flashcards
How do plant diseases affect people?
Crop plants fail - people suffer. May starve, decline in economy and unemployment. Can threaten ecosystems.
Describe ring rot
Bacterial disease of potatoes, tomatoes and aubergines. Caused by Gram positive bacterium Clavibacter michiganensis.
Damages leaves, tuber and fruit.
Destroys up to 80% of crop and no cure. Fields cannot be used for 2 years after infection.
Describe tobacco mosaic virus (TMV)
Infects tobacco plants and 150 other species, like tomatoes, peppers, cucumbers, petunias, delphiniums.
Damages leaves, flowers, and fruit, stunting growth and reducing yield.
No cure.
Describe potato blight (tomato blight and late blight)
Caused by fungus-like protoctist oomycete Phytophthora infestans.
Hyphae penetrate host cells, destroying leaves, tuber, fruit.
No cure - needs management, chemical treatments and resistant strains.
Describe black sigatoka
Banana disease from fungus Mycosphaerella fijiensis.
Attacks and destroys leaves. Hyphae penetrate and digest the cells, turning the leaves black.
Can cause a 50% reduction in yield.
Resistant strains being developed - good husbandry and fungicide treatment can control the spread.
No cure.
How do animal diseases affect humans?
Effect human health and damage economies. Range from mild to fatal.
Describe tuberculosis (TB)
Bacterial disease of humans, cows, pigs, badgers and deer.
Caused by Mycobacterium tuberculosis and M.bovis.
Damages and destroys lung tissue and suppresses the immune system.
People affected by HIV/AIDS are more likely to develop TB infections.
Curable by antibiotics and preventable by improving living standards and vaccination.
Describe bacterial meningitis
Bacterial infection of Streptococcus pneumoniae or Neisseria meningitidis of the brain meninges.
Can spread to the rest of the body causing septicaemia and death.
Affects very young children and teenagers 15-19.
Blotchy red/purple rash that does not disappear when pressed with a glass.
25% have permanent damage.
Antibiotics can cure and vaccines can protect.
Describe HIV/AIDS
AIDS caused by HIV which targets T helper cells in the immune system.
Gradually destroys the immune system so people are more susceptible to other diseases, like TB, pneumonia and cancer.
HIV is a retrovirus with RNA as genetic material. Contains enzymes reverse transcriptase, so RNA transcribes a single strand of DNA in the host cell.
Passed by bodily fluids, through unprotected sex, shared needles, contaminated blood products and from mothers to babies during pregnancy, birth or breast feeding.
No vaccine and no cure, but anti-retroviral drugs slow progression.
Describe influenza (flu)
Viral infection from Orthomyxoviridae of ciliated epithelia cells. Kills them, making airways open to secondary infection.
Fatal in young children, elderly and those with chronic illness.
Affects humans, pigs, birds and chickens.
3 strains - A, B, C. Strain A is most virulent and classified further by proteins on the surface e.g. A (H1N1) and A (H3N3). Mutate regularly.
Flu vaccines given annually to protect. No cure.
Describe malaria
Protoctista Plasmodium and spread by bites of infected Anopheles mosquitos.
Plasmodium has complex life cycle, reproducing in the female mosquito. Females need 2 blood meals to gain protein for egg laying. This is where the disease passes to humans.
Invades red blood cells, liver and the brain.
Disease recurs giving vulnerability to other diseases.
No vaccine and limited cures.
Have to control the vector. Killed by insecticides and removing standing water to stop breeding.
Nets, long sleeved clothing can prevent biting and spread.
Describe ring worm
Fungal disease affecting cattle, dogs, cats and humans.
In cattle this is caused by Trichophyton verrucosum.
Grey-white, crusty, infectious, circular areas on the skin.
Not damaging but unsightly and itchy.
Anti-fungal creams.
Describe athletes foot
Fungal disease of Tinia pedia.
Form of human ring worm, that grows and digests warm, moist skin between toes.
Cracking and scaling, which is itchy and sore.
Anti-fungal creams.
