communicable disease Flashcards
(27 cards)
what is a communicable disease
an illness due to specific infectious agent or its toxic products that arise through transmission of that agent or its products from an infected person animal or inanimate reservoir to a susceptible host either directly or indirectly
communicable period
the time during which an infectious agent may transfer indirectly or directly from an infected person to another person, from an infected animal or humans or from an infected person to animals including athropod
how can harmful organisms can be spread/enter the body
- indirect contact
- direct contact
- blood transfusions
- placenta
- breast milk
- vectors - mosquitos
what is cholera
- an infection by the bacteria
- infects small intestine of humans, causing profuse watery diarrhoea, vomiting and muscle cramps
- transmitted via the faecal-oral route
what is malaria
- caused by?
- transmitted by?
- caused by parasites of the plasmodium group
- transmitted via mosquitoes
- an endemic disease
what is tuberculosis
- caused by?
- spread by?
- cauased by a species of Mycobacterium. (mycobacterium tuberculosis) and is mainly a disease of the lungs
- its an airborne disease (human - human via droplets in the air
what is HIV/AIDS
- caused by?
- transmitted by?
- caused by the human immunodeficiency virus which attacks key cells in the immune system, over time the infected person developts aquired immunodeficiency syndrome (AIDS)
- trasmitted through certain bodily fluids:
sexual transmissioon
injection into the blood stream when sharing needles, verticle transmission (passing of the virus from an infected mother to her baby
breast feeing
what are viruses found as
intracellular parasites in all kinds of organisms including humans and other animals, plants, fungi, bacteria and protists
3 stages of a viral infection
- attachment - viral particle encounters outer surface of body cell, attaches to receptor sites of proteins on the cell’s plasma membrane
- penetration - host cell engulfs virus by endocytosis
- uncoating - digestion of the capsid releases the viral DNA, which is replicated in the host cells nucleus using viral enzymes
viral proteins are synthesized in the cytoplasm, using the hosts enzymes to form new viral particles. after maturing, these are released to infect other cells
what is influenza
+ who is more at risk
’ the flu’
contagious respiratory illness caused by any of of the many influenza virus.
- older people, young children and people with certain health conditions are at higher risk for serious flu complications
influenza symptoms
- high fever
- headache
- fatigue
- dry cough
- nausea
endemic, epidemic and pandemic meaning
endemic - constantly present in a certain population, with relatively low spread
epidemic - when there is a sudden increase in cases spreading through a large population like a country
pandemic - when there is a sudden increase in cases spreading through several countries, continents or the whole world
what is the vector of malaria
the female anopheles mosquito
–> has adapted mouthparts so a fine tube penetrates a blood vessel
how is malaria transmitted
- infected mosquito bites human
- plasmodia in mosquitoes saliva enter bloodstream
- plasmodia invade liver where they multiply, produce gametes and infect blood
- another mosquito picks up gametes in blood after a bite
- sexual reproduction in the mosquitoes intestine produces plasmodia which migrate to salivary glands
- mosquito infects more individuals
explain the reproduction of malaria in plasmodia
- plasmodia invade red blood cells and multiply
- plasmodia reproduce asexually in the blood
- red blood cells rupture, releasing plasmodia
- some plasmodia invade more red blood cells
symptoms of malaria
symptoms appear from one week to a year and are usually severe e.g.
- headache
- vomiting
- shivering
- joint pain
- fever
why are vaccines difficult to treat malaria
- different forms of the parasite all have different antigens (proteins) on their surface
- vaccines work by stimulating production of antibodies
- antibodies which “recognise” and destroy one form of the parasite would be useless against another form
strategies to control malaria
reducing mosquito numbers –> stock ponds with fish to each mosquito, oil on surface, spray with insecticide
avoiding being bitten –> insect repellent, mosquito nets, long clothing
drugs –> malaria drugs (anti malarial) before infection
black sigatoka
- caused by
- infects
- transmitted
- caused by a fungus
- infects banana plants
- transmitted via spores in the wild + direct contact. Spores germinate and grow into the leaf via the stomata
late blight
- caused by
- infects
- transmitted by
- caused by a fungus-like protoctist
- infects potato and tomato plants
- trasmitted by spore-like structures in the wind + direct contact
ring rot
caused by
infects
trasmitted
- caused by a bacterium
- infects potatoes, tomatoes and aubergines
- transmitted through contaminated equipment or infected water
tobacco mosaic virus
- caused by a virus
- infects tobacco plants, tomatoes, peppers and about 150 other plant species
- transmitted through damaged tissue via direct contact from humans or equipment
physical barriers for how plants defend against disease
- waxy cuticle
- bark of trees
- cellulose cell walls
- lignified cell walls
what is cellulose and what is it used for
a carbohydrate made of beta glucose monomers attaached with 1-3 glycosidic bonds and sometimes 1-6 , forming helical structures
- used to strength cell walls
- blocks sieve plates in the phloem, sealing off the infected cells and preventing spread via this transport system
