module 4.1: communicable disease Flashcards
what is a pathogen
a microorganism that causes a disease
what is a host
the organism in which the pathogen lives in
how do pathogens live
by taking nutrition from their host, but also cause damage in the process
what is the kingdom that bacteria belongs to
prokaryotae
can bacteria reproduce rapidly or slowly
slowly
what is the cause of reproduced-rapidly bacteria
causes disease by damaging cells or releasing waste products and/or toxins that are toxic to the host
what is the effect of bacteria in plants and what does it live
the bacteria can often live in the vascular tissues
causes blackening and death of these tissues
where does fungi normally live
lives under the skin where it is hyphae, which forms a mycelium which grow under the skin surface
what does fungus sending out specialised reproductive hyphae do
grow to the surface of the skin to release spores which causes redness and irritation
in plants, where does the fungus live
in the vascular tissue, where it gains nutrients
what does the hyphae do in plants
it releases extracellular enzymes eg. cellulases, to digest the surrounding tissue, which causes decay
what will fungus do to plants overall
leaves will often become mottled in colour , curl up and shrivel, before dying. fruit and storage organs, such as tubers (potatoes), will turn black and decay
what do viruses do
- invade cells
- take over the genetic machinery and other organelles of the cell
- they then can cause the cell to manufacture more copies of the virus
- these will eventually burst, releasing many new viruses which will infect healthy cells
how do protoctista harm organisms
- enter host cell
- feed on the content as they grow
what are the examples of pathogens (bacteria)
tuberculosis
bacterial meningitis
ring rot in plants
what are the examples of pathogens (virus)
HIV/AIDS
influenza
tobacco mosaic virus
what are the examples of pathogens (fungus)
black sigatoka in banana plants
ringworm in cattle
athlete’s foot
what are the examples of pathogens (protoctista)
malaria
blight
what causes tuberculosis
Mycobacterium tuberculosis and M.bovis
what does tuberculosis affect
affects many parts of the body, killing the cells and tissues. the lungs are often the most affected
what is bacterial meningitis caused by
the bacteria Neisseria meningitidis or Streptococcus pneumonia
what does Bacterial Meningitis affect
it is an infection of the meninges, that is, the membranes that surrounds the brain and spinal cord
- the membranes become swollen, which may cause damage to the brain and nerves
what is ring rot in plants caused by
bacterium Clavibacter michiganensis susp. Sepedonicus
what does ring rot in plants affect
ring rot is a disease causing a ring of decay in the vascular tissue of the potato tuber, accompanied by leaf wilting
what is HIV/AIDS caused by
human immunodeficiency virus
what does HIV/AIDS affect
it attacks cells in the immune system and compromises the immune response
what is influenza affected by
viruses from the Orthomyxoviridae family
what does influenza affect
it attacks the respiratory system and causes muscle pains and headaches
what is tobacco mosaic virus caused by
a virus of the same name
what does tobacco mosaic virus affect
it causes mottling and discolouration of leaves
what is black sigatoka in banana plants caused by
the fungus Mycosphaerella fijiensis
what does black sigatoka affect
causes leaf spots on banana plants and reduces yield
what is blight caused by
the protoctistan Phytophthora infestans
what does blight affect
affects tomatoes and potatoes, particularly the leaves and (in potatoes) the tubers
what is ringworm in cattle caused by
the fungus Trichophyton verrucosum
what does ringworm in cattle affect
growth of the fungus in the skin causes spores to erupt through the skin, causing a rash
what is athletes foot caused by
the fungus trichophyton rubrum
what does athletes foot affect
grows under the skin on the feet, particularly between the toes
what is malaria caused by
the protoctistan Plasmodium falciparum, P. vivax, P. ovale, or P. malariae
what does malaria affect
it is a parasite in the blood that causes headache and fever and may progress to coma and death
what is direct transmission
passing a pathogen from host to new host, with no intermediary
what is indirect transmission
passing a pathogen from host to new host, via a vector
what is transmission
passing a pathogen from an infected individual to an uninfected individual
what is a vector
an organism that carries a pathogen from one host to another
in short, what is the life cycle of a pathogen in their host
- travel from one host to another (transmission)
- entering the host’s tissues
- reproducing
- leaving the host’s tissues
what are the different types of direct transmission
- direct physical contact
- faecal-oral transmission
- droplet infection
- transmission by spores
describe how pathogens are transmitted by physical contact
touching a person who is infected or touching contaminated surfaces (including soil) that harbour the pathogens
how can pathogen transmitted by direct contact be prevented
better hygiene (i.e: washing hands regularly — especially after using the toilet, keeping surfaces clean — especially door handles, cleaning and disinfecting cuts and abrasions, sterilising surgical instruments, and using condoms during sexual intercourse
describe how pathogens transmitted by faecal - oral
usually by eating food or drinking water contaminated with the pathogen. For example food poisoning and cholera
how can faecal-oral transmission be prevented
by not using human sewage as crop fertiliser, and by treating wastewater and drinking water, as well as by thoroughly washing fresh food (using treated water), and via careful preparation (i.e: thoroughly cooking all food)
describe how pathogens are transmitted by droplets
the pathogen is carried in tiny water droplets in the air
how do we reduce the risk of droplet infection
by covering your mouth when coughing or sneezing. use a tissue and ensure the tissue is disposed of correctly
describe transmission by spores
these can be carried in the air or reside on surfaces or in the soil
how do you reduce transmission by spores
by wearing a face mask and washing skin after contact with soil
what are some social factors that affect transmission
. overcrowding — many people living and sleeping together in one house
. poor ventilation
* poor health — particularly if a person has HIV/AIDS, as they are more likely to contract other diseases
* poor diet
* homelessness
* living or working with people who have migrated from areas where a disease is more common
why is tuberculosis not transmitted easily but still could be spread
it often takes living in close proximity to people with the disease for a long time before it is transmitted. the BCG vaccination given to teenagers successfully reduced the prevalence of tuberculosis in Western Europe
- however, with increased migration and many economic migrants living in overcrowded, poorly ventilated conditions, the incidence of tuberculosis is rising in many Western cities
what is the life cycle of Plasmodium
- a female anopheles mosquito sucks blood from a person infected with malaria
- the plasmodium develops from the gametes in the infected blood and migrates to the salivary glands of the mosquito
- the mosquito bites an uninfected person
- the plasmodium from the mosquito migrate into the person’s liver
- the plasmodium then migrate into their blood
- the person now has malaria
describe the transmission in plants
plant pathogens can also be spread by direct and indirect means
- many pathogens are present in the soil and will infect plants by entering the roots — especially if these have been damaged as a result of replanting, burrowing animals or movement caused by a storm
- any fungi produce spores as a means of sexual or asexual reproduction. these spores may be carried in the wind — airborne transmission
- once a pathogen is inside the plant, it may infect all the vascular tissue. pathogens in the leaves are distributed when the leaves are shed and carry the pathogen back to the soil where it can grow and infect another plant
- pathogens can also enter the fruit and seeds, and will then be distributed with the seeds — so that many or all of the offspring are infected
- indirect transmission of a pathogen often occurs as a result of insect attack. spores or bacteria become attached to a burrowing insect, such as a beetle, which attacks an infected plant – when that beetle attacks another plant, the pathogen is transmitted to the uninfected plant. The beetle is acting as a vector
how does disease and climate affect the transmission of plant pathogens
- many protoctists, bacteria and fungi can grow and reproduce more rapidly in warm and moist conditions
- as global warming alters our climate tropical pathogens will be able to survive more easily in Europe
- tropical diseases may become more common in Europe as a result