B5 - communicable diseases

communicable diseases definition

• communicable diseases are caused by pathogens such as bacteria n viruses

• can be passed on from one person to another

non-communicable diseases definition

non-communicable diseases cannot be transmitted from one person to another

factors affecting health

• diet:

  • if you don’t eat enough nutrients you may suffer from starvation, anaemia or rickets.

  • if you eat too much, of the wrong food you may suffer from obesity, some cancers or type 2 diabetes.

• stress:

  • high levels of stress can lead to multiple health problems.

  • include heart diseases, certain cancers n mental health problems.

• life situations - include:

  • where you live

  • gender

  • financial status

  • ethnic group

  • levels of free healthcare

  • number of children

  • local sewage n rubbish disposal

how do pathogens cause diseases?

• bacteria rapidly divide (binary fission), produce toxins which cause the feeling of illness.

• sometimes they directly damage the cells.

• viruses take over the cells of your body, live n reproduce inside the cell, destroying them.

ignaz semmelewis discovery

• he insisted that his medical students wash their hands before delivering babies

• this decreased the amount of deaths caused by infection in child delivery.

other discoveries

• louis pasture developed vaccines against diseases.

• joseph lister started to use antiseptic chemicals to destroy pathogens.

• microscopes improved, it became possible to see pathogens.

preventing the spread

hygiene

• hand washing

• using disinfectants

• keep raw meat away from cooked food

• maintaining hygiene of people working in agriculture

• coughing n sneezing into a tissue

vectors

• destroying vectors

• controlling vectors

vaccinations + isolating individuals

• giving individuals vaccinations

• isolating individuals

measles

• measles is a virus spread by droplet infection.

• causes rashes and fever.

• prevent spread by isolation or vaccinations.

HIV

• flu type illness

• early stage can be controlled by antiretroviral drugs

• virus attacks the immune system

• spread by sexual contact or exchange of fluids

tobacco mosaic

• tobacco mosaic virus is spread by contacts n vectors

• damages leaves n reduces photosynthesis

• prevented by field hygiene n pest control.

salmonella

• salmonella is spread through undercooked food n poor hygiene

• can cause fever, abdominal cramps, diarrhoea, n vomiting by toxins (produced by bacteria)

• poultry are vaccinated to prevent spread

gonorrhoea

• gonorrhoea is a sexually transmitted disease

• can cause discharge from genitals, pain in urination

• can be treated with antibiotics.

• use condoms n limit sexual partners to prevent spread

rose black spot

• rose black spot is a fungal disease of plants where purple or black spots develop on leaves, which often turn yellow and drop early

• it affects the growth of the plant as photosynthesis is reduced

• it is spread in the environment by water or wind

• rose black spot can be treated by using fungicides n/or removing n destroying the affected leaves

malaria

• malaria is caused by parasitic protists

• it is spread by the bite of a female mosquito

• which damages the red blood cells, n causes fevers n shaking.

• the spread of malaria is controlled by preventing mosquitos, from breeding n by using mosquito nets to avoid bites

protists

• protists group of eukaryotic n usually unicellular organisms

• only a small number of protists are pathogenic, but the diseases they cause are often serious

• need a vector to transfer from one host to the next

non-specific defences

• the non-specific defence systems of the human body against pathogens include:

  • skin

  • nose

  • trachea n bronchi

  • stomach

phagocytes

• phagocytes engulf n digest pathogens, this can be non-specific or helped by antibodies which cause clumping of pathogens

• phagocyte surrounds the pathogen n releases enzymes to digest n break it down to destroy it

lymphocytes

• lymphocytes produce antibodies.

• antibodies are Y-shaped proteins – each individual has the potential to make millions of different types of antibodies, each with a slightly different shape

• antibody production aims to produce the antibody that is complementary to the antigens on the surface

lymphocytes

• lymphocytes can produce antitoxins

• these counteract the toxins released by pathogens

pathogens spread through air

• bacteria, fungal spores n viruses spread through air

• spread through droplet infection

• droplet infection is caused by coughing/ sneezing - others breathe in the pathogens

pathogens spread through contact

• direct contact

• animals can act as vectors

• sexually transmitted diseases r spread through contact

  • cuts

  • scratches

  • needles

pathogens spread through water

• fungal spores in water can spread

• eating raw food n sewage

• diarrhoea, cholera n salmonella spread