Communicable Diseases

• Direct contact 
• Exchange of body fluids e.g. blood or saliva
• Air
• Food or water
• Vectors e.g. insects

• Hygiene e.g proper sanitation and cleaning facilities
• Vaccination 
• Isolation - keep a person from direct contact or exchange of body fluids
• Controlling vectors
• Barrier cntraception e.g. condoms

Cause:

Person eating food containing bacteria or the food is prepare in unhygienic conditions. The salmonella bacteria secretes toxins.

Symptoms:

Fever, cramps, vomiting, diarrhoea.

How to reduce it:

Poultry are vaccinated tor reduce the risk of chicken products containing salmonella.

Type of STI

Cause:

Type of bacteria spread through sexual contact.

Symptoms:

Thick yellow/green discharge from penis or vagina and pain on urinating.

Prevention:

Barrier method e.g. condom.

Treatment:

Penicillin, however there are types of penicillin resistant bacteria which makes treatment difficult.

Cause:

Caused by bacteria spread through air. The bacteria has a thick waxy coat and it lies dormant for many years. 

Symptoms:

Bacteria attacks respiratory system which causes lung damage, coughig, fever and fatigue.

Treatment:

A course of antibiotics. 3/4 are taken daily fo six months to fight the drug resistant strains. 

Prevention:

BCG vaccination is 50 - 80% effective but its very expensive.

Cholera - infects small intestine and causes diarrhoea and sever dehydration. Spread by water.

Chlamydia - STI that causes penis/vagina discharge and ain on urination

Heliobacter - infects stomach where they attack lining and causes stoa=mach ulcers and spread by saliva.

Caused:

Virus spread by inhaling sneeze and cough droplets

Symptoms:

Fever, red skin rash across the body and can be fatal if there are complications

Treatment:

No specific tratment, doctors treat symptoms and hope patients immune system can fight the virus - several weeks

Prevention:

Vaccination - MMR at 15 months

Cause:

Sexual contact, exchage of body fluids e.g. blood

Symptoms:

Flu - like

Treatment:

Antivetroviral drugs to try to control the virus

The virus can enter lymph nodes which attacks body's immune cells

Could lead to: AIDS (more susceptible to infections)

Influenza:

Sypmtoms: fever, sore throat, runny nose and muscle ache

Prevention: flu vaccines for the some strains - there are many

Ebola:

Causes: contact and infected body fluids

Symptoms: flu like but can cause haemorrhagic fever and internal bleeding which has high risk of death

• Eukaryotic organisms
• Unicellular or multicellular
• Some produce toxins - harm plants and animals
• Reproduce by releasing airborne spores
• Atletes foot is common in humans
• Many plant fungal diseases causing huge crop loss

Causes:

Airborne fungal spores which the wind spreads for miles 

Symptoms:

Affects ash trees by causing leaf loss and bark lesions - FATAL

Treatment:

No treatment 

Prevention:

Infected tress cut down and burnt 

Causes:

Fungal spores spread through water or blown around and germinate on a new plant

Symptoms:

Purple balck patches and early leaf loss - can die

Treatment + Prevention:

Chemical fungicides used to kill fungus oon affected plants and controll spread of disease

Majority of protists are single celled and microscopic

Types of protists: algae, amoebas + slime moulds

Protists are parasites of animals e.g. protist that causes malaria

Causes:

Malarial protist spread by female mosquitoes vectors and as they feed on blood and infects human with malaria.

Symptoms:

Repeated episodes of fever; blood and liver damage - potentially fatal

Prevention:

• Killing mosquitoes or preventing them from breeding
• Avoid being biitten by mosquitoes using a repellent or sleeping under a mosquito net
• Prevent malaria developing if you're infected by taking anti malarial medicine

Skin - protects body from physical damage, dehydration, entry of microorganisms.

Blood - When the skin is cut the platelets in the blood clot at the site of the wound and this stops microorganisms entering damaged surface.

Muceous membranes - lines trachea, bronci in the lungs and the nose. Mucus secreted traps microorganisms in the passageways. 

Lungs - Cilia transports mucus and trapped microorganisms across membrane surface and out of the body.

Eyes - tears in the eyes contain lysozyme which kill bacteria

Stomach - HCl in stomach creates low pH environment destroying microorganisms

Sweat - produced by skin contains chemicals that kill microorganisms

• Spots on leaves
• Growths
• Discolouration
• Malformed stems and leaves
• Areas of decay
• Stunted growth
• Presence of pests

Causes:

Bacteria that enters plant through wounds on roots or stem

Symptoms:

Plant tissues grow abnormally and produce swellings called galls and pprevents plant from being able to transport water and nutrients

Prevention:

Infected plants removed

Cell walls: Made of cellulosethat helps protect plant cells from being invade. To breakk it microorganisms have to produce special enzymes

Leaf cuticle: reduces water loss by evaporation and prevents fungi, bacteria and fungi from entering  the leaf tissue.

Plant stems: surrounded by a layer of dead plant cells that are tough and wwody that is difficult for herbivores and pathogens to penetrate

Thorns and hairs: slows down rate at whcich herbivorous animals can feed on a plant. The hairs are used to defend plants from insects.

Spines: they're sharp to make it difficult for herbivores to reach the plant tissue. 

Moving leaves: curl or droop when touched to reduce surface area of the leaf  available for the herbivores to eat or dislodge insects from plants

Mimicry: adapt to look like other plants to prevent herbivores eating them

Antimicrobial chemicals: kills or slows growth of pathogens. Some target specific pathogens and some are effective against a range of pathogens.

Poisons: have a bitter taste so herbivores don't eat them. Some cause severe side effects and death.