B5 communicable diseases Flashcards
What is the difference between communicable diseases and non-communicable diseases?
Communicable diseases are caused by pathogens that can be passed from one person to another
Non-communicable diseases cannot be transmitted from one person to another
What are some factors that can affect health?
diet
-lack of nutrients, food, ED, obesity
stress
-too much, linked to range of health problems (heart disease, cancer)
life situations
-area, gender, financial status, ethnic group, level of free health care
(communicable diseases- diarrhoea, malaria)
(non communicable diseases- heart disease, cancer)
illness
What is a communicable disease?
it is an infection that is caused by pathogens such as bacteria and viruses
can be passed from one person to the other (infectious)
(tuberculosis, flu)
What is a non-communicable disease?
cannot be transmitted from one person to the other
(heart disease, arthritis)
What illnesses can viruses lead to?
can trigger changes leading to cancers
HPV (human papilloma virus-> cervical cancer)
What can defects in the immune system be the result of?
-genetic makeup
-poor nutrition
-infection (HIV/AIDS)
What can defects in the immune system lead to?
higher risk of suffering from communicable diseases
What are immune reactions caused by?
pathogens
ie reaction to common cold
What can immune reactions lead to?
trigger allergies to environmental factors
cause skin rashes, hives, asthma
How are physical and mental health linked?
severe physical ill health can lead to mental illnesses (depression etc)
What does malnutrition lead to?
health issues
-deficiency diseases
-weakened immune system
-obesity
-cardiovascular diseases
-type 2 diabetes
-cancer
What are microorganisms that cause disease called?
Pathogens
infect animals and plants, causing disease
What are some examples of pathogens?
bacteria, viruses, protists, fungi
What are communicable diseases caused by?
- directly by a pathogen
- by a toxin made from a pathogen
How are communicable diseases passed?
from one infected individual to another uninfected individual
What are some examples of communicable diseases?
-common cold, tonsillitis
-tetanus, influenza, HIV/AIDS
What is an example of a communicable disease passing between different species?
- infected dogs can pass rabies onto people
- tuberculosis can pass from badgers to cows, cows to people
What are the most common pathogens in plants?
viruses and fungi
What are bacteria?
single celled living organisms
smaller than animal and plant cells
living (can survive outside a host)
can be treated by antibiotics
What are some uses for bacteria?
- make food (yogurt, cheese)
- treat sewage
- make medicine
- decomposers in the environment and body
What are the most common pathogens in humans?
Bacteria and Viruses
What is a virus?
even smaller than bacteria
non living
cannot be treated by antibiotics
How do bacteria cause disease inside the body?
-divide rapidly by splitting in 2 (Binary fission)
-may produce toxins that affect the body (cause symptoms)
- sometimes directly damaging the cell
How do bacteria divide/reproduce?
binary fission
How does a virus cause disease inside the body?
- take over the cells in the body
- live and reproduce inside the cell
- damage and destroy cells
What are common symptoms of disease?
- high temperature
- headaches
- rashes
caused by the body responding to the pathogens toxins and cell damage
How do pathogens spread?
Through the air
-droplet infection, human expel tiny droplets with pathogens from breathing system when coughing, sneezing or talking. Others breathe in the droplets
-flu, influenza, common cold
Direct contact
- common in plants
-infected leaf left in field can infect entire new crop
-humans, STI (syphilis, chlamydia), direct contact of skin
-HIV/AIDS, hepatitis enter through direct sexual contact, bodily fluids (cuts, scratches, needle punctures)
-animals can be a vector of plant and animal diseases (carrying pathogen between infected and uninfected individuals)
By water
-plants. fungal spores carried in splashes of water
-humans, eating raw, uncooked, contaminated food. Drinking water containing sewage
(salmonella, cholera)
- enters through digestive system
Lifestyle factors
- crowded living conditions, no sewage system etc
What is a vector?
a carrier of a pathogen between infected and uninfected individuals, can be between different species
can carry plant and animal pathogens
(ie mosquito)
What is a culture medium?
a liquid or gel containing nutrients
What are conditions microorganisms need to grow?
- warmth
- oxygen
- culture medium (carbohydrate, minerals, nitrogen source, chemicals)
How can cultures become contaminated?
skin, air. soil, water around
What is a mutation?
a change in the DNA
in pathogens it can create a new and dangerous pathogen
Why is the maximum temperature for culture incubation in schools 25 degrees C?
- 37 degrees is human body temperature
- high risk of growing dangerous pathogens
- low temp, reduce risk of growing harmful bacteria
Why are industries allowed to incubate cultures at 37 degrees C?
- enables microorganisms to grow quicker
- can be used for use faster
What is the growth rate of bacteria affected by?
- temperature
- available nutrients
- oxygen levels
- pH
How can you prevent the growth of bacteria?
-raise or lower the temperature
- chemicals to stop them growing/killing them (disinfectant for environment around, antiseptic for human skin, antibiotics inside the body)
Ignaz Semmelwies + what did he discover?
He was a doctor mid 1850’s
-Many women were died from childbed fever a few days after birth, no cause
-he noticed medical students didn’t wash their hands between dissecting corpses to delivering babies. He thought they could be carrying disease from the bodies to the patients
- he insisted medical students wash their hands before delivering babies
Louis Pasteur + Joseph Lister -> what did they discover?
Mid to late 19th century
Louis Pasteur: showed microorganisms caused disease, developed vaccines (anthrax, rabies)
Joseph Lister: used antiseptic chemicals in operating theatres to destroy pathogens before causing any infection
How can hygiene prevent the spread of communicable diseases?
- hand washing (after toilet, before cooking, after animal contact etc)
- using disinfectant (kitchen surfaces, toilets, reduce number of pathogens)
- keeping raw meat away from food eaten uncooked (prevent pathogen spread)
- coughing/sneezing into handkerchief, tissue, hands (then wash hands)
- maintaining hygiene of people and agricultural machinery (prevent spread of plant disease)
How can isolating infected individuals prevent the spread of communicable diseases?
-less amounts of healthy people come into contact with them
-less likely pathogens pass on
- same for plants
- only works for small, movable plants
How can destroying or controlling vectors prevent the spread of communicable diseases?
spread of diseases can be prevented or reduced
- houseflies carry human disease
- mosquitos carry a range of disease (malaria, dengue fever)
How do vaccination work to prevent the spread of communicable diseases?
- doctors introduce a small amount of dead or inactive form of a specific pathogen to the body
- prepares the immune system for the live pathogen. If there becomes contact with live pathogen, body won’t be ill
- success protecting large numbers of humans and animals
- cannot protect plants, no immune system
What is Measles and how is it spread?
- fever, red rash
- spreads through droplet infection
- can cause blindness, brain damage, death
- no treatment, if infected then person must isolate
-rare in the UK
What is HIV/AIDS?
- HIV leads to AIDS
- HIV: mild, flu like illness, attacks immune cells. remains inside immune system until system is so badly damaged it can’t deal with other infections, or cancers.
- Then it has become AIDS
onset of AIDS depends on - level of nutrition
- overall health
- access to antiretroviral drugs
How is HIV spread?
- direct sexual contact, exchange of bodily fluids (ie blood, drug users share needle, unscreened blood used for transfusion)
- passed from mother to child from breast milk
no cure, spread can be prevented
-use condoms
- not sharing needles
- screening blood
- HIV positive mothers bottle feeding children
What is TMV?
- widespread plant pathogen affecting over 150 species of plants (ie tomatoes, tobacco plants)
- causing distinct mosaic patterns on leaves, virus destroys plant cells
- affects the growth of the plant, affected areas don’t photosynthesise, reducing crop yield
How is TMV spread?
- by contact between diseased plants and healthy plants
- insects can act as vectors
- virus can remain infection in soil for about 50 years
- no treatment, farmers now grow TMV restraint-strains, also good field hygiene and good pest control prevents spread.
What are Salmonella?
- bacteria that live in the guts of many different animals.
- found in raw meat, poultry, eggs and egg products (mayonnaise)
- can cause salmonella food poisoning if ingested
- causes of infection: eating undercooked food, eating food prepped in unhygienic conditions
Salmonella + symptoms?
symptoms develop within 8-72 hours
- abdominal cramps, vomiting, diarrhoea
- caused by secreted toxins
- can be fatal in young children and elderly
- more serious in countries with malnutrition
What are ways of preventing Salmonella?
- poultry are vaccinated against Salmonella in the UK
- keep raw chicken away from food eaten raw/uncooked
- avoid washing raw chicken
- wash hands and surfaces thoroughly
- cook chicken thoroughly
What is Gonorrhoea?
-STD
- spread by unprotected sexual contact with infected person
- early stages have symptoms, then becomes symptomless
- early symptoms: thick yellow/green discharge from the vagina or penis, pain on urination
- untreated, can cause long term pelvic pain, infertility, ectopic pregnancies
- bacterial, can be treated with antibiotics, however their are antibiotic resistant strains
- all sexual partners of infected individual should be treated to prevent further spread
- prevent spread by using barrier method (condom), reduce number of sexual partners
What are examples of bacterial diseases in plants?
-rose black spot
-usually found in tropical and sub tropical regions
Agrobacterium tumefaciens- causes crown galls (mass of unspecialised cells between the root and the shoot of growing plants)
-insert plasmids into plant cells, cause mass to grow
-scientists can make use of this: manipulate bacteria so they carry desirable genes to infect plant cells with.
What are fungal diseases + examples?
Athletes foot- fungal skin condition
- fungal diseases can be fatal when attack the lungs or brains or ill people
- can develop damaged heart valves
- antifungal drugs, but hard to treat deep tissue infections
Plants
- common, huge crop areas are lost yearly
- stem rusts, rotting diseases
What is Rose black spot?
fungal disease of rose leaves
- causes purple/black spots on leaves
- bad for gardens or commercial flower growers
- leaves often turn yellow, drop early, reduces photosynthesising area, plant doesn’t flower well
- spores carried by wind, spread by rain drops splashing from leaf to leaf.
- stay dormant over winter on stems and dead leaves
- can prevent by burning or removing dead leaves, chemical fungicides
- specially bred roses resistant to black spot, disease still can’t be prevented or cured
What are protists?
a type of single celled organisms
- cause range of diseases, relatively rare pathogens
- carried diseases often serious and damaging
-usually involve a vector (mosquitos etc) to transfer to host (ie malaria)
What is Malaria?
- disease caused by protist pathogens, parasites (live and feed on other living organisms)
- lifecycle-> time in human body and time in female mosquito body
- reproduce sexually in mosquito but asexually in human body
- mosquito feeds 2 meals of human blood before laying eggs, protist passed into bloodstream
- protist travels human body through bloodstream
- protists burst out of blood cells: causes human body a fever and shaking
- can be fatal or weakening
How can Malaria be treated?
- combination of drugs (not always available in countries with malaria problems)
- Protists can become resistant
- using insecticide-impregnated mosquito nets (prevent mosquitos biting humans
- use insecticide to kill mosquitos in home, office etc
- remove standing water, spray water with insecticide to kill larvae (remove breeding ground)
- antimalarial drugs (travellers), kills parasites if in blood.
What are the skin defences to pathogens?
- barrier. prevents bacteria and viruses reaching tissue beneath. Cuts break barrier, restored by body by platelets to clot the cut and scab. Forms a seal over the cut, stops pathogens entering
- antimicrobial secretions to destroy pathogenic bacteria
- healthy skin is covered with microorganisms, help keep healthy, act as an extra barrier to pathogens
What are respiratory and digestive system defences to pathogens?
- nose hairs, produce mucus. Hair + mucus trap air particles that may contain pathogens or irritate the lungs. (working in pollution, snot becomes black, proves defence works)
-Trachea and Bronchi also secrete mucus, trap air pathogens. Cilia line them, they beat to waft mucus up to back of throat to be swallowed - stomach produces acid, destroys microorganisms in swallowed mucus, also any other ingested.
What are immune system defences against pathogens?
- second line of defence: white blood cells
WBC
-Ingest microorganisms: ingest, digest and destroy pathogens so they can’t make you ill
-Produce antibodies: target particular bacteria/viruses + destroy them. Unique antibody to each pathogen. If made once, can be quickly made again if repeatedly infected, stopping getting ill twice.
-Producing antitoxins: counteract the toxins produced by the pathogens
What are examples of plant pathogens?
Aphids
- sharp mouthparts, penetrate phloem vessels so they can feed on sugar rich phloem sap
- attack in huge numbers, depriving plant cells of photosynthesis products
- vector (transfer virus, bacteria and fungi on their mouthparts)
Worms and insect larvae
- live in the soil
- feed in or on plant roots
- cannot absorb water or mineral ions effectively (damaged)
- plant fails to grow/thrive
How can aphids be destroyed?
-chemical pesticides
- biological pest control (enclosed space ie greenhouse)
- release aphid eating insect (ie ladybug + their larvae) to control population, doesn’t impact crop success
-
How does mineral deficiency lead to non communicable diseases in plants?
- Plants take magnesium ions form soil to make chlorophyll needed for photosynthesis.
- If level of ions in soil is low, plant cannot make enough chlorophyll
- Leaves become yellow, growth slows due to lack of photosynthesis
CALLED CHLOROSIS
- level of ions can be replaced with soil fertilisers, but if not replaced then plant will eventually die
What are symptoms of plant disease?
- stunted growth (mineral deficiency)
- spots on leaves (black rose spot)
- areas of decay or rotting (black rose spot, potato blights)
- growths (crown galls caused by bacterial infection)
- malformed stems and leaves (due to aphid infestation etc)
- discolouration (chlorosis, tmv)
- presence of visible pests (aphids, caterpillars etc)
How can disease in garden plants be identified?
by comparing symptoms in living plant with disease description in gardening manual/online
How can disease be identified in crop plants or forest trees?
- experts visit area to observe natural environment
- test samples of diseased material in lab, to identify pathogen (DNA analysis etc)
What are physical barriers in plants against pathogens?
- cellulose wall strengthens plant cells, also resist invasion of microorganisms (aphids break barrier, give pathogens way into cells)
- Tough waxy cuticle on leaf surface, acts as barrier to pathogen entryway. Only access at stomata
- Bark on trees, layer of dead cells on outside of stems, hard for pathogens to penetrate. When cells are shed, pathogens fall too
- Leaf fall, deciduous trees lose leaves in autumn, any leaf infection fall off tree with leaves.
What are chemical barriers in plants against pathogens?
- produce antibacterial chemicals, protecting pathogen invasion
- plant uses as antibiotics (mint, witch hazel= mild antiseptics in cosmetics)
How do plants defend themselves against herbivores?
- poison deters herbivores (foxgloves, deadly nightshade)
- thorns make it unpleasant, painful to eat the plant (brambles, cacti), may not deter insects
- hairy stems and leaves deter eating, laying eggs. Can combine with poison (nettles)
-drooping or curling when touched (frightening animals) - Mimicry, plants droop to mimic unhealthy plants. Can mimic butterfly eggs to avoid others laying on them
