Communicable disease

• Communicable disease

  Disease that can be passed between animals and plants individuals, which can be transmitted directly or indirectly
• Pathogens

  Harmful microorganisms that cause communicable diseases
• Types of pathogens

  • Bacteria
  • Fungi
  • Virus
  • Protoctista
• Direct transmission


  • Physical contact made between an infected animal or plant, spreading the pathogen between individuals
  • Can take place via bodily fluids such as saliva, blood and semen
• Indirect transmission

  • Pathogens are not spread through physical contact
  • Animal vectors e.g. mosquitoes and aphids
  • Air or waterborne transmission by cough droplets or fungal spores
  • Fomites, such as door handles, which are objects onto which pathogens are shed
  • Human movement, which transport infected material on footwear, vehicles and tools
• Factors that weaken the immune system

  • HIV infection sufferers
  • Elderly people
  • Babies and young children
  • Chronic underlying conditions, like asthma and diabetes
• A weak immune system makes it much harder to fight off disease
• Crowded spaces that facilitate disease transmission

  • Nursing and residential homes
  • Prisons
  • Hospitals
  • Homeless shelters
• People living in close proximity to other people are like to spread pathogens
• Limited access to healthcare or lack of engagement with health professionals can mean disease are not treated early enough and their progression is more serous
• Poor healthcare is a key issue in many developing countries
• Black Sigatoka


  A disease affecting the leaves of banana plants
• Black Sigatoka


  • It is a major economic issue for banana production, as it can cause yield losses of over 50%
• Transmission

  1. Black sigatoka is spread through both direct and indirect contact

  2. Transmission is more likely in conditions of high humidity and rainfall

  3. Infective spores are airborne, while infective conidia are waterborne
• Control of black Sigatoka

  1. Aerial application of fungicides

  2. Removal of affected leaves

  3. Maintaining space between plants

  4. Adequate drainage

  5. Around 15-20% of the final price of bananas is accounted for by the cost of control measures in plantations
• Ringworm


  A fungal infection that is most common in cattle, but can affect all mammals and is zoonotic
• Treatment of ringworm

  1. Is with at least two applications of antifungal cream, 3-5 days apart

  2. The crusts of the skin must be removed to allow the cream to reach the fungus

  3. The crusts must then be burnt to prevent transmission by indirect contact
• Transmission / Prevention of ringworm

  1. Direct contact with infected skin areas is usually how ringworm spreads

  2. Ringworm can also be transmitted indirectly because the fungus produces spores the can be viable for many years

  3. Regularly cleaning and disinfecting animal housing, particularly when introducing new animals

  4. Avoiding high stocking densities of animals

  5. Ensuring animal housing is dry

  6. Allowing animals to have regular exposure to sunlight
• Athletes Foot


  A fungal infection affecting the feet, mainly in between the toes, but any part of the body can be affected if infected skin is scratched and the fungus is transferred
• Treatment

  Is with antifungal creams, sprays, powders and antifungal medication
• Transmission

  1. Transmission of athletes foot is usually indirect contact with contaminated objects

  2. Warms, humid environments promote growth and spread of the fungus, so transmission often occurs in showers, in swimming pools and changing rooms, by sharing fomites, such as socks and towels

  3. Direct contact with infected skin can also transmit the fungus
• Prevention


  1. Keep feet clean and dry

  2. Wear footwear in high risk areas

  3. Avoid potential fomites with other people
• Protista disease (Protist)


  Disease caused by protist
• Malaria


  • Disease caused by protist
  • Resulting in the cyclical symptoms of fever, chills and untimely death if left untreated
  • The parasite can also use birds, bats and other animals as hosts
• Pathogen

  • Malaria is caused by several species of the Plasmodium genus
  • P. falciparum causes the most malarial deaths worldwide
  • P. vivax can remain in the liver for years without causing symptoms
  • The parasite grows and multiplies in erythrocytes, causing them to burst every 2-3 days, releasing Plasmodium into the bloodstream
• Treatment

  1. Malaria is treated using antimalarial medication such as doxycycline and mefloquine

  2. A preventative course of this medication should be taken prior to travel to known high-risk regions – this can reduce the risk of malaria by up to 90%

  3. Different antimalarial medication can be used to treat the disease if the preventative course does not work
• Transmission/Prevention

  1. Insect vectors, specially the female anopheles mosquito when it takes blood meal from an infected person

  2. Malaria is most common in Africa, asia and south America because the climate is suitable warm for the mosquito to live in and the probability of biting an infected person is higher

  3. Removing insect vector is 100% effective but not in a large scale

  4. Sleeping under mosquito nets

  5. Applying insect repellent such as citronella

  6. Covering exposed skin help reduce the risk of being bitten
• Late Blight


  • Disease caused by protist that affects potatoes and tomatoes which can result in famine
• Pathogen

  • Late blight is caused by PHYTOPTHORA INFESTANS
  • The protist cause spores to develop on the leaves of infected plants and germ tubes to grow through the leaf epidermis
  • Wounds, eyes and lenticels on tubers also allow infection
• Treatment

  1. Fungicides are most commonly used, although resistance to some have been developed

  2. Individual plants are unlikely to survive one they are infected, sometimes dying within a week
• Transmission/Prevention

  1. Spores can be airbone or waterborne, infecting soil and plants

  2. Spores can encyst if the conditions are too cold and develop only when temperatures are above 15dc

  3. Developing blight resistant cultivars helps to reduce susceptibility of plants to the pathogen and control its spread

  4. Forecasting when weather conditions may promote transmission means that fungicides can be sprayed at optimal times
• TB - Tuberculosis


  A infectious disease of the lungs caused by bacteria, without treatment can be very fatal
• Pathogen

  • Caused by mycobacterium tuberculosis
  • In cattle's is cause by mycobacterium Bovis which can affect humans
• Treatment

  • Use of anti-biotics
  • Vaccinations such as BCG vaccine, are available for some strains of TB, but not all of these are routine childhood vaccinations in the UK
• Transmission/Preventions

  • TB is spread via infected droplets form the lungs are coughed into the air and breathed in by others
  • Transmission can be prevented by using tissues when coughing or sneezing and having good handwashing practice
• Bacterial Meningitis


  Results in the inflammation of the membranes surrounding the brain and spinal cord and is a very serious disease, without treatment can result in sepsis and death
• Pathogen

  • Streptococcus pneumoniae
  • Haemophilus influenza type B (Hlb)
• Treatment


  • Antibiotics
• Transmission/Prevention

  • Is via direct contact
  • Vaccinations are available to help prevent infection and spread of the disease
• Ring Rot


  Is a bacterial disease affecting potatoes and tomatoes in cool regions of northern and eastern Europe