4.1

• A disease is an abnormal condition of body or mind that causes discomfort, difficulty to function or stress to an individual.
• Diseases can be classified into 2

  • infectious diseases
  • non-infectious diseases
• Infectious disease

  • Caused by infections of pathogens directly through mediums and vectors
  • A disease that can be transmitted from one individual to another
  • Example: Tuberculosis, flu, ringworm, tinea, leptospirosis, dengue fever, malaria fever, Zika fever
• Non-infectious disease

  • Caused by genetic factor or lifestyle
  • A disease that cannot be transmitted from one individual to another
  • Examples: Cancer, hypertension, asthma, cardiovascular diseases
• Infectious diseases are spread by pathogens, the organisms that cause diseases.
• Example of pathogens

  • bacteria
  • protozoa
  • fungi
  • worms
  • virus
• Infectious diseases are spread by pathogens transmitted from an infected person (host) to another person through vectors and mediums such as water, air and contact
• Airborne diseases

  • Droplet transmission
  • Dust transmission
• Droplet transmission

  • Pathogen containing droplet sprays from the mouth and nose of an infected person through sneezing, coughing, talking, yawning or breathing
• Dust transmission

  • Bacteria in the spit (saliva) of an infected person dry up and form spores which are spread together with the dust in the air
• Prevention of airborne diseases

  • cover the mouth and nose when sneezing, coughing or yawning
  • do not spit everywhere
  • avoid being in a crowded place
  • ensure the living place gets enough light as ultraviolet rays can kill certain microorganisms in the air
• Examples of airborne diseases

  • tuberculosis
  • flu
  • Severe Acute Respiratory Syndrome (SARS)
  • Influenza A (H1N1)
  • chicken pox
• Waterborne diseases

  • Infection through water usually happens in areas with inadequate water supply, poor sanitisation and floods
  • A person can be infected by pathogens when he drinks the contaminated water
• Waterborne diseases

  • cholera
  • typhoid
  • amoebic dysentery
• Prevention of waterborne diseases

  • add chlorine into swimming pools and water supply systems
  • build toilets with good sanitation
  • boil drinking water properly
  • wash hands with soap after using the toilet
• Examples of diseases transmitted through contact

  • ringworm
  • tinea
  • syphilis
  • gonorrhoea
• Ringworm and tinea are caused by fungi. Accidentally touching the infected skin or wearing the clothes of an infected person will cause infections to occur
• Diseases like syphilis and gonorrhoea can spread through sexual intercourse. Pathogens of these diseases are present in body fluids such as semen and vaginal fluid
• The HIV virus that causes AIDs can also be transmitted through sexual intercourse, blood as well as exposure to syringe sharing among patients and among drug addicts
• Animals that transmit pathogens are called vectors
• Cockroach - Salmonella typhi

  Fly - Salmonella typhi

  Aedes mosquito - Dengue virus

  Aedes mosquito - Zika virus

  Anopheles mosquito - Plasmodium malariae

  Rat - Leptospira sp. bacteria
• Disease: Malaria

  Symptoms: shivering, fever and sweating

  Pathogen: Plasmodium malariae

  Vectors: female Anopheles mosquito

  Way of infection: Mosquito bite
• Disease: Cholera

  Symptoms: diarrhea and vomiting

  Pathogen: Vibrio cholerae bacteria

  Vectors: fly

  Way of infection: contaminated food and water
• Disease: Dengue

  Symptoms: joint pain, fever, headache, watery eyes

  Pathogen: virus

  Vectors: Aedes mosquito

  Way of infection: mosquito bite
• Disease: Zika

  Symptoms: fever, rashes, joint pain, conjunctivitis

  Pathogen: virus

  Vectors: Aedes mosquito

  Way of infection: mosquito bite
• Disease: Typhoid

  Symptoms: fever, intestinal bleeding, conjunctivits

  Pathogen: Salmonella typhi bacteria

  Vectors: cockroach, fly

  Way of infection: contaminated food and water
• Disease: Leptospirosis

  Symptoms: fever, headache, muscle pain

  Pathogen: Leptospira sp. bacteria

  Vectors: rat

  Way of infection: contaminated food and water
• How do Vectors spread Diseases?

  Mosquito

  1. A mosquito that already has pathogens in its salivary gland sucks the blood of an uninfected person.
  2. The mosquito secretes saliva when sucking the blood to prevent blood clotting. The infection spreads throughout the body of the person.
  3. Another mosquito that bites the infected person transmits the disease to another victim
• Fly

  1. A fly that lands on dirt has pathogens on its legs and body
  2. The fly transmits the pathogens to the food.
  3. The pathogens enter the body of the person who eats the contaminated food.
• Mechanism to Prevent the Spread of Infectious Diseases

  Primary stage

  IMPROVING HEALTH

  • Improving personal and family hygiene, cleanliness of living places and sanitation systems
• Mechanism to Prevent the Spread of Infectious Diseases

  Primary stage

  STRENGTHENING THE BODY'S DEFENCE SYSTEM

  • Getting vaccines and immunisation for babies, children, pregnant women, food premises operators, hajj pilgrims and travellers.
• Mechanism to Prevent the Spread of Infectious Diseases

  • FREQUENT HEALTH CHECK-UPS
  • MAINTAINING A HEALTHY LIFESTYLE - inhaling clean air, eating a balanced diet
• SECONDARY STAGE

  • Determining transmission of infections through active and passive case detection
  • Giving early treatment to patients
  • Separating patients from others
• TERTIARY STAGE

  • Controlling vector populations
  • Destroying vector breeding and hiding places
  • Fogging to kill vectors
  • Enforcing laws by issuing compounds to owner of dirty food premises
  • Protecting hosts
  • Using mosquito nets or mosquito coils
  • Wearing thick clothes