diseases

• Disease

  A specific abnormal condition which adversely impairs the normal functions of an organism
• Types of disease

  • Acquired Disease
  • Congenital Disease
  • Genetic Disease
  • Hereditary Disease
  • Infectious Disease
• Acquired Disease

  A disease state that begins at some point during the patient's life
• Congenital Disease

  A disease state that is present at birth/pre-birth of a patient (can be genetic or infectious)
• Genetic Disease

  Disease state caused by one or more genetic mutations
• Hereditary Disease


  Disease state which is caused by genetic mutation and can be passed on through a family
• Infectious Disease


  A disease state which is caused by the presence of pathogenic microbial agents
• Infectious disease factors

  • Airborne
  • Foodborne
  • Waterborne
  • Contagious contact
• Lifestyle disease factors

  • Increased sedentary lifestyle
  • Increased calorific intake
  • Reduced micronutrient intake
  • Drug/substance abuse
• Infectious Disease Agents

  • Multicellular Parasites
  • Bacteria/fungi
  • Viruses
  • Prions
• Leprosy

  • Caused by infection via the mycobacteria: M. Leprae/M. lepromatosis, is spread via close contact with infected patients (skin/respiratory tract)
  • Symptoms: ranging from runny nose/dry scalp -> skin lesions/muscle weakness -> destruction of nasal cartilage/destruction of nerves
  • 1980: ~5.2 million cases/2020: ~200,000
  • Global prevalence: 50% of cases are India
  • Cured via multidrug therapy (6 months)
• Malaria

  • Caused by infection by Plasmodium organism which is transmitted via bites of the infected mosquitos
  • Symptoms: fever/fatigue/vomiting -> jaundice, seizures, coma, death
  • 247 million cases / 620,000 deaths (2021)
  • Prevalence: Sub-Saharan Africa (~80% cases)
  • Prevention: mosquito control (insecticide nets and indoor residual spraying)
  • Medication: Anti-malarial drug can prevent or interrupt transmission, while developed vaccine have a potential 77% protection rate
• Influenza

  • Caused by a series of influenza viruses, commonly transmitted via respiratory droplets produced from coughing/sneezing
  • Multiple vectors (Aquatic birds/Mammals/Humans/Cattle/Pigs)
  • Symptoms: Fever/Runny Nose/Sore Throat/Muscle Pain
  • 3-5 million severe cases per year, (300,000-600,000 deaths per year)
  • Prevention: Mass vaccinations (tri/quad-rivalent), anti-viral drugs (oseltamivir/zanamivir), infection control (frequent hand-washing/alcohol-based hand sanitizer/covering mouth/nose during infection)
• Creutzfeldt-Jakob Disease (CJD)

  • Caused by the misfolding of a protein (prion) which causes the breakdown and damage of brain tissue with infected
  • Only 10% of CJD has been linked to inheritance with the cause currently being unknown, but linked to ingestion of prion material (human or zootonic)
  • Symptoms: rapidly progressing dementia -> memory loss/personality changes/hallucinations
  • 100% fatal
  • No known prevention/cure
  • ~7-8,000 infected per year
• Vitamin A deficiency

  • Caused lack of vitamin A in blood/tissue, due to reduced or no consumption of Pro-vitamin A from the diet
  • Symptoms: Blindness/Increased Infection rate/keratosis internal and external epithelial
  • Globally prevalent: More common in Sub-Saharan Africa
  • ~251 million affected, ~250,000-500,000 under 5 deaths annually
  • Prevention: Increased and improved diet, with improved provitamin A compounds (Pepper/Leaf-Green Vegetables)
• Obesity

  • Caused by: Excessive consumption of energy-dense foods, sedentary lifestyle, lack of physical activity
  • Increased risk of CHD, deep vein thrombosis, infertility, stroke, dementia, depression, reduced mobility, gout and death
  • Globally prevalent, increased in High Developed Economy Countries
  • 700 million (12% of global population) with 2.8 million dying per year
  • Prevention: Improved and reduced diet, improved mobility/exercise, surgery
• Depression

  • A mental state which is characterised by low mood, aversion to activity, loss of pleasure or joy
  • Causes are currently not fully elucidated, but linked to alteration in brain chemistry, stressful life events, drug abuse
  • Approximately 300 million people (4.4% of global population)
  • Treatment is currently forms of psychotherapy and psychopharmacology
• Disease burden

  • The impact in which a health issue has on an area
  • Measured by the financial cost, mortality, and morbidity of the disease states
  • Can be specific or broad, measuring a single disease in an area, or the overall global effect of the disease
  • Measured via YPLL (years of potential life lost) and DALY (disability-adjusted life year)
• YPLL

  • A simple estimate of the number of years that a person's life is shortened due to a disease
  • 932,000,000 YPLL were lost globally in 2004 (WHO)
• DALY

  • Like YPLL, but considers years where the patient is also unhealthy during their disease state, measuring the economic and social burden of people who are very sick
  • 1,500,000,000 DALY were lost globally in 2004 (WHO)
• Disease burden by category

  • Premature Birth
  • Neuropsychiatric
  • Infectious Disease
  • Cardiovascular
  • Cancer
  • Injuries
• Roles of different organisations

  • Researchers
  • Health Care
  • Government
• Researchers

  Fundamental to gather and analyse the behaviours, symptoms, risk factors, and trends of diseases and infected people, provide support to develop treatments and assess the risks of new diseases
• Health Care

  Treating individual cases, gathering large-scale datasets, and improving life expectancy and quality
• Government

  Providing support mechanisms of healthcare and well-being, ensure that policies exist to support framework for pandemic and disease prevention
• Non-communicable diseases

  Disease which can't be transferred from a diseased individual and non-diseased individual
• Examples of non-communicable diseases

  • Cancer
  • Atherosclerosis
  • Diabetes
• Infectious diseases

  Diseases which are transferable between people
• Cardiovascular diseases

  • Coronary Heart Disease - reduced blood supply to heart muscles
  • Cerebrovascular Disease - reduced blood supply to the brain
  • Peripheral Arterial Disease - reduced blood supply to the limbs
  • Rheumatic Heart Disease - damage to the heart muscles and valves from a fever
  • Congenital Heart Disease - birth defects which affect development and function of the heart tissue
  • Deep Vein thrombosis - blood clots in the leg veins, which can dislodge and move to the heart/lungs
• Atherosclerosis

  • Characterised by the development of lesions within the walls of arteries
  • Begins with macrophage infiltration which absorbs excess cholesterol within the intracellular space
  • The cholesterol rich macrophage clump together to form a thick debris-filled plaque
  • The formation of the plaque narrows the blood vessel, which slows the flow oxygen-rich blood to organs and limbs
  • This reduces the efficiency of organs and limbs as there is a reduced oxygen transfer from the red blood cells into these organs/tissues
  • Plaques can grow or break off, which can form blood clots, which completely restrict blood flow resulting in CHD/CVD
• Risk/Prevention factors for Atherosclerosis


  • prevention:
  • Healthy diet (reduced refined carbohydrates, reduced added sugars, reduction/free of trans-fatty acids)
  • Increased Physical Activity
  • Stress management/good sleep
  • Air Pollutant free environment
  • Smoke Free Lifestyle
  • Increased N-3 fatty acid consumption
  • Risk:
  • Poor Nutrition (Fat/sugar filled diet)
  • Sedentary Lifestyle
  • Increased Psychological Stress
  • Exposure to cigarette smoke
  • High Air Pollution
  • Insulin Resistance
  • Hypertension
• Peto's paradox

  At a species level, the incidence of cancer does not appear to correlate with the number of cells in an organism
• Naked mole rats

  • Resistant to cancer, while their cells can become cancerous, they will not develop into tumours
  • Evidence suggest that a polysaccharide produced by the Naked Mole Rat which blocked the development of tumours
• African Elephants

  • Have 20 copies of the tumour suppressor gene (TP53), while humans have 1
• cancer evolution within the body

  1. genetically altered epithelium cell
  2. hyperplasia - cell divides more rapidly than normal
  3. dysplasia - cell changes form
  4. in situ cancer - cells stay in one place
  5. malignant tumour (cancer) - cancer cells invade normal tissue and enter blood and lymph, metastases form at distant sites

  
• risk/prevention of cancer

  • intrinsic factors (not modifiable) - random errors in DNA replication
  • extrinsic factors:
  • endogenous (partially modifiable) - biological ageing, hormones, inflammation, growth factors, genetic susceptibility
  • exogenous (modifiable) - lifestyle and behavioural factors (smoking, diet, physical activities), tumour viruses, EODCs (radiation, chemical carcinogens: pollution, second-hand smoke)