Global distribution of Diseases

Outline the aspects that contribute towards good health[6] #

  • good health is complete physical, mental and social well being;
  • ref. to balanced diet;
  • regular exercise/regular physical activity;
  • which ensure body is in best condition;
  • to combat disease
  • limit drug intake/alcohol intake/smoking;
  • improving ability to cope with stress/other benefits of exercise;
  • regular sleep/rest + reasons

Discuss the possible reasons for the global distribution of coronary heart diseases[6] #

  • mainly confined to developed/affluent countries;
  • mainly due to lifestyle/sedentary;
  • fatty diets;
  • high in saturated fats;
  • cigarette smoking;
  • alcohol intake;
  • obesity;
  • high blood pressure;
  • lack of exercise;
  • fast foods

Explain the possible reasons for the global distribution of TB[8] #

  • it is a pandemic disease (globally distributed);
  • it is an endemic disease (always present);
  • most prevalent in developing countries;
  • some of the TB strains becoming more resistant;
  • AIDS pandemic;
  • poor housing – overcrowding
  • breakdown of TB control programme;
  • partial treatment of TB;
  • poor sanitation;
  • poor medical facilities;
  • TB spread in meat and milk;
  • high rate of transmission – droplet infection

Explain the possible reasons for the global distribution of measles[8] #

  • most commonly affects developing countries;
  • in places where conditions are overcrowded and insanitary;
  • measles requires several booster shots to develop full immunity;
  • in large cities with high birth rates, it can be difficult to give boosters or even follow up cases of measles;
  • refugees from these areas can spread the disease around, which makes it much more difficult to treat than smallpox;
  • measles is highly infectious;
  • poor response to vaccine (children do not respond well to one dose of vaccine);
  • deficiency immune system;
  • or protein energy malnutrition;
  • need several boosters which are expensive;
  • high birth rates and flighting populations make it difficult for boosters;
  • follow up cases and trace contacts also impossible;

Explain the possible reasons for the global distribution of HIV/AIDS[8] #

  • is a pandemic disease (globally distributed);
  • an epidemic (always present);
  • most prevalent in developing countries;
  • linked to TB;
  • some of the TB strains becoming more resistant;
  • AIDS pandemic;
  • partial treatment of due to inability to purchase ARVs;
  • poor medical facilities;
  • Highly confined in sub-Saharan Africa ;
  • the poor health care delivery systems in many affected countries
  • High levels of rape and the breakdown of traditional sexual mores are associated with military destabilisation, refugee crisis and civil war

How cigarette smoking can lead to coronary heart disease[8] #

  • main cause of CHD is atherosclerosis;
  • carbon monoxide/nicotine in smoke responsible;
  • cholesterol deposited in, inner layers/.linings of artery walls;
  • form plaques which lead to restriction of blood flow/clotting which can block vessels;
  • smoking increases blood cholesterol/fat level;
  • nicotine causes constriction of coronary arteries/arterioles;
  • rise in blood pressure makes damage to walls more likely;
  • increases number of platelets stimulating formation of blood clots;
  • nicotine makes platelets more sticky;
  • smoking causes rise in ratio of VLDLs/LDLs, to HDLs in blood so more atherosclerosis/cholesterol deposited;
  • decrease concentration of antioxidants/Vitamin C/vitamin E, so increasing damage to artery walls by free radicals;

Discuss the factors that should be taken into account when deciding how to share limited resources between prevention and treatment of coronary heart disease[8] #

  • treatment is expensive due to technology and professional expertise of surgeons;
  • after – care also expensive (immunosuppressant drugs, e.t.c.);
  • NHS working on tight/limited budget;
  • preventive measures cheaper;
  • not so dependent on expensive equipment/manpower;
  • very expensive to advertise/train/employ health educators;
  • difficulty in disseminating information;
  • prevention saves a lot of suffering for potential victims;
  • and families;
  • e.g. may cause financial difficulties if wage earner affected/fatherless family/e.t.c;
  • in terms of years of healthy life gained preventive measures may be better;
  • great demand for treatment because heart disease so common;
  • moral dimension – if a treatment is available should we not make resources available to use it;
  • more lives can be saved by preventative measures;

Reasons why coronary heart disease is so common in developed countries[8] #

  • caused by many factors most of which are common in developed countries;
  • smoking s common risk factor;
  • carbon monoxide and nicotine are the components responsible;
  • carbon monoxide reduces oxygen carrying capacity;
  • increasing strain on the cardiovascular system;
  • nicotine increases stickiness of platelets, raising risk of clotting;
  • diets tend to be rich in saturated fats;
  • increased blood cholesterol and hence atherosclerosis;
  • cause rise in ratio of LDLs to HHDLs;
  • hypertension/high blood pressure common which puts arteries under strain;
  • lack of exercise is a risk factor and life style/ occupations often sedentary

Describe and explain the ways through which cholera is transmitted[8] #

  • food and waterborne disease;
  • due to lack of proper sanitation/poor hygiene by infected person;
  • feaces from infected person;
  • contains Vibrio cholerae, the causative agent;
  • contaminate water supply/water borne;
  • water used to irrigate crops;
  • sewage and water supply not separated / human faeces (sewage);
  • contaminates water supply;
  • person drinks water / eats food / swims in contaminated water;
  • transmitted to uninfected person;
  • via contaminated water;
  • via contaminated food;
  • e.g. vegetables irrigated with raw sewage;
  • e.g. washing/bathing in contaminated water;
  • pass out (of infected person) in feaces/(bacteria) leave person in faeces;
  • infected people handle food/cooking utensils without washing hands;

Outline the reasons why cholera is more likely to spread in less developed countries.[6] #

  • lack of education/knowledge of hygiene;
  • poor sanitation;
  • lack of sewage treatment;
  • raw sewage used to irrigate/fertilise crops;
  • lack of water treatment;
  • unable to control outbreaks due to lack of rehydration treatments;
  • natural disasters;
  • poor economy;
  • civil unrest/migrants;

Role of economic factors in the prevention and control of cholera[8] #

  • waterborne disease;
  • caused when water is infected by feaces from carrier/sufferer;
  • important to purify water;
  • important to have proper sewage treatment;
  • developing countries often cannot afford the required measures;
  • partly because they have large debts;
  • education needed about importance of hygiene + economic link;
  • cost money to train teachers/run advertising campaigns/build schools;
  • locate and isolate carriers/sufferers;
  • cost money to build hospitals/isolation wards/trace contacts/train staff/pay nurses;
  • (economic) aid available in form of oral rehydration packs for treatment;
  • cheap and effective;
  • from international aid e.g. Red Cross;
  • antibiotics can cure but often too expensive;
  • little incentive for drug companies to develop cured because developing countries cannot afford them;

Explain why it has been proved difficult to develop a vaccine to control the spread of cholera[8] #

  • V. cholerae in intestine;
  • out of reach of immune system;
  • antigenic concealment;
  • antibodies broken down in intestine;
  • antibodies are proteins;
  • ref to pH and effect on structure or shape; e.g. in the stomach
  • denaturation;
  • vaccine stimulates antibodies in, blood / lymph;
  • not in gut;
  • oral vaccine needed;
  • mutation;
  • different strain idea;
  • AVP; e.g. not required in developed countries;
  • developing countries cannot afford to develop vaccines;
  • no / limited, demand;
  • cholera can be treated with ORT;
  • can be treated with antibiotics

Explain how an infected is likely to have acquired malaria[6] #

  • bitten by mosquito carrying malarial parasite;
  • genus Anopheles/female;
  • injects parasites with saliva/anticoagulant;
  • ref to vector;
  • mosquito fed on/bit/took a blood meal from an infected person;
  • transmission by needle;
  • injected into blood;
  • after use by someone with malaria;
  • (needle) shared/reused/used but not sterile;
  • Transmission across placenta;
  • Blood transfusions;

Explain the ways in which the transmission of the malaria life cycle can be disrupted[8] #

  • reduce mosquito numbers
    • stock ponds with fish (Gambusia) to eat larvae ; R kill mosquitoes
    • oil on surface ;
    • spray bacteria (Bacillus thuringiensis) to kill mosquito larvae ;
    • DDT / pesticide spray ;
    • release of sterile male mosquitoes ;
    • draining, ponds / bodies of water ;
  • avoid being bitten by mosquitoes
    • wear insect repellant ;
    • long sleeved clothes ;
    • sleep under nets ;
    • nets soaked in, insecticide / repellant ;
    • sleep with, pigs / dogs ;
  • use drugs to prevent infection
    • use, prophylactic drug / quinine / chloroquine / larium / artimesinin / vibrimycin
    • tetracycline / antimalarial ;
    • use malaria vaccine ;

Outline the problems associated with controlling the spread of malaria[8] #

  • resistance of, Plasmodium / pathogen, to drugs;
  • eukaryote / protoctist, has many genes;
  • many surface antigens / antigenic variation; A ref to mutation
  • inside red blood cells / in liver cells / antigen concealment;
  • difficult for immune system to operate / idea;
  • dormant / in body for a long time / symptomless carriers / long incubation;
  • different stages in life cycle in the body;
  • resistance of, vector / mosquito, to insecticides; A mutation / selection
  • mosquito, breeds in small areas of water; A implications
  • breeds quickly;
  • mosquitoes, spread over large area / widely distributed / fly a long way;
  • mosquito control programmes disrupted by war etc;
  • lack of infrastructure (for control programmes);
  • problems with sleeping nets, described;
  • more effective when soaked in insecticide;

Causes of sickle cell anaemia[6] #

  • a faulty occurs on the haemoglobin molecule;
  • the 6th amino acid of the beta chain (146 amino acids)
  • glutamic acid is replaced by valine;
  • glutamic acid carries a negative charge and its polar, valine is non-polar;
  • deoxygenated become less soluble;
  • haemoglobin crystalises into a rigid rod-shaped fibre;
  • it is a result of a base in substitution;
  • thymine of a DNA triplet code CTC is replaced by adenine to make a CAC;
  • the affected gene is on chromosome 11;
  • the faulty gene is codominant;
  • effect expressed only in homozygous condition

Reasons for classifying TB as a social disease and lung cancer as a self-inflicted disease #

  • TB
    • social disease is due to social conditions/behaviour
    • social factors aid to the spread of TB;
    • poor housing;
    • poverty/social class;
    • poor diet, i.e. people with low immunity from malnutrition are also vulnerable;
    • overcrowding living conditions;
    • TB droplet infection/airborne infection;
    • people sleeping/living together are at increased risk;
    • prolonged exposure;
    • poor unlikely to seek/complete treatment;
    • TB is classified in other disease categories e.g. infectious;
  • Lung cancer
    • Self-inflicted disease is due to one‘s behaviour;
    • most lung cancers are caused by smoking;
    • tar in tobacco smoke is a carcinogen;
    • which alters DNA In epithelial cells;
    • mutation
    • development of malignant tumours;

Social and economic factors in the prevention of HIV AIDS[8] #

  • HIV transmitted by sexual intercourse with infected person/mother to child;
  • education on ways of preventing transmission is important;
  • education in work places on methods of preventing the spread of HIV;
  • education on use of condoms to reduce risk of infection during intercourse
  • sharing unsterilized needles among illicit drug users;
  • injecting drug users can be advised not to share needles;
  • sharp instruments like razors/shaving machines must not be shared;
  • HIV+ not willing to disclose status/unwilling to go for testing;
  • fear of stigmatization by society
  • ARVs available but not affordable to all;
  • prostitution due to poverty;
  • polygamy/promiscuity;
  • Government to inject more money in awareness campaigns;
  • HIV+ women (in developing countries) can be advised not to breastfeed;
  • HIV+ women to take antiretroviral drugs (navirapine) before delivery;
  • Blood collected from blood donors routinely screened for HIV and heat treated to kill any viruses

Describe why vaccination managed to eradicate small pox and reasons for failure to eradicate measles,tuberculosis, malaria and cholera. #

  • Small pox
    • varilosa virus stable
    • (harmless) strain of (live) vaccine effective
    • vaccine could be kept for a long time (6 months)
    • infected people were easy to identify
    • ring vaccination was possible
    • political stability during that time
  • Malaria
    • no vaccine/no effective vaccine against the protozoan
    • resistance of Plasmodium to drugs
    • resistance of vector/mosquitoes to DDT/deldrin/insecticide
    • difficulty of mosquito control
    • expensive to expand the programme
    • civil wars disrupt the
  • Measle
    • caused by an RNA virus
    • viruses are intracellular pathogens
    • antigenic concealment
    • have a short time in the blood
    • major changes in the epitate as a result of mutation
    • poor response to vaccine (children do not respond well to one dose of vaccine)
    • deficiency immune system
    • or protein energy malnutrition
    • need several boosters which are expensive
    • high birth rates and flighting populations make it difficult for boosters
    • follow up cases and trace contacts also impossible
    • refugees and immigrants from reservoirs of the infection
    • it is highly infectious resulting in the whole population requiring vaccination which is highly expensive
    • the virus is of hiring attenuated virus can be virulent
  • Tuberculosis
    • some strains of TB bacteria resistant to drugs;
    • the AIDS pandemic;
    • poor housing and rising homelessness in inner cities in the developed world;
    • the breakdown of TB control programmes particularly in the USA;
    • partial treatment for TB increases the chance of drug resistance in Mycobacterium;
    • attacks many of the poorest and socially disadvantaged because it is spread by airborne droplets;
    • so people who are overcrowded are particularly at risk;
    • those with low immunity particularly because of malnutrition or being HVI+ are also vulnerable;
    • transmission is easily achieved but the bacteria may remain in the lung, or in the lymphoid tissue for years until they become active;
  • Cholera
    • V. cholerae in intestine;
    • out of reach of immune system;
    • antigenic concealment;
    • antibodies broken down in intestine;
    • antibodies are proteins;
    • to pH and effect on structure or shape; e.g. in the stomach
    • denaturation;
    • vaccine stimulates antibodies in, blood / lymph;
    • not in gut;
    • oral vaccine needed;
    • mutation;
    • different strain idea;
    • AVP; e.g. not required in developed countries
    • developing countries cannot afford to develop vaccines
    • no / limited, demand
    • cholera can be treated with ORT
    • can be treated with

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