O Level Notes : Geography - Settlement And Population - Population and diseases

There is a relationship between demographic trends and diseases. In most instances if ailments are not handled carefully and timeously, they can degenerate into pandemics resulting in the death of many people within a short period of time.

There is a distinction between common diseases in developed and developing countries. Less economically developed countries are usually affected by nutritional, Bacterial and viral diseases. The root cause of diseases affecting people in developing countries is poor health care delivery system, poor diets, sanitation and poverty in general. In contrast, people in developed countries are more affected by diseases like obesity, various cancers and these diseases have their genesis in their life styles thus they are mainly referred to as life style diseases.

Diseases causes, symptoms and treatment





Method of treatment or compacting and prevention



Affected countries


Causes of the




It is an infectious disease which causes severe diarrhoea due to infection of small intestines


Mainly caused by intake of food

and water contaminated by a bacteria called vibrio cholerae

Dry mucus membranes Loss of skin elasticity

Severe diarrhoea Abdominal muscle cramps Rapid heart beat vomiting electrictrolyte

Abstaining from shacking hands on social gathering. Regular testing

for water quality to ensure safe drinking water. Washing hands and fruits under running water Boiling water before use or oral rehydration using salt and sugar solution.


DRC Mozambique Zambia






It is caused by a water borne parasite  or parasitic worm called schistsoma


Faeces and urine with blood. Fatigue. Abdominal pain


Wear protective clothes when using unprotected water Use of drugs for example praziquanted









Caused by a virus which causes an immune deficiency syndrome in a person.

Having an unprotected sex with an infected person.

Use of unsterilized gadgets like razor blades, shaving machines etc.


Loss of appetite and body weight influenza- like tuberclosis opportunistic infections and tumors


Use of anti-retro viral drugs to boost immunity (ARVs). Abstinence from sex.

Use of condoms Awareness campaigns by NGOs and on electronic and print media.

Prevention of mother to child transmission in the case of pregnancy


Zimbabwe Kenya Malawi


Effects of HIV/AIDS in developing countries

The HIV/AIDS pandemic or epidemic has heavily affected developing countries. Though its effects have spread across the globe, developing countries are the most affected because of their vulnerability. Developing countries are vulnerable because of poverty which exposes a lot of people to infections. Because of poverty prostitution where unprotected sex is practiced is high, intergenerational marriages where young girls marry older infected men is high, and ways to deal with infections are poor. Without donor funding towards HIV/AIDS, most developing countries would be in worse positions. Cultural and religious practices also worsen the situation for developing countries. For example, in the early years of HIV infections in Africa, those infected were thought to be bewitched. Even today some religions do not acknowledge the diseases and are against the use of medications such as nevaripin  and ARVs.  The  HIV/AIDS  pandemic  has  the  following  effects  on population:

  • Low life expectancy- for Zimbabwe it fell to below 35years around 2008. ARVs have improved the situation
  • An increase in child headed families
  • An increase in the number of orphans
  • High prevalence of opportunistic infections such as TB and meningitis
  • High death rates
  • High dependency  ratio-  the  economically active  constitutes  the  largest number of deaths from the disease. This leaves youths and elderly with few people to support them.
  • Increased poverty- HIV/AIDS triggers a vicious cycle of poverty. It is caused by poverty which leads to prostitution and the death of those infected leaves behind orphans who are poor.
  • Poor economic development- resources are channeled towards fighting the disease which should be used to develop the country.

Common diseases in developed countries

There is a variation between diseases in developed and developing countries. People in developing countries are mainly affected by hygienic, nutritional and viral diseases where as people in developed countries are mainly affected by lifestyle diseases. Life style diseases are ailments which are caused by a person's habits or way of life. Some of the most common lifestyle diseases are heart diseases, obesity, cancer, bronchitis and liver cirrhosis. Such diseases are caused by lack of physical activities, unhealthy diets and drug abuse.

shows the death toll of people due to life style diseases 2012





Number of death(millions)

Cardiovascular stroke and heart disease








Liver cirrhosis









According to World Health Organisation (WHO) have in the year 2012 lifestyle diseases we responsible for about 68% of all deaths globally most of the causalities being experienced in the developed countries.


Cancer is an ailment caused by multiplying errors in the copying of D.N.A. It affects

different parts of the body but the most affected are heart, cervices, lungs and the prostrate in males. A rapid increase in cancer cases have been blamed at sedentary occupations and life styles which require little physical exertion. The cancer surge is also blamed to excessive consumption of super refined food and GMOs (genetically modified foods). Cancer patients are normally assisted through chemotherapy operations in which radioactive substances are used to burn the affected cells.

Herbalists  also  claim  that  there  are  several  herbs  which  can  cure  cancer effectively.

Liver cirrhosis

This disease is caused by excessive consumption of alcohol. If alcohol is consumed in excess, it damages liver cells hence results in an ailment called liver cirrhosis. A person affected by liver cirrhosis loses appetite, has swollen abdomen and feels tired all the time.


Habitual suckers create a higher risk of being affected by smoking related diseases. Emphysema is a disease which affects a person, when alveoli is damaged resulting in a very short breath. People affected by emphysema feels as if they are suffocating. Their breathing is often supported by supplementary oxygen.

Heart diseases

Heart diseases are also very common in developed countries. Foods with a high content of cholesterol and toxic substances in ciggarate smoke causes the arteries to narrow. When arteries are narrowed it forces the heart to work harder. When working harder, blood pressure is increased. In the long run such conditions result in a weak heart which is the fertile ground for proliferation of cardiovascular diseases, for example, strokes and heart failure.


Obesity is a condition which exists when a person has excess weight due to the presence of excess fat in one's body. A person is said to be obese if one's body mass index is 30 or more, body mass index is a value obtained by calculating a person's weight and height. Obesity is blamed at having too much food with high starch and fat content. It has been estimated that between 2016 and 2018, about 38.9% of American adults are clinically obsessive and about 18.5% teens and children. This therefore implies that about 58.3% of America's population is clinically obese. Obesity has its roots in excess unhealthy diets and lack of physical activities.


Presence of an ailment in any area leads to social and economic impacts. Although the outbreak of diseases creates a ready market for chemical drugs, the presence of diseases brings more harm than good to people. Most governments have tried their level best to eradicate diseases but still diseases continue to take a significant toll socially and economically. Most diseases often lead to deaths thereby increasing mortality rates in a country. Such a development adversely impacts on a nation socially since it ushers in many infants into orphanages.

A high death toll also negatively impacts on a country economically since it often leads to a labour crisis. The death of many adults in the economically active age group  creates  a  labour  deficiency  in  industries  hence  lower  production. A government handling cases of diseases outbreak is also disadvantaged economically. This is so because government revenue which was supposed to be spent on income generating projects will be channelled to the health sector. An unhealthy population also implies less production in industries. Both the infected and affected people result in low production in the sense that the affected are forced by ill health to be away from work.

Diseases lead to loss of life hence most families lose those that provide for their wellbeing. This in turn results in more cases of child headed families, increased dependant loads and an increase in the number of school drop outs.


Stage 2

This stage is also referred to as the early expanding stage where birth rates remain high but death rates begin to fall drastically to about 20 per 1000. Birth rates remains high due to ineffective family planning methods, social and religious beliefs. Countries found in stage 2 thrives on an agrarian economy so couples bear more children to ensure adequate supply of labour in their fields. Improved diets and better working conditions are responsible for the decline in death rates. Most African countries are found in this stage and some of them includes Zambia, Zimbabwe and Kenya.

Stage 3

Stage 3 is the late expanding stage which is a reflection of an industrialised state. At this stage birth rate begins to fall rapidly whilst death rate continues to fall to about 12 people per 1000. Such a scenario results in a constant increase in population. Countries in stage 3 are the ones which experiences the highest natural increase. The fall in birth rate are mainly due to effective family planning methods, an improvement in health care delivery system, increased level of woman emancipation and the increased desire for material possessions than children. Some of the countries found in this stage are South Africa, China and Australia.

Stage 4

This is the low stationary stage which is the reflection of a highly industrialised state or country. In this stage both birth and death rates are low. They drop to a level of about 10 people per 1000. This stage is characterised by a high number of aged population and a low number of infants hence a labour deficiency for their industrial operation so they thrive on hired labour. Some of the countries found in this stage are Japan, USA and France. It is also know as the transitional stage.

Stage 5

Stage 5 is the late expanding stage characterised by mortality rates which are higher than birth rate. In this stage both death rate and birth are low but birth rate is lower than death rate resulting in a decline in population. Countries in this stage have no natural increase they have natural decrease in population. Countries like