Environmental variables and its roles in disease transmission


According to Obasi (2004) defined environment as the sum total of all external condition influencing the growth and development of an organism.

The key to man’s health lies largely in his environment. In fact, most of man’s ill-health can be traced to adverse environmental variable such as water pollution, soil pollution, air pollution, poor housing condition, poor environmental sanitation and insect vectors of disease which pose a constant threat to man’s health. For description purpose, environment has been divided into three components. All closely related via, physical which include water, soil, housing, waste and radiation, biological which include plant and animals life like bacteria, viruses’ insect, rodent and animals social which include customs, culture, habits, income, occupation and religion (Park, 2007).

According to Lesley (2004) environmental variable are factors that exist in man’s physical surrounding that affect man, flora, funna either positively or negatively.

According to Avwoke (2012) environmental variable are factors that influence the state of health of an individual causing environmental pollution and disease transmission.

According to Gilpin (2008) environmental variables is any factor, biotic or abiotic that influence living organism and also changes the local environment.

Types of environmental variable

According to Park (2009) the following are types:

  • Environmental sanitation
  • Water sanitation
  • Overcrowding
  • Improper disposal of refuse/excretal
  • Poor housing condition
  • Poor personal hygiene

Environmental sanitation

Environmental Sanitation is activities aimed at improving or maintaining the standard of basic environmental conditions affecting the well-being of people. These conditions include (i) clean and safe water supply (ii) clean and safe ambient air (iii) efficient and safe animal, human, and industrial waste disposal (iv) protection of food from biological and chemical contaminants and (v) adequate housing in safe surrounding.

The term sanitation covers the whole field of controlling the environment with view of preventing disease and promoting health. The high death rate, infant mortality rate, sickness rate. And poor standard of health are in-fact largely due to defective environmental sanitation. Therefore, improvement of environmental sanitation is crucial for the prevention of disease and promotion of health of individuals and communities. Culpin (2008).

Water sanitation

Water sanitation is defined as a process of cleaning and purifying water so it is safe for use. Example of water sanitation is filter that removes impurities from water.

Olojoba (2009) stated that lack of clean water can lead to disease transmission. These diseases are major causes of suffering and death in an emerging situation. Poor water sanitation also, causes disease transmission. Because there can be no state of positive health and wellbeing without safe water.

Therefore an unwholesome water supply can cause long term health problem for occupants. Most of the ill-health which affects human especially in developing countries can be traced to lack of safe and unwholesome water supply (Parks, 2009).


According to World Health Organization (WHO), overcrowding is a situation in which more people are living within a single dwelling than there is space for, so that movement is restricted and rest, sleep, privacy will be difficult.

Overcrowding can lead to infectious disease, lack of sleep, violence, frustration, anxiety and mental disorder. Overcrowding can also promote the spread of respiratory tract disease such as tuberculosis, influenza and diphtheria. In most case children are said to be more affected. It is as a result of unemployment and lack of finance, which can lead to psychosocial stress, unhappiness and probably mental disorder.

Improper disposal of refuse/excreta

The improper disposal of refuse/ excretal can result in contamination of water bodies (rivers) which can lead to water borne disease such as typhoid, paratyphoid fever, dysenteries, diarrhea, cholera etc.

The improper disposal of refuse have several harmful effects, including health risks and contamination of surround, emission of offensive odor and reducing the aesthetic beauty of the environment it can also constitute health hazards through fly-infestation, causes unsighthliness, soil pollution, water pollution and air pollution. Olojoba (2009).

Waste management is important because improper stored refuse can cause health, safety and economic problem.

Poor housing condition

Housing includes not only the physical structure providing shelter, but also immediate surroundings, and their related community services and facilities. Poor housing condition can be caused through choosing of the site, the floor, the walls, the roof, the room, and the total surrounding. Poor housing condition are associated with a wide range of health conditions including respiratory infections, asthma, injuries, rat infestation and mental disorder (Aibor & Olorunda, 2006).

Poor personal hygiene

Poor personal hygiene can be a sign of self neglect, which is the inability or unwillingness to attend to one’s personal needs. Poor personal hygiene often accompanies certain mental or emotional disorders including several depression and psychotic disorder. Poor person hygiene is one of the environmental variable that are capable of transmitting disease such as skin infection, eczema, scabies etc. because when one is not neat or not kept clean or in the right proportion, it  will be to pose one to one serves of infection or the other (Hogan, 2011).

The implication of environmental variable on the environment

  • Water pollution
  • Air pollution
  • Soil pollution
  • Climate change

 Water pollution

Water pollution refers to adverse changes in the composition or conditions of water, rendering it less suitable for use. These changes may be physical, chemical or biological in water quality that affect living organisms or makes water unsuitable for desired uses. Olojoba (2009).

The source of pollution resulting from these are:

  1. Sewage which contains decomposable organic matter and pathogenic agents.
  2. Industrial and trade waste, which contain toxic agent ranging from mental salts to complex synthetic organic chemicals.
  3. Agricultural pollutant, which comprise of fertilizers and pesticides and
  4. Physical pollutant is heat.

Even if the source of water supply and its treatment are of high standard, water pollution may still occur due to corrosion of pipes, leaky joints, and cross connections between water supply pipes and sewage drainage pipes.

Air pollution

According to LaPlace (1987) as cited in (Olojoba, 2009) is the contamination of the atmosphere by waste product at levels that are unhealthy to human-beings and their environment. The air pollution signifies the presence in the ambient (surrounding) atmosphere of substance e.g. gases mixtures of gases and particulate matter generated by the activities of man in concentrations that interfere with human health, safety or comfort, or injuries to vegetation and animals and other environmental media resulting in chemicals entering the food chain or been present in drinking water and are said to be more affected. In short, it is psychosocial stress, leading to unhappiness and probably mental disorders.

Thereby constituting additional source of human exposure the direct effect of air pollutants on the plants, animals and soil can influences the structure and function of Ecosystem, including self regulation ability, thereby affecting the quality of life. Air pollution is one of the present day health problems throughout the world.

Soil pollution

Soil pollution is the physical change or the addition of chemical substances to the soil in such a quality that the soil cannot be used for its intended application. The physical change may be degradation resulting from construction, indiscriminate disposal of refuse into the soil. The polluting chemical substance maybe solid waste, liquid or gaseous wastes. The gaseous waste is mainly air pollutant that is wash down through precipitation or dry deposition directly into the soil. The liquid waste may be directly discharged as a source of waste disposed or applied resource to the soil like in irrigation process and addition of fertilizer and it can also be cause by direct dumping of solid waste.

Climate change

Many scientists regard anthropogenic (human caused) global climate change to be the most important environmental issue of our time. Global climate changes have been identified as the greatest challenge facing human civilization in the 21st century. Both adaption and mitigation are needed. The two are complementary responses to the many threats posed by the increasing GHG (green house gas) emission (Olojoba, 2009).

The health implication of environmental variable on human health

Outbreak of communicable disease

Environmental variable lead to communicable disease, these are diseases that are transmitted by direct contact with an affected individual or the individual’s discharges or by indirect means (by a vector).

Flies/rodents infestation

Environmental factor/variable leads to flies/rodent infestation through indiscriminate management of solid waste (refuse) and waste water result to infestation of fly eggs and larvae. Flies could perch on feces and also thrive on food wastes of refuse and subsequently contaminate man’s food and water transmitting cholera, bacillary dysentery, amoeba, dysentery, typhoid and paratyphoid fever (Olojoba, 2009).

Rodents can also transmit the following disease to man such as Lassa fever, plaque, marine typhus, rat bite fever (Olojoba, 2009).

 Water-borne disease

According to Otiti (2013) it have been estimated that 80% of human disease in the world are attributed to unsafe water. Therefore water-borne diseases are diseases due to drinking water that contain disease causative organism. The causative organism can gain entry through contamination of water by human or animal faeces or urine infected with pathogenic bacteria or viruses which are directly transmitted when the water is drunk or used in the preparation of food. Example of these diseases is cholera, typhoid fever, diarrhea, and poliomyelitis etc.

The role of environmental variable in disease transmission

Poor environmental sanitation

According to Otiti (2013), poor environmental sanitation can cause diseases such as malaria typhoid fever, plaque, Lassa fever, typhoid fever, cholera etc. when the environment is not cleared of bushes and kept in a good manner and also when there is no proper waste management all these can affect human health and pose man to series of ill health.

Poor water sanitation

According to Otiti (2013) poor water sanitation can lead to water related disease whose example are cholera, typhoid fever, diarrhea disease, eczema, trachoma, scabies, ascariasis. Due to the consumption of disease causative organisms, when there is no proper treatment of water supply sources and when there is no high standard of personal hygiene.

Improper disposal of refuse/excretal

According to Park (2009) improper disposal of refuse can cause disease such as typhoid, paratyphoid, dysentery, diarrhea, cholera, look-worm, ascariasis, intestinal infections and parasitic infection. These diseases are not only a burden on the community in term of sickness, mortality and a low expectation of life but a basic deterrent to social and economic progress to human health.


According to Park (2009), overcrowding is a health problem dwellings which can promote the spread of respiratory infection such as tuberculosis, influenza, diphtheria and causes mental disorders, high morbidity and mortality rate are observed where housing condition are not standard which affect health.

Poor housing condition

According to Parks (2009) poor housing can result to cause disease such as respiratory disease, skin infection, accident, rat infestation which can affect human health and well being.

The possible ways of reducing environmental variable

The possible ways of reducing environmental variable in disease transmission according to Park (2009):

Enforcement and implementation of laws

The government should initiate policies and legislation for protection and development of the environment so as to control the environmental factors to prevent the transmission of diseases.

Proper waste disposal management

Waste should be properly disposal so as to prevent odor nuisance, fly infestation, rodent infestation, unsightliness of the environment, also the burning of refuse in dumps, incinerators and settlements generate air pollutants like dark dense smoke, particles and offensive odor, this should be discouraged.

Regular inspection of premises

Premises should be inspected regularly so as to keep the environment in right order and prevent diseases from the environment. The use of pesticides should be encouraged and all pot holes should be closed, also prevent stagnant water in the environment which encourages the breeding of flies and mosquitoes.

Proper personal hygiene

Proper personal hygiene should be done or carried out both inside and outside. Like cleaning the environment, washing of dirty utensils and clothes etc. personal hygiene prevent the transmission of disease when everything is kept in order.

Effective environmental sanitation

Effective environmental sanitation should be carried out in the environment always so as to prevent disease. It also makes us to see the beauty of the environment, and it provide a safe environment for human dwelling and increase the aesthetic beauty of the environment.

Health education of the public

The public should be enlightened on how to take care of the environment, through proper environmental sanitation, good personal hygiene regular inspection of premises. If all these are done it will promote the environment and prevent disease transmission.


In conclusion of this seminar work, there should be effective inspection of communities by Environmental Health Officer. And health educate the general public so as to help reduce the risk of environmental variable in disease transmission.


I hereby recommend that:

  1. There should be effective educator of masses on the effect of poor environmental sanitation practices.
  2. There should be proper waste disposal channels i.e.
  3. government should provide an approved site for refuse disposal
  4. Provision of adequate toilet facilities and clean water in public places.
  5. Adequate funding through government and private partnership.


Aibor, M. S. & Olorunda, J. O. (2006). Environmental Health in 21st Century for Professionals and Student. Lagos: Devine Favour.

Avwoke, P. (2012). Principles of Epidemiology and Disease Control: EHT 201 [Lecture Note] Ofuoma – Ughelli: Delta State College of Health Technology, Environmental Health Department.

Gilpin, A. (2008). Dictionary of Environmental and Sustainable Development Retrieved http://www.earth Org/view/article/200786.

Hogan, C. (2011). Abiotic Factor Retrieved from http://www.earth Org/view/article/149786.

Lesley, N. M. &Bouvier, M. D. (2012). Environment Factor affecting the transmission of respiratory disease retrieved from DOI:1010161.

Missour, M. (2011), Department of Health and Senior Service Retrieved from health mo goo/ living Environment.

Olojoba, A. O  (2009). Millennium Technology in Waste Management and Environmental Pollution Mitigation. Ughelli: Ama- Ohoror.

Otiti, O. (2007). Business Dictionary Retrieved from www.Earth.org/view/article/149786.

Park, K (2009) Preventive and Social Medicine (20th Ed) India: Banarsidas Bhanot.

Stromberg, B. E. (2004). More Scholarly. Articles Retrieved from www. Ncbi:Mnih Goo/Pubmed 1460201.

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