Principles of control of Communicable Disease

Principles of control of Communicable Disease

  No man is an island; entire of itself; man is a social being thriving within the fabric of community living. It is, therefore, quite natural that certain communicable diseases, particularly those where the causative agents are microbes, find ample, opportunities to spread among others in the community. The incidence of a communicable disease is the resultant reaction of an infective agent and a susceptible host in a favorable environment. It is true that the infective process cannot start if any link of this triad is broken. But it is equally true that the task is not as easy as it sounds to be. 



Despite an immense explosion of our knowledge of epidemiology and disease control techniques, the vast majority of the human population has not yet been able to free itself from even the many preventable and deadly communicable diseases. Whereas major advances have occurred in the western world in the field of communicable disease control, the progress in the underdeveloped countries has been very slow and communicable diseases still remain as the principal cause of morbidity and mortality of the masses. The way of life in underdeveloped societies contains innumerable defects, many of which are deleterious to health and offer a fertile environment for growth of microbial agents and their spread. In a country like Bangladesh with unstable economy and increasing population pressure, with lack of adequate food supply and nutrition, with poor housing and education, the body defense mechanism of the people is low; unhygienic disposal of human excreta and garbage polluting the soil and water supply, non-availability of safe drinking water, uncontrolled breeding of insects and pests—all these encourage creation of an environment where infective disease agents not only thrive but also find favorable vehicles of transmission. But the situation as it prevails today must not be viewed with apathy and inertia and efforts must be continued with renewed vigor in all areas to contain the menace of communicable diseases. The government and the local bodies must assume the responsibilities for ensuring the availability of adequate food through more efficient agriculture and animal husbandry, arrange construction and preservation of water supply in villages, make a liberal allocation to education and health sectors. give priority to maternity, child welfare, and immunization activities and improve people’s access to health resources. Political pressure for prestigious projects should be resisted and more employment and job opportunities created so as to improve the socio-economic condition. Much help has been given by world bodies and outside agencies to assist the government in various projects pertaining to health. But the success of these projects depends on the people’s acceptance and collaboration, and these should be operated largely by local people. Medical education should include the experience of both clinical and preventive medicine with equal importance so that the doctors can encourage people to make full use of preventive medicine and advise them about healthy living and techniques to avoid communicable diseases in particular.


Plus, read to get the facts and list of infectious diseases types, causes, prevention, and treatment, and learn how they spread.



Communicable Disease cycle

It refers to the stages through which most of the communicable diseases pass during their natural course in man. The stages are (i) Incubation period (described under sub-chapter 5 of chapter IV): (ii) Prodromal stage—a short period when the patient experiences some vague symptoms, such as headache, nausea, body ache, etc.; (iii) Fastigium—manifestation of signs and symptoms; (iv) Stage of defervescence—is also a part of clinical-stage when the body’s defense mechanism to fight the invading pathogenic organism comes into play, and the patient starts feeling better: (v) Convalescence— in this stage the patient although may have recovered from the clinical manifestations, may still harbor the causative agent: (vi) Defection— in this stage, the person has fully recovered from the disease, but in some cases, he may still continue harboring the disease organism for a varying period of time. The measures for the prevention and control of communicable diseases have been mentioned under each disease covered by this article. However, the general principles of their control are given here under the following broad headings

Prevention of Spread for Communicable Disease

  • Early diagnosis and treatment. The potential of disease transmission exists in an individual who harbors an infectious The risk of infection for exposed susceptible will remain until the agent of infection has been eliminated or reduced to such an extent that the hazard no longer exists. Early diagnosis and effective treatment are the main interventions of disease control through which the elimination of infectious agents is possible.
  • After the diagnosis, the first step that needs to be taken for the control of a communicable disease is the notification to health authorities. This helps in taking appropriate measures to prevent further spread of the disease.

In addition to reporting to the local authorities, reports in respect of certain prescribed diseases under International Health Regulations or under surveillance by WHO is required to be sent to the World Health Organization. Diseases under Surveillance by WHO, established by the World Health Assembly, are louse-borne typhus fever and relapsing fever, paralytic poliomyelitis, malaria, and viral influenza. The diseases subjected to the International Health Regulations (1969), Third Annotated Edition, 1983, WHO Geneva, i.e., internationally quarantinable diseases are a plague, yellow fever, cholera, and smallpox.

  • This implies a restriction of movement of apparently healthy persons who have been exposed to a communicable disease during its incubation period, in order to prevent disease transmission. (a) Absolute or complete quarantine: The limitation of freedom of movement of persons exposed to a communicable disease for a period of time no longer than the longest incubation period of the disease. (b) Modified quarantine: A selective or partial limitation of freedom of movement of persons, commonly on the basis of known or presumed differences in susceptibility and related danger of disease transmission. It may be designed to meet particular situations. Examples are the exclusion of children from school, exemption of immune persons form provisions applicable to susceptible persons, etc. It includes personal surveillance, the practice of close medical or other supervision of contents in order to permit prompt recognition of infection or illness but without restricting their movements.

Quarantine measures may also be applied by the health authority to ship, an aircraft or other means of transport to prevent the spread of disease.

  • Isolation is the separation of infected persons from those not infected for the period of communicability of the disease. While isolation is still an essential element in the control of certain diseases, there is a decreasing reliance on this measure. It is futile to impose isolation if there is a large component of inapparent infection or if maximal infectivity precedes overt illness. However, isolation may be recommended only when the risk of transmission of the infection is exceptionally high.


A. Epidemiological investigation occupies an important place in investigation and control of an epidemic outbreak, It helps in the verification of diagnosis, tracking out the source of infection, determining the extent of spread of infection (secondary cases), the factors influencing the spread of the disease and recommending appropriate remedial measures.


B.Protecting Susceptible Hosts

The susceptible hosts or people at risk may be protected by immunization or chemoprophylaxis. (a) Immunization— active or passive (the subject has been discussed in detail in Chapter XIV under ‘immunology’ (b) Chemoprophylaxis: Drug prophylaxis as a control measure has been found useful in certain diseases, such as malaria (proguanil, pyrimethamine, chloroquine, etc.) pneumonic plague (tetracycline). meningococcal meningitis (sulphadiazine), etc.  

C.Interruption of Transmission

Breaking the chain of transmission is a major step for the control of communicable diseases. The measures to be taken are: (a) purification of water or provision for pure drinking water, maintenance of proper sanitation and good personal hygiene, and pasteurization of milk, (b) integrated control of vectors, (c) practice of safe sex. D.Destruction of Microbes This can be achieved through the process of disinfection and sterilization. Disinfection means the destruction of micro-organisms of infectious diseases whereas sterilization aims at the destruction of all micro-organisms including their spores. This subject is discussed in detail at the end of this chapter under sub-chapter 9 (Disinfection and Sterilization).