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DISEASE PREVENTION AND CONTROL Dr Bayapa Reddy M.D. Assistant Professor Community Medicine 7/3/2012 Dr NBR Com Med CMCH&RC


Introduction Every disease has certain weak points susceptible to attack. Identify these weak points and break the weakest links in the chain of transmission. This requires sound epidemiological knowledge of the disease Magnitude Distribution in time, Place and person Multifactorial causation Sources of infection Dynamics of transmission. 7/3/2012 Dr NBR Com Med CMCH&RC

Control Measures:

Control Measures These are delayed due to incomplete knowledge of Aetiology of the causating agent The reservoir or source of infection The route(s) of transmission The susceptible host (people at risk) 7/3/2012 Dr NBR Com Med CMCH&RC

The choice of methods :

The choice of methods Depend upon factors such as Availability of proper tools and techniques, Relative cost effectiveness, efficiency and acceptability. Community participation (involvement), Political support and Inter­sectoral co-ordination 7/3/2012 Dr NBR Com Med CMCH&RC

Weakest links in the chain of disease transmission:

Weakest links in the chain of disease transmission Controlling the reservoir Interruption of transmission Protect The susceptible host 7/3/2012 Dr NBR Com Med CMCH&RC

Controlling the reservoir :

Controlling the reservoir EARLY DIAGNOSIS NOTIFICATION EPIDEMIOLOGICAL INVESTIGATIONS ISOLATION TREATMENT QUARANTINE : this method of disease control, has become outdated. It has been replaced by active surveillance. 7/3/2012 Dr NBR Com Med CMCH&RC


EARLY DIAGNOSIS Rapid identification of disease plays crucial role in the control of a communicable disease. Early diagnosis is needed for To treatment the patients For epidemiological investigations, e.g., to trace the source of infection from the known or index case to the unknown. To study the time, place and person distribution For the institution of prevention and control measures. 7/3/2012 Dr NBR Com Med CMCH&RC


NOTIFICATION Once an infectious disease has been detected (or even suspected), it should be notified to the local health authority. Begin control measures, including the provision of medical care to patients. Diseases which are considered to be serious menaces to public health are included in the list of notifiable diseases. International Health regulations Cholera Plague and Yellow fever Diseases under surveillance by WHO Louse-borne typhus fever Relapsing fever Paralytic polio Malaria Viral influenza -A SARS diseases Small pox etc . 7/3/2012 Dr NBR Com Med CMCH&RC


EPIDEMIOLOGICAL INVESTIGATIONS The outbreak investigation helps to identify The source of infection The factors influencing its spread in the community. These may include geographical situation, climatic condition, social, cultural and behavioural patterns, The character of the agent, reservoir, the vectors and vehicles, and the susceptible host populations 7/3/2012 Dr NBR Com Med CMCH&RC


ISOLATION Defination: Separation for the period of communicability of infected persons or animals from others in such places and under such conditions, as to prevent or limit the direct or indirect transmission of the infectious agent from infected to susceptible. 7/3/2012 Dr NBR Com Med CMCH&RC

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Isolation has a distinctive value in the control of some infectious diseases. e.g., diphtheria, cholera, streptococcal respiratory disease, pneumonic plague, etc. If the diseases have large component of subclinical infection and carrier state even the most rigid isolation will not prevent the spread of the disease. e.g., polio, hepatitis A, and typhoid fever. Highly infectious before diagnosis Eg Mumps 7/3/2012 Dr NBR Com Med CMCH&RC

Duration of isolation :

Duration of isolation The duration of isolation is determined by the duration of communicability of the disease and the effect of chemotherapy on infectivity. Eg Chickenpox Until all lesions crusted; usually about 6 days after onset of rash. Measles From the onset of catarrhal stage through 3rd day of rash. Cholera and Diphtheria : 3 days after tetracyclines started, until 48 hours of antibiotics (or negative cultures after treatment) 7/3/2012 Dr NBR Com Med CMCH&RC


TREATMENT Many communicable diseases have been tamed by effective drugs. The objective of treatment is To kill the infectious agent when it is still in the reservoir before it is disseminated. Reduce the communicability of disease Cut short the duration of illness and Prevent development of secondary cases Limit the disability Individual treatment or mass treatment. 7/3/2012 Dr NBR Com Med CMCH&RC


QUARANTINE The limitation of freedom of movement Absolute quarantine: well persons or domestic animals exposed to communicable disease for a period of time not longer than the longest usual incubation period of the disease. Modified quarantine A selective or partial limitation of freedom of movement, such as exclusion of children from school. Segregation The separation for special consideration, control of observation of some part of a group of persons (or domestic animals) from the others to facilitate control of a communicable disease. e.g., removal of susceptible children to homes of immune persons 7/3/2012 Dr NBR Com Med CMCH&RC

Interruption of transmission:

Interruption of transmission This may mean changing some components of man's environment to prevent the infective agent from a patient or carrier from entering the body of susceptible person. Eg; water can be a medium for the transmission of many diseases such as typhoid, dysentery, hepatitis A, cholera and gastroenteritis. simple chlorination to complex treatment of water will eliminate these diseases. 7/3/2012 Dr NBR Com Med CMCH&RC

Interruption of transmission:

Interruption of transmission Clean practices such as hand washing, adequate cooking, prompt refrigeration of prepared foods and withdrawal of contaminated foods will prevent most food­borne illnesses . Vector control also includes destruction of stray dogs, control of cattle, pets and other animals to minimise spread of infection among them, and from them to man. personal hygiene and proper handling of secretions and excretions. 7/3/2012 Dr NBR Com Med CMCH&RC

Protect The susceptible host :



ACTIVE IMMUNIZATION Strengthening of the host defences is one of the way to control the spread of infection. Active immunization is one of the most powerful and cost-effective weapons of modern medicine. There are some infectious diseases whose control is solely based on active immunization, e.g., polio, tetanus, diphtheria and measles. Vaccination against these diseases is given as a routine during infancy and early childhood with periodic boosters to maintain adequate levels of immunity. 7/3/2012 Dr NBR Com Med CMCH&RC


PASSIVE IMMUNIZATION Three types of preparations are available for passive immunity – Normal human immunoglobulin, Specific (hyperimmune)human immunoglobulin Antisera or anti-toxins. Passive immunity will provide immunity for 6 months. 7/3/2012 Dr NBR Com Med CMCH&RC


CHEMOPROPHYLAXIS Chemoprophylaxis implies the protection from, or prevention of disease. Causal prophylaxis Implies the complete prevention of infection by the early elimination of the invading or migrating causal agent. For example, there is no causal prophylaxis available against malaria. Clinical prophylaxis Implies the prevention of clinical symptoms; it does not necessarily mean elimination of infection. 7/3/2012 Dr NBR Com Med CMCH&RC


NON-SPECIFIC MEASURES Non­specific factors have played a dominant role in the decline of Diseases E.g., tuberculosis, cholera, leprosy and child mortality The industrialized world, declined these Diseases long before the introduction of specific control measures. Improvements in the quality of life e.g., better housing, water supply, sanitation, nutrition, education. legislative measures To formulate integrated programme Effective implementation. 7/3/2012 Dr NBR Com Med CMCH&RC


NON-SPECIFIC MEASURES Community involvement In disease surveillance, Disease control and other public health activities. scarcity of funds, lack of an effective health infrastructure, public health laboratory facilities, equipment, supplies, trained personnel (e.g., epidemiologists). Public awareness needed for the investigation and control of communicable diseases 7/3/2012 Dr NBR Com Med CMCH&RC


Surveillance Definition : the continuous scrutiny of all aspects of occurrence and spread of disease that are pertinent to effective control. prerequisite to the rational design and evaluation of any disease control programme. The ultimate objective of surveillance is prevention. Surveillance goes beyond the passive reporting of cases. It includes laboratory confirmation of presumptive diagnosis finding out the source of infection, routes of transmission identification of all cases and susceptible contacts Serological surveillance identifies patterns of current and past infection. 7/3/2012 Dr NBR Com Med CMCH&RC

Types of Surveillance:

Types of Surveillance Individual surveillance: This is surveillance of infected persons until they are no longer a significant risk to other individuals Local population surveillance : e.g., surveillance of malaria National population surveillance: e.g., surveillance of smallpox after the disease has been eradicated. 7/3/2012 Dr NBR Com Med CMCH&RC

International surveillance :

International surveillance At the international level, the WHO maintains surveillance of important diseases e.g., influenza, malaria, polio, etc. Gives timely warning to all national governments. Surveillance, if properly pursued, can provide the health agencies with an overall intelligence and disease-accounting capability. 7/3/2012 Dr NBR Com Med CMCH&RC

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7/3/2012 Dr NBR Com Med CMCH&RC THANK YOU

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