Concepts of Disease PDF

CONCEPTS OF DISEASE Prepared by: Joy V. Pagaduan, RPh.  What I s H E A L T H ? The World Health Organization (WHO), defines health as ‘a state of complete physical, mental and social wellbeing and not merely the absence of sickness or infirmity. What constitutes ‘complete physical, mental and s...

CONCEPTS OF DISEASE Prepared by: Joy V. Pagaduan, RPh.  What I s H E A L T H ? The World Health Organization (WHO), defines health as ‘a state of complete physical, mental and social wellbeing and not merely the absence of sickness or infirmity. What constitutes ‘complete physical, mental and social wellbeing’ in a human being ? Does physical well- being imply an ability to run a marathon? Does a shy and self-effacing person lack social wellbeing?  What is disease? Consider the following definitions of disease: A condition which alters or interferes with the normal state of an organism and is usually characterized by the abnormal functioning of one or more of the host’s systems, parts or organs (Churchill’s Medical Dictionary, 1989). A morbid entity characterized usually by at least two of these criteria: recognized aetiologic agents, identifiable groups of signs and symptoms, or consistent anatomical alterations (elsewhere, ‘morbid’ is defined as diseased or pathologic) (Stedman’s Medical Dictionary, 1990). Potential insufficient to satisfy the demands of life’ as outlined by Bircher (2005) in his definition of health above  Three components of disease DIAGNOSTIC SIGNS:  is a signal that can be seen by someone else  any objective evidence of a disease that can be observed by others (for example a skin rash or lump) SYMPTOMS signal that’s felt or noticed by the person who has it, but may not be easily seen by anyone else. THREE MAIN TYPES OF SYMPTOMS : Remitting symptoms: When symptoms improve or resolve completely, they are known as remitting symptoms. For examples, symptoms of the common cold may occur for several days and then resolve without treatment. Chronic symptoms: These are long-lasting or recurrent symptoms. Chronic symptoms are often seen in ongoing conditions, such as diabetes, asthma and cancer Relapsing symptoms: These are symptoms that have occurred in the past, resolved, and then returned. For instance, symptoms of depression may not occur for years at a time but can then return PROGNOSIS  Non recovery  Worsening symptoms  Reduced life expectancy AKA: DEATH Average number of years that a person can expect to live in "full health" by taking into account years lived in less than full health due to disease and/or injury. MORBIDITY AKA: ILLNESS refers to the consequences and complications (other than death) that result from a disease. PHARMACOEPIDEMIOLOGY is the study of the use and effects of drugs in human populations, as distinct from individuals, the latter being the focus of clinical pharmacology PHARMACOGENOMICS is the study of how genes affect a person's response to drugs. This relatively new field combines pharmacology (the science of drugs) and genomics (the study of genes and their functions) to develop effective, safe medications and doses that will be tailored to a person's genetic makeup a branch of health economics, is a subject that grew up around the need for healthcare providers to balance the ever-growing costs of healthcare against limited resources. PHARMACOECONOMICS FOUR LEVELS OF ANALYSIS 1. COST IDENTIFICATION consists of determining the full cost in monetary units of a particular therapeutic intervention, including hospitalization, working days lost, etc., as well as direct drug costs 2.COST-EFFECTIVENESS ANALYSIS aims to quantify outcome as well as cost. This is where the real problems begin. The outcome measure most often used in cost- effectiveness analysis is based on prolongation of life, expressed as life-years saved per patient treated. 3. COST-UTILITY ANALYSIS is designed to include allowance for quality of life, as well as survival, in the calculation, and is yet more controversial, for it becomes necessary somehow to quantify quality – not an endeavour for the faint-hearted. - quality-adjusted life-years (QALYs). 4.COST–BENEFIT ANALYSIS fulfils this need in principle, by translating healthcare improvements into monetary units that can be directly balanced against costs, to assess whether any given procedure is, on balance, ‘profitable’ CLASSIFICATION OF DISEASE Types of Diseases A. CONGENITAL DISEASE : The disease which is present from birth (e.g. hole in the heart in infants). They are caused by some genetic abnormality or metabolic disorder or malfunctioning of an organ. B. ACQUIRED DISEASE : The disease which may occur after birth during one’s lifetime.  ACQUIRED DISEASES MAY GENERALLY BE CLASSIFIED INTO (i) Infectious diseases : The diseases which can be transmitted from diseased healthy person to person. e.g. measles. (ii) Degenerative diseases : The diseases caused by the malfunction of some vital organs of the body e.g. heart failure (iii) Deficiency diseases : These are caused due to nutritional deficiency such as that of minerals or vitamins in the diet e.g. anaemia (Fe), Beri- beri (vitamin B). (iv) Cancer : This is an abnormal, uncontrolled and unwanted growth of cells. e.g. breast cancer.  ACQUIRED DISEASES ARE STUDIED UNDER TWO CATEGORIES COMMUNICABLE DISEASES : The diseases which can be transmitted from an infected person to a healthy person. NON-COMMUNICABLE DISEASES : These diseases do not spread from an affected person to a healthy person  DIRECT TRANSMISSION DIRECT CONTACT BETWEEN THE INFECTED PERSON AND THE HEALTHY PERSON : Diseases like small pox, chicken pox, syphilis, gonorrhoea spread through direct contact. DROPLET INFECTION : The infected person throws out tiny droplets of mucus by coughing, sneezing or spitting. These droplets may contain the pathogen. By inhaling the air containing the droplets, a healthy person may get the infection. Diseases like common cold, pneumonia, influenza, measles, tuberculosis and whooping cough spread through droplet infection CONTACT WITH SOIL contaminated with disease-causing viruses and bacteria. ANIMAL BITE : Viruses of rabies are introduced through the wound caused by the bite of rabid animals, especially dogs. The virus is present in the saliva of the rabid animals  INDIRECT TRANSMISSION The pathogens of certain diseases reach the human body through some intermediate agents BY VECTORS: such as houseflies, mosquitoes, and cockroaches AIR-BORNE : The pathogens may reach humans with air and dust. OBJECT BORNE (FONITE BORNE): Many diseases are transmitted through the use of contaminated articles, such as clothes, utensils, toys, door handles, taps, syringes and surgical instruments WATER BORNE : If potable water (drinking water) is contaminated with pathogens of diseases such as cholera, diarhhea, hepatitis or jaundice, it reaches a healthy person upon consuming such water