Medical Terminology in Epidemiology and Public Health PDF

Medical Terminology in Epidemiology and Public Health Assisstant professr Dr. Shahrazad S. Al Jobori MBChB., FICSM/Community Medicine University of Kerbala – College of Medicine Lecture objectives: Become aware of some epidemilogical terms related to infectious diseases What is the WH...

Medical Terminology in Epidemiology and Public Health Assisstant professr Dr. Shahrazad S. Al Jobori MBChB., FICSM/Community Medicine University of Kerbala – College of Medicine Lecture objectives: Become aware of some epidemilogical terms related to infectious diseases What is the WHO definition of health? Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity. The definition has not been amended since 1948. Epidemiology is defined as “the study of the distribution and determinants of health-related states or events in specified populations and the application of this study to control of health problems. Epidemiology is the study of how disease is distributed in populations and the factors that influence or determine this distribution. Why does a disease develop in some people and not in others? The premise underlying epidemiology is that disease, illness, ill health, and excellent health status are not randomly distributed in human populations. Human disease results from an interaction of the host (a person), the agent (e.g., a bacterium), and the environment (e.g., polluted air). Although some diseases are largely genetic in origin, virtually all disease results from an interaction of genetic, behavioral, and environmental factors, with the propotions differing for different diseases. Many of the underlying principles governing the transmission of disease are most clearly demonstrated using communicable diseases as a model.  Epidemiological Levels of disease Endemic is defined as the habitual presence of a disease within a given geographic area and is referred to as the baseline or endemic level of the disease. It may also refer to the usual occurrence of a given disease within such an area. This level is not necessarily the desired level, which may in fact be zero, but rather is the observed level. Thus, the baseline level is often regarded as the expected level of the disease. While some diseases are so rare in a given population that a single case warrants an epidemiologic investigation (e.g., rabies, plague, polio), other diseases occur more commonly so that only deviations from the norm warrant investigation e.g. cholera & measles. Occasionally, the amount of disease in a community rises above the expected level. Epidemic refers to an increase, often sudden, in the number of cases of a disease above what is normally expected in that population in that area Outbreak : Carries the same definition of epidemic, but is often used for a more limited geographic area. Let us assume that a food becomes contaminated with a microorganism. If an outbreak occurs in the group of people who have eaten the food, it is called a common-vehicle exposure, because all the cases that developed were in persons exposed to the food in question. Pandemic: Refers to an epidemic that has spread over several countries or continents, usually affecting a large number of people.eg COVID19, small pox Zoonotic Diseases: Disease Transmitted from Animals to Humans A zoonosis (zoonotic disease or zoonoses - plural) is an infectious disease that is transmitted between species from animals to humans (or from humans to animals). Zoonotic diseases are caused by viruses, bacteria, parasites, and fungi. These can cause many different types of illnesses in people and animals, ranging from mild to serious illness and even death. Examples of zoonotic diseases: Anthrax, brucellosis, avian flue, COVID19, Ebola, rabies,  Surveillance Surveillance is a fundamental role of public health. The Centers for Disease Control and Prevention (CDC) defined epidemiologic surveillance as the “ongoing systematic collection, analysis, and interpretation of health data essential to the planning, implementation, and evaluation of public health practice closely integrated with the timely dissemination of these data to those who need to know.”  Suriellance System Information Action Surveillance may be carried out to monitor changes in disease frequency or to monitor changes in the levels of risks for specific diseases. Much of our information about morbidity and mortality from disease comes from programs of systematic disease surveillance. Reservoir: Indicates any person, animal, arthropod, plant, substance or combination of these in which an infectious agent normally lives and multiplies, on which it depends primarily for survival, and where it reproduces itself in such a manner that it can be transmitted to a susceptible host. Portal of Exit: A portal of exit is a way for a microorganism to leave the reservoir. For example, the microorganism may leave the reservoir through the nose or mouth when someone sneezes or coughs, or can be carried away from the body by feces from an infected bowel. Portal of Entry: The portal of entry is the means by which the infectious microorganisms gains access into the new host. This can occur, for example, through ingestion, breathing, or skin puncture. Mode of transmission: describes the mechanisms by which the infectious agent is spread to humans. The modes (means) of transmission are: Contact (direct and/or indirect), Droplet, Airborne, Vector and Common Vehicle. Incubation period: is the time interval between initial contact with the infectious organism and the first appearance of symptoms associated with the infection. Period of communicability: Is the time during which an infectious agent may be transferred directly or indirectly from an infected person to another person; from an infected animal to humans; or from an infected person to animals. Susceptibility: (including immunity) provides information on human or animal populations at risk of infection, or that are resistant to either infection or disease. Information on subsequent immunity consecutive to infection is also given. Carrier State: In this situation, the individual harbors the organism, but is not infected as measured by serologic studies (no evidence of an antibody response) or by evidence of clinical illness. This person can still infect others, although the infectivity is often lower than with other infections. Carrier status may be of limited duration or may be chronic, lasting for months or years. One of the best-known examples of a long-term carrier was Typhoid Mary, who carried Salmonella typhi and died in 1938. Over a period of many years, she worked as a cook in the New York City area, moving from household to household under different names. She was considered to have caused at least 10 typhoid fever outbreaks that included 51 cases and 3 deaths. Methods of control of infecious diseases are described under the following headings: A. Preventive measures: for individuals and groups. B. Control of patient, contacts and the immediate environment: measures designed to prevent further spread of the disease from infected persons, and specific best current treatment to minimize the period of communicability and to reduce morbidity and mortality. C. Epidemic measures: describes those procedures of an emergency character designed to limit the spread of a communicable disease that has developed widely in a group or community, or within an area, state or nation. D. Disaster implications: given a disaster, indicates the likelihood that the disease might constitute a major problem if preventive actions are not initiated. E. International measures: outlines those interventions designed to protect populations against the known risk of infection from international sources. The WHO Collaborating Centres, the CDC, and other operational institutions can provide national authorities with the services following: laboratory diagnosis, consultation, analysis of information, production and distribution of standard and reference materials and reagents, training, organization of collaborative research, and provision of further information on specific diseases. F. Measures in case of deliberate use of biological agents to cause harm (formerly bioterrorism measures): for selected diseases, this new section provides information and guidelines for public health workers who may be confronted with a threatened or actual act of deliberate use with a specific infectious disease agent. Isolation and quarantine are public health practices used to protect the public by preventing exposure to people who have or may have a contagious disease. Isolation separates sick people with a contagious disease from people who are not sick. Quarantine separates and restricts the movement of people who were exposed to a contagious disease to see if they become sick. These people may have been exposed to a disease and do not know it, or they may have the disease but do not show symptoms. Important referenes to search for updates in health information: 1- Iraqi Academic scientific Journals 2- Google scholar 3- pupmed 4- World health organizaion website 5- American, Canadian & British Universities websites 6- Research Gate  References: 1- WHO website 2-CDC 3- Epidemiology: Leon Gordis