Module 3: Health Statistics and Epidemiology (PDF)

NCM 3115 COMMUNITY HEALTH NURSING 2) HEALTH STATISTICS AND EPIDEMIOLOGY BACHELOR OF SCIENCE IN NURSING / LEVEL 3 FIRST SEMESTER / 2024-2025 MODULE 3 TOOLS...

NCM 3115 COMMUNITY HEALTH NURSING 2) HEALTH STATISTICS AND EPIDEMIOLOGY BACHELOR OF SCIENCE IN NURSING / LEVEL 3 FIRST SEMESTER / 2024-2025 MODULE 3 TOOLS The method of measuring population size is to determine the increase in the population using data obtained during two DEMOGRAPHY census periods. Demography – science that deals with the study of the Population size allows the nurse to make comparisons about human population size, affected by births, deaths and population changes over time. migration; composition(structure of the population) and b. Relative increase is the crucial difference between the two distribution in space. census counts expressed in recent years relative to the population It also focuses on population changes- movement from place size made during an earlier year census. to place, trends in fertility rates and birth-death rates. Importance of demography in CHN: Relative increase= Pt-Po o To know how large the population is in a Po community o Characteristics of the population that makes them Where: Pt – population size at a later time Po- population size at an earlier time exposed to certain health conditions o Helps to determine the nature and magnitude of Scenario: In 2016, a census was conducted by the Philippine existing and potential community health problems Statistics Authority at the 2nd Congressional District of Iloilo with a if he posses the knowledge about the population population size of 155,000. Another census was conducted year size, composition and distribution in space. 2019 with a population size increase to 555,000. Determine the relative increase in population of the 3nd district. 1A. SOURCE OF DATA Given: Pt = 555,000 1. CENSUS Po = 155,000 an official and periodic enumeration of population. Solution: During the census, demographic, economic and social data 555,000 -155,000 are collected from a specified population group. 155,000 These data are then collated, synthesized and are made = 2.571437755 or 2.57 Conclusion: The relative increase of population is 2.571437755 or known to the public for purpose of determining and 2.57. explaining trends in terms of population changes and planning programs and services. There are two ways of assigning people when the census is 1C. COMPOSITION being taken: Population composition refers to a certain variables such as a. de jure method - done when people are assigned sex, age, occupation and educational level. to the place they usually lives in regardless of where they are at the time of the census. 1. Sex composition – compares the number of males to the b. de facto - people are assigned to the place where number of females in the population. they are physically present at the time of the census regardless of their usual place of Sex Ratio =number of males residence number of females x 100 The sex ratio represents the number of males for every 100 1B. POPULATION SIZE females in the population. refers to the number of people in a given place or area at a 2. Age composition: given time. Median Age – divides the population into two equal parts. So, if the median age is said to be19 years old, it means half a. Absolute increase per year measures the number of people that of the population belongs to 19 years and above, while the are added to the population per year. This is computed using the following data: other half belongs to ages below 19 years old. Absolute increase per year = Pt – Po Dependency Ratio – compares the number of economically t dependent with economically productive group in the Where: Pt – population size at a later year population. Po – population size at an earlier year o 0 – 14 years old and 65 years old and above are t - number of years between time o and tine t considered economically dependent. o 15 – 64 years old – are considered productive age Scenario: In 2017, the population rose to 555,000. What is the group absolute increase per year of the population in Guimaras if the it had a population of 155,000 in 2014? (𝑃𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 0 − 14 + 𝑃𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛64 >) 𝑇𝑜𝑡𝑎𝑙 (𝐴𝑔𝑒)𝐷𝑒𝑝𝑒𝑛𝑑𝑒𝑛𝑐𝑦 𝑅𝑎𝑡𝑖𝑜 𝑥 100 𝑊𝑜𝑟𝑘𝑖𝑛𝑔 𝑎𝑔𝑒 𝑝𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 15 − 64 Given: Pt = 555,000 Po = 155,000 𝑃𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 0 − 14 t = 3 𝐶ℎ𝑖𝑙𝑑 𝐷𝑒𝑝𝑒𝑛𝑑𝑒𝑛𝑐𝑦 𝑅𝑎𝑡𝑖𝑜 𝑥 100 𝑊𝑜𝑟𝑘𝑖𝑛𝑔 𝑎𝑔𝑒 𝑝𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 15 − 64 555,000 - 155,000 3 𝑃𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛64 > = 133,333.33 Absolute increase per year 𝑂𝑙𝑑 − 𝐴𝑔𝑒 𝐷𝑒𝑝𝑒𝑛𝑑𝑒𝑛𝑐𝑦 𝑅𝑎𝑡𝑖𝑜 𝑥 100 𝑊𝑜𝑟𝑘𝑖𝑛𝑔 𝑎𝑔𝑒 𝑝𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 15 − 64 Conclusion: There were 133,333.33 people added to the population per year. LOURDES 3E 1  COMMUNITY HEALTH NURSING 2 (NCM 3115) 1D. DISTRIBUTION 6. Influenza It can be described in terms of urban-rural distribution, 7. Urinary tract infection population density and crowding index. 8. Tuberculosis 9. Injuries Urban-Rural Distribution – simply illustrates the proportion 10. Heart diseases of people living in urban compared to the rural areas. Crowding index – describe the ease by which a communicable disease can be transmitted from one host to LEADING CAUSES OF MORTALITY another susceptible host. This described by dividing the 1. Diseases of the heart number of persons in a household with the number of rooms 2. Diseases of the vascular system used by the family for sleeping. 3. Pneumonias 4. Malignant neoplasms/cancers Population density – determine how congested a place is. 5. All forms of tuberculosis It can be computed by dividing the number of people living 6. Accidents in a given land area. 7. COPD 8. Diabetes mellitus HEALTH INDICATORS 9. Nephritis/Nephritic syndrome 10. Diseases of respiratory system CRUDE BIRTH RATE The Crude birth rate is only a rough measure of fertility in the LIFE EXPECTANCY population since it makes use of the mid-year population refers to the number of years a person can expect to live. (which ignores the number of men and women incapable of is based on an estimate of the average age that members of childbearing) as its denominator. This rate is obtained using a particular population group will be when they die. the following formula: The current life expectancy for Philippines in 2020 is 71.28 years, a 0.18% increase from 2019 𝑇𝑜𝑡𝑎𝑙 𝑙𝑖𝑣𝑒 𝑏𝑖𝑟𝑡ℎ𝑠 𝑖𝑛 𝑎 𝑐𝑎𝑙𝑒𝑛𝑑𝑎𝑟 𝑦𝑒𝑎𝑟 𝐶𝑟𝑢𝑑𝑒 𝐵𝑖𝑟𝑡ℎ 𝑅𝑎𝑡𝑒 𝑥 1000 𝑀𝑖𝑑 − 𝑦𝑒𝑎𝑟 𝑝𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑖𝑛 𝑓𝑜𝑟 𝑡ℎ𝑎𝑡 𝑦𝑒𝑎𝑟 PHILIPPINE HEALTH SITUATION CRUDE DEATH RATE The national health situation gives us an idea of the health is the total number of deaths to residents in a specified situation in the communities where nurses work geographic area (country, state, county, etc.) divided by the Because of the different conditions prevailing in these total population for the same geographic area (for a specified communities, their health picture expectedly varies. time period, usually a calendar year) and multiplied by 1,000 DEMOGRAPHIC PROFILE 𝑁𝑜. 𝑜𝑓 𝑑𝑒𝑎𝑡ℎ𝑠 𝑖𝑛 𝑎 𝑦𝑒𝑎𝑟 The Philippines is one of the most populous countries in the 𝐶𝑟𝑢𝑑𝑒 𝐷𝑒𝑎𝑡ℎ 𝑅𝑎𝑡𝑒 𝑥 1000 𝐸𝑠𝑡𝑖𝑚𝑎𝑡𝑒𝑑 𝑚𝑖𝑑 − 𝑦𝑟 𝑝𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 𝑠𝑎𝑚𝑒 𝑦𝑒𝑎𝑟 world. In 2000, the country’s population was 75.3 million (109 INFANT MORTALITY RATE million 2020) This rate is considered one of the most sensitive indices of In 1999, the average life expectancy at birth was 68.6 years the health conditions obtained in a population. Infant deaths (71.28 for females and 66.03 for males. (life expectancy are associated with acute communicable diseases and such 2019 is at 71 years) factors as poor environmental sanitation and poor hygiene. 39% of the population was estimated to be in 0-14 age group (1994) 𝐼𝑛𝑓𝑎𝑛𝑡 𝑀𝑜𝑟𝑡𝑎𝑙𝑖𝑡𝑦 𝑅𝑎𝑡𝑒 𝑡𝑜𝑡𝑎𝑙 𝑑𝑒𝑎𝑡ℎ𝑠, < 1𝑦𝑟 𝑜𝑓 𝑎𝑔𝑒 𝑖𝑛 𝑎 𝑐𝑎𝑙𝑒𝑛𝑑𝑎𝑟 𝑦𝑒𝑎𝑟 𝑥 1000 5% were 60 years old and above 𝑡𝑜𝑡𝑎𝑙 𝑙𝑖𝑣𝑒 𝑏𝑖𝑟𝑡ℎ𝑠 𝑖𝑛 𝑡ℎ𝑒 𝑠𝑎𝑚𝑒 𝑦𝑒𝑎𝑟 Dependency ratio at 79, means 79 people (0-14 and 60 yrs and above) depend of 100 people in the productive age MATERNAL MORTALITY RATE group (15-59) This rate measures the risk of dying from causes with There are about 249 people for every square kilometer childbirth. Maternal death is defined as the death of a mother territory. Metro Manila has he highest population density directly due to pregnancy, labor and puerperium within 90 (16,051) and CAR has the lowest (75) days of delivery. The population in Urban areas is increasing from 37% in 1984 (UNICEF, 1986) the figure increase to 44% ten years 𝑡𝑜𝑡𝑎𝑙 𝑚𝑎𝑡𝑒𝑟𝑛𝑎𝑙 𝑑𝑒𝑎𝑡ℎ𝑠 𝑖𝑛 𝑎 𝑐𝑎𝑙𝑒𝑛𝑑𝑎𝑟 𝑦𝑒𝑎𝑟 later 𝑀𝑎𝑡𝑒𝑟𝑛𝑎𝑙 𝑀𝑜𝑟𝑡𝑎𝑙𝑖𝑡𝑦 𝑅𝑎𝑡𝑒 𝑥 1000 𝑡𝑜𝑡𝑎𝑙 𝑙𝑖𝑣𝑒 𝑏𝑖𝑟𝑡ℎ𝑠 𝑖𝑛 𝑡ℎ𝑒 𝑠𝑎𝑚𝑒 𝑦𝑒𝑎𝑟 In 2018, a total of 1,668,120 live births were registered, which is equivalent to a crude birth rate (CBR) of 15.8 or SPECIFIC RATE OF MORTALITY 16 births per thousand population. is the number of deaths from a specified cause per 1,000 In 2019, death rate for Philippines was 5.9 per 1,000 people. person-years at risk. The numerator is typically restricted to Death rate of Philippines fell gradually from 8 per 1,000 resident deaths in a specific geographic area people in 1970 to 5.9 per 1,000 people in 2019. The fertility rate for Philippines in 2019 was 2.555 births per 𝑑𝑒𝑎𝑡ℎ𝑠 𝑓𝑟𝑜𝑚 𝑎 𝑔𝑖𝑣𝑒𝑛 𝑐𝑎𝑢𝑠𝑒 𝑖𝑛 𝑎 𝑦𝑟 𝑆𝑝𝑒𝑐𝑖𝑓𝑖𝑐 𝑅𝑎𝑡𝑒 𝑜𝑓 𝑀𝑜𝑟𝑡𝑎𝑙𝑖𝑡𝑦 𝑥 1000 woman, a 0.97% decline from 2018. The fertility rate for 𝑒𝑠𝑡𝑖𝑚𝑎𝑡𝑒𝑑 𝑚𝑖𝑑 − 𝑦𝑟 𝑝𝑜. 𝑓𝑜𝑟 𝑡ℎ𝑒 𝑠𝑎𝑚𝑒 𝑦𝑟 Philippines in 2018 was 2.580 births per woman, a 3.52% decline from 2017. LEADING CAUSES OF MORBIDITY The infant mortality rate for Philippines in 2019 was 19.239 1. Acute respiratory infection deaths per 1000 live births, a 2.16% decline from 2018. 2. Acute lower respiratory tract infection (Pneumonia) Maternal mortality rate: 121 deaths/100,000 live births (2017 3. Bronchitis estimated) 4. Hypertension 5. Acute watery Diarrhea LOURDES 3E 2  COMMUNITY HEALTH NURSING 2 (NCM 3115) EPIDEMIOLOGY o For example, seasonal variation in mosquito Epidemiology – is the study of abundance in response to annual variation in the distribution and determinants of health-related states or temperature and rainfall can cause strongly events in specified populations, and the application of this seasonal patterns of disease incidence study to the control of health problems. Secular trend Science is concerned with the circumstances under which o describes the occurrence of disease over a diseases occur, where diseases tend to flourish and where prolonged period, usually years they do not. o it is influenced by the degree of immunity in the Field of science, which is concerned with the various factors, population and possibly nonspecific measures and conditions that determine the occurrence and such as improved socioeconomic and nutritional distribution of health, disease, defects, disability and death levels among the population. among groups of individuals. Study of the distribution and dynamics of disease occurrence USES OF EPIDEMIOLOGY in human populations as a basis for determining preventive 1. Elucidation of “cause” of disease and control measures. 2. Identification of high risk groups Epidemiology 3. Evaluation of preventive and control measures o scientific discipline with sound methods of 4. For health planning scientific inquiry at its foundation. 5. Understanding the natural history of diseases o data-driven and relies on a systematic and 6. Determine whether epidemiologic data are consistent with unbiased approach to the collection, analysis, and etiological hypothesis interpretation of data. 7. Provide knowledge of disease frequency and distribution o draws on methods from other scientific fields, during epidemic and non-epidemic times including biostatistics and informatics, with biologic, economic, social, and behavioral FUNCTION OF THE EPIDEMIOLOGY NURSE sciences. 1. Implement public health surveillance. 2. Monitor local health personnel conducting disease DISTRIBUTION surveillance. Epidemiology is concerned with the frequency and pattern of 3. Conduct and/or assist other health personnel in outbreak health events in a population: investigation. Frequency refers not only to the number of health events 4. Assist in the conducted of rapid survey and surveillance such as the number of cases of meningitis or diabetes in a during disasters population, but also to the relationship of that number to the 5. Assist in the conduct of surveys, program evaluations and size of the population. other epidemiologic studies. o The resulting rate allows epidemiologists to 6. Assist in the conduct of training course in epidemiology. compare disease occurrence across different 7. Assist the epidemiologist in preparing the annual report and populations. financial plan. Pattern refers to the occurrence of health-related events by 8. Responsible for inventory and maintenance of epidemiology time, place, and person. and surveillance unit (ESU) equipment Endemic – an infection is said to be endemic in a population when that infection is constantly maintained at a baseline CAUSATION OF DISEASES level in a geographic area without external inputs. o For example, chickenpox is endemic in the United FACTORS OF DISEASE CAUSATION Kingdom, but malaria is not Predisposing factors are the factors which create a state Epidemic - is the rapid spread of disease to a large number of susceptibility, making the host vulnerable to the agent. of people in a given population within a short period of time. These are age, sex and previous illnesses. o For example, in meningococcal infections, an Enabling factors are those which assist in the development attack rate in excess of 15 cases per 100,000 of (or in recovery from) the disease; e.g. housing conditions, people for two consecutive weeks is considered socio-economic status. an epidemic. Precipitating factors are those which are associated with Sporadic – refers to a disease that occurs infrequently and immediate exposure to the disease agent or onset of irregularly disease, e.g. drinking contaminated water, close contact with o occurring occasionally, singly, or in scattered a case of pulmonary TB. instances o Examples of sporadic diseases include tetanus, Reinforcing factors are those which aggravate an already rabies, and plague. existing disease, e.g. malnutrition, repeated exposures. Pandemic – an outbreak of a disease that occurs over a Risk factors are the conditions, quality or attributes, the wide geographic area (such as multiple countries or presence of which increases the chances of an individual to continents) and typically affects a significant proportion of have, develop or be adversely affected by a disease the population. process. The risk factor need not necessarily cause the o Example: Covid 19 disease but does increase the probability that the person exposed to the factor may get the disease easily. Herd immunity - (or community immunity) occurs when a high percentage of the community is immune to a disease (through vaccination and/or prior illness), making the spread of this disease from person to person unlikely. Seasonal variation - In time series, that part of the movement which is assigned to the effect of the seasons on the year, (e.g. seasonal variation in rainfall) LOURDES 3E 3  COMMUNITY HEALTH NURSING 2 (NCM 3115) CONCEPTS ON CAUSATION OF DISEASES: factors can also be sufficient factors that combine with the MODERN VIEWS agent. The epidemiological triad can be applied to non-infectious 1. GERM THEORY diseases where the agent could be ‘unhealthy behaviors, unsafe practices, or unintended exposures to hazardous Germ theory was proposed by Louis Pasteur (1822 –1895) substances’. and Robert Koch (1843 –1910). Germ theory postulates that every human disease is caused by a microbe or germ, which 2. WHEEL THEORY is specific for that disease and one must be able to isolate the microbe from the diseased human being. The Germ The theory visualizes human disease in the form of a wheel, theory viewed diseases in terms of a causal network similar which has a central hub representing the genetic to that of Fracastoro, but with much more detail about the components and the peripheral portion representing the nature of germs and possible treatments. environmental component. Organisms that cause disease inside the human body are Like any wheel, the outer part (environmental component) called pathogens. Bacteria and Viruses are the best know has spokes (3 in this model) and the environmental pathogens. Fungi, protozoa’s and parasites can also cause component is thus divided into 3 sub components, disease. representing the social, biological and physical components of the environment. Infectious diseases are typically classified as bacterial, viral, protozoal and so on. Knowing what bacteria are responsible To maintain health one has to take regular exercises and for a particular disease indicates what antibiotic treatment to adequate rest, follow personal hygiene, eat nutritionally apply. balanced diet, abstain from the abuse of drugs and alcohol, take care of one’s mental well-being and develop social skills Diseases are said to be infectious or communicable if to interact in a positive manner within society. pathogens can be passed from one person to another. 3. WEB OF CAUSATION THEORY LEVELS OF PREVENTION The “epidemiological triad theory” was very effectively used Primary Prevention by Leavel and Clark in explaining the natural history of o seeks to prevent a disease or condition at a pre- disease and levels of prevention. pathologic state; to stop something from ever The terms primary, secondary and tertiary prevention were happening. first documented in the late 1940s by Hugh Leavell and E. o strategies emphasize general health promotion, Guerney Clark from the Harvard and Columbia University risk factor reduction, and other health protective Schools of Public Health, respectively. Both were pioneers measures. These strategies include health in Public Health. education and health promotion programs Leavell and Clark described the principles of prevention designed to foster healthier lifestyles and within the context of epidemiologic triangle model of environmental health programs designed to Causation of diseases of Host, Agent and Environment. improve environmental quality. Secondary prevention EPIDEMIOLOGICAL TRIANGLE o focuses on individuals who experience health problems or illnesses and who are at risk of A number of models of disease causation have been developing complication. Activities are directed at proposed. Among the simplest of these is the epidemiologic early diagnosis and prompt intervention, thereby triad or triangle, the traditional model for infectious disease. reducing severity and enabling the client to return The triad consists of an external agent, a susceptible host, to normal. Its purpose is to cure disease, slow its and an environment that brings the host and agent together. progression, or reduce its impact on individuals or Also called the Ecologic Model by Levell and Clark, refers communities. to the interplay of agent (causative etiologic factor), host Tertiary prevention possessing intrinsic factors) and the environment (extrinsic o occurs when a defect or disability is permanent factors). and irreversible. It involves minimizing the effects of long-term disease or disability by interventions 1. EPIDEMIOLOGIAL TRIAD direct at preventing complications and Agent – any environmental factor or stressor (biological, deteriorations. Tertiary prevention strategies are chemical, mechanical, physical and psychological) whose both therapeutic and rehabilitative measures once presence or absence can lead to illness or disease. disease is firmly established. The etiologic agent may be any microorganism that can cause infection. EPIDEMIOLOGICAL TRIAD The pathogenicity of an agent is its ability to cause disease; The standard model of infectious disease causation under pathogenicity is further characterized by describing the the epidemiological triad theory states that an external agent organism's virulence and invasiveness. can cause diseases on a susceptible host when there is a Virulence refers to the severity of infection which can be conducive environment. expressed by describing the morbidity (incidence of disease) Within the epidemiological triad the agent is known as a and mortality (death rate) of the infection. ‘necessary’ factor. It has to be present for morbidity, The invasiveness of an organism refers to its ability to although it may not inevitably lead to disease. For the invade tissue. disease to occur it needs the combination of what have been Other factors should be considered in describing the agent: called ‘sufficient’ factors. These would include a host, which o Infecting dose – (the number of organisms might be an individual or group of individuals who are necessary to cause disease) susceptible to the agent. Susceptibility might be on the basis o Method of transmission of age, sex, ethnic group or occupation. Environmental o Site of entrance of the organism into the host o Host defences LOURDES 3E 4  COMMUNITY HEALTH NURSING 2 (NCM 3115) o Host species Internal transmission occurs when the organisms are carried within the vector. If the pathogen is not changed by 2. RESERVOIR OF AN ORGANISM IS THE SITE WHERE IT its carriage within the vector, the carriage is called RESIDES, METABOLIZES, AND MULTIPLIES. harborage. The source of the organism is the site from which it is The other form of internal transmission is called biologic, transmitted to a susceptible host, either directly or indirectly the organism is changed biologically during its passage through an intermediary object. through the vector ( e.g. malaria parasites in the mosquito The reservoir and source can be different and can also be vector) the same, as in an individual who is a permanent nasal carrier of S. Aureus and who disseminates organisms from HOST this site. Person(s) who may or may not be at risk of acquiring a Etiologic Factors: disease based on family history of disease, lifestyle habits 1. Biological agents: virus, fungi, bacteria, and age; the state of health of a host at any given time a helminthes, protozoa, ectoparasites. result of the interaction of genetic endowment with the 2. Chemical elements: environment over his/her entire lifespan. ▪ Carcinogens The organism may enter the host through the skin, mucous ▪ Allergens membranes, lungs, gastrointestinal tract, or genitourinary ▪ Transfats tract, and it may enter fetuses through the placenta. 3. Nutritive elements: excessive or deficiencies Development of disease in a host reflects agent 4. Mechanical factors: accidents, trauma characteristics and is influenced by host defence 5. Physical; e.g. when one is struck by lighting mechanisms, which may be nonspecific or specific. 6. Psychological: stress Specific defence mechanisms or immunity may be natural, resulting from exposure to the infectious agent, or artificial, METHOD OF TRANSMISSION resulting from active or passive immunization. The method of transmission is the means by which the Nonspecific defence mechanisms include the skin, agent goes from the source to the host. The four major mucous membranes, secretions, enzymes, the inflammatory methods of transmission are by contact, by common vehicle, response, genetic factors, hormones, nutrition, behavioural by air or via a vector. patterns, and the presence of other diseases. Contact transmission – the agent is spread directly, indirectly or by airborne droplets. ENVIRONMENT Direct contact – organisms are transmitted directly from the All factors external to the host that may or may not source to the susceptible host without involving an predispose the person to the development of a disease. This intermediate object, this is also referred as person-to-person includes: transmission. E.g. Hepatitis A. o physical environment – includes inanimate Indirect transmission – organisms are transmitted from a objects and geophysical condition such as climate source, either animate or inanimate, to a host by means of o biological environment – includes all the things an inanimate object. E.g. Pseudomonas organisms from one around the host individual to another by means of a shaving brush. o socio-economic environment – includes Droplet spread – organisms that travel through the air very economic condition, level of economic short distances, that is, less the 3 feet from a source to a development, presence of social problems and the host. The organisms are not airborne in the true sense, e.g. like. leprosy. Common – vehicle transmission – refers to agents EPIDEMIOLOGICAL METHOD transmitted by a common inanimate vehicle, with multiple cases resulting from such exposure. It is a tool in nursing process, similar to the nursing process. o This includes diseases in which food or water as The steps are labeled differently but, in essence, they both well as drugs and parenteral fluids are the vehicles involve a series of circular, dynamic problems-solving of infection. E.g. food-borne salmonellosis, actions. waterborne shigellosis, and bacteraemia resulting The epidemiological process is a systematic course of action from use of IV fluids contaminated with a gram- taken to identify/; negative organism. 1. who is affected (persons) Airbone transmission – refers to infection spread by 2. where the affected persons reside (place) droplet nuclei or dust. 3. when the persons were affected (time) o The droplet nuclei are the residue from the 4. causal factors of health and disease occurrence evaporation of Fluid from droplets, are light (host, agent, environment determinants) enough to be transmitted more than 3 feet from the 5. prevalence and incidence of health and disease source, and may remain airborne for prolonged (frequencies) periods. E.g. TB, the source may be a coughing 6. prevention and control measures (levels of patient who creates aerosols of droplet nuclei that prevention) in relation to the natural life history of contain tubercle bacilli. a disease or a condition Infectious agents may be contained in dust particles, which may become resuspended an d transmitted to hosts. EPIDEMIOLOGICAL PROCESS Vector borne transmission, in which arthropods are the Has eight (8) basic steps, these steps may overlap and may vectors. Vector transmission may be external or internal. not always follow a sequential pattern. They are interrelated External, or mechanical, transmission occur when and dependent on each other. organisms are carried mechanically to the vector. LOURDES 3E 5  COMMUNITY HEALTH NURSING 2 (NCM 3115) Step 1 – Determine the Nature, Extent and Possible TYPES OF EPIDEMIOLOGICAL STUDIES Significance of the Problem. Historical-analytical method – study of the disease A. Natural life history of condition occurrence over long periods of time, e.g. leprosy B. Determinants influencing condition Experimental epidemiology – the method is concerned 1. Primary data (essential agent) with observations made on artificially induced epidemics or Bacteria/Parasite/Virus Nutrition and diseases in experimental laboratory and is mainly utilized Psychosocial for search studies. 2. Contributory data - Agent , Host & Environment Field epidemiology – this is concerned with observation of C. Distribution patterns - Person, Time & Place a specific disease as it actually occurs in the field under D. Condition frequencies - Incidence, Prevalence & natural conditions Biostatistical Measurement o Case study – study on the affected individual and his immediate environment with the family as the Step 2 – Develop Tentative Hypothesis (es). unit of investigation. Hypothesis – is a tentative theory or supposition o Field investigation of epidemic – investigation of provisionally adopted to explain facts and to guide in further situation of acutely developing diseases and is investigations. therefore an emergency epidemiology. (single This step usually reveals a variety of generalizations, family study) influences, theories and speculations which require o Field survey – cross – section study and it appraisal and critical judgment. determines prevalence. It seeks to determine the A must be selected on the basis of needs, interest, and frequency of a disease at a specified time or of availability of resources. total diseases in a whole population. The source of infection revolves on the host, agent and o Field review – long term study, usually more environment. comprehensive than that of the field survey.Its objective is to determine incidence rather than Step 3 – Collect and Analyze Further Data to Test prevalence of the disease during a period of time. Hypothesis (es). Identify the group selected for attack by the disease or OUTLINE OF PLAN FOR EPIDEMIOLOGICAL problem under investigation. INVESTIGATION Variations can be identified through study of attack rates. Testing hypothesis helps to determine if the initial control 1. Establish fact of presence of epidemic measures were sufficient to resolve the current outbreak. o Verify diagnosis o Reporting Step 4 – Plan for Control o Is there unusual prevalence of the disease 2. Establish time and space of the group of community Identify preventive activities based on the knowledge of o Are cases limited to or concentrated in any natural history of the disease in question. particular geographical subdivision of the afftected Determine the following: population at risk, levels of community? prevention, feasibility of implementing the plan, priorities in o Relation of cases by days of onset to onset of the relation to legal mandates, significance of the problems first known cases relative to other community needs, and the feasibility of 3. Relations to characteristic of the group of community. implementing the control plan. o Age, group , sex, occupation, color, past immunization, etc. Step 5 – Implement the Control Plan o Sanitary facilities, water supply , food, known Plan implementation must be a multisectoral- carrier multidisciplinary taking into consideration the beliefs, 4. Correlation of all data obtained attitudes, and customs of the community o Summary of the data o Build up the case for the final conclusion utilizing Step 6 – Evaluate Control Plan all the evidence available Apply the problem-solving approach, how well the objectives o Establish the source of epidemic , manner of of the process were met; how the current situation compares spread to the situation prior to the investigation. o Make suggestion as to the control and prevention Practicability of the control measures and feasibility and cost of future outbreaks in terms of money, time, staff, facilities and community support should be analyzed. STEPS IN OUTBREAK INVESTIGATION Step 7 – Make Appropriate Report 1. Prepare for field work. The nurse makes immediate and accurate reporting which 2. Establish an existence of an outbreak will provide a basis for future investigation and control o Cluster – is an aggregation of cases in a given measures. area over a particular period without regards to whether the number of cases is more than the It should include what was involved in the epidemiological expected. process, diagnosis, factors, events, leading to the epidemic, o Outbreak or epidemic – is the occurrence of control measures, process evaluation, and recommendation more cases of disease that expected in a given for preventing similar situation. area or among a specific group of people over a particular period of time. Step 8 – Conduct Research 3. Verify Diagnosis 4. Define and identify cases o Establish a case definition o Identify and count cases LOURDES 3E 6  COMMUNITY HEALTH NURSING 2 (NCM 3115) 5. Perform descriptive epidemiology o selective examinations 6. Developing hypotheses 2. Disability limitation 7. Evaluate hypotheses o adequate treatment to arrest the disease process 8. Refine hypotheses and execute additional studies because: and to prevent further complications and sequalae o unrevealing analytic studies = poor hypotheses o provision of facilities to limit disability and to o may need more specific exposure histories prevent death o may need more specific control group 9. Implement control and prevention measures NATURAL HISTORY OF DISEASES AND LEVELS OF 10. Communicate findings PREVENTION 11. Follow up recommendations Time Period Prepathogenesis Period of Pathogenesis Stage Prior to Development of Presymptomatic → Early Clinical Disease Disease → Advanced Clinical Disease NATURAL LIFE HISTORY OF DISEASE Natural history of disease – progression of Level of Prevention: Primary Prevention Secondary Prevention Tertiary Prevention a disease process in an individual over time, in the absence Activities: 1. Health Promotion 1. Early Case Finding 1. Limit Disability of treatment. For example, untreated infection with HIV causes a a. Health Education a. Individuals a. Arrest or slow b. Counseling b. Families disease process spectrum of clinical problems beginning at the time of c. Community b. Prevent death if seroconversion (primary HIV) and terminating with AIDS and (Screening possible Program) c. Provide usually death. supportive care 2. Specific Protection 2. Early Treatment 2. Rehabilitation a. Immunizations a. Cure or prevent a. Retraining progression of b. Prevent exposure disease b. Occupational to carcinogens therapy which cause b. Prevent spread of disease disease (primary c. Physical therapy prevention for unaffected individuals) c. Prevent complications and sequelae 3. Rehabilitation o provision of hospital and community facilities for retraining and education for maximum use of remaining capacities o education of the public and industry to utilize the PREVENTIVE MEASURE IN THE NATURAL HISTORY rehabilitated as full employment as possible OF DISEASES o selective placement Prepathogenesis period – interrelationships of agent, host o work therapy in hospitals and environmental factors where there is the production of o use of sheltered colony stimulus. EPIDEMIOLOGY AND SURVEILLANCE UNIT 1. Health Promotion It is an epidemiologic information service, the unit is mainly o health education responsible for providing timely and correct information on o good standards of nutrition adjusted to diseases in the locality. developmental phases of life National Epidemic Sentinel Surveillance System (NESS) o attention to personality development – hospital based information system that monitors the o provision of adequate housing, recreation and occurrence of infectious diseases with outbreak potential. agreeable working conditions o marriage counseling and sex education TYPES OF EPIDEMIOLOGICAL STUDIES o genetics 1. Historical-analytical method – study of the disease o periodic selective examinations occurrence over long periods of time, e.g. leprosy 2. Specific Protection 2. Experimental epidemiology – the method is concerned o use of specific immunization with observations made on artificially induced epidemics or o attention to personal hygiene diseases in experimental laboratory and is mainly utilized o use of environmental sanitation for search studies. o protection against occupational hazards 3. Field epidemiology – this is concerned with observation of o protection from accidents a specific disease as it actually occurs in the field under o use of specific nutrients natural conditions o avoidance of allergens a. Case study – study on the affected individual and his immediate environment with the family as the Period of pathogenesis – reaction of the host to the unit of investigation. stimulus b. Field investigation of epidemic – investigation of situation of acutely developing diseases and is 1. Early diagnosis and prompt treatment therefore an emergency epidemiology. (single o case finding measures, ind.and mass family study) o screening surveys LOURDES 3E 7  COMMUNITY HEALTH NURSING 2 (NCM 3115) c. Field survey – cross – section study and it o Hypotheses about the determinants of disease determines prevalence. It seeks to determine the arise from considering the characteristics of frequency of a disease at a specified time or of person, place, and time and looking for total diseases in a whole population. differences, similarities, and correlations. d. Field review – long term study, usually more Consider the following examples: comprehensive than that of the field survey.Its o Differences: If the frequency of disease differs in objective is to determine incidence rather than two circumstances, it may be caused by a factor prevalence of the disease during a period of time. that differs between the two circumstances. o Similarities: If a high frequency of disease is found THE PHASES OF EPIDEMIOLOGIC APPROACH in several different circumstances and one can I. Descriptive Epidemiology - concerned with disease identify a common factor, then the common factor distribution and frequency may be responsible. II. Analytical Epidemiology – attempts to analyze the causes o Correlations: If the frequency of disease varies in or determinants of disease through hypothesis testing relation to some factor, then that factor may be a III. Intervention or Experimental Epidemiology – answers cause of the disease. questions about the effectiveness of new methods for o Person: Personal Characteristics and controlling diseases or for improving underlying conditions Behavior IV. Evaluation Epidemiology – attempts to measure the ▪ There are many personal characteristics and effectiveness of different health services and programs. behaviors that are relevant to health status and might be considered "exposures" or risk DESCRIPTIVE EPIDEMIOLOGY factors that ought to be considered when conducting research on the determinants of For purposes of understanding the interrelationships of disease or when trying to predict risk such as: factors that bring about community health problems, this o Occupation module will only discuss descriptive epidemiology. o Diet The various aspects involved in descriptive epidemiology are o Smoking the following: o Alcohol consumption Observation and recording of existing patterns of occurrence o Medications of the health condition under study o Family history of disease Description of the disease/condition as to person, place and o Religious practices, e.g. dietary time characteristics restrictions or restrictions on drinking Analysis of the general pattern of occurrence of the disease alcohol or tobacco use or condition o Leisure activities, e.g., exercise o Sexual habits 1. Observation and recording of existing patterns of o Place: Variation by Location occurrence of the health condition ▪ Where one lives, works, and travels can o In order to describe the occurrence of disease provide clues about relevant exposures. In condition, the nurse needs to recognize or identify addition, surveillance data showing how the disease with reasonable certainty. This is done disease frequency varies geographically, or by conducting screening and case finding. even within the same workplace, might o Screening is the presumptive identification of provide valuable clues about the etiology of a unrecognized diseases or defects through the health problem. application of diagnostic tests or laboratory ▪ Does the frequency of disease vary from examinations and clinical assessment. country to country? Or state to state? o Case finding is done to look for previously ▪ Does it vary among cities or neighborhoods? unidentified cases of diseases. Both are applied to ▪ Does it vary within different parts of a large well persons and therefore, should consider the workplace? sensitivity and specificity of the tests. o Variation in Disease Over Time o Sensitivity is the proportion of persons with a ▪ Public health surveillance systems provide disease who will test positive on a screening test. the data to monitor the frequency of health It measures how often a test correctly generates a problems over time, and this is vitally positive result for people who have the condition important for identifying outbreaks and that’s being tested for (also known as the “true trends in disease frequency over time. One positive” rate). should consider changes in disease o Specificity is the proportion of persons without the frequency on several different scales disease who have negative results on a screening depending upon the disease of interest. test. It measures a test’s ability to correctly ▪ Has the frequency of disease changed over generate negative result for people who don’t several decades? (e.g., tuberculosis, polio) have the condition that’s being tested for (also ▪ Does frequency of disease vary in a cyclic known as the “true negative” rate). way that relates to the seasons? (e.g., influenza) 2. Description of the disease/condition as to person, place ▪ Has it changed over the course of days? and time characteristics (e.g., outbreaks of foodborne illness) o Descriptive epidemiology searches for patterns by ▪ There are certain variations in time examining characteristics of person, place, & time. distribution of diseases: o These characteristics are carefully considered o Short-time fluctuations (epidemic) when a disease outbreak occurs, because they – changes of disease frequency in provide important clues regarding the source of the outbreak. LOURDES 3E 8  COMMUNITY HEALTH NURSING 2 (NCM 3115) very short time, which are time. It is the level immunity of the group which is characteristic of epidemics. contributed by the state of immunity of each o Point epidemics – cases are member exposed to the offending agent Exposure or contact rate simultaneously; secondary cases o Exposure or contact rate represents opportunities o Continuing epidemics – cases for progressive transfer or transmission of an occur intermittently infectious agent to a susceptible host and depends o Cyclic variations – this refers to on the frequency of contact and facility of recurrent fluctuations of disease transmission. frequency which may exhibit cycles The probability of transfer depends upon: lasting for certain periods. o Size of reservoir o Secular variations – this refers to o Facility of transmission long term changes in disease frequency CHANCE o Other Factors That Can Produce Changes in Chance is the probability of contact between the source of Disease Frequency Over Years or Decades infection and the 1. Changes in incidence due to susceptible individual which will depend upon: environmental or life-style changes. o the number of sources of infection ( the more 2. Improvements in diagnosis may sources the greater the chances of exposure) increase cases reported even o the location of the source of infection (the nearer though the incidence may not be the susceptible population, the greater the changing. chances of exposure) 3. Changes in record keeping (accuracy) o the number of immunes (the lower the number of can create what appear to be immunes, the greater the chances of exposure changes in disease rates. 4. Improved treatment may decrease mortality rates 5. Changes in the age distribution of a population can produce changes in the overall rate of disease, even if age-specific rates are not changing. 3. Analysis of the general pattern of occurrence of the disease or condition o After establishing the disease frequency and distribution in a population and defining the characteristics of the disease in terms of time, place and person, the nurse proceeds to correlate the data and attempts to formulate a causal association between the disease under study and the probable factors surrounding it. o This state is called hypothesis testing. o The exposure factors and the disease will be tested or proven in the next phase of the epidemiological process. Forms by Which the Community Reacts to Disease Endemic – constant presence of a disease or infectious agent within a given geographic area Sporadic – happening in scattered instances Epidemic – the occurrence in a community or region of cases of an illness (or an outbreak) clearly in excess of expectancy Two types of epidemics Common source epidemic – this is due to exposure of a group of persons to a common vehicle such as food or water. Propagated epidemic – this results from direct or indirect transmission of an infectious agent from an infected to a susceptible person. Pandemic – worldwide occurrence e.g. HIV/AIDS, COVID- 19 Factors Affecting the Reaction of the Community/Population to Disease Agent Invasion Herd Immunity o Herd immunity is the state of resistance of a population group to a particular disease at a given LOURDES 3E 9