Public health

Part of aserieson
Public health
Outline
Subfields Community health Dental public health Environmental health Epidemiology Health economics Health education Health promotion Health policy Health politics Mental health Occupational safety Rehabilitation (penology) Sexual and reproductive health Sanitation World health (Global health-International health)
Prevention Disease surveillance Health promotion(Behavior change) Health indicators
Listsand categories Terminology Journals National public health agencies
Medicine portal Society portal
v t e

Public healthis "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals".^[1][2]Analyzing the determinants ofhealthof apopulationand the threats it faces is the basis for public health.^[3]Thepubliccan be as small as a handful of people or as large as a village or an entire city; in the case of apandemicit may encompass several continents. The concept ofhealthtakes into account physical,psychological, andsocial well-being, among other factors.^[4]

Public health is aninterdisciplinaryfield. For example,epidemiology,biostatistics,social sciencesandmanagementofhealth servicesare all relevant. Other important sub-fields includeenvironmental health,community health,behavioral health,health economics,public policy,mental health,health education,health politics,occupational safety,disability,oral health,gender issuesin health, andsexual and reproductive health.^[5]Public health, together withprimary care, secondary care, andtertiary care, is part of a country's overallhealthcaresystem. Public health is implemented through thesurveillanceof cases andhealth indicators, and through thepromotion of healthy behaviors. Common public health initiatives include promotion ofhand-washingandbreastfeeding, delivery ofvaccinations, promoting ventilation and improved air quality bothindoorsandoutdoors,suicide prevention,smoking cessation,obesity education, increasinghealthcareaccessibility and distribution ofcondomsto control the spread ofsexually transmitted diseases.

There is a significant disparity in access to health care and public health initiatives betweendeveloped countriesanddeveloping countries, as well as within developing countries. In developing countries, public health infrastructures are still forming. There may not be enough trainedhealthcare workers, monetary resources, or, in some cases, sufficient knowledge to provide even a basic level of medical care and disease prevention.^[6][7]A major public health concern in developing countries is poormaternalandchild health, exacerbated bymalnutritionand poverty coupled with governments' reluctance in implementing public health policies. Developed nations are at greater risk of certain public health crises, including childhood obesity, although overweight populations in low- and middle-income countries are catching up.^[8]

From the beginnings ofhuman civilization, communities promotedhealthand foughtdiseaseat the population level.^[9][10]Incomplex,pre-industrialized societies, interventions designed to reduce health risks could be the initiative of different stakeholders, such as army generals, the clergy or rulers. Great Britain became a leader in the development of public health initiatives, beginning in the 19th century, due to the fact that it was the first modernurban nationworldwide.^[11]The public health initiatives that began to emerge initially focused onsanitation(for example, the Liverpool andLondon sewerage systems), control ofinfectious diseases(including vaccination andquarantine) and an evolving infrastructure of various sciences, e.g. statistics, microbiology, epidemiology, sciences of engineering.^[11]

Public health has been defined as "the science and art ofpreventing disease", prolonging life and improvingquality of lifethrough organized efforts and informed choices ofsociety,organizations(public and private),communitiesandindividuals.^[2]Thepubliccan be as small as a handful of people or as large as a village or an entire city. The concept ofhealthtakes into account physical,psychological, andsocial well-being. As such, according to theWorld Health Organization, "health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity".^[4]

Public health is related toglobal healthwhich is the health of populations in the worldwide context.^[12]It has been defined as "the area of study,researchand practice that places a priority on improving health and achieving equity in "Health for all" people worldwide".^[13]International health is a field ofhealthcare, usually with a public health emphasis, dealing with health across regional or national boundaries.^[14]Public health is not the same as public healthcare (publicly funded health care).

The termpreventive medicineis related to public health. The American Board of Preventive Medicine separates three categories of preventive medicine: aerospace health,occupational health, and public health and general preventative medicine. Jung, Boris and Lushniak argue that preventive medicine should be considered the medical specialty for public health but note that the American College of Preventive Medicine and American Board of Preventive Medicine do not prominently use the term "public health".^[15]: 1Preventive medicine specialists are trained ascliniciansand address complex health needs of a population such as by assessing the need fordisease preventionprograms, using the best methods to implement them, and assessing their effectiveness.^{[15]: 1, 3}

Since the 1990s many scholars in public health have been using the termpopulation health.^[16]: 3There are no medical specialties directly related to population health.^[15]: 4Valles argues that consideration ofhealth equityis a fundamental part of population health. Scholars such as Coggon and Pielke express concerns about bringing general issues of wealth distribution into population health. Pielke worries about "stealth issue advocacy" in population health.^[16]: 163Jung, Boris and Lushniak consider population health to be a concept that is the goal of an activity called public health practiced through the specialty preventive medicine.^[15]: 4

Lifestyle medicineuses individual lifestyle modification to prevent or revert disease and can be considered a component of preventive medicine and public health. It is implemented as part ofprimary carerather than a specialty in its own right.^[15]: 3Valles argues that the termsocial medicinehas a narrower and morebiomedicalfocus than the term population health.^[16]: 7

The purpose of apublic health interventionis to prevent andmitigatediseases,injuries, and other health conditions. The overall goal is to improve the health of individuals and populations, and to increaselife expectancy.^[17][18]

Public health is a complex term, composed of many elements and different practices. It is a multi-faceted,interdisciplinaryfield.^[11]For example,epidemiology,biostatistics,social sciencesandmanagementof health services are all relevant. Other important sub-fields includeenvironmental health,community health,behavioral health,health economics,public policy,mental health,health education,health politics,occupational safety,disability,gender issuesin health, andsexual and reproductive health.^[5]

Modern public health practice requiresmultidisciplinaryteams of public health workers and professionals. Teams might includeepidemiologists,biostatisticians,physician assistants,public health nurses,midwives,medical microbiologists,pharmacists,economists,sociologists,geneticists,data managers,environmental health officers(public health inspectors),bioethicists, gender experts, sexual and reproductive health specialists,physicians, andveterinarians.^[19]

The elements and priorities of public health have evolved over time, and are continuing to evolve.^[11]Common public health initiatives include promotion ofhand-washingandbreastfeeding, delivery ofvaccinations,suicide prevention,smoking cessation,obesity education, increasinghealthcareaccessibility and distribution ofcondomsto control the spread ofsexually transmitted diseases.^[20]

Public health aims are achieved through surveillance of cases and thepromotion of healthy behaviors,communitiesandenvironments. Analyzing the determinants ofhealthof apopulationand the threats it faces is the basis for public health.^[3]

Many diseases arepreventablethrough simple, nonmedical methods. For example, research has shown that the simple act ofhandwashingwith soap can prevent the spread of manycontagious diseases.^[21]In other cases, treating a disease or controlling apathogencan be vital to preventing its spread to others, either during an outbreak ofinfectious diseaseor throughcontamination of foodorwatersupplies.

Public health, together withprimary care, secondary care, andtertiary care, is part of a country's overallhealth caresystem. Many interventions of public health interest are delivered outside ofhealth facilities, such asfood safetysurveillance, distribution ofcondomsandneedle-exchange programsfor the prevention of transmissible diseases.

Public health requiresGeographic Information Systems(GIS) because risk, vulnerability and exposure involve geographic aspects.^[22]

A dilemma in public health ethics is dealing with the conflict betweenindividual rightsand maximizingright to health.^[23]: 28Public health is justified byconsequentialistutilitarianideas,^[23]: 153but is constrained and critiqued byliberal,^[23]deontological,principlistandlibertarianphilosophies^{[23]: 99, 95, 74, 123}Stephen Holland argues that it can be easy to find a particular framework to justify any viewpoint on public health issues, but that the correct approach is to find a framework that best describes a situation and see what it implies about public health policy.^[23]: 154

The definition ofhealthis vague and there are many conceptualizations. Public health practitioners definition of health can different markedly from members of the public orclinicians. This can mean that members of the public view the values behind public health interventions as alien which can cause resentment amongst the public towards certain interventions.^[23]: 230Such vagueness can be a problem forhealth promotion.^[23]: 241Critics have argued that public health tends to place more focus on individual factors associated with health at the expense of factors operating at the population level.^[16]: 9

Historically, public health campaigns have been criticized as a form of "healthism", as moralistic in nature rather than being focused on health. Medical doctors, Petr Shkrabanek and James McCormick wrote a series of publications on this topic in the late 1980s and early 1990s criticizing the UK'sthe Health of The Nationcampaign. These publications exposed abuse of epidemiology and statistics by the public health movement to support lifestyle interventions and screening programs.^{[24]: 85 [25]}A combination of inculcating a fear of ill-health and a strong notion of individual responsibility has been criticized as a form of "health fascism" by a number of scholars, objectifying the individual with no considerations of emotional or social factors.^{[26]: 8 [25]: 7 [27]: 81}

When public health initiatives began to emerge in England in modern times (18th century onwards) there were three core strands of public health which were all related to statecraft: Supply of clean water andsanitation(for exampleLondon sewerage system); control ofinfectious diseases(includingvaccinationandquarantine); an evolving infrastructure of various sciences, e.g. statistics, microbiology, epidemiology, sciences of engineering.^[11]Great Britain was a leader in the development of public health during that time period out of necessity: Great Britain was the first modernurban nation(by 1851 more than half of the population lived in settlements of more than 2000 people).^[11]This led to a certain type of distress which then led to public health initiatives.^[11]Later that particular concern faded away.

With the onset of theepidemiological transitionand as the prevalence ofinfectious diseases decreased through the 20th century, public health began to put more focus onchronic diseasessuch ascancerandheart disease. Previous efforts in many developed countries had already led to dramatic reductions in theinfant mortality rateusing preventive methods. In Britain, the infant mortality rate fell from over 15% in 1870 to 7% by 1930.^[28]

A major public health concern indeveloping countriesis poormaternaland child health, exacerbated bymalnutritionand poverty. TheWHOreports that a lack ofexclusive breastfeedingduring the first six months of life contributes to over a million avoidable child deaths each year.^[29]

Public health surveillance has led to the identification and prioritization of many public health issues facing the world today, includingHIV/AIDS,diabetes,waterborne diseases,zoonotic diseases, andantibiotic resistanceleading to the reemergence of infectious diseases such astuberculosis.Antibiotic resistance, also known as drug resistance, was the theme ofWorld Health Day 2011.

For example, the WHO reports that at least 220 million people worldwide have diabetes. Its incidence is increasing rapidly, and it is projected that the number of diabetes deaths will double by 2030.^[30]In a June 2010 editorial in the medical journalThe Lancet, the authors opined that "The fact that type 2 diabetes, a largely preventable disorder, has reached epidemic proportion is a public health humiliation."^[31]The risk oftype 2 diabetesis closely linked with the growing problem ofobesity. The WHO's latest estimates as of June 2016^[update]highlighted that globally approximately 1.9 billion adults wereoverweightin 2014, and 41 million children under the age of five were overweight in 2014.^[32]Once considered a problem in high-income countries, it is now on the rise in low-income countries, especially in urban settings.^[33]

Many public health programs are increasingly dedicating attention and resources to the issue of obesity, with objectives to address the underlying causes includinghealthy dietandphysical exercise. TheNational Institute for Health and Care Research(NIHR) has published a review of research on whatlocal authoritiescan do to tackle obesity.^[34]The review covers interventions in the food environment (what people buy and eat), thebuiltandnatural environments, schools, and the community, as well as those focussing onactive travel,leisure servicesand public sports,weight management programmes, andsystem-wide approaches.^[35]

Health inequalities, driven by the social determinants of health, are also a growing area of concern in public health. A central challenge to securing health equity is that the same social structures that contribute to health inequities also operate and are reproduced by public health organizations.^[36]In other words, public health organizations have evolved to better meet the needs of some groups more than others. The result is often that those most in need of preventative interventions are least likely to receive them^[37]and interventions can actually aggravate inequities^[38]as they are often inadvertently tailored to the needs of the normative group.^[39]Identifying bias within public health research and practice is essential to ensuring public health efforts mitigate and don't aggravate health inequities.

TheWorld Health Organization(WHO) is aspecialized agency of the United Nationsresponsible for international public health.^[40]The WHO Constitution, which establishes the agency's governing structure and principles, states its main objective as "the attainment by all peoples of the highest possible level of health".^[41]The WHO's broad mandate includes advocating for universal healthcare, monitoring public health risks, coordinating responses to health emergencies, and promoting human health and well-being.^[42]The WHO has played a leading role in several public health achievements, most notably theeradicationofsmallpox, the near-eradication of polio, and the development of anEbola vaccine. Its current priorities includecommunicable diseases, particularlyHIV/AIDS,Ebola,COVID-19,malariaandtuberculosis;non-communicable diseasessuch as heart disease and cancer;healthy diet, nutrition, andfood security;occupational health; andsubstance abuse.^[43][44]

Most countries have their own governmental public health agency, often called the ministry of health, with responsibility for domestic health issues.

For example, in theUnited States, state and localhealth departmentsare on the front line of public health initiatives. In addition to their national duties, theUnited States Public Health Service(PHS), led by theSurgeon General of the United States Public Health Service, and theCenters for Disease Control and Prevention, headquartered inAtlanta, are also involved with international health activities.^[45]

Most governments recognize the importance of public health programs in reducing the incidence of disease, disability, and the effects ofagingand other physical and mental health conditions. However, public health generally receives significantly less government funding compared with medicine.^[46]Although the collaboration of local health and government agencies is considered best practice to improve public health, the pieces of evidence available to support this is limited.^[47]Public health programs providingvaccinationshave made major progress in promoting health, including substantially reducing the occurrence ofcholeraandpolioand eradicatingsmallpox, diseases that have plagued humanity for thousands of years.^[48]

The World Health Organization (WHO) identifies core functions of public health programs including:^[49]

• providing leadership on matters critical to health and engaging in partnerships where joint action is needed;
• shaping aresearchagenda and stimulating the generation, translation anddisseminationof valuable knowledge;
• setting norms and standards and promoting and monitoring their implementation;
• articulating ethical andevidence-based policyoptions;
• monitoring the health situation and assessing health trends.

In particular, public health surveillance programs can:^[50]

• serve as anearly warning systemfor impending public health emergencies;
• document the impact of an intervention, or track progress towards specified goals; and
• monitor and clarify the epidemiology of health problems, allow priorities to be set, and informhealth policyand strategies.
• diagnose, investigate, and monitor health problems and health hazards of the community

Many health problems are due to maladaptive personal behaviors. From anevolutionary psychologyperspective, over consumption of novel substances that are harmful is due to the activation of an evolvedreward systemfor substances such as drugs, tobacco,alcohol,refined salt,fat, andcarbohydrates. New technologies such as modern transportation also cause reducedphysical activity. Research has found thatbehavior is more effectively changedby taking evolutionary motivations into consideration instead of only presenting information about health effects. The marketing industry has long known the importance of associating products with high status and attractiveness to others. Films are increasingly being recognized as a public health tool, with theHarvard University'sT.H. Chan School of Public Healthcategorizing such films as "impact filmmaking."^[51]In fact,film festivalsandcompetitionshave been established to specifically promote films about health.^[52]Conversely, it has been argued that emphasizing the harmful and undesirable effects of tobacco smoking on other persons and imposing smoking bans in public places have been particularly effective in reducing tobacco smoking.^[53]Public libraries can also be beneficial tools for public health changes. They provide access to healthcare information, link people to healthcare services, and even can provide direct care in certain situations.^[54]

As well as seeking to improve population health through the implementation of specific population-level interventions, public health contributes to medical care by identifying and assessing population needs for health care services, including:^{[55][56][57][58]}

• Assessing current services and evaluating whether they are meeting the objectives of thehealth care system
• Ascertaining requirements as expressed byhealth professionals, the public and other stakeholders
• Identifying the most appropriate interventions
• Considering the effect on resources for proposed interventions and assessing their cost-effectiveness
• Supporting decision making in health care and planning health services including any necessary changes.
• Informing, educating, and empowering people about health issues

Some programs and policies associated with publichealth promotionand prevention can be controversial. One such example is programs focusing on the prevention ofHIVtransmission throughsafe sexcampaigns andneedle-exchange programs. Another is the control oftobacco smoking. Many nations have implementedmajor initiativesto cut smoking, such as increased taxation and bans on smoking in some or all public places. Supporters argue by presenting evidence that smoking is one of the major killers, and that therefore governments have a duty to reduce the death rate, both through limitingpassive (second-hand) smokingand by providing fewer opportunities for people to smoke. Opponents say that this undermines individual freedom and personal responsibility, and worry that the state may be encouraged to remove more and more choice in the name of better population health overall.^[59]

Psychological research confirms this tension between concerns about public health and concerns about personal liberty: (i) the best predictor of complying with public health recommendations such as hand-washing, mask-wearing, and staying at home (except for essential activity) during theCOVID-19 pandemicwas people's perceived duties to prevent harm but (ii) the best predictor of flouting such public health recommendations was valuing liberty more than equality.^[60]

Simultaneously, while communicable diseases have historically ranged uppermost as aglobal healthpriority,non-communicable diseasesand the underlying behavior-related risk factors have been at the bottom. This is changing, however, as illustrated by theUnited Nationshosting its first General Assembly Special Summit on the issue of non-communicable diseases in September 2011.^[61]

There is a significant disparity in access to health care and public health initiatives betweendeveloped countriesanddeveloping countries, as well as within developing countries. In developing countries, public health infrastructures are still forming. There may not be enough trainedhealth workers, monetary resources or, in some cases, sufficient knowledge to provide even a basic level of medical care and disease prevention.^[6][7]As a result, a large majority of disease and mortality in developing countries results from and contributes to extremepoverty. For example, many African governments spend less than$100 USD per person per year on health care, while, in the United States, thefederal governmentspent approximately $10,600 USD per capita in 2019.^[62]However, expenditures on health care should not be confused with spending on public health. Public health measures may not generally be considered "health care" in the strictest sense. For example, mandating the use of seat belts in cars can save countless lives and contribute to the health of a population, but typically money spent enforcing this rule would not count as money spent on health care.

Large parts of the world remained plagued by largely preventable or treatable infectious diseases. In addition to this however, many developing countries are also experiencing anepidemiological shiftandpolarizationin which populations are now experiencing more of the effects of chronic diseases as life expectancy increases, the poorer communities being heavily affected by both chronic and infectious diseases.^[7]Another major public health concern in the developing world is poormaternaland child health, exacerbated bymalnutritionand poverty. TheWHOreports that a lack ofexclusive breastfeedingduring the first six months of life contributes to over a million avoidable child deaths each year.^[29]Intermittent preventive therapyaimed at treating and preventingmalariaepisodes among pregnant women and young children is one public health measure inendemiccountries.

Since the 1980s, the growing field ofpopulation healthhas broadened the focus of public health from individual behaviors andrisk factorsto population-level issues such asinequality, poverty, and education. Modern public health is often concerned with addressing determinants of health across a population. There is a recognition that health is affected by many factors including class, race, income, educational status, region of residence, andsocial relationships; these are known as "social determinants of health". The upstream drivers such as environment, education, employment, income, food security, housing,social inclusionand many others effect the distribution of health between and within populations and are often shaped by policy.^[65]A social gradient in health runs through society. The poorest generally have the worst health, but even the middle classes will generally have worse health outcomes than those of a higher social level.^[66]The new public health advocates for population-based policies that improve health in an equitable manner.

The health sector is one of Europe's most labor-intensive industries. In late 2020, it accounted for more than 21 million employment in theEuropean Unionwhen combined with social work.^[67]According to theWHO, several countries began theCOVID-19 pandemicwith insufficient health and care professionals, inappropriate skill mixtures, and unequal geographical distributions. These issues were worsened by the pandemic, reiterating the importance of public health.^[68]In the United States, a history of underinvestment in public health undermined the public health workforce and support for population health, long before the pandemic added to stress, mental distress, job dissatisfaction, and accelerated departures among public health workers.^[69]

Health aidto developing countries is an important source of public health funding for many developing countries.^[71]Health aid to developing countries has shown a significant increase after World War II as concerns over the spread of disease as a result ofglobalizationincreased and the HIV/AIDS epidemic in sub-Saharan Africa surfaced.^[72][73]From 1990 to 2010, total health aid from developed countries increased from 5.5 billion to 26.87 billion with wealthy countries continuously donating billions of dollars every year with the goal of improving population health.^[73]Some efforts, however, receive a significantly larger proportion of funds such as HIV which received an increase in funds of over $6 billion between 2000 and 2010 which was more than twice the increase seen in any other sector during those years.^[71]Health aid has seen an expansion through multiple channels including private philanthropy,non-governmental organizations, private foundations such as theRockefeller Foundationor theBill & Melinda Gates Foundation, bilateral donors, and multilateral donors such as theWorld BankorUNICEF.^[73]The result has been a sharp rise in uncoordinated and fragmented funding of an ever-increasing number of initiatives and projects. To promote better strategic cooperation and coordination between partners, particularly among bilateral development agencies and funding organizations, theSwedish International Development Cooperation Agency(Sida) spearheaded the establishment of ESSENCE,^[74]an initiative to facilitate dialogue between donors/funders, allowing them to identify synergies. ESSENCE brings together a wide range of funding agencies to coordinate funding efforts.

In 2009 health aid from theOECDamounted to $12.47 billion which amounted to 11.4% of its total bilateral aid.^[75]In 2009, Multilateral donors were found to spend 15.3% of their total aid on bettering public healthcare.^[75]

Debates exist questioning the efficacy of international health aid. Supporters of aid claim that health aid from wealthy countries is necessary in order for developing countries to escape thepoverty trap. Opponents of health aid claim that international health aid actually disrupts developing countries' course of development, causes dependence on aid, and in many cases the aid fails to reach its recipients.^[71]For example, recently, health aid was funneled towards initiatives such as financing new technologies likeantiretroviral medication,insecticide-treated mosquito nets, and new vaccines. The positive impacts of these initiatives can be seen in the eradication of smallpox andpolio; however, critics claim that misuse or misplacement of funds may cause many of these efforts to never come into achievement.^[71]

Economic modeling based on theInstitute for Health Metrics and Evaluationand theWorld Health Organizationhas shown a link between international health aid in developing countries and a reduction in adult mortality rates.^[73]However, a 2014–2016 study suggests that a potential confounding variable for this outcome is the possibility that aid was directed at countries once they were already on track for improvement.^[71]That same study, however, also suggests that 1 billion dollars in health aid was associated with 364,000 fewer deaths occurring between ages 0 and 5 in 2011.^[71]

To address current and future challenges in addressing health issues in the world, theUnited Nationshave developed theSustainable Development Goalsto be completed by 2030.^[76]These goals in their entirety encompass the entire spectrum of development across nations, however Goals 1–6 directly addresshealth disparities, primarily in developing countries.^[77]These six goals address key issues inglobal public health,poverty, hunger andfood security, health, education,gender equalityandwomen's empowerment, andwaterandsanitation.^[77]Public health officials can use these goals to set their own agenda and plan for smaller scale initiatives for their organizations. These goals are designed to lessen the burden of disease and inequality faced by developing countries and lead to a healthier future. The links between the various sustainable development goals and public health are numerous and well established.^[78][79]

From the beginnings ofhuman civilization, communities promotedhealthand foughtdiseaseat the population level.^[9][10]Definitions of health as well as methods to pursue it differed according to the medical, religious and natural-philosophicalideas groups held, the resources they had, and the changing circumstances in which they lived. Yet few early societies displayed the hygienic stagnation or even apathy often attributed to them.^[80][81][82]The latter reputation is mainly based on the absence of present-daybioindicators, especiallyimmunologicalandstatisticaltools developed in light of thegerm theory of diseasetransmission.^[83][84]

Public health was born neither inEuropenor as a response to theIndustrial Revolution. Preventive health interventions are attested almost anywhere historical communities have left their mark. InSoutheast Asia, for instance,Ayurvedicmedicine and subsequentlyBuddhismfostered occupational, dietary and sexual regimens that promised balanced bodies, lives and communities, a notion strongly present inTraditional Chinese Medicineas well.^[85][86]Among theMayans,Aztecsand other early civilizations in theAmericas, population centers pursued hygienic programs, including by holdingmedicinal herbalmarkets.^[87]And amongAboriginal Australians, techniques for preserving and protecting water and food sources, micro-zoning to reduce pollution and fire risks, and screens to protect people againstflieswere common, even in temporary camps.^[88][89]

Western European,ByzantineandIslamicatecivilizations, which generally adopted aHippocratic,Galenicorhumoralmedical system, fostered preventive programs as well.^{[90][91][92][93]}These were developed on the basis of evaluating the quality of localclimates, includingtopography, wind conditions and exposure to the sun, and the properties and availability of water and food, for bothhumansand nonhumananimals. Diverse authors ofmedical,architectural,engineeringandmilitary manualsexplained how to apply such theories to groups of different origins and under different circumstances.^[94][95][96]This was crucial, since under Galenism bodily constitutions were thought to be heavily shaped by their materialenvironments, so their balance required specific regimens as they traveled during differentseasonsand between climate zones.^[97][98][99]

Incomplex,pre-industrialized societies, interventions designed to reduce health risks could be the initiative of different stakeholders. For instance, inGreekandRoman antiquity, army generals learned to provide for soldiers' wellbeing, including off thebattlefield, where most combatants died prior to the twentieth century.^[100][101]InChristianmonasteriesacross theEastern Mediterraneanand western Europe since at least the fifth centuryCE,monksandnunspursued strict but balanced regimens, including nutritiousdiets, developed explicitly to extend their lives.^[102]Androyal, princely andpapal courts, which were often mobile as well, likewise adapted their behavior to suit environmental conditions in the sites they occupied. They could also choose sites they considered salubrious for their members and sometimes had them modified.^[103]

Incities, residents and rulers developed measures to benefit the generalpopulation, which faced a broad array of recognizedhealth risks. These provide some of the most sustained evidence for preventive measures in earlier civilizations. In numerous sites the upkeep ofinfrastructures, including roads, canals and marketplaces, as well aszoningpolicies, were introduced explicitly to preserve residents' health.^[104]Officials such as themuhtasibin the Middle East and theRoad masterin Italy, fought the combined threats ofpollutionthroughsin,ocular intromissionandmiasma.^{[105][106][107][108]}Craftguildswere important agents of waste disposal and promotedharm reductionthrough honesty andlabor safetyamong their members. Medical practitioners, including public physicians,^[109]collaborated with urban governments in predicting and preparing for calamities and identifying and isolating people perceived aslepers, a disease with strong moral connotations.^[110][111]Neighborhoodswere also active in safeguarding local people's health, by monitoring at-risk sites near them and taking appropriate social and legal action against artisanal polluters and neglectful owners of animals. Religious institutions, individuals and charitable organizations in bothIslamand Christianity likewise promoted moral and physical wellbeing by endowing urban amenities such as wells, fountains, schools and bridges, also in the service ofpilgrims.^[112][113]In western Europe and Byzantium, religiousprocessionscommonly took place, which purported to act as both preventive and curative measures for the entire community.^[114]

Urban residents and other groups also developed preventive measures in response to calamities such aswar,famine,floodsandwidespread disease.^{[115][116][117][118]}During and after theBlack Death(1346–53), for instance, inhabitants of theEastern MediterraneanandWestern Europereacted to massive population decline in part on the basis of existing medical theories and protocols, for instance concerning meat consumption and burial, and in part by developing new ones.^{[119][120][121]}The latter included the establishment ofquarantinefacilities and health boards, some of which eventually became regular urban (and later national) offices.^[122][123]Subsequent measures for protecting cities and their regions included issuing healthpassportsfor travelers, deploying guards to createsanitary cordonsfor protecting local inhabitants, and gathering morbidity and mortality statistics.^{[124][125][126]}Such measures relied in turn on better transportation and communication networks, through which news on human and animal disease was efficiently spread.

With the onset of theIndustrial Revolution, living standards amongst the working population began to worsen, with cramped and unsanitary urban conditions. In the first four decades of the 19th century alone,London's population doubled and even greater growth rates were recorded in the new industrial towns, such asLeedsandManchester. This rapidurbanizationexacerbated the spread of disease in the largeconurbationsthat built up around theworkhousesandfactories. These settlements were cramped and primitive with no organizedsanitation. Disease was inevitable and its incubation in these areas was encouraged by the poor lifestyle of the inhabitants. Unavailable housing led to the rapid growth ofslumsand theper capitadeath ratebegan to rise alarmingly, almost doubling inBirminghamandLiverpool.Thomas Malthuswarned of the dangers of overpopulation in 1798. His ideas, as well as those ofJeremy Bentham, became very influential in government circles in the early years of the 19th century.^[127]The latter part of the century brought the establishment of the basic pattern of improvements in public health over the next two centuries: a social evil was identified, private philanthropists brought attention to it, and changing public opinion led to government action.^[127]The 18th century saw rapid growth in voluntary hospitals inEngland.^[128]

The practice ofvaccinationbegan in the 1800s, following the pioneering work ofEdward Jennerin treatingsmallpox.James Lind's discovery of the causes ofscurvyamongst sailors and its mitigation via the introduction offruiton lengthy voyages was published in 1754 and led to the adoption of this idea by theRoyal Navy.^[129]Efforts were also made to promulgate health matters to the broader public; in 1752 the British physician SirJohn PringlepublishedObservations on the Diseases of the Army in Camp and Garrison, in which he advocated for the importance of adequate ventilation in themilitarybarracksand the provision oflatrinesfor the soldiers.^[130]

The first attempts at sanitary reform and the establishment of public health institutions were made in the 1840s.Thomas Southwood Smith, physician at theLondon Fever Hospital, began to write papers on the importance of public health, and was one of the first physicians brought in to give evidence before thePoor Law Commissionin the 1830s, along withNeil ArnottandJames Phillips Kay.^[131]Smith advised the government on the importance ofquarantineand sanitary improvement for limiting the spread of infectious diseases such ascholeraandyellow fever.^[132][133]

The Poor Law Commission reported in 1838 that "the expenditures necessary to the adoption and maintenance of measures of prevention would ultimately amount to less than the cost of the disease now constantly engendered". It recommended the implementation of large scale governmentengineeringprojects to alleviate the conditions that allowed for the propagation of disease.^[127]TheHealth of Towns Associationwas formed at Exeter Hall London on 11 December 1844, and vigorously campaigned for the development of public health in theUnited Kingdom.^[134]Its formation followed the 1843 establishment of the Health of Towns Commission, chaired by SirEdwin Chadwick, which produced a series of reports on poor and insanitary conditions in British cities.^[134]

These national and local movements led to thePublic Health Act, finally passed in 1848. It aimed to improve the sanitary condition of towns and populous places in England and Wales by placing the supply of water, sewerage, drainage, cleansing and paving under a single local body with the General Board of Health as a central authority. The Act was passed by theLiberalgovernmentofLord John Russell, in response to the urging of Edwin Chadwick. Chadwick's seminal report onThe Sanitary Condition of the Labouring Populationwas published in 1842^[135]and was followed up with a supplementary report a year later.^[136]During this time,James Newlands(appointed following the passing of the 1846 Liverpool Sanatory Act championed by the Borough of Liverpool Health of Towns Committee) designed the world's first integrated sewerage system, in Liverpool (1848–1869), withJoseph Bazalgettelater creatingLondon's sewerage system(1858–1875).

The Vaccination Act 1853 introduced compulsorysmallpox vaccinationin England and Wales.^[137]By 1871 legislation required a comprehensive system of registration run by appointed vaccination officers.^[138]

Further interventions were made by a series of subsequentPublic Health Acts, notably the1875 Act. Reforms included the building ofsewers, the regularcollection of garbagefollowed byincinerationor disposal in alandfill, theprovision of clean waterand the draining of standing water to prevent the breeding of mosquitoes.

TheInfectious Disease (Notification) Act 1889(52 & 53 Vict.c. 72) mandated the reporting of infectious diseases to the local sanitary authority, which could then pursue measures such as the removal of the patient to hospital and the disinfection of homes and properties.^[139]

In the United States, the first public health organization based on a state health department and local boards of health was founded inNew York Cityin 1866.^[140]

DuringThe Weimar Republic, Germany faced many public health catastrophes.^[141]TheNazi Partyhad a goal of modernizing health care withVolksgesundheit, German forpeople's public health; this modernization was based on the growing field ofeugenicsand measures prioritizing group health over any care for the health of individuals.^[142]The end of World War 2 led to theNuremberg Code, a set of research ethics concerning human experimentation.^[143]

The science ofepidemiologywas founded byJohn Snow's identification of a polluted public water well as the source of an 1854choleraoutbreak in London. Snow believed in thegerm theoryof disease as opposed to the prevailingmiasma theory. By talking to local residents (with the help ofReverend Henry Whitehead), he identified the source of the outbreak as the public water pump on Broad Street (nowBroadwick Street). Although Snow's chemical and microscope examination of a water sample from theBroad Street pumpdid not conclusively prove its danger, his studies of the pattern of the disease were convincing enough to persuade the local council to close the well pump by removing its handle.^[144]

Snow later used adot mapto illustrate the cluster of cholera cases around the pump. He also used statistics to illustrate the connection between the quality of the water source and cholera cases. He showed that theSouthwark and Vauxhall Waterworks Companywas taking water from sewage-polluted sections of theThamesand delivering the water to homes, leading to an increased incidence of cholera. Snow's study was a major event in the history of public health and geography. It is regarded as the founding event of the science ofepidemiology.^[145][146]

With the pioneering work inbacteriologyof French chemistLouis Pasteurand German scientistRobert Koch, methods for isolating thebacteriaresponsible for a given disease and vaccines for remedy were developed at the turn of the 20th century. British physicianRonald Rossidentified themosquitoas the carrier ofmalariaand laid the foundations for combating the disease.^[147]Joseph Listerrevolutionizedsurgeryby the introduction ofantisepticsurgeryto eliminateinfection. French epidemiologistPaul-Louis Simondproved thatplaguewas carried byfleason the back ofrats,^[148]and Cuban scientistCarlos J. Finlayand U.S. AmericansWalter ReedandJames Carrolldemonstrated that mosquitoes carry the virus responsible foryellow fever.^{[149]: 481 [150]}Brazilian scientistCarlos Chagasidentified atropical diseaseand its vector.^[149]: 481

Education and training of public health professionals is available throughout the world in Schools of Public Health, Medical Schools, Veterinary Schools, Schools of Nursing, and Schools of Public Affairs. The training typically requires auniversity degreewith a focus on core disciplines ofbiostatistics,epidemiology,health services administration,health policy,health education,behavioral science, gender issues, sexual and reproductive health, public health nutrition, andoccupationalandenvironmental health.^[151][152]

In the global context, the field of public health education has evolved enormously in recent decades, supported by institutions such as theWorld Health Organizationand theWorld Bank, among others. Operational structures are formulated by strategic principles, with educational and career pathways guided by competency frameworks, all requiring modulation according to local, national and global realities. Moreover, integrating technology or digital platforms to connect to low health literacy LHL groups could be a way to increase health literacy.^[153]It is critically important for the health of populations that nations assess their public health human resource needs and develop their ability to deliver this capacity, and not depend on other countries to supply it.^[154]

In theUnited States, the Welch-Rose Report of 1915^[155]has been viewed as the basis for the critical movement in the history of the institutional schism between public health and medicine because it led to the establishment of schools of public health supported by theRockefeller Foundation.^[156]The report was authored byWilliam Welch, founding dean of theJohns Hopkins Bloomberg School of Public Health, andWickliffe Roseof the Rockefeller Foundation. The report focused more on research than practical education.^[156][157]Some have blamed the Rockefeller Foundation's 1916 decision to support the establishment of schools of public health for creating the schism between public health and medicine and legitimizing the rift between medicine's laboratory investigation of the mechanisms of disease and public health's nonclinical concern with environmental and social influences on health and wellness.^[156][158]

Even though schools of public health had already been established inCanada,EuropeandNorth Africa, the United States had still maintained the traditional system of housing faculties of public health within their medical institutions. A $25,000 donation from businessmanSamuel Zemurrayinstituted theSchool of Public Health and Tropical Medicine at Tulane Universityin 1912 conferring its first doctor of public health degree in 1914.^[159][160]TheYale School of Public Healthwas founded byCharles-Edward Amory Winslowin 1915.^[161]TheJohns Hopkins School of Hygiene and Public Healthwas founded in 1916 and became an independent, degree-granting institution for research and training in public health, and the largest public health training facility in the United States.^{[162][163][164]}By 1922, schools of public health were established atColumbiaandHarvardon the Hopkins model. By 1999 there were twenty nine schools of public health in the US, enrolling around fifteen thousand students.^[151][156]

Over the years, the types of students and training provided have also changed. In the beginning, students who enrolled in public health schools typically had already obtained a medical degree; public health school training was largely a second degree formedical professionals. However, in 1978, 69% of American students enrolled in public health schools had only abachelor's degree.^[151]

Schools of public health offer a variety of degrees generally fall into two categories: professional or academic.^[166]The two major postgraduate degrees are theMaster of Public Health(MPH) or theMaster of Sciencein Public Health (MSPH). Doctoral studies in this field includeDoctor of Public Health(DrPH) andDoctor of Philosophy(PhD) in a subspecialty of greater Public Health disciplines. DrPH is regarded as a professional degree and PhD as more of an academic degree.

Professional degrees are oriented towards practice in public health settings. TheMaster of Public Health,Doctor of Public Health,Doctor of Health Science(DHSc/DHS) and theMaster of Health Care Administrationare examples of degrees which are geared towards people who want careers as practitioners of public health in health departments, managed care and community-based organizations, hospitals and consulting firms, among others. Master of Public Health degrees broadly fall into two categories, those that put more emphasis on an understanding of epidemiology and statistics as the scientific basis of public health practice and those that include a more wide range of methodologies. A Master of Science of Public Health is similar to an MPH but is considered an academic degree (as opposed to a professional degree) and places more emphasis on scientific methods and research. The same distinction can be made between the DrPH and the DHSc: The DrPH is considered a professional degree and the DHSc is an academic degree.^{[167][168][169]}

Academic degrees are more oriented towards those with interests in the scientific basis of public health andpreventive medicinewho wish to pursue careers in research, university teaching in graduate programs, policy analysis and development, and other high-level public health positions. Examples of academic degrees are theMaster of Science,Doctor of Philosophy,Doctor of Science(ScD), and Doctor of Health Science (DHSc). The doctoral programs are distinct from the MPH and other professional programs by the addition of advanced coursework and the nature and scope of adissertationresearch project.

• John Graunt(1620–1674) was a British citizen scientist who laid the foundations for epidemiology.^[170]
• Edward Jenner(1749–1823) created thesmallpox vaccine, the first vaccine in the world. He is often known as "the father ofimmunology".
• Benjamin Waterhouse(1753–1846) introduced thesmallpox vaccinein the United States.
• Lemuel Shattuck(1793–1859) has been described as an "architect" and "prophet" of American public health^[171]
• John Snow(1813–1858) was 'the father of modern epidemiology'.^[172]
• Sir Joseph William Bazalgette(1819–1891) created asewer network for central Londonin response to theGreat Stinkof 1858. This proved instrumental in relieving the city fromcholeraepidemics.^[173]
• Louis Pasteur(1822–1895) conducted research that laid the foundation for our understanding of the causes and preventions of diseases.
• Robert Koch(1843–1910) used his discoveries to establish that germs "could cause a specific disease"^[174]and directly provided proofs for thatgerm theory of diseases, therefore creating the scientific basis of public health,^[175]saving millions of lives.^[176]
• Charles V. Chapin(1856–1941) public health advocate and researcher credited with planting "the roots of quality in public health" in the United States^[177]
• Sara Josephine Baker(1873–1945) was an "instrumental force in child and maternal health"^[178]
• Nora Wattie(1900–1994) led the development of public health services and sanitation, and education in improving women and child health in the poorestslumsofGlasgow, for which she received theOBE.^[179]
• Jonas Salk(1914–1995) developed one of the firstpolio vaccinesand campaigned vigorously for mandatory vaccinations.
• Ruth Huenemann(1910–2005) She became a pioneer in the study ofchildhood obesityin the 1960s studying the diet and exercise habits of Berkeley teenagers.^[180]
• Edmond Fernandes( 1990-) Demonstrated proof of concept to end the burden ofMalnutritionin India and around the world.^[181]
• Dilip Mahalanabis- Credited to have evolved and utilizedORSto save thousands of lives during theliberation war.

In Canada, thePublic Health Agency of Canadais the national agency responsible for public health, emergency preparedness and response, and infectious andchronic diseasecontrol and prevention.^[182]

Since the 1959Cuban Revolution, theCuban governmenthas devoted extensive resources to the improvement ofhealth conditionsfor its entire population via universal access to health care. Infant mortality has plummeted.^[149]: 483Cuban medical internationalismas a policy has seen the Cuban government sent doctors as a form of aid and export to countries in need in Latin America, especiallyVenezuela, as well as Oceania and Africa countries.

Public health was important elsewhere in Latin America in consolidating state power and integrating marginalized populations into the nation-state. In Colombia, public health was a means for creating and implementing ideas of citizenship.^[183]In Bolivia, a similar push came after their 1952 revolution.^[184]

Though curable and preventive, malaria remains a major public health issue and is the third leading cause of death in Ghana.^[185]In the absence of a vaccine, mosquito control, or access to anti-malaria medication, public health methods become the main strategy for reducing the prevalence and severity of malaria.^[186]These methods include reducing breeding sites, screening doors and windows, insecticide sprays, prompt treatment following infection, and usage of insecticide treated mosquito nets.^[186]Distribution and sale of insecticide-treated mosquito nets is a common, cost-effective anti-malaria public health intervention; however, barriers to use exist including cost, household and family organization, access to resources, and social and behavioral determinants which have not only been shown to affect malaria prevalence rates but also mosquito net use.^[187][186]

The United States lacks a coherent system for the governmental funding of public health, relying on a variety of agencies and programs at the federal, state and local levels.^[202]Between 1960 and 2001, public health spending in the United States tended to grow, based on increasing expenditures by state and local government, which made up 80–90% of total public health spending. Spending in support of public health in the United States peaked in 2002 and declined in the following decade.^[203]State cuts to public health funding during theGreat Recessionof 2007–2008 were not restored in subsequent years.^[204]As of 2012, a panel for theU.S. Institute of Medicinepanel warned that the United States spends disproportionately far more on clinical care than it does on public health, neglecting "population-based activities that offer efficient and effective approaches to improving the nation's health."^[205][203]As of 2018^[update], about 3% of government health spending was directed to public health and prevention.^{[48][206][207]}This situation has been described as an "uneven patchwork"^[208]and "chronic underfunding".^{[209][210][211][212]}TheCOVID-19 pandemichas been seen as drawing attention to problems in the public health system in the United States and to a lack of understanding of public health and its important role as acommon good.^[48]