global health global health global health is the health of the populations in the worldwide context; it has been defined as "the area of study, research, and practice that places a priority on improving health and achieving equity in health for all people worldwide". problems that transcend national borders or have a global political and economic impact are often emphasized. thus, global health is about worldwide health improvement (including mental health), reduction of disparities, and protection against global threats that disregard national borders, including the most common causes of human death and years of life lost from a global perspective. the world health organization in geneva, switzerlandpart of a series onpublic 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 sexual and reproductive health sanitation world health (global health - international health) prevention disease surveillance health promotion (behavior change) health indicators lists and categories terminology journals national public health agencies medicine portal society portal global health is not to be confused with international health, which is defined as the branch of public health focusing on developing nations and foreign aid efforts by industrialized countries. one way global health can be measured is through the prevalence of various global diseases in the world and their threat to decrease life expectancy in the present day. estimates suggest that in a pre-modern, poor world, life expectancy was around 30 years in all regions of the world (mainly due to high infant mortality). another holistic perspective called one health can be used to address global health challenges and to improve global health security. the predominant agency associated with global health (and international health) is the world health organization (who). other important agencies impacting global health include unicef and world food programme (wfp). the united nations system has also played a part in cross-sectoral actions to address global health and its underlying socioeconomic determinants with the declaration of the millennium development goals and the more recent sustainable development goals. definition open global health at opencon 2015 global health employs several perspectives that focus on the determinants and distribution of health in international contexts. medicine describes the pathology of diseases and promotes prevention, diagnosis, and treatment. public health emphasizes the health of populations. epidemiology helps identify risk factors and causes of health problems. demography provides data for policy decisions.< economics emphasizes the cost-effectiveness and cost-benefit approaches for the optimal allocation of health resources. other social sciences such as sociology, development studies, psychology, anthropology, cultural studies, and law can help understand the determinants of health in societies. both individuals and organizations working in the domain of global health often face many questions regarding ethical and human rights. critical examination of the various causes and justifications of health inequities is necessary for the success of proposed solutions. such issues are discussed at the bi-annual global summits of national ethics/bioethics councils. history life expectancy by world region, from 1770 to 2018 global health as a discipline is widely acknwoledged to be of imperial origin and the need for its decolonisation has been widely recognised. the global health ecosystem has also been criticised as having a feudal structure, acting for a small group of institutions and individuals based in high-income countries which acts similar to an imperial "crown".some key leaders of the decolonising global health movement are seye abimbola and madhukar pai. important steps were taken towards global co-operation in health with the formation of the united nations (un) and the world bank group in 1945, after world war ii. in 1948, the member states of the newly formed united nations gathered to create the world health organization. a cholera epidemic that took 20,000 lives in egypt in 1947 and 1948 helped spur the international community to action. the who published its model list of essential medicines, and the 1978 alma ata declaration underlined the importance of primary health care. at a united nations summit in 2000, member nations declared eight millennium development goals (mdgs), which reflected the major challenges facing human development globally, to be achieved by 2015. the declaration was matched by unprecedented global investment by donor and recipient countries. according to the un, these mdgs provided an important framework for development and significant progress has been made in a number of areas. however, progress has been uneven and some of the mdgs were not fully realized including maternal, newborn and child health and reproductive health. building on the mdgs, a new sustainable development agenda with 17 sustainable development goals (sdgs) has been established for the years 2016–2030. the first goal being an ambitious and historic pledge to end poverty. on 25 september 2015, the 193 countries of the un general assembly adopted the 2030 development agenda titled transforming our world: the 2030 agenda for sustainable development. several major initiatives began in the 2000s, including the vaccine alliance gavi in 2000, the global fund to fight aids, tuberculosis and malaria in 2002, u.s. president's emergency plan for aids relief in 2003, the u.s. president's malaria initiative in 2005. in this decade and as part of the monterrey consensus (which didn't pursue goals as aggressively as many activists had urged), an increasing emphasis was put on measuring improvement in health outcomes, rather than merely the amount of money spent. in 2015 a book titled "to save humanity" was published, with nearly 100 essays regarding today's most pressing global health issues. the essays were authored by global figures in politics, science, and advocacy ranging from bill clinton to peter piot, and addressed a wide range of issues including vaccinations, antimicrobial resistance, health coverage, tobacco use, research methodology, climate change, equity, access to medicine, and media coverage of health research. measures measures of global health include disability-adjusted life year (daly), quality-adjusted life years (qalys), and mortality rate. disability-adjusted life years disability-adjusted life years per 100,000 people in 2004: no data less than 9,250 9,250–16,000 16,000–22,750 22,750–29,500 29,500–36,250 36,250–43,000 43,000–49,750 49,750–56,500 56,500–63,250 63,250–70,000 70,000–80,000 over 80000 main article: disability-adjusted life year the daly is a summary measure that combines the impact of illness, disability, and mortality by measuring the time lived with disability and the time lost due to premature mortality. one daly can be thought of as one lost year of "healthy" life. the daly for a disease is the sum of the years of life lost due to premature mortality and the years lost due to disability for incident cases of the health condition. quality-adjusted life years main article: quality-adjusted life year qalys combine expected survival with expected quality of life into a single number: if an additional year of healthy life is worth a value of one (year), then a year of less healthy life is worth less than one (year). qaly calculations are based on measurements of the value that individuals place on expected years of survival. measurements can be made in several ways: by techniques that replicate gambles about preferences for alternative states of health, with surveys or analyses that infer willingness to pay for alternative states of health, or through instruments that are based on trading off some or all likely survival time that a medical intervention might provide in order to gain less survival time of higher quality. infant and child mortality main articles: infant mortality and child mortality infant mortality and child mortality for children under age 5 are more specific than dalys or qalys in representing the health in the poorest sections of a population, and are thus especially useful when focusing on health equity. added section morbidity main article: morbidity morbidity measures include incidence rate, prevalence, and cumulative incidence, with incidence rate referring to the risk of developing a new health condition within a specified period of time. although sometimes loosely expressed simply as the number of new cases during a time period, morbidity is better expressed as a proportion or a rate. health topics respiratory tract infections main article: respiratory tract infection infections of the respiratory tract and middle ear are major causes of morbidity and mortality worldwide. some respiratory infections of global significance include tuberculosis, measles, influenza, coronaviruses and pneumonias caused by mycobacterium tuberculosis, morbillivirus, haemophilus influenzae and pneumococci respectively. the spread of respiratory infections is exacerbated by crowded conditions, and poverty is associated with more than a 20-fold increase in the relative burden of lung infections. diarrheal illnesses main article: diarrhea diarrhea is the second most common cause of child mortality worldwide, responsible for 17% of deaths of children under age 5. poor sanitation can increase transmission of bacteria and viruses through water, food, utensils, hands, and flies. dehydration due to diarrhea can be effectively treated through oral rehydration therapy with dramatic reductions in mortality. important nutritional measures include the promotion of breastfeeding and zinc supplementation. while hygienic measures alone may be insufficient for the prevention of rotavirus diarrhea, it can be prevented by a safe and potentially cost-effective vaccine. hiv/aids main articles: hiv and aids the hiv/aids epidemic has highlighted the global nature of human health and welfare and globalization has given rise to a trend toward finding common solutions to global health challenges. numerous international funds have been set up in recent times to address global health challenges such as hiv. since the beginning of the epidemic, more than 70 million people have been infected with the hiv virus and about 35 million people have died of hiv. globally, 36.9 million people were living with hiv at the end of 2017. an estimated 0.8% of adults aged 15–49 years worldwide are living with hiv, although the burden of the epidemic continues to vary considerably between countries and regions. the who african region remains most severely affected, with nearly 1 in every 25 adults (4.1%) living with hiv and accounting for nearly two-thirds of the people living with hiv worldwide. human immunodeficiency virus (hiv) is transmitted through unprotected sex, unclean needles, blood transfusions, and from mother to child during birth or lactation. globally, hiv is primarily spread through sexual intercourse. the risk-per-exposure with vaginal sex in low-income countries from female to male is 0.38% and male to female is 0.3%. the infection damages the immune system, leading to acquired immunodeficiency syndrome (aids) and eventually, death. antiretroviral drugs prolong life and delay the onset of aids by minimizing the amount of hiv in the body. malaria main article: malaria malaria is a mosquito-borne infectious disease caused by the parasites of the genus plasmodium. symptoms may include fever, headaches, chills, muscle aches and nausea. each year, there are approximately 500 million cases of malaria worldwide, most commonly among children and pregnant women in developing countries. the who african region carries a disproportionately high share of the global malaria burden. in 2016, the region was home to 90% of malaria cases and 91% of malaria deaths. the use of insecticide-treated bed nets is a cost-effective way to reduce deaths from malaria, as is prompt artemisinin-based combination therapy, supported by intermittent preventive therapy in pregnancy. international travelers to endemic zones are advised chemoprophylaxis with antimalarial drugs like atovaquone-proguanil, doxycycline, or mefloquine. global consumption and international trade in deforestation-associated commodities could also indirectly influence malaria risk. many primary commodities cause deforestation and deforestation can increase malaria transmission. consumption of such commodities in developed nations could increase malaria risk in developing nations. bacterial pathogens global number of deaths (a) and ylls (b), by pathogen and gbd super-region, 2019 overall age-standardised mortality rate per 100 000 population for 33 pathogens investigated, 2019 a gbd study reported global estimates of death rates from (33) bacterial pathogens, finding such infections are contributing to one in 8 deaths (or ~7.7 million deaths), which could make it the second largest cause of death globally in 2019. neglected tropical diseases main article: neglected tropical diseases more than one billion people were treated for at least one neglected tropical disease in 2015. for instance, neglected tropical diseases are a diverse group of infectious diseases that are endemic in tropical and subtropical regions of 149 countries, primarily effecting low and middle income populations in africa, asia, and latin america. they are variously caused by bacteria (trachoma, leprosy), viruses (dengue, rabies), protozoa (human african trypanosomiasis, chagas), and helminths (schistosomiasis, onchocerciasis, soil transmitted helminths). the global burden of disease study concluded that neglected tropical diseases 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