Socioeconomic disparities caused by income, ethnicity and relative poverty constitute major and growing determinants of health to at-risk populations, regardless of the average income of their country of residence.

A new PLOS Collection, "Blue Marble Health: the mismatch between national wealth and population health", features research and commentary from PLOS Medicine and PLOS Neglected Tropical Diseases that examines the paradoxical disease burden among poor people living in wealthy nations.

The Collection features a new Editorial from Dr. Peter Hotez - Co-Editor-in-Chief of PLOS Neglected Tropical Diseases, Dean of the National School of Tropical Medicine at Baylor College of Medicine and President of the Sabin Vaccine Institute - entitled "Ten Global "Hotspots" for Neglected Tropical Diseases" that identifies Texas as one hotspot due to evidence that cysticercosis, cutaneous leishmaniasis, dengue fever and even Chagas disease are widespread both in South Texas and even in parts of Houston, which is emerging as the first major city in the United States with a serious NTD burden.

Two key PLOS papers, each published in the fall of 2013, stimulated the genesis of this Blue Marble Health Collection, which was curated by Dr. Peter Hotez and Dr. Larry Peiperl, Chief Editor of PLOS Medicine.

The first, from PLOS Neglected Tropical Diseases, entitled "NTDs V.2.0: 'Blue Marble Health' - Neglected Tropical Disease Control and Elimination in a Shifting Health Policy Landscape" found that while some NTDs such as river blindness, loiasis, African sleeping sickness, and schistosomiasis are largely or exclusively diseases of sub-Saharan Africa, paradoxically many of the world's highest concentration of NTDs occur in the 20 wealthiest economies - the group of 20 (G20) countries - especially in the mostly hidden pockets of extreme poverty that can be found in the big middle-income nations, such as Indonesia or in areas of the BRICS countries, including northeastern Brazil, northern India, and southwestern China. Moreover, the disease burden from NTDs is alarmingly high in the southern United States, especially in Texas and the Gulf Coast, in areas of Australia with large Aboriginal populations such as the Northern Territories, and Eastern Europe.

A parallel editorial in PLOS Medicine entitled "Poor Health in Rich Countries: A Role for Open Access Journals" noted that relative poverty within a society is a stronger predictor of health than aggregate measures of economic power such as GNP or per-capita income. For example, tens of millions of Americans living in poverty, including many people of color, "experience levels of health that are typical of middle-income or low-income countries." The editorial concluded that, for many issues that affect the health of people of lower socioeconomic status, clear-cut distinctions between "domestic" and "cross-border" research are becoming increasingly difficult to draw.

"Blue Marble Health advances the understanding that wherever socioeconomic inequality is pervasive, neglected diseases and other conditions naively assumed to arise only in the context of national poverty will be widespread. We encourage the community of biomedical and social scientists, humanists, health economists, healthcare professionals, and public health workers to submit papers to us at PLOS that highlight health disparities among the poor and otherwise disadvantaged populations - those who are often forgotten in the world¹s middle- and high-income countries" said Dr. Hotez and Dr. Peiperl.