● At least three landmark 21st-century policy documents are spurring the global health movement: the WHO Report of the CMH, the UN Millennium Declaration, which outlined a set of Millennium Development Goals, and the Report of the Commission for Africa.

● Until recently, this advocacy had largely neglected a group of parasitic and tropical infections known as neglected tropical diseases (NTDs) that cause an extraordinary health and socioeconomic burden on the world's poorest people living in Africa, Asia, and the Americas.

● The NTDs can be controlled or eliminated through low-cost "rapid impact" drug packages.

The age of hypocrisy has been succeeded by that of indifference, which is worse, for indifference corrupts and appeases: it kills the spirit before it kills the body. It has been stated before, it bears repeating: the opposite of love is not hate, but indifference.
-Elie Wiesel, A Jew Today

During this first decade of the 21st century, we have a new sense of urgency about the plight of the poor in developing countries. The well-educated layperson in North America, Europe, or Japan is more aware than ever about the suffering of people living in the "South," the developing countries of sub-Saharan Africa, Asia, and the Americas. The human catastrophe of HIV/AIDS and concerns about influenza pandemics and SARS also help to focus attention on health problems in developing countries.

Meanwhile, an unprecedented and extraordinary advocacy effort is also fueling this global health awareness. Bono, Angelina Jolie, Brad Pitt, Bill and Melinda Gates, Jeffrey Sachs, Oprah Winfrey, Bob Geldof, Tony Blair, Jimmy Carter, and Bill Clinton are health advocates for the poorest people. Their efforts not only captivate world attention but also infuse an element of glamor into solving global health problems. Between 2005 and 2006 alone, Bono, Bill Gates, and Melinda Gates were named Time magazine Persons of the Year; the Time Global Health Summit in New York was branded the "Woodstock of global health"; Brad Pitt narrated a 6-h documentary, "Rx for Survival, a Global Health Challenge," for PBS; former President Clinton featured global health issues at his annual Clinton Global Initiative; and Bono and Bobby Shriver launched Product RED to support HIV/AIDS, malaria, and tuberculosis relief at the 2006 World Economic Forum in Davos, Switzerland.

These activities stimulated an unprecedented level of interest in global health issues from both undergraduate and graduate public health and medical students. During the academic year, young students often request my advice on how they can help solve a health problem in a developing country. I am not the only faculty member to have this experience--university-wide global health institutes are springing up at Duke, Vanderbilt, Harvard, Emory, University of Washington, and elsewhere, as university deans and presidents scramble to keep up with student interest.

Policy Documents Became Public Health Manifestos

At least three landmark 21st-century policy documents serve as manifestos to spur the global health movement. The first traces to January 2000, when World Health Organization (WHO) Director-General Gro Harlem Brundtland launched the Commission on Macroeconomics and Health (CMH) and appointed Jeffrey Sachs of Columbia University, New York, N.Y., to serve as its chair. He and his colleagues were charged with analyzing the impact of health on development, and their Report of the CMH, which was illustrated with examples of how health investments translate into economic development, articulates a profound relationship between disease and chronic poverty. It led influential finance ministers and policymakers to see improvements in global health as an important tool for reducing poverty.

Also during 2000, the General Assembly of the United Nations (UN) adopted the UN Millennium Declaration, calling for sustainable development and for eradicating poverty. It laid out eight millennium development goals (MDGs) along with a set of specific targets for the year 2015, three of which emphasize health, including the sixth MDG "to combat AIDS, malaria and other diseases." The third "manifesto," the Report of the Commission for Africa, commissioned by former British Prime Minister Tony Blair, calls for accelerating development in Africa. This report became an important blueprint for the Group of Eight (G8) nations at their 2005 summit in Gleneagles, Scotland.

Unlike many other international declarations, the CMH Report, the MDGs, and the Report of the Commission for Africa continue to influence global policymakers. Equally important, together with the new advocacy by leaders and celebrities, the global health manifestos stimulated high-level efforts to develop funding sources for supporting disease control, including substantial contributions from both the G8 nations and prominent private philanthropic organizations such as the Bill &Melinda Gates Foundation.

New Funding Focuses on Diseases Prevalent in the Developing World

Some of this new funding targets the sixth MDG, which calls for combating HIV/AIDS, malaria, and other diseases. For instance, under the aegis of the President's Emergency Plan for AIDS Relief (PEPFAR) and the President's Malaria Initiative (PMI), the U.S. government is pouring tens of billions of dollars into new programs fighting these diseases. Meanwhile, the international Global Fund to Fight AIDS, Tuberculosis, and Malaria (The Global Fund) also committed billions to support interventions against these diseases, while the Bill&Melinda Gates Foundation committed more than $1 billion.

In practical terms, these extraordinary commitments mean that unprecedented numbers of poor people in Africa and elsewhere are receiving lifesaving antiretroviral medications for treating HIV/AIDS as well as drugs and bed nets for treating and preventing malaria.

However, with the exception of funds from the Gates Foundation, this recent flurry of global health advocacy and resource mobilization is largely bypassing the "other diseases" component of the sixth MDG. This neglect is particularly true for a group of tropical infections that are part of a health and socioeconomic burden of extraordinary dimensions. Only now are world leaders and global health advocates beginning to recognize the critical importance of this core group of 13 neglected tropical diseases (NTDs) that include the major parasitic worm infections of humans, such as ascariasis (roundworm), hookworm, trichuriasis (whipworm), lymphatic filariasis (LF or elephantiasis), schistosomiasis (snail fever), onchocerciasis (river blindness), and dracunculiasis (guinea worm); an important group of infections caused by single-celled protozoan parasites such as Chagas'disease, leishmaniasis, and human African trypanosomiasis (sleeping sickness); and some bacterial infections, including trachoma, Buruli ulcer, and leprosy.

While many observers know something about the impact of HIV/AIDS and malaria on the developing world, far fewer know about this core group of NTDs, some of which are particularly common among the poorest people. The NTDs are the most common infections afflicting the world's poor. Of the 6.6 billion people on Earth, an estimated 1 billion live on less than $1 per day, while 2.7 billion live on less than $2 per day. Approximately one-fourth of the poorest 2.7 billion people suffer from ascariasis, trichuriasis, or hookworm infection, parasitic worm infections that are transmitted through warm, moist soil of tropical developing countries, while 1 in 10 of the poorest suffers from schistosomiasis, 1 in 20 from LF and trachoma, and 1 in 50 from onchocerciasis (Table 1). One or more of the seven most common NTDs-ascariasis, trichuriasis, hookworm infection, schistosomiasis, LF, trachoma, and onchocerciasis- affect about 1 billion people.

Many of these NTDs are co-endemic, making it common for poor people to be simultaneously infected with multiple NTDs. Of the 56 nations with five or more co-endemic NTDs, 40 are found in Africa, 9 in Asia, 5 in the Americas, and 2 in the Middle East. Africa accounts for all cases of dracunculiasis, 99% of onchocerciasis, almost 90% of schistosomiasis, approximately 40% of LF and trachoma, and one-third of all hookworm infections. Impoverished areas of Asia, especially Southeast Asia and the Indian subcontinent, account for more than one-half of all hookworm cases, ascariasis, and LF.

Hookworm, schistosomiasis, LF, and onchocerciasis also remain highly endemic in focal regions of American tropics and subtropics, especially in Central America and Brazil, where these NTDs are a living legacy of the Middle Passage, the forced transportation of Africans to the Americas. Today, these NTDs still primarily afflict the poor and marginalized people living in the region. In addition to their geographic overlap  and co-endemicity, the major NTDs exhibit a remarkable set of common features, all of which adversely affect the health and socioeconomic status of the poorest people.

Several Common Features among Neglected Diseases

Not all policymakers realize or appreciated the high prevalence of NTDs. For instance, the conditions giving rise to NTDs are seldom found in capital cities, where many government officials work and live. Instead, NTDs are concentrated in rural areas, particularly regions where subsistence farming is practiced. Therefore, unlike HIV/AIDS, the NTDs afflict forgotten people. Exceptions, such as dengue fever and leptospirosis, are common in urban slums.

Another feature of NTDs is that they are often not emerging infections such as avian influenza, SARS, Ebola, Lyme disease, West Nile virus infection, and HIV/AIDS, that have either newly appeared in the population or have rapidly increased in incidence or geographic range. Instead, NTDs have plagued humankind for centuries, and this fact is well documented through descriptions of the dramatic clinical manifestations of some NTDs, particularly leprosy, dracunculiasis, schistosomiasis, hookworm infection, and trachoma, in ancient texts, including the Bible, the Talmud, the Vedas, the writings of Hippocrates, and Egyptian medical papyri. An exception is NTDs that reappear after public health breakdowns during civil or international conflicts. For example, human African trypanosomiasis and kala-azar tragically reappeared during conflicts in Angola, the Democratic Republic of the Congo, and Sudan.

Another common feature of NTDs is that they are mostly chronic. Further, many such diseases cause disability and disfigurement. Even though they are caused by microbial or multicellular pathogens, which are transmitted either from person to person or through contact with contaminated soil, water, or arthropod vectors, NTDs tend not to exhibit classic features of infections such as acute febrile illness. Instead, NTDs mostly cause chronic conditions that lead to long-term disabilities and, in some cases, disfigurement.

For example, chronic hookworm and schistosomiasis produce longstanding anemias, which retard growth and impair memory and cognitive growth. In pregnant women, such anemias result in low neonatal birth weight and increased maternal morbidity and mortality. Meanwhile, onchocerciasis and trachoma cause impaired vision or blindness, while Chagas' disease causes a chronic and severely disabling heart condition. LF onchocerciasis, guinea worm  infection, leishmaniasis, Buruli ulcer, and leprosy cause either limb disuse or profound disfigurement that may prevent affected individuals from working.

Particular Features of NTDs Suggest Public Health Policy Changes

NTDs have a high disease burden but low mortality. Although an estimated 530,000 people die each year from NTDs, these numbers pale when compared to HIV/AIDS or malaria, each of which leads to as many as 3 million deaths annually. Therefore, placing NTDs on the radar screens of world leaders and policymakers entails having them focus on something other than disease-related deaths. We need some other mechanism to convince policymakers that these "other diseases" deserve the attention they accord to HIV/AIDS and malaria.

One such approach is to use disability-adjusted life years, or DALYs, which measure the healthy life years lost from either premature death or disability. Because of the chronic, disabling, and disfiguring components of NTDs, DALYs ascribed to them are substantial. Another great value in DALYs is that they facilitate comparisons of one condition with another. The data illustrate that the total disability resulting from the NTDs is almost as great as that from HIV/AIDS and even more than the disability from malaria or tuberculosis (Table 2).

This devastating comparison has critical implications for international efforts to control infectious diseases. Today, much of the global enterprise targeting infections focuses primarily on HIV/AIDS, malaria, and tuberculosis. The rationale goes beyond merely comparing DALY estimates and pointing out the high disease burden resulting from the NTDs. Instead, an increasing body of evidence indicates that NTDs exhibit geographic overlap and co-endemicity not only with each other, but also with AIDS and malaria. Moreover, new evidence suggest that the morbidities from NTDs are additive with and, in some cases, increase susceptibility to HIV/AIDS and malaria. Therefore, instead of tackling the big three conditions in isolation, the Global Fund, PEPFAR, and PMI should consider embracing NTDs as part of a "gang of four."

Consequences of NTDs at the Personal and Societal Levels

The blinding and disfiguring ravages of NTDs are stigmatizing and, in some societies, are considered a sign of a curse or the "evil eye." Thus, they may lead families, communities, and sometimes health care professionals to ostracize individuals. This social stigma strikes young women particularly hard, particularly when they are abandoned by their husbands and families, prevented from holding or kissing their children, or unable to marry altogether.

NTDs also have broader poverty-promoting features and other socioeconomic and international development consequences that extend well beyond their health impact. Thus, NTDs not only occur in the setting of poverty; they also promote poverty. For example, the cognitive and intellectual impairments that derive from hookworm-associated anemia severely affect childhood education in terms of school performance and attendance. Reduced attendance leads to reduced future wage-earning capacity, possibly by as much as 43%, while chronic hookworm infection among agricultural workers reduces their productivity in Africa, Asia, and the Americas.

Similarly, lymphatic filariasis continues to have a huge impact on productive capacity and costs a significant percentage of India's gross national product, trachoma leads to $5.3 billion in worldwide losses annually, and leishmaniasis accounts for 0.43% of the French Guiana social security budget. However, we are only beginning to understand the full economic impact of the NTDs.

Thus, the health impact of NTDs reflects not only their chronic and disabling features, but also brings educational and socioeconomic consequences that may be greater. Neglect occurs at many different levels: at the community level because the NTDs arouse fear and inflict stigmas, at the national level because NTDs are often a low priority for health ministers, and at the international level because they are not perceived as global health threats equivalent to the highmortality big three conditions. Also internationally, there has been a dearth of research and development activities concerning the NTDs.

The stigma of NTDs contributes to suffering, delays searching for help, promotes nonadherence to treatment, hurts families and communities, and ultimately lessens support for services, control, and research, according to Mitchell Weiss of the Swiss Tropical Institute. Paul Hunt, the UN Special Rapporteur on the right to the highest attainable standard of health, points out that relief from the suffering caused by the NTDs is a fundamental human right, which unfortunately has been largely ignored. Despite their global importance, however, so far the total dollars thus far committed to NTD control are measured in millions, not billions. This is a tragic situation because there are new opportunities to control or even eliminate the most common NTDs through large-scale administration of a so-called rapid impact package of low-cost or donated anti-infective drugs, such as albendazole or mebendazole for the intestinal helminth infections, ivermectin or diethylcarbamazine for the filarial infections, praziquantel for schistosomiasis and other fluke infections, and azithromycin for trachoma. Because many of these drugs are donated or available as inexpensive generics, the package can administered for as little as 50 cents per person per year.

In parallel are expanded research and development efforts for new drugs, diagnostics, and so-called "antipoverty" vaccines to combat the NTDs. Thus, the neglect may change, because of a new resolve by the WHO and national ministries of health, together with several key publicprivate partnerships dedicated to NTD control through mass drug administration, as well as nonprofit product development partnerships to manufacture new control tools. Further, many of the organizations involved in NTD control have begun to partner through a new alliance known as the Global Network for NTDs that is working to mobilize resources and to promote high-level advocacy, including from former presidents Clinton and Carter, as well as Jeffrey Sachs, television star Alyssa Milano, and WHO Director-General Margaret Chan. Moreover, student groups are beginning to voice their concerns about NTDs and their huge impact on the world's poorest people.

SUGGESTED READING

Hotez, P. J. 2008. Forgotten people, forgotten diseases: the neglected tropical diseases and their impact on global health and development. ASM Press, Washington, D.C.

Hotez, P. J. 2008. Neglected infections of poverty in the United States of America. PLoS Neglected Trop. Dis. 2:e256.

Hotez, P. J. 2009. One world health: neglected tropical diseases in a flat world. PLoS Neglected Trop. Dis. 3:3405.

Hotez, P. J., J. M. Bethony, S. C. Oliveira, P. J. Brindley, and A. Loukas. 2008. Multivalent anthelminthic vaccine to prevent hookworm and schistosomiasis. Expert Rev. Vaccines 7:745-752.

Hotez, P. J., P. J. Brindley, J. M. Bethony, C. H. King, E. J. Pearce, and J. Jacobson. 2008. Helminth infections: the great neglected tropical diseases. J. Clin. Invest. 118:1311-1321.

Hotez, P. J., A. Fenwick, L. Savioli, and D. H. Molyneux. 2009. Rescuing the "bottom billion" through control of the neglected tropical diseases. Lancet 373:1570-1675.

Hotez, P. J., and M. T. Ferris. 2006. The antipoverty vaccines. Vaccine 24:5787-99.

Hotez, P. J., D. H. Molyneux, A. Fenwick, J. Kumaresan, S. E. Sachs, J. D. Sachs, and L. Savioli. 2007. Control of neglected tropical diseases. N. Engl. J. Med. 357:1018-1027.

Hotez, P. J., and P. P. Wilkins. 2009. Toxocariasis: America's most common neglected infection of poverty and a helminthiasis of global importance? PLoS Neglected Trop. Dis. 3:e400.

Comments (0)

Subscribe to this article's comment feed

Show/Hide comment form

Name

Email

Website

Title

Comment

smaller | bigger

Subscribe via email (Registered users only)

I have read and agree to the Terms of Usage.

Add Comment