Several simple statistics speak eloquently of the inequalities in health that exist in the world today. Thanks to widespread access to an array of effective drugs and vaccines, infectious diseases now account for only one out of 10 deaths in the world’s richest countries. Yet among the poorest people, six in 10 still die of infectious diseases, according to the World Health Organization (WHO). Half of these deaths, in other words, could be prevented.

As appalling as those numbers are, they shouldn’t be surprising. According to the Global Forum for Health Research, every year more than US $70 billion is spent worldwide on health research and development by the public and private sectors. An estimated 10% of this is used for research into 90% of the world's health problems. This is what is called "the 10/90 gap". The consequences of that profound inequity are visible around the world.

Preventable Diseases Continue to Kill Millions

One result is that many preventable illnesses continue to claim millions of lives. Over 4 billion acute cases of diarrheal diseases occur every year, primarily in children in developing countries, according to the WHO. Two million children die annually from diarrhea.

Lower respiratory infections such as pneumonia are another scourge of children. Almost 4 million people died of lower respiratory infections in 2002, many of them children under five.

Malaria, banished in most of the developed world, remains a leading killer in many poor corners of the world, especially sub-Saharan Africa, where 90 percent of the world’s cases occur. Malaria infects at least 500 million people worldwide every year.

Measles, too, still thrives. This childhood infection, which can be prevented with a cheap and effective vaccine, still kills an estimated 700,000 annually, lives that could be spared with a simple immunization.

The list goes on. Tuberculosis claims 2 million victims, 90 percent of them in developing countries. About one-third of the world’s population is infected. Almost 40 million people worldwide are infected with HIV/AIDS. Thanks to new anti-viral drugs, HIV/AIDS has become a manageable disease instead of a death sentence. But in the world’s hardest hit places, most AIDS patients do not have access to life-saving drugs.

Devastating Afflictions Remain Neglected

Another consequence of the unequal allocation of the world’s health resources is that diseases that afflict the world’s poorest people have been largely ignored. According to Doctors Without Borders, of the 1393 new drugs approved from 1975 to 1990, just 13 drugs—barely one percent––were for infectious diseases that disproportionately affect the developing world.

Chagas disease has received proportionately little attention from medical science, for example; yet this devastating illness, the world’s third most prevalent parasitic disease, is a leading health concern throughout South and Central America. Between 16 and 18 million people are infected, and 100 million more are at risk of contracting the parasite, which kills an estimated 45,000 people a year.

Another neglected disease is leishmaniasis. The most deadly form of this parasitic illness, called visceral leishmaniasis, afflicts some 1.5 million people, primarily in the Indian subcontinent, Ethiopia, Kenya, Sudan and Brazil. Untreated, the disease is more than 90% fatal. In India alone, as many as 200,000 die every year.

Also deadly if untreated is African trypanosomiasis, or sleeping sickness, a parasitic disease that infects half a million people worldwide and causes 50,000 deaths annually. Although drugs have been developed to treat it, growing drug resistance has rendered many of them ineffective. As is true for almost all neglected diseases, there has been little interest in researching and developing alternatives.

Millions are Trapped in a Vicious Cycle of Disease and Poverty

The toll goes beyond lives lost. Many of these illnesses also disrupt communities and undermine nations’ economic growth. Diseases like HIV/AIDS and tuberculosis strike young adults just when they would normally be contributing most to their family, their community and their country’s economic progress. In countries where diseases such as malaria are endemic, widespread illness erodes economic growth and discourages foreign investment. In fact, Africa's gross domestic product (GDP) would be up to $100 billion greater annually if malaria had been eliminated years ago, according to the World Health Organization. The result is deeper poverty, which in turn makes it more difficult for hard-hit countries to eliminate disease, creating a vicious circle that causes even more illness. The economic toll of Chagas disease alone exceeds 8 billion (US$) a year—a vast sum in the impoverished countries where it remains a scourge.