GENERAL DISEASES

Despite medical advances that have produced hundreds of drugs that are safe and effective against bacteria, viruses, fungi and parasites, infectious diseases are still a major cause of death, disability and social and economic upheaval for millions around the world.

More than 90 percent of the deaths from infectious diseases worldwide are caused by only a handful of diseases. These diseases - lower respiratory infections, HIV/AIDS, diarrheal diseases, tuberculosis, malaria and measles (see table 1) - are also the leading cause of death in sub-Saharan Africa (see Chart 1). And, while not major killers, a number of the world's 'neglected' infectious diseases such as lymphatic filariasis, trachoma, intestinal parasites, leprosy and onchocerciasis cause chronic disability and stigma for millions. (see Map 1).

Leading Causes of Death Due to Infectious Diseases …. 2002

Lower respiratory infections …. 3.9 million …. 19 percent
HIV/AIDS …. 2.8 million …. 17 percent
Diarrheal diseases …. 1.8 million …. 13 percent
Tuberculosis …. 1.6 million …. n/a
Malaria …. 1.2 million …. 8 percent
Measles …. 0.6 million …. 4 percent
Neonatal Causes …. 37 percent
Others (including noncommunicable diseases) …. 10 percent

[Source: World Health Report, 2004 WHO]

Beyond the general ecology of many developing countries, a number of social and economic factors contribute to the high rates of infectious disease. Poverty, lack of access to health care, antibiotic resistance, evolving human migration patterns, new infectious agents, and changing environmental and development activities all contribute to the expanding impact of infectious diseases.

Overcrowded and poor living conditions make those living in poverty especially vulnerable to communicable diseases such as tuberculosis and cholera. Limited access to health care and drugs renders otherwise treatable conditions such as malaria, and tuberculosis fatal for the poor. Poor nutrition and compromised immune systems are also key risk factors for several major killers including lower respiratory infections, tuberculosis and measles.

HIV/AIDS, which has claimed millions of lives in the past two decades, has joined with other emerging and re-emerging diseases to have a significant impact on global health and to change global disease progression patterns. Since the early 1990s, the tuberculosis epidemic has largely been driven by the HIV/AIDS pandemic. Fueled by growing antibiotic resistance, inappropriate prescription of ineffective drugs, and poor adherence to medication, infectious diseases once believed to be under control have re-emerged as major global threats.

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A very important basic rule for hygiene and for preventing the spread of infectious diseases that may be transmitted through contact, is to make sure your hands are washed thoroughly. Learn about the proper method here: WASHING HANDS

Illness and death from infectious diseases are particularly tragic because they are largely preventable and treatable. For instance, in 2002, 75 percent of all deaths due to infectious diseases occurred in southeast Asia and sub-Saharan Africa. Southern Africa, which is home to 10 percent of the world's population, accounted for more than 40 percent of deaths due to infectious diseases. In fact, more than 60 percent of all deaths in the region were due to infectious diseases.

[The 6 neglected diseases are: leprosy, lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminths and trachoma.] Not surprisingly, the poorest and most vulnerable are the most severely affected by infectious diseases. Children and women are especially susceptible to the impact of infectious diseases. Children in developing countries, already lacking proper nutrition, may also lack access to affordable measles vaccinations and simple interventions for diarrheal diseases. Children are also the group most likely to die from malaria. Women now account for more than 50 percent of new HIV infections and, among adults, pregnant women are the most at-risk for malaria.

The repercussions of these diseases go well beyond morbidity and mortality statistics. Poverty not only characterizes the circumstances in which infectious diseases thrive, but the cycle of poverty is exacerbated by lost productivity, missed educational opportunities, and high health-care costs for the affected and their families.

Communities and societies also bear an economic burden of caring for those who are sick (see Chart 3). Diseases such as HIV/AIDS, malaria and tuberculosis affect those who are in the prime productive stages of life, while pneumonia and diarrheal diseases more often cut short the lives of children before their fifth birthday. Diseases such as trachoma lead many blind adults to pull children from school to care for the family, leaving a future generation uneducated. Fear and ignorance stigmatize those who affected by diseases such as HIV/AIDS, tuberculosis and lymphatic filariasis, denying them much needed social support and other socio-economic opportunities.

LOWER RESPIRATORY INFECTIONS

Among infectious diseases, lower respiratory infections are the leading cause of mortality overall and a primary cause of death for children under age five. Most of these deaths occur in developing countries where children's immune systems are often already weakened by malnutrition and other diseases. Pneumonia, primarily a bacterial infection of the lungs, is the most serious of the lower respiratory infections, despite the fact that it can usually be effectively treated with antibiotics, if they are available and affordable.

DIARRHEAL DISEASES

Diarrhea is a leading cause of childhood morbidity and mortality in developing countries. It is caused by ingesting certain bacteria, viruses or parasites present in water or food, and can be spread by utensils, hands or flies. Diarrheal disease causes considerable dehydration, which may quickly lead to death when not promptly treated.

Cholera, one of the most severe diarrheal diseases, is a significant cause of illness and death in developing countries. An acute bacterial infection of the intestine, cholera is spread the consumption of contaminated food or water. Cholera symptoms include acute watery diarrhea and vomiting, which can result in severe dehydration and rapidly lead to death. Other diarrheal disease pathogens include rotavirus, escherichia coli, salmonella, shigella and giardia.

Diarrheal diseases can be prevented through access to clean, safe drinking water and through proper sanitation measures, including hand washing and safe disposal of human waste. While diarrhea generally can be easily treated using oral rehydration solution (ORS), a combination of glucose and sodium dissolved in water that replaces essential electrolytes lost through diarrhea, long-term prevention solutions require investments in water and sanitation, as well as changes in behavior to prevent unnecessary transmission of disease agents.

TUBERCULOSIS

Tuberculosis (TB) kills nearly 2 million people every year, more than 90 percent of whom live in developing countries. While it is estimated that about one-third of the world's population is infected with the bacteria that causes TB, the infection remains dormant throughout the lives of most healthy people. The lifetime risk for developing the disease is generally 5-10 percent.

For HIV-positive individuals, who have compromised immune systems and other risk factors, the lifetime risk exceeds 30 percent. Pulmonary TB affecting the lungs is the most common and infectious form. Symptoms of pulmonary TB include a chronic cough, severe weight loss, night sweats and progressive, irreversible lung destruction.

TB transmission is less likely to occur in properly ventilated and uncrowded environments. Thus TB's association with poverty is aggravated by the fact that those who live in crowded and poor circumstances are at greater risk of exposure. Tuberculosis can be treated effectively through widely available drugs, but 50 percent of those left untreated will die of the disease.

Malaria is a leading killer of children under five and a major contributor to adult morbidity in sub-Saharan Africa. More than 300 million cases and more than one million deaths occur each year. An estimated 10,000 women and 200,000 infants die annually due to malaria infection, and severe malarial anaemia accounts for more than half of these deaths.

Malaria is caused by a parasite that is transmitted through the bite of the Anopheles mosquito. Individuals infected with the parasite that causes malaria may experience several weeks or months of poor health, and children and pregnant women are less likely to recover than adults who have built up some immunity to the disease. Symptoms include fevers with chills, headache, back pain, sweating, weakness, nausea and anaemia.

Malaria disproportionately affects people living in poverty (see Map 3). For adults who survive malarial attacks social and economic consequences include low productivity and depression.

Because of malaria's pervasiveness, combating malaria is an important poverty reduction strategy. Transmission may be prevented through the use of insecticide-treated nets and indoor residual spraying with insecticides. Malarial disease can be prevented with prophylactic anti-malarial drugs. Those who have been infected with the malaria parasite can be treated with relatively inexpensive anti-malarial drugs where available and affordable. However, drug resistance to the anti-malarial drugs chloroquine and sulfadoxine-pyrimethamine has, in some regions, rendered them virtually ineffective.

MEASLES

Despite the availability of effective vaccines, measles is still a major childhood killer in developing countries. Children account for more than 50 percent of measles deaths annually, and the disease is responsible for 4 percent of the total deaths of children each year. Caused by a virus, measles is highly communicable and is transmitted by contact with nasal or throat secretions emitted through sneezing or coughing of infected persons. Measles symptoms typically consist of a high fever, cough, runny nose and a generalized rash. Complications that accompany measles, such as pneumonia, diarrhea and malnutrition are often fatal to children living in developing countries.

REASONS FOR HOPE

Success stories from around the globe have provided clear evidence that infectious diseases can be controlled, even in the world's poorest countries. We know how to dramatically reduce the devastating impact of killer diseases with medicines and tools that are affordable and easy to use.

MALARIA

Thanks to simple interventions, such as insecticide-treated nets to prevent transmission of infection and early and effective treatment, malaria has been contained in a number of countries around the world. It is estimated that as many as one in two malaria deaths can be prevented if people have ready access to rapid diagnosis and prompt treatment with appropriate medicine.

TUBERCULOSIS

More than a million lives have been spared from tuberculosis in the past decade due to the success of TB control efforts in countries such as China, India, Nepal and Peru.

CHILDHOOD ILLNESS

In 1977, only 5 percent of the world's children were vaccinated. Today, that figure has climbed to 75 percent and more than 3 million lives have been saved each year. This is largely thanks to the work of the Bill and Melinda Gates Vaccination Program. If the right tools are made available worldwide, there is no question that we can reduce infectious disease and deaths.

WHAT NEEDS TO BE DONE

Many countries have demonstrated that even in low-resource settings, the burden of infectious disease can be reduced if there is strong political will and the basic resources and infrastructure to support use of low-cost interventions. But this is not easy. Efforts to reduce the incidence of infectious disease require substantial resources, often beyond those available in the poorest countries.

Progress must also be supported by firm political commitments at the international level. Just this year, President George Bush of the United States called on the world to join the United States in a major new initiative to halt the spread of malaria. This initiative will focus efforts on proven interventions in the highest burden countries in Africa. These commitments must be backed by resources that are sufficient to enable communities to have the basic tools needed to routinely monitor and control disease.

The scope is significant: we need to increase the world's supply of diagnostics, medicines, vaccines and other lifesaving tools. Effective disease control is possible, but will only become a reality when every nation, regardless of size, location or wealth, has the capacity to recognize, prevent and respond to the threats posed by infectious disease.

Multi-sectoral approaches, including partnerships between the public and the private sector, as well as non-governmental organizations and philanthropic institutions, are critical to providing resources in the scope that is required. Partnerships that have formed to address these issues include The Global Fund to Fight AIDS, TB and Malaria, bringing significant new resources to countries battling these diseases, and the Children's Vaccine Program, funded by the Bill & Melinda Gates Foundation, seeking universal immunization against measles and other diseases.

By Jeffrey D. Sachs, January 4, 2007

Listen for a moment to the beautiful and dignified voices of Africa's mothers. Despite their burdens of poverty and hunger, they will tell you not of their endless toil but of their hopes for their children. But softly, ever so softly, they will also recount the children they have lost, claimed by a sudden fever, children who died in their arms as they were carried in a desperate half-day's journey by foot from the village to the nearest clinic.

This is the ineffable sadness of malaria. Another African child has died of malaria since you started reading this article. Perhaps 2 million children in all will succumb this year. The long-term consequences are insidious as well as tragic and even relate to the ability of the U.S. to prevail against the jihadists. Not only does malaria sap worker productivity and scare away business investment, but it also, paradoxically, increases the rate of population growth. Instead of having two or three children, couples in a malarial region often choose to have six or seven--unsure how many will survive.

Malaria also helps create a poverty trap with special ferocity in Africa. By a quirk of ecological fate, Africa has the world's heaviest toll of this disease, the result of its tropical climate, its specific types of mosquitoes and its limitless mosquito-breeding sites. Children are struck down in unmatched numbers. And Africa's disease toll from malaria may be even higher than previously recognized. Recent research has found that malaria infection increases the likelihood that an HIV-infected individual will transmit the AIDS virus to others. Many millions are also infected simultaneously with malaria and worm infections, multiplying the disease burden.

Osama bin Laden has called for jihad in Africa, trying to capitalize on its extreme poverty. Here's how we can respond. While malaria has shaped Africa's poverty trap, it is a trap that can finally be unlocked. Spectacular technological advances, some stunningly simple, offer practical and low-cost solutions. The most obvious one is insecticide-treated bed nets, now cleverly engineered to last up to five years. The cost to manufacture, ship and distribute each net is $10. A new generation of medicines based on artemisinin, an extract from a traditional Chinese herbal remedy, is remarkably effective in treating cases of the disease, at a cost of about a dollar per treatment.

Yet these solutions still aren't reaching the vast proportion of Africans in need. Hard as it is for us to imagine, Africa's households simply can't afford even $10 for a net, or a dollar for medicines when a child falls sick. Nor can African governments carry these costs on meager budgets or take extra vital steps to train local health workers and ensure that every village has reliable access to effective medicines.

Here is where you and I come in. Considering the costs of the nets, medicines and other components of malaria control, a comprehensive program would cost about $4.50 per African at risk, or about $3 billion a year for the whole continent. This is an amount that is too large for Africa but truly tiny for the rich world. Let me put the $3 billion in perspective: there are a billion of us in the high-income world--that amounts to $3 a person, or one Starbucks coffee a year. It's around 12.5% of the estimated $24 billion in Wall Street's Christmas bonuses.

We should bring forth armies of Red Cross volunteers to distribute bed nets and to offer village-based training for tens of thousands of villages across Africa. In a brilliant demonstration of people power and modern logistics, Red Cross volunteers distributed nets to more than half the households of Togo in 2004 and Niger in 2005 in a matter of a few days in each country. That successful delivery model should be replicated across Africa, by 2010 if not earlier, but this will depend on mobilizing the needed resources.

New citizens' movements, including Malaria No More malarianomore.org and Nothing but Nets nothingbutnets.net) have been established to achieve the needed breakthrough. We can each contribute $10 for a bed net. We can each learn more about the disease and become antimalaria leaders in our communities, schools, churches and businesses.

We can urge our governments to work with the private sector and citizens' groups to win the fight against malaria during this decade. President Bush recently took a good step in scaling up the U.S. government's malaria-control efforts, but much more needs to be done to ensure that aid reaches the hundreds of millions of Africans at risk.

Together we can choose peace over jihad and life over violence. Through our common resolve, we can prove the power we each have to save a life.

[Jeffrey D. Sachs, author of The End of Poverty, directs the Earth Institute at Columbia University]