WASHINGTON, D.C. - Experts estimate that unless aggressive action is taken, nearly 1 billion people worldwide will be infected with tuberculosis (TB) in the year 2020, resulting in nearly 70 million deaths.
According to information presented at a news conference here in conjunction with World TB Day, TB continues to remain the most deadly infectious disease in the world, leading to more deaths worldwide in 1998 than in any other year in history. It is the leading killer of women ages 15 to 44, and kills more than 100,000 children each year. One out of three people carry the bacterium, resulting in about 8 million new cases per year, with approximately 3.5 million of these cases infectious. However, because each of these cases may exist undiagnosed in the community for about two years, at any given time, there are approximately 16 million people suffering from TB.
The cases are primarily concentrated in Southeast Asia - more than half of the cases in the world are in India, Pakistan, Bangladesh, Indonesia and the Philippines. Because the fear of TB has primarily disappeared in the West, the panel expressed concern over the failure of developed countries to understand the scope of the problem. Although as a nation, goals for treating people with active TB are being met, the tools to treat the disease are not being consistently used on a global level, resulting in the risk of multidrug resistant TB, according to Arata Kochi, MD, director, communicable disease prevention and control, World Health Organization (WHO), Geneva.
"It's only within the last three or four years that we've developed the surveillance system that we have gained a much better appreciation of how much TB there is in the world and where it is. For this reason, there's been a lack of investment in new drugs and various other ways to prevent TB," said Kochi.
According to the WHO Report on the Tuberculosis Epidemic 1998, directly observed treatment, short-course (DOTS) is the most effective treatment strategy available for controlling TB. Its five critical elements work together to cure infectious patients and break the cycle of transmission. The elements include:
Between 1991 and 1997, the number of countries adopting DOTS strategies increased from 10 to more than 100; however, only 16% of patients with TB are receiving DOTS. Between 2 million to 3 million people are dying from TB every year, a number which Kochi called "simply unacceptable." Additionally, because of limited access, 1 million patients with TB, particularly those in Asian-Pacific and third-world countries, are receiving inadequate treatment.
"Inadequate treatment has significant consequences. First, it leads to marked drug-resistant TB in patients; second, it increases the threat of multidrug resistant TB to others; third, it is simply a waste of resources; and fourth, it makes TB control programs more difficult and more expensive," he said.
The DOTS strategy focuses on people with active TB and has a proven level of efficacy that rivals most vaccines. However, according to Ken Castro, MD, director of the Division of TB Elimination, Centers for Disease Control and Prevention (CDC), Atlanta, it has not been put to optimal use.
"The fundamentals of TB elimination are not complex; in fact, they are fairly simple. You properly diagnose someone with active TB, then you provide treatment, ideally with DOTS with multiple drugs to ensure that the bacteria is killed, and at the same time you have to identify exposed individuals and provide preventive treatment to those at highest risk so they never develop active disease," said Castro. "Although the strategy is not complex, building and sustaining the global commitment needed to implement the strategy is indeed a daunting task. To beat TB, however, it will take a long-term commitment that is sustained at least until the last cases are gone."
Normally, treatment success rates run in excess of 80% and cost between $40 and $60, the panel said. However, in the face of multidrug-resistant TB, with the standard treatment regimen, these rates will fall to less than 60%. In addition, more money must then be spent on expensive, second-line drugs which cost between $1,000 and $10,000, depending on the regimen. Although the treatment success rates can be increased with this effort, prohibitively high costs limit the amount of help that can be offered to all afflicted.
"In countries that we work with in south Asia, the average per capita expenditure per year is around $3 to $4. The cost of treating multidrug resistant TB is approximately 3,000 times the average expenditure," said Castro.
In the United States, 43 states have reported persons with multidrug-resistant TB. Although the status of the epidemic varies from community to community, Castro believes that many areas lack the resources to properly screen for TB, apply DOTS, perform the necessary follow-up investigations, and reach out to high-risk populations, including foreign-born individuals. Preliminary analysis of data for 1998 have shown that about 42% of all TB cases are found in individuals born outside of the United States, when just over decade ago, only 22 cases of TB were found in foreign-born US residents. Most of these cases are a result of infections acquired years earlier in areas of the world where TB remains a serious threat.
"You could argue, why not just do a good job here? However, we live in a world of global economy, with our own residents traveling throughout the world and exposing themselves to TB," said Castro.
Along with substance abusers and individuals in homeless shelters, people with HIV are also at a higher risk for TB; it has become the most common AIDS-related disease throughout the world. In countries such as Tanzania and Kenya, the number of TB cases has doubled and in some instances, tripled within the past five years.
According to Castro, there is not a precise estimate of the number of people with TB in the United States who are co-infected with HIV, although from 1988 to 1992, outbreaks of multidrug resistant TB in several cities, including New York, predominantly affected persons with HIV in hospitals, prisons and hospice care settings. However, Castro stated that the recent decline in TB has been almost more pronounced in areas where there is a lot of overlap between the two epidemics, illustrating a very fast response and mobilization of efforts in treating TB in the setting of HIV.
"There's a certain level of optimism once you acknowledge what needs to be done and then you do it, " he said.
According to Castro, most Americans fail to recognize the threat of TB. There is a belief that it is a disease of the past, although it presents itself in a form today that is more complex than that seen in earlier generations.
"If we don't stop TB today, the TB our grandchildren face tomorrow will be even more difficult to cure and become more deadly," he said.
Castro believes the United States serves an excellent model in demonstrating the success of mobilizing its weapons against TB. After a resurgence in TB toward the end of the 1980s and the beginning of the 1990s, there have been six, consecutive years of declining TB trends. However, he warned against complacency following success.
"Just a decade ago, we were in a similar place. TB cases were declining, and it appeared as if our country was on its way to eliminating TB. Unfortunately, we accepted the status quo, assumed TB was under control, and allowed the control infrastructure to deteriorate. This assumption resulted in a resurgence of TB and the emergence and establishment of wide spread drug resistance," he said.
In 1996, the federal appropriation for the U.S. TB effort was $120 million, according to Fran Du Melle deputy managing director, American Lung Association (ANA), New York. That number has remained stable in the ensuing years. Because of inflation, however, less money is actually being spent on TB control today than in the past. "The numbers are dropping precisely because we have been investing in TB control. If this support erodes, we face the inevitable increase in TB cases," she said.
The ANA is urging Congress to increase US support for international TB control efforts, recommending an appropriation of $60 million earmarked to continue development on an integrated global TB control program. The ANA is currently a founding partner in the international "STOP TB" initiative, which aims to analyze current TB control efforts and encourage greater government commitment at the international, regional and country levels for TB control. It also aims to promote increased research and development of new TB vaccines, diagnostics and medicines.
Ninety-five percent of the people infected with TB live in developing countries, and most of them are poor, said Richard Skolnik sector manager, The World Bank Group, Washington, D.C. Therefore, placing greater emphasis on TB control is necessary to prevent a vicious poverty cycle, particularly for those people in third-world countries who are at the greatest risk for developing TB. The cycle begins with ill health, leads to lost income and the expenditure of money on health care that poverty-stricken individuals do not have, and results in debt.
Because the highest incidence of TB is found in young adults between the ages of 20 and 40, this places additional burden on the economical well being of developing countries. Premature death, along with the loss of many years at work, limits a country's productivity.
"TB has a tremendous negative impact on social, political and economical health of countries and must be at the top of the agenda of a poverty-oriented organization such as the World Bank," he said.
Although tremendous progress has been achieved in treating persons with active TB, Castro believes we have only scratched the surface in terms of screening for latent infection and providing preventive therapy. He proposed that what we decide to do globally will ultimately benefit the United States
"If we sit back and allow drug resistance to grow unchecked, we may one day be faced with incurable TB in our midst. As we move to the next phase - focusing on the elimination of TB - we must recognize that this era will be even more challenging, with the remaining cases harder to reach, find, and in many cases, harder to treat," said Castro. "A message of consistency and sustained response is not as glamorous as a quick fix, but recognizing the alternative, we really have no choice."
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