Emerging diseases remain a global concern

Infectious diseases are responsible for 26% of mortality worldwide.

Issue: May 2007

SAN DIEGO — Global emergence and re-emergence of diseases remain a challenge because of the microbes’ abilities to replicate and mutate, according to Anthony S. Fauci, MD.

Fauci, director of the National Institute of Allergy and Infectious Disease, described three types of disease challenges: emerging, which he said includes HIV and severe acute respiratory disease (SARS); re-emerging and resurging, which includes West Nile virus in the United States; and deliberately emerging, which includes bioterrorism, such as the anthrax attacks that followed the Sept. 11, 2001 terrorist attacks.

Recently, researchers addressing the threat of emerging and re-emerging diseases have been at a slight advantage due to vaccines, therapeutics, diagnostics and genomics, Fauci said. Research must continue to prevent the emergence of these microbes, he said.

“Evolution is not on our side. What do we have? We have intellect and will, and we have public health measures and biomedical research,” Fauci said.

Fauci presented the keynote address at the 2007 American Academy of Asthma, Allergy and Immunology Annual Meeting held here.

Global threat

Anthony S. Fauci

In 1963, Ivan Cockburn declared victory and stated that the world will be free of infectious disease threats in the foreseeable future. In 1968, the U.S. Surgeon General urged the medical community to turn its focus away from infectious diseases and focus on chronic diseases, such as heart disease.

“Not only did they not understand the inherent nature of infectious disease, but they were completely disregarding that we live in a global community,” Fauci said.

Today, infectious diseases are the second leading cause of mortality worldwide and the leading cause of mortality in people from birth to 29 years of age, according to Fauci. The “matrix” of infectious diseases, or the leading infectious diseases worldwide, includes respiratory diseases, HIV/AIDS, diarrheal diseases, tuberculosis and malaria, he said.

The world exists in a delicate balance of survival, Fauci said. The mutation of microbes tips the balance, and further research, vaccines and therapeutics might tip the balance back. These recent advances have given researchers and scientists the upper hand, according to Fauci.

HIV/AIDS

HIV/AIDS is the leading cause of mortality due to an infectious disease in the world and in history, according to Fauci. About 39.5 million people worldwide have HIV; 90% of these cases occur in developing nations. About 1.4 million people in the United States are infected with HIV, he said.

HIV is a prototypical emerging disease. In 1981, the first reports involved about 20 gay men in New York, Los Angeles and San Francisco; 26 years later, it is one of the most catastrophic health crises that civilization has experienced, along with the bubonic plague and the influenza pandemic of 1918, Fauci said.

Since 1981, federal funding for HIV/AIDS has reached $190 billion, with almost $23 billion spent last year alone, according to Fauci. Researchers developed the first antiretroviral in 1987, and since then, the FDA has approved more than 22 other antiretrovirals, which is more than all the other antivirals combined. Antiretrovirals saved 3 million life-years in the United States between 1996 and 2006, which surpassed the cost-benefit ratio of every other life-saving measure, including bypasses, renal transplants, dialysis and drugs, such as atorvastatin (Lipitor, Pfizer) and antihypertensives, Fauci said.

International programs, such as the President’s Emergency Plan for AIDS Relief (PEPFAR), are designed to increase access to antiretroviral access in developing nations. Before September 2004, less than 10,000 people in Africa were receiving antiretroviral treatment, according to Fauci. Now, 822,000 people are receiving antiretrovirals. Combined with treatment from the Global Fund to Fight AIDS, Tuberculosis and Malaria, 1.6 million people are receiving antiretrovirals. Despite these programs, only 25% of people who need treatment are receiving it, Fauci said.

The world cannot keep up by only treating HIV, according to Fauci. A multifaceted approach that includes condoms, syringe exchanges and interruption of mother-to-child transmission are all key to prevent HIV, Fauci said.

A recent Lancet study in which researchers found that male circumcision reduced new HIV infections by 48% in Uganda and 53% in Kenya is very promising, according to Fauci.

Old diseases, ongoing issues

Malaria results in 1.3 million deaths each year, mostly in children younger than 5, Fauci said. Approximately 350 to 500 million clinical episodes occur each year, which are “dreadfully neglected,” and every 30 seconds, a child – usually in Africa – dies from malaria, he said.

However, research into better candidate vaccines is underway, Fauci said. In 2005, President George W. Bush launched the President’s Malaria Initiative (PMI), which aims to reduce mortality associated with malaria by 50% among people in 15 countries in Africa that experience the highest malaria burden. Six million people have received prevention or treatment services, and PMI aims to assist an addition 11 million people this year.

Fauci said that another historically forgotten disease — tuberculosis — still affects much of the world. Approximately 20% of global TB strains are resistant to isoniazid, and 10% of those strains are resistant not only to the first-line treatments, but to fluoroquinolones and at least one injectable drug, such as kanamycin, as well.

Fauci defined West Nile virus as a re-emerging disease because it has been present in Africa and the Middle East for centuries and migrated to the United States in 1999. In 2001, the United States reported 66 cases of West Nile virus and nine deaths. In 2002, cases increased to 4,156 and 284 deaths, and in 2003, 9,862 cases were identified along with 264 deaths, according to Fauci. The disease is present and will not be eradicated because the three ingredients needed for the spread of West Nile virus – mosquitoes, birds and people – will always be present, he said.

Following the Sept. 11, 2001, attacks, the distribution of anthrax through letters resulted in 18 confirmed cases and five deaths.

The government constructed a strategic plan and infrastructure to deal with the threat of not only the deliberate release of disease, but the entire issue of emerging and re-emerging diseases, according to Fauci.

“Resources to respond to a biodefense situation have immediate and long-range help for naturally occurring disease,” Fauci said.

Newly emerging

SARS began in the Guangdong Province in China in November 2002, but the Chinese were not forthcoming with information, according to Fauci. After a Chinese physician stayed at a hotel in Hong Kong, the disease spread through other travelers and led to the crisis in fall 2003, he said. Approximately 8,000 cases of SARS and 774 deaths occurred.

Researchers recognized the disease in February 2003, sequenced the SARS coronavirus in March 2003 and developed a vaccine that entered into clinical trials in December 2004, according to Fauci. It was the shortest time frame from the identification of a microbe to the creation of a vaccine in the history of vaccine research. These resources had been building up because of the bioterror threat, he said.

Influenza is an example of both a re-emerging and newly emerging disease, according to Fauci. Usually, the vaccine requires tweaking each year, but overall, the public is familiar with the strains. However, sometimes a new influenza strain emerges that civilization is not familiar with. Keeping this in mind, pandemic preparedness must be integrated with season influenza preparedness, he said.

“We are guiding our efforts in pandemic flu with what needs to be done with seasonal flu,” Fauci said.

Vaccination is key to prevent flu emergence. This year, manufacturers distributed 102 million doses, which is the highest ever distributed, he said.

Although the H5N1 virus has infected millions of birds in Southeast Asia, it is still inefficient at bird-to-human or human-to-human transmission; however, preparation is necessary, according to Fauci. New drugs and vaccines have been in development during the past three years, he said. A new DNA platform vaccine is currently underway at the NIH.

In addition, a Canadian study suggested that influenza vaccine might offer cross protection until a new vaccine is available, Fauci said. – by Lauren Riley

For more information:

Fauci AS. Emerging and re-emerging infectious diseases: the perpetual challenge to global health. Presented at: The 2007 American Academy of Asthma, Allergy and Immunology Annual Meeting; Feb. 23-27, 2007; San Diego.