More than one-quarter of all deaths worldwide are caused by infectious diseases. In the US, more tiran 170,000 people die from these diseases each year-and the number is likely to get much higher. In just the last few years...

  • Reemerging diseases that were nearly eradicated in the US, such as measles, malaria and tuberculosis, now are occurring in increasing numbers.
  • Influenza A H1N1, known as the swine flu, was first detected in Mexico in April 2009. The virus has sparked a growing outbreak of illness among people both in the US and worldwide. A vaccine to protect against the H1N1 virus became available in October 2009.
  • Bird (avian) flu has killed more than half of those infected-though none of these cases has occurred in the US to date and most cases have resulted from people having direct contact with infected birds or contaminated surfaces. Should the virus mutate to permit human-to-human transmission, the death rate could rise into the millions.
  • Methicillin-resistant Staphylococcus aureus (MRSA) now is the sixth-leading cause of death in the US. It is a strain of bacteria that causes an infection-often called "staph"-that can be deadly even when patients are treated with state-of-the-art antibiotics.

Here, Georges Benjamin, MD, executive director of the American Public Health Association, answers questions about the risks for infectious diseases…

  • Are epidemics on the rise? Yes. Every two or three years, there's a new epidemic somewhere in the world. The term "epidemic" means that a particular health-related issue—an infectious disease, obesity, even car accidents—is occurring more often than expected. The frequency of epidemics seems to be increasing.

One of the reasons for the increase is that global warming has extended the population and range of mosquitoes, leading to increases in malaria, dengue fever and other mosquito borne diseases.

In addition, human and animal populations worldwide are living in closer proximity than in the past. More than half of all infectious diseases can infect species other than their original hosts. Many of the most dangerous pathogens, including the virus that causes AIDS, originated in animals and only later developed the ability to infect humans.

A century ago, a disease in a remote area might sicken or kill a few dozen people and then "burn out." Now more than two billion people fly on airplanes every year. A deadly pathogen, such as Ebola virus, easily could spread into more populated areas and infect thousands-or worse.

  • How dangerous is the next epidemic likely to be? It depends on the organism. In the best-case scenario, something such as a cold virus could mutate and gain the ability to infect more people than it had in the past. But because this virus isn't lethal, it would be more of a nuisance than anything else.

The most serious epidemics involve organisms that are both highly transmissible and lethal. The Spanish flu of 1918-1919 had both of these traits. It was readily passed from person to person, and it was uncommonly virulent. Worldwide, it killed between 20 million and 40 million people within about two years and has been called the most devastating epidemic in recorded history.

A disease that can be transmitted via indirect contact-for example, from inhaling airborne organisms from sneezes-is more likely to emerge as an epidemic than a disease that can be transmitted only under specific circumstances, such as hepatitis C from infected blood.

  • If you had to guess, what epidemic is likely to be next? There's no way to know. Any infectious organism could be involved. Many bacterial infections (such as tuberculosis) have reached epidemic proportions, but we often can control these illnesses with antibiotics.

Viral infections are more worrisome. We have only a few antiviral drugs. Viruses replicate far more rapidly than bacteria, which means that they can develop drug resistance more quickly than bacteria. The same mechanism also allows them to mutate rapidly into more lethal forms.

  • Is it likely that an epidemic will be caused by bioterrorism? It's a serious risk. People used to need specialized training and sophisticated equipment to produce or disseminate lethal agents. This is no longer the case. Knowledge in general is more widely available than it used to be, thanks to the Internet, and technology is more available and affordable.

It doesn't take much sophistication to launch a crude attack.In 7984, a religious cult in Oregon spiked area salad bars with a Salmonella culture. No one died, but more than 750 people were sickened. It was the largest bioterrorist attack in the US.

  • What emergency supplies do you suggest we have on hand? \7e recommend stockpiling at least a three-day supply of nonperishable foods, such as canned meats, fish, beans, fruits and vegetables. Check the expiration dates every six months. Also, have on hand one gallon of water per person per day. Be aware that your water supply also needs to be rotated because microbes may build up in it. Also, try to keep prescriptions filled and pain relievers/fever reducers on hand.
  • Should we stockpile antibiotics? You don't want to stockpile an antibiotic, because you don't know which one you are going to need.
  • What will the authorities do? State health departments and the Centers for Disease Control and Prevention have surveillance systems that look for unusual symptoms or disease clusters that could indicate an emerging epidemic. In the early years of the AIDS crisis, it was noted that there was an increase in requests for a drug used to treat a rate fungal infection. This, along with an increase in unusual diseases later known to be associated with AIDS, indicated that a new organism was spreading fast.

Once a new (or reemerging) infectious disease has been identified, the goal is to both treat it and limit its spread. In addition to educating the public, public health officials might resort to isolation (keeping sick patients away from the general population to avoid infecting others) or quarantine (isolating people who have been exposed to an organism but who may or may not actually have the disease). There also will be a push to develop vaccines and other medications to treat the disease, protect healthy people and limit the spread of the disease.
It almost sounds as if the government will have everything under control. What are your thoughts on that? There is a need for people to be as self-reliant as they can. Local officials will help as soon as they can, but the government cannot do everything. The greater the number of people who are self-reliant, the more help that will be available for those who are unable to help themselves.

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