New York Articles: BACK
A Modern Menace: Emerging Infectious Diseases
Rebecca Sweat
Vision
Fall 2006 Issue
NY
In Queens, New York, an 80-year-old man mowed his front lawn and began complaining of extreme fatigue to his wife. Unable to eat, he vomited, then went to bed. The next morning he woke up with a sweltering fever and struggled to utter even single-syllable words. A little later he collapsed in a chair and was rushed by ambulance to the emergency room. Before the end of the day his organs began to fail, and he suffered a heart attack and died.
This may sound like an episode from a television drama, but it's an actual medical case from August 1999. Just a short time before his death, the man had been bitten by a mosquito carrying the West Nile virus, a pathogen that had never before been seen in the Western Hemisphere. He was the first North American to die from the disease, but in the weeks that followed, others in the New York metropolitan area succumbed to the same mysterious illness. Since then there have been over 20,000 reported human cases of West Nile virus in the United States, more than 800 of which ended in death. In addition, countless similarly infected crows, chickens, pelicans and other birds have died. The virus has proved to be an elusive enemy as mosquitoes carry it across the continent.
At first, of course, there was a media uproar over the West Nile virus, yet it is just one of a long list of emerging infectious diseases in the world today—caused by contagions that have only recently been discovered. Avian Flu (see "Preparing for the Next Pandemic") has also grabbed the headlines, but others on the list include dengue, Ebola and Marburg hemorrhagic fevers; Nipah virus encephalitis; Hendra virus disease; Lassa fever; hantavirus pulmonary syndrome; monkeypox; Lyme disease; SARS; and drug-resistant forms of tuberculosis, malaria, staphylococcal infection and salmonellosis. All of these have the potential to wreak havoc on humanity, just as another virus on the list, the human immunodeficiency virus (HIV), has already done. June 5, 2006, marked the 25th anniversary of the first reported cases of the HIV-related disease that came to be known as acquired immunodeficiency syndrome, or AIDS. Since then an estimated 25 million people worldwide have died from it.
But, many ask, how can this be? After all, medical science has made incredible advances in the last century. "By the early 1970s, people were looking at progress with antibiotics and vaccines and thought the real problems of mankind were going to be related to old age rather than communicable diseases," observes Klaus Stohr, director of the Influenza Task Force for the World Health Organization (WHO) in Geneva, Switzerland.
This optimism led to a widespread belief that humankind had won the war against infectious diseases. Medical researchers began to focus their efforts on chronic ailments such as cancer and heart disease rather than communicable diseases.
Yet today, Stohr continues, "there are far more virulent, difficult-to-treat infectious diseases than there were 20 or 30 years ago. Many new diseases have been emerging, and there has also been a resurgence of infections like malaria and tuberculosis."
According to WHO, at least 30 new infectious diseases have emerged in the last 20 years, many of which evade traditional therapies and have no cure. With so many deadly pathogens coming on the scene, notes Stohr, "infectious diseases are once again the leading cause of death in the world—something that hasn't been the case since the pre-antibiotic era of the early 1900s."
THREE OF A KIND
Emerging infectious diseases can be grouped into three categories of causation: viruses that have mutated or genetically recombined to become new strains or novel microbes; viruses that had previously existed only in one part of the world and started appearing in new regions; and viruses that may have existed for millennia but weren't discovered until recent years.
A disease that fits into the first category is AIDS, which came into being through genetic recombination, says Roy Anderson, fellow of the Royal Society and professor of infectious disease epidemiology at the University of London's Imperial College. "Recombination is when two different viruses infect the same cell, then the genomes get jumbled and something totally novel comes out," he explains. HIV, for instance, is thought to be a fusion of the simian immunodeficiency virus (SIV), which infects monkeys and apes, and a similar virus that infects humans.
An example of the second category is the West Nile virus. This pathogen was first isolated in Uganda in 1937. It confined itself to Africa, the Middle East and Europe for about six decades before showing up in the United States. Migrating birds may have carried the virus to Europe, but how it got to North America is uncertain. One widely expressed theory is that an infected mosquito was inside someone's luggage on a flight to New York.
Lyme disease is an example of the third category. "Lyme disease was first identified in 1976 in the Northeastern United States, but it was probably around long before that," suggests Bruno Chomel, professor of zoonoses at the School of Veterinary Medicine at the University of California, Davis. "Mankind suddenly came in contact with the virus," he theorizes, "when housing developments started being built closer and closer to the woodlands where a large number of white-tailed deer lived. The deer were the reservoir hosts of the Lyme disease virus" (see "The Zoonotic Connection").
All three types of emerging infectious diseases have one thing in common, scientists say, and that is the human role in facilitating the new pathogens' emergence. "In almost every case humans are the most important single factor in the surge of new diseases, whether it's feeding cow tissue to cattle, causing mad cow disease; people eating exotic animals, as in the case of Ebola; or air travel spreading dengue around the world," claims Thomas Monath, chief scientific officer with Acambis, a vaccine development company in Cambridge, Massachusetts. He explains that people are not simply victims of emerging infections but are actually helping to cause or exacerbate them through changes they make to the natural world.
PEOPLE PROBLEMS
One of the primary ways in which humans have facilitated the emergence of new diseases is by making alterations to animal ecosystems. "There are environments in the developing world that used to be quite remote but are now much less so as a result of human activities like deforestation, dam projects, irrigation, road construction and extensive agriculture," says Jim Hughes, director of Global Infectious Disease Programs at Emory University and former director of the National Center for Infectious Diseases at the Centers for Disease Control (CDC) in Atlanta, Georgia.
Wilderness areas are often home to unique microbes—bacteria, parasites or viruses not found anywhere else. When people enter these ecosystems, they may encounter these pathogens for the first time. If they become infected, they take the pathogens with them wherever they go, thereby spreading disease.
Following the human disruption of ecosystems, animals themselves can also contribute to the spread of deadly microbes. "Once forests are cleared, the wildlife that used to live there have no choice but to migrate farther out in search of food and land in which to live," says Stephen Corber, manager of Disease Prevention and Control at the Pan American Health Organization in Washington, D.C. "Often they end up in suburbs and farming communities, where they make contact with people. If they're bringing diseases with them, that's when you have problems."
A CHANGE IS IN THE AIR
Weather patterns can also come into play. In much of the world, average daily temperatures appear to be rising. Whether this warming is primarily an anthropomorphic effect—a result of automobile and truck exhaust, the use of fossil fuels, emissions from coal-powered generating plants, and other so-called greenhouse gases that have entered the atmosphere—or primarily the result of cyclical changes in the climate makes little difference to the pathogen. Either way, higher temperatures can greatly affect disease transmission.
"As the environment becomes warmer, it becomes more hospitable to insect vectors [disease-transmitting organisms] such as mosquitoes," says David Freedman, professor of medicine at the University of Alabama's Division of Geographic Medicine. Mosquitoes don't do well in very cold or very dry climates, he notes. Rising temperatures, along with increased rainfall (which can occur in association with global warming), make it possible for mosquitoes to survive in previously inhospitable climates, thus broadening their range. Some mountainous regions in Africa never had a malaria problem in the past because the higher altitudes were too cold for the mosquitoes to breed. But in recent years, Freedman says, "as average temperatures become warmer, we're starting to get reports of malaria in some of those regions, because the mosquitoes are now able to survive at those higher altitudes."
Warmer temperatures can also have a dramatic effect on the transmissibility of viruses carried by vectors. "When a mosquito feeds on an individual carrying a virus, that virus then has to replicate for a period of time before it can be transmitted by the mosquito as it feeds on another host," Monath explains. This is the "extrinsic" incubation period of the virus. An increase of a single degree in average temperature will shorten that extrinsic period dramatically, he continues. "That means the interval between acquiring the infection and being able to transmit it shortens. Since mosquitoes live only a short time, that can have a dramatic effect on increasing transmission."
CLOSE QUARTERS
Other new viruses have emerged in the developing world, particularly Southeast Asia, where it's common practice for people to keep their farm animals in their front yard or even inside their homes. "The cities are often overcrowded, and because of lack of space, people typically live in very close proximity to their livestock," Chomel notes. "It's not unusual for a family to sleep in the loft of a barn, while keeping their cows, goats and pigs downstairs."
This close proximity of animals to people creates opportunities for an exchange of pathogens between animal and human hosts. "If a human infected with a virus comes in contact with an animal that has a similar type of virus, the genetic material of the two pathogens can get mixed up and recombine, which can result in the emergence of a new virus that infects both animals and people," Anderson says. "This is not something that happens overnight or with one transmission event," he adds. "In the beginning the animal pathogens may not be very transmissible, but slowly their transmissibility increases and they start to gain fitness in humans."
The concern, though, is not just with diseases transmitted from domesticated animals. In China, exotic animals like civets, snakes, tree shrews, flying squirrels, badgers and pangolins are considered delicacies. "These animals are sold at the wet markets [markets that sell live animals], which are very crowded environments, with many different animal species and people crammed together," Hughes says. "Any viruses carried by these animals can be transmitted to people via consumption, if people handle the animals, or sometimes if they just come into the same air space." It appears that SARS got its start at a wet market in Hong Kong when infected masked palm civets transmitted the virus to people in the market.
Of course, the consumption of exotic animals is not limited to Asia. In Africa, for instance, monkeys, apes and other local animals are potential meat choices. Guinea pigs and their larger cousins, capybaras, are commonly eaten in Peru and Brazil. Armadillos are considered taste treats in Central America. The bottom line, Chomel says, is that "the practice of consuming wild species opens the door for a much wider variety of pathogens—those of wild animals—to come in contact with humans and develop transmissibility."
MEETING RESISTANCE
Another factor that contributes to the development of bacterial pathogens in particular is the overuse and misuse of antibiotics. Widespread antibiotic use in the beef and dairy industry, for instance, is necessary to maintain animal health in unhygienic feedlots. Bacteria that are naturally resistant or immune to the antibiotic tend to multiply when the drug eliminates the harmless species. If this surviving strain later finds its way through the food supply to a human host, the disease it causes can be devastating because of its ability to resist treatment. Recent campaigns to encourage the complete cooking of hamburger and poultry have largely countered this danger.
This type of selection scenario has unfortunately operated within the medical field as well to create new antibiotic-resistant bacteria. "The public has the perception that you give them a pill and everything is fixed," says Trish Perl, director of Hospital Epidemiology and Infection Control at Johns Hopkins University in Baltimore, Maryland. "People will often insist that they need an antibiotic when they have a cold or the flu, and sometimes doctors will give in to these demands. The problem is that colds and flu are caused by viruses, which are not treatable with antibiotics."
The CDC acknowledged this problem and responded in the 1990s with an aggressive campaign to educate both doctors and patients on appropriate use of antibiotics. According to numerous studies published in the past five years, some overall decreases in such prescriptions have been seen, but the percentage of antibiotics prescribed in doctors' offices for viral infections remains astonishingly high. This is not always due to patients demanding an antibiotic. Sometimes physicians prescribe them when they can't make a definite diagnosis, or they may give them as a preventive measure.
"With so many antibiotics in the environment, we're pressuring these bacteria to evolve into resistant strains," Perl asserts.
Hugh Pennington, president of the Society for General Microbiology in the United Kingdom and retired professor of medicine at the Institute of Medical Sciences at the University of Aberdeen, explains the process. When people take antibiotics, "the drug kills the defenseless bacteria, leaving behind—or `selecting'—those that can resist it. These renegade bacteria then multiply and become the predominant microorganism."
Today there are drug-resistant forms of tuberculosis, malaria, and E. coli, Staphylococcus, Streptococcus and Salmonella infections, to name just a few of the superbug diseases that have emerged in recent years. Because they are resistant to antibiotics, some consider them to be genetically new organisms. "Some infections are now so resistant to the drugs we have available that they are virtually untreatable," remarks Hughes of Emory University (see "Murderous Microbes").
THE SEARCH FOR SOLUTIONS
With so many infectious diseases emerging, it can all sound quite ominous. Still, "you don't need to be terrified," Corber assures. "You do, however, need to be aware of microbial threats. You need to understand what measures you can take to minimize your chances of becoming infected." That includes hand-washing after using the toilet or handling raw meat; the appropriate use of antibiotics; and before traveling to developing countries, seeking input from health officials regarding what can be done to minimize risks of acquiring diseases like malaria. These are steps that individuals can and must take, says Corber.
Governments, too, have important roles to play. "Governments need to spend enough money on quality surveillance so that these problems can be picked up early," remarks Pennington. "Without knowing what's coming and what's here already, it's impossible to do anything to curb the problem, and we're not going to be able to react as quickly as we need to. It's also important that governments set aside enough money for basic research."
Stohr sums up the situation this way: "Infectious diseases are not something we can just ignore. A constant investment in attention is necessary. The moment we become complacent, the moment we start thinking we've won the battle, infectious diseases will be back."
Courtesy: www.lymeinfo.net
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Historically Warm Winter Means Longer Season For Ticks
The Open Press
Mount Kisco, NY
January 13, 2007
From his vantage point in Northern Westchester County about 35 miles above New York City, in the Hudson Valley, Dr. Daniel Cameron says he is seeing new cases of Lyme disease (LD) on a regular basis this winter. The Hudson Valley which has the highest incidence of Lyme disease in the country.
According to NOAA's National Climatic Data Center, "five states had their warmest December on record (Minnesota, New York, Connecticut, Vermont, New Hampshire) and no state was colder than average in December."
While LD and its co-infections are thought of as seasonal here, with the largest numbers being reported from April to October, this strange weather pattern is changing those observations, and that is cause for concern. "I have had an increase in patients this winter with new infections and it makes me wonder how many more are out there going unnoticed," says Cameron.
"In the spring, summer, and early fall when people contract flu-like symptoms, and no once else has the flu, a doctor may look at other possible causes, even when the patient does not present with a rash or Bell's Palsy. But in the coming weeks when temperatures may finally drop, when colds and flu are common, and a patient walks in with flu-like symptoms or disseminated joint paint, it may be easy to assume it's the flu, and not consider other causes," says Cameron, who has a clinical practice in Mount Kisco, NY, and is the author of a number of papers and studies regarding the treatment of tick-borne illnesses. "That scenario may create misdiagnosis or treatment delays."
"I took two ticks off me, and sure enough, there was a bull's eye rash and the whole bit. I think the ticks came in on my cats," says Art Eichorn, a Somers, NY resident and patient of Cameron's. "I definitely feel sick," he adds, and has since started taking antibiotics.
Another concern Cameron sees regarding this unusually warm winter, "Someone may have visited our area at Thanksgiving or Christmas this year and may have returned home with a Lyme infection unbeknownst to him and his doctor. They may not consider Lyme during flu season in other parts of the country."
The Univ. of Rhode Island's Tick Resource Center reports, ticks "will remain active through the winter as long as the temperatures are above freezing and the ground is not frozen or covered by snow."
Dr. Cameron is a board-certified internist and epidemiologist, on the board of the International Lyme and Associated Diseases Society (ILADS), and lead author of ILADS' Evidence-based guidelines for the management of Lyme disease, published in 2004.
For more information on Daniel Cameron, MD, please go to Lymeproject.com or ILADS.org
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A new tick in town
Increased presence of nasty Lone Star raises Lyme disease fears; Schumer calls for more federal funds
Andrew Strickler, Newsday Staff Writer
July 7, 2006
An aggressive type of tick has gained a foothold in the area's parks and woodlands, raising new concerns about Lyme disease on Long Island, state health officials said yesterday.
Sen. Charles Schumer yesterday called on the federal government to become more involved in combating the disease. Schumer (D-N.Y.) and members of patient advocacy groups said they are particularly concerned this year because of the increased presence of the Lone Star tick.
"I don't think that there is a disease that is so widespread and causes so much harm that gets so little funding," Schumer said at West Hills County Park in Melville yesterday.
Lone Star ticks, most active in the summer, can detect a host - including humans - at a distance, making them more dangerous than deer ticks, which typically wait for direct contact to attach to a host, according to the Centers for Disease Control and Prevention. The Lone Star tick has migrated north from the southeastern United States, the CDC said.
Local health officials said they do not know how much the Lone Star tick will spread the disease, but they worry about the implications of the tick's northward migration.
Thousands have contracted Lyme disease, a bacterial infection most often carried by ticks, on the Island in recent years.
The state Department of Health reports that the number of yearly incidences of Lyme disease in Suffolk County doubled to 561 cases from 2003 to 2004, with a slight decrease to 542 in 2005. Cases of Lyme disease in Nassau County jumped from 59 cases in 2004 to 122 cases in 2005. In its most recent numbers, the CDC reported 51,000 cases of Lyme disease in New York in 2004, putting New York at the top of the list nationally.
The disease can have long-term, devastating effects. Diane Leary's fight with the disease started with a single bite at a company picnic at Heckscher State Park in 1987. A few days later, she developed a rash she says she initially ignored.
"I never thought it was going to get so bizarre and change my whole life around," she said.
Leary's rash was the first step in a harrowing journey through pain and fatigue, vertigo and neurological problems so severe, Leary said, she had to give up her job at a bank.
Schumer has proposed a bill that would authorize $100 million to be spent over five years on Lyme disease research and education. Another $250,000 would be spent over two years to fund an advisory committee.
A Schumer spokeswoman said about 30 percent of the ticks examined by a Nassau laboratory in 2004 and 2005 were Lone Star ticks. So far this year, the lab has identified four Lone Star ticks in Nassau, and the CDC has confirmed finding pockets of them on the Island.
Although Lyme disease can be cured with antibiotics, health officials say the disease is often overlooked or misdiagnosed. The cause of the problem, said Dr. Benjamin J. Luft, head of the Stony Brook University Hospital infectious diseases division, is the small size of tick bites and the similarity between Lyme symptoms - skin rash, joint pain and headaches - and those of other diseases.
"It's ideal for a stealth kind of infection," he said.
Nassau County Health Department spokeswoman Cynthia Brown said the increase in Lyme disease cases in Nassau did not necessarily reflect an increased risk to the public. Brown said the department was spending more time investigating the disease, producing more verified cases.
Leary, of Massapequa, who heads the Long Island Lyme Association patient advocacy group, said such efforts must be just one part of a broader public awareness campaign.
"I think the numbers [of Lyme disease cases] are much higher," she said. "There are so many who are misdiagnosed."
Lone Star lowdown
Unlike deer ticks, which wait for a host to pass by before attaching, the Lone Star tick can detect an animal's respiration at 30 or more feet and pursue the host.
Latin name: Amblyomma Americanum
Common names: Lone Star tick; Southern tick
Description: Adults are 1/3 inch long, 1/2 inch long when engorged. Brown and tan in color. Females show white "lone star" mark on back.
Distribution: Primarily found in the southeastern and southern United States and Texas; pockets found in New York, New Jersey and Rhode Island.
Favorite hosts: Deer, birds, rodents, livestock, humans.
Habitat: Wooded areas; brush, tall grass and leafy debris; along creeks and rivers.
Transmission: The bacteria Borrelia burgdorferi, which causes Lyme disease, is usually transmitted through bites of certain species of ticks.
Prevention: Tuck pants into socks and use a pesticide; avoid wooded areas; do thorough tick checks; avoid deer and other animals that may carry ticks.
SOURCE: Centers for Disease Control and Prevention
http://www.newsday.com/news/printedition/longisland/ny-litick074809050jul07,0,3297667.story?coll=ny-linews-print
© 2006 The National Lyme Disease Memorial Park Project
