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Tackling The
Animal-To-Human
Link In Illness

By Lawrence K. Altman
NY Times
3-25-6 
 
ATLANTA, March 24 " Stronger ties between veterinarians and physicians are needed to prevent further outbreaks of the animal diseases that have caused deaths and serious illness among humans in many countries in recent years, international health officials said at a meeting here.
 
The diseases are known as zoonoses because they affect animals primarily, and humans only incidentally. The AIDS, SARS and A(H5N1) avian influenza viruses and at least eight other infectious agents carried by animals have led to new and emerging human diseases in recent years.
 
The spread of new and emerging diseases can be a two-way street as people occasionally transmit human diseases like tuberculosis to elephants in captivity in the United States and Sweden and mongooses in Africa.
 
The latest and most visible zoonosis is A(H5N1) avian influenza. Through illness and culling, the virus has led to the death of an estimated 200 million birds worldwide. In Asia and Europe, the virus has caused 185 human cases of which 104 have been fatal.
 
New diseases are occurring in part because of globalization and because people are encroaching on areas once reserved for wildlife. After the AIDS virus infected tens of millions of people worldwide and an animal disease, anthrax, was deliberately spread through the United States postal system after Sept. 11, public health has become intertwined with national security.
 
Experts at the three-day International Symposium on Emerging Zoonoses said they had no way of predicting what human disease would emerge next from an animal source.
 
Preventing further outbreaks, participants said, will require a variety of measures, including more education about zoonoses among veterinarians and physicians; more integration of animal diseases into health plans; the creation of more laboratories to detect animal diseases; and possibly changes in the foods people eat and the animals they keep as pets.
 
Breaking down barriers among government agencies, academia and special interest groups will be needed as scientists seek new ways to collect reliable evidence to protect the health of animals and humans, participants said.
 
But "no single institution has the capacity to do all this," said Dr. Pierre Formenty, a veterinarian and epidemiologist at the World Health Organization in Geneva.
 
The meeting was the first between the World Animal Health Organization, a cooperative of chief veterinary officers from 167 countries, based in Paris, and the federal Centers for Disease Control and Prevention, based in Atlanta, said Dr. Lonnie King, the dean of Michigan State University's veterinary school.
 
Dr. King is soon joining the C.D.C., which is expected to become a laboratory and epidemiology reference center for the animal organization.
 
"We are creating the conditions for the spread of these viruses" that cause zoonoses and human illness through tourism, hunting and farming, said Dr. Bruno Chomel, a professor of zoonoses at the University of California, Davis.
 
For example, Dr. Chomel said, the corn mouse that carries the virus that causes Argentine hemorrhagic fever has spread its range with changes in farming, leading to outbreaks of the bleeding disease.
 
The liver infection caused by the hepatitis E virus, which has been detected mainly in poor countries, is being increasingly recognized in wealthy countries in small numbers. Two outbreaks of hepatitis E occurred recently in Japan after people ate raw liver from infected wild boar and deer, Dr. Chomel said.
 
In 1999, scientists discovered the Nipah virus among pig workers in Malaysia and Singapore who developed inflammation of the brain and respiratory illness. Farming practices on pig farms where fruit trees were abundant created opportunities for transmission of the Nipah virus, said Dr. Peter W. Daniels of the Australian Animal Health Laboratory in Geelong.
 
Fruit bats carried the Nipah virus, and it was transmitted to pigs that lived in an open farm environment. In turn, the virus was transmitted to humans and their pets.
 
Additional factors favoring Nipah virus transmission were disrespect for regulations and the frequent breaking of rules to increase profits. It was a lesson that self-regulation must be realistically audited, Dr. Daniels said.
 
The demand for exotic pets can also spread zoonoses.
 
Customs inspectors recently stopped the potential spread of A(H5N1) virus in Belgium by catching a man trying to smuggle infected Thai eagles that had been stuffed alive in a roller tube.
 
Cats, leopards and tigers have died from A(H5N1) avian influenza in southeast Asia and Europe. Though the number of cases is small, they have raised concern that the virus could become a bigger problem among felines. The 10,000 tigers now being kept as pets in the United States outnumber the 6,000 in the wild worldwide, Dr. Chomel said.
 
Another zoonosis, rabies, killed 50,000 people in 2005, mainly from dog bites in Africa and Asia despite availability of an effective vaccine, according to the World Health Organization.
 
In poor countries, many dogs go unvaccinated because they are believed to be strays. But many strays turn out not to be strays, said Dr. Jakob Zinsstag of the Swiss Tropical Institute in Basel. In a pilot study in Chad, his team vaccinated and tagged stray dogs. When the Swiss team recaptured stray dogs, it found that 70 percent had been vaccinated, concluding that their owners had let them roam freely and that opportunities existed to conduct rabies vaccination programs.
 
Many disease outbreaks like avian influenza often lead to mass cullings that create practical and emotional problems for animal health workers, said Dr. Larry Granger, a veterinarian at the United States Department of Agriculture in Riverdale, Md. When mass euthanasia of animals is carried out, all workers should be debriefed to help relieve their stress, Dr. Granger said.
 
 
Patricia A. Doyle, DVM, PhD- Bus Admin, Tropical Agricultural Economics Univ of West Indies
Please visit my "Emerging Diseases" message board at:
http://www.emergingdisease.org/phpbb/index.php
Also my new website:
http://drpdoyle.tripod.com/
Zhan le Devlesa tai sastimasa
Go with God and in Good Health
 

 

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