Health Experts Fight Spread of Animal Diseases to Humans

GENEVA, Switzerland, May 3, 2004 (ENS) - Ecological changes caused by human activity represent "by far" the most important factor in the emergence of diseases that jump from animals to humans, the World Health Organization said today. The United Nations health agency opened a three day meeting of international experts at its Geneva headquarters today with the twin goals of preventing and improving responses to such diseases.

When diseases cross from animals to humans they are called zoonoses, and the world has been plagued with these illnesses during the past two years. Severe Acute Respiratory Syndrome (SARS) and avian influenza outbreaks, and other illnesses, such as mad cow disease and its human form, variant Creutzfeldt-Jakob disease, will be on the agenda as the experts consider what lessons can be learned from the numerous outbreaks of zoonoses.

WHO is holding the meeting jointly with the UN Food and Agriculture Organization, the Office International des Epizooties (OIE) and the Dutch Health Council.

The experts' meeting comes as China has confirmed a new outbreak of SARS with nine new cases. Chinese authorities Friday reported test results confirming that a 53 year old woman who died in Anhui Province on April 19 was infected with the SARS coronavirus. The woman, a medical doctor, was the mother of a 26 year old postgraduate student who had been conducting research at the National Institute of Virology in Beijing. The student remains hospitalized in Anhui.

A striped civet is a little larger than a house cat. Civets have been linked to the occurrance of SARS. (Photo courtesy Missouri Botannical Garden)

In addition, 1,000 more people who had close contact with the infected persons are being monitored for the development of symptoms.

Since April 22, the seven patients in Beijing are now being treated in isolation in a single facility, Ditan Hospital, as a risk reduction strategy.

Some 8,100 cases of SARS in 26 countries were reported in 2003 when the previously unknown respiratory disease which started in Guangzhou, China found its way to every continent.

On April 17, the Guangzhou Evening Newspaper reported that Chinese scientists have discovered that the coronavirus that causes SARS is also carried by foxes and domestic cats, as well as civet cats, according to Lin Jinyan, the leader of a SARS control and prevention research team in Guangdong Province. At a seminar held in Guangzhou, Lin reported that other wild animals were also found to carry the virus.

Experts have also tested foxes, hedge-shrews and cats collected in the province and discovered that some carried the SARS coronavirus.

On January 16, 2004, World Health Organization experts said that the SARS coronavirus or a SARS-like coronavirus was linked to civet cats.

WHO Regional Director for the Western Pacific Dr. Shigeru Omi said that the new SARS outbreak in China does not yet constitute a serious public health threat, but he stressed the need for continued "high vigilance."

A WHO mission has arrived in Beijing in response to a request from the Chinese government to investigate what may have happened at the laboratory and also to assist the government to conduct an epidemiological investigation. "We will learn from the experience and share it with other laboratories," Dr. Omi said.

Earlier this year a highly contagious strain of bird flu erupted in Asia, sparking fears that in a worst case scenario it could mutate into a deadly human-to-human infection.

Other zoonoses that have not received as much media attention are still serious threats in many parts of the world. For instance, dogs are the main reservoir of the Leishmania parasites that cause visceral leishmaniasis in Iran. Transmitted by the bite of some species of sand flies, more than 90 percent of the world's cases of visceral leishmaniasis occur in Bangladesh, Brazil, India, Iran, Nepal, and Sudan.

At the Pasteur Institute in Tehran, Dr. Sima Rafati oversees a blood sample being taken from a dog. She is pursuing research on the development of DNA vaccines for dogs, which are the main reservoir of the Leishmania parasites in Iran. (Photo by Andy Crump courtesy WHO/TDR)

"WHO seeks to protect global public health," says Dr. François Meslin, WHO Coordinator for Zoonoses Control. "As recent outbreaks have demonstrated, inter-sectoral and inter-disciplinary cooperation is crucial to ensuring that international public health is not compromised."

A serious risk to human health can start with something as small as a flea. The New Mexico State Department of Health Friday confirmed bubonic plague infections in two Santa Fe County cats, and the agency says several people exposed to the sick cats will be given antibiotics to prevent them from contracting the plague.

Plague is generally transmitted to people through the bites of infected fleas from rodents. The disease also can be transmitted by direct contact with infected animals - including rodents, wildlife, and pets.

Bubonic plague is of zoonotic concern, as individuals may contract disease from either infected fleas or contact with discharges or blood from the cat. An even greater threat occurs when the disease in cats progresses to pneumonic plague. This has been documented in cats, including transmission to veterinarians and owners.

Transmission of diseases like SARS or bird flu from animals to humans depends on many factors, including complex interactions between human and animal hosts, the causative microbial agent, and the environment, and for WHO and its partners, this week's consultation aims to provide guidance in strengthening capacity of countries and that of the international community to collect and share information across many sectors.

"Identifying the next zoonotic disease of international public health importance will not be easy," says Dr. Meslin, "We hope that the consultation will provide new tools that may make this possible in the near future."