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Modified Habitats Pose Threat of Zoonotic Diseases

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  • Modified Habitats Pose Threat of Zoonotic Diseases

    MÉRIDA, Mexico, Dec 3 (IPS) - A breakout of yellow fever among monkeys caught authorities in Argentina and Brazil, and the Pan-American Health Organisation (PAHO), off-guard in October.

    As in dozens of cases that occur every year, the outbreak was the result of growing interaction between wild animals and humans and changes in habitats, which is generating new diseases and reviving old ones.

    Ebola, encephalitis, avian influenza, pulmonary hemorrhagic syndrome, viral hepatitis, leptospirosis and HIV, the AIDS virus, are just a few of the diseases that according to scientists emerged from the relationship between animals and humans, and that claim thousands or even millions of lives a year while generating huge economic losses around the world.

    "Climatic factors and human activity that is increasingly destructive and close to wild animals trigger diseases that in the past we could not even imagine, or that we believed had disappeared," Silvia Alonso, a researcher with the Royal Veterinary College at the University of London, told IPS.

    Alonso, a zoonotic disease expert, is taking part this week in the Dec. 1-5 International Ecohealth Forum 2008 in Mérida, on Mexico’s southeastern Yucatan peninsula

    She is one of about 600 academics, scientists, government officials and activists from 82 countries participating in the event, organised by Canada’s International Development Research Centre (IDRC) to share reasearch on how ecohealth approaches can tackle pressing global issues such as climate change, food security, disease, and economic development.

    In one of the forum’s panels, James Mills, chief of the Medical Ecology Unit at the United States Centres for Disease Control and Prevention, said there are around 175 "emerging" or new diseases of zoonotic origin.

    Mills said an investigation he headed discovered that temperature changes outside of the normal patterns increased the presence of rodents in different parts of the United States, as well as the incidence of new human diseases traced back to hantavirus and arenavirus.

    The expert said he had no doubt that climate change, mainly blamed on the burning of fossil fuels, is responsible for the appearance of new diseases.

    Alonso, however, is not so sure about that argument. "Climatic factors undoubtedly have an influence, but there are numerous other factors that we cannot rule out," she said.

    "It must also be taken into consideration that we now have new scientific instruments for detecting zoonotic diseases that may have been present for a long time, but that we are only just now finding," she added.

    Innocent Rwego, a researcher at Makerere University in Kampala, Uganda, said that in the forests of his country and the Democratic Republic of Congo (DRC), the population of wild gorillas is suffering serious health problems due to the proximity of people.

    In Uganda's Bwindi Impenetrable National Park, on the border with the DRC, up to eight tourists a day interact with the gorillas, paying tour guides 500 dollars an hour to spend time with the animals, he said.

    Just imagine if you have eight different people visiting your house every day, how many diseases you could catch from them, said Rwego.

    The veterinarian reported that in recent months, gorillas have been found with facial paralysis from a kind of polio, which he said was due to human contact.

    Children also pay a price for contact with animals. Dogs roam wild in the bush in many parts of Africa, where they kill or bite wild animals and eat their feces, before returning to the village and playing with children, who often pick up diseases as a result, said Rwego.

    PAHO has a regional alert system for zoonotic diseases, including yellow fever, dengue, Chagas disease and avian influenza.

    On Nov. 13, PAHO reported an outbreak of yellow fever in monkeys in Argentina and Brazil, and recommended a vaccination campaign among humans, as well as stepped-up surveillance of monkeys and close monitoring of the spread of the mosquito-borne disease.

    In January, it had reported an outbreak of avian influenza in the Dominican Republic.

    Alonso, from the Royal Veterinary College, said there is obviously a close relationship between environment and health, and that interaction between humans and animals necessarily has some kind of effect.

    She said emerging infections are caused by previously unknown or nonexistent agents for which human activities that directly or indirectly alter the environmental balance serve as a catalyst.

    "This has occurred throughout history," said Alonso. What is new today, she added, is the accelerated destruction of habitats and the excessive or undesired proximity with wild animal species, which causes problems to multiply.
    "The next major advancement in the health of American people will be determined by what the individual is willing to do for himself"-- John Knowles, Former President of the Rockefeller Foundation