Infectious disease risk increases as a result of climate change

    SickKids researchers anticipate increases in infectious disease in Canada

    TORONTO, March 10 /CNW/ - Scientists at The Hospital for Sick Children
(SickKids) have published an article highlighting the potential impacts to
human health, resulting from climate change. Infectious diseases, including
those transmitted by insects and animals, fungal infections, water and
food-borne illnesses, and disease transmitted from one person to another, are
expected to increase in areas where the diseases are already present and will
spread to new areas of the globe, including Canada. The article will be
published in the March 11th issue of the Canadian Medical Association Journal.
    SickKids epidemiologist Dr. David Fisman, a scientist in the Child Health
Evaluative Sciences program at SickKids Research Institute, and his colleagues
Dr. Amy Greer and Victoria Ng, reviewed current data on changes to the
environment and to weather patterns observed as a result of the warming of the
earth's atmosphere, and related this to changes in the incidence and
distribution of various types of infectious disease. Their review integrates
data about disease dynamics, insects, the changing climate and ecosystems, and
outlines some of the anticipated impacts on infectious disease incidence and
burden in Canada.
    Fisman, Greer and Ng predict that the biggest impact of temperature
increases in Canada will be an expansion of the habitat range of
disease-carrying insects such as ticks and mosquitoes. The range of these
insects is anticipated to spread northward, along with the diseases they carry
including Lyme disease and other coinfecting tick-borne diseases such as
babesiosis (a malaria-like condition), and anaplasmoses (a group of tick-borne
blood diseases). These types of infections present health risks to both humans
and animals - Lyme disease, for example, can lead to cardiac and neurological
infections as well as arthritic symptoms.
    While ticks that spread Lyme disease are already present in southern Nova
Scotia, Ontario, and British Columbia, shorter winters and higher temperatures
will allow them to thrive in almost all populated regions of Canada. As well,
early springs and longer summers will lead to a longer transmission season and
an increase in disease incidence in mosquito-borne diseases such as West Nile.
    The authors also anticipate that climate change will lead to higher
numbers of water- and food-borne disease outbreaks in the Canadian population.
Increases in precipitation, higher temperatures and flooding are linked to
outbreaks of gastrointestinal and respiratory diseases caused by bacteria,
protozoans and viruses - even in the presence of water-treatment facilities.
Although Canadians have access to food and water that are remarkably safe by
global standards, recent examples of large waterborne disease outbreaks in
Canada include the 2000 Walkerton water disaster, and a 2001 outbreak of
Cryptosporidium in North Battleford, Saskatchewan, that sickened over
6000 people. The confluence of increased flooding, heavy rains and warmer
temperatures may make such events more frequent occurrences. Fisman, Greer and
Ng advise that we will have to be even more vigilant to ensure the highest
treatment standards in order to safeguard our water and food resources.
    "An immediate impact of these changes is that physicians will need to
have knowledge of these diseases and their symptoms, so that in the event a
patient arrives with an unusual rash, an undiagnosed arthritis, or
gastroenteritis, a correct diagnosis can be made and effective treatments
prescribed," stated Fisman. The paper noted that the impact of climate change
on infectious diseases will be most severe in developing countries, where
infectious diseases remain an important source of death in all age groups, and
where infrastructure may not be sufficient to effectively treat or prevent
    A key objective of this paper is to urge policy makers and public health
organizations to proactively prepare for these changes, by measuring and
collecting baseline data on disease incidence in Canada and around the world.
The authors suggest that by monitoring infections, the data collected will aid
in anticipating and hopefully preventing outbreaks. While there are
organizations around the world that are already starting to work towards this
goal, including the Intergovernmental Panel on Climate Change (UN), the
International Development Research Centre (Canada), and the World Health
Organization Global Environmental Change Program, the authors stress the need
for more cross-border collaborative approaches worldwide in order to protect
populations against these threats.
    Fisman and his team also emphasize the importance of multidisciplinary
research in understanding and combating problems caused by climate change:
"These changes highlight the relationships that exist between humans, insects,
animals and the environment," says Dr. Greer. "We need to reach beyond the
traditional academic boundaries, to allow cross-disciplinary studies to be
conducted between environmental scientists, health professionals, ecologists,
geographers, as well as the veterinary community, because these new diseases
may also impact livestock and wildlife populations."
    Innovative research in Fisman's lab is continuing to examine
relationships between the environment and human health. Recent work has
documented the importance of humidity, rainfall, ultraviolet radiation, and
water conditions as factors that may cause the "seasonality" of infectious
diseases (e.g., "cold and flu season"). In addition, they are investigating
patterns between environmental conditions and reported outbreaks of
gastroenteritis, in an effort to be able to better predict and prevent these
from happening in the future.
    Dr. Fisman acknowledges SickKids for allowing their group to pursue a
non-traditional approach to studying human diseases. "We are glad to work in
an institution that encourages us to break down the traditional research
barriers and to follow the evidence to where it leads." The researchers are
also supported by the US National Institute of Allergy and Infectious
Diseases, the Early Researcher Award Program of the Ontario Ministry of
Research and Innovation, and SickKids Foundation.

    The Hospital for Sick Children (SickKids), affiliated with the University
of Toronto, is Canada's most research-intensive hospital and the largest
centre dedicated to improving children's health in the country. As innovators
in child health, SickKids improves the health of children by integrating care,
research and teaching. Our mission is to provide the best in complex and
specialized care by creating scientific and clinical advancements, sharing our
knowledge and expertise and championing the development of an accessible,
comprehensive and sustainable child health system. For more information,
please visit SickKids is committed to healthier children for
a better world.

For further information:

For further information: Janice Nicholson, Public Affairs, The Hospital
for Sick Children, (416) 813-6684,

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