Origin of malaria discovered
17 August 2009
An international group of researchers has traced the source of
malaria to chimpanzees. The team identified several new parasites from
chimpanzees and showed that malaria jumped from animals to humans, much
the way that HIV, SARS and swine flu originated.
Until now, malaria's origin had been unclear. Although chimpanzees
were known to harbour a parasite, called Plasmodium reichenowi,
that is closely related to the dominant human malaria parasite,
Plasmodium falciparum, most scientists assumed incorrectly that
these parasites had co-existed separately in human and chimpanzee
ancestors for the last 5 million years. Chimpanzees are native to
equatorial Africa.
The newly discovered parasites not only demonstrate how malaria
originated, but represent potentially powerful tools for developing
vaccines and treatments against this deadly scourge. Discovery of these
parasites indicates that there is a much broader range of close
relatives to the human parasite than were previously recognized, some of
which might provide key insights in drug development or act as vaccines
that could prevent human malaria.
The findings were published in the 3 August 2009 Proceedings of
the National Academy of Sciences.
Senior author Dr Nathan Wolfe of the Global Viral Forecasting
Initiative and Stanford University said, "This discovery shows that
ancient diseases, such as malaria, can originate in the same way that
modern pandemics do, namely by jumping from animals to humans. We now
know that malaria, while at least thousands of years old, did not
originate in humans but rather was introduced into our species,
presumably by the bite of a mosquito that had previously fed on a
chimpanzee."
Raynard S Kington, MD, PhD, Acting Director of the National
Institutes of Health (NIH), said, "Dr Wolfe's discovery of the origin of
human malaria is a perfect example of the kind of research supported by
the NIH Director's Pioneer Award program, which gives outstanding
investigators a chance to test exceptionally innovative and potentially
paradigm-shifting ideas,"
Wolfe and his colleagues sampled wild and wild-born captive
chimpanzees in Cameroon and Ivory Coast. In Cameroon researchers
collected samples from chimpanzees during routine health exams in three
different wildlife sanctuaries. They were primarily wild-born animals
brought to the sanctuaries after being confiscated by authorities or
abandoned by human owners.
In Ivory Coast scientists from the Robert Koch Institute and Max
Planck Institute for Evolutionary Anthropology collected tissue and
blood samples from 10 chimps that had died due to anthrax, respiratory
disease or other reasons in the Tai National Park. Samples were analyzed
in the laboratory of Stephen Rich, PhD, at the University of
Massachusetts, Amherst.
"It is now clear that a new disease that successfully jumps from an
animal to a human can last not just for decades, but millennia or more,"
Wolfe said. "This makes the task of stopping future disease spillovers
from animals to humans vital, not only for saving lives today, but for
the health of people for many generations to come."
Every year malaria:
- accounts for 500 million cases per year;
- results in more than one million deaths — mostly children;
- includes 1,300 cases in the United States;
- cuts economic growth by as much as 1.3 percent in countries with
high disease rates;
- occurs primarily in tropical and subtropical regions such as
Central and South America, Southeast Asia, sub-Saharan Africa, the
Caribbean and the South Pacific Islands.
The Global Viral Forecasting Initiative has spent the last ten years
developing a global system to prevent pandemics. By coupling innovative
surveillance in field sites throughout the world with a consortium of
top laboratories, GVFI is able to characterize the diversity of viruses
and other agents as they move from animals to humans. GVFI virus hunter
Nathan Wolfe, has studied how this happens -- and how frequently it
happens -- and has identified a number of new infectious diseases. The
group's work provides basic insights into how pandemics are born and
employs cutting-edge strategies to prevent the next major pandemic.
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