Malaria Soars with Rainforest Cutting
Small change in forest cover can
double malaria rate
SciDev.Net,
June 22, 2010
MONTEVIDEO, URUGUAY -- A small reduction in
tropical rainforest cover can increase malaria incidence by nearly 50
per cent, a study in the Brazilian Amazon has found.
Open spaces and partially sunlit pools of
water, typical conditions of deforested landscapes, provide an ideal
habitat in which the Anopheles darlingi mosquito— the main
vector of the malaria parasite in the Amazon — can live and lay its
eggs, according to the study, published online early in Emerging
Infectious Diseases.
The authors, from the University of Wisconsin,
Madison in the United States, and Santo Antonio Energia in Brazil, an
energy
consortium, studied high-resolution satellite
data of land cover from 54 Brazilian health districts bordering Peru
from 1996 to 2006. They also examined health data collected in the same
areas in 2006.
They found that a four per cent change in
forest cover was associated with a 48 per cent increase in malaria
incidence.
Areas with less deforestation had a lower
malaria risk, suggesting a link between conservation practices and
health.
"We believe that the small change in
deforestation is greatly amplifying the number of mosquito vectors, and
thereby increasing malaria risk in humans," said Sarah Olson, lead
author of the study.
"Local land management and development policies
should weigh this human health risk along with the economic benefits of
deforestation."
Kevin Lafferty, an ecologist at the University
of California Santa Barbara, who questioned the links between climate
change and malaria last year, said:
"Certainly, deforestation can create conditions
that favour mosquitoes. Also, human populations tend to move into areas
that are recently deforested. If these are migrants that bring malaria
with them, they can set off epidemics.
"But it is important to formally quantify the
link between deforestation and malaria, whatever the causal chain."
However, he added that "economics trumps
climate change [and deforestation] when it comes to determining the
future of malaria.
"[Economics] is an overlooked aspect of malaria
given the current emphasis on climate change, but there is good
evidence that endemic malaria is much more likely in poor countries and
that malaria makes poor countries even poorer. It is a vicious cycle."
