Science. "How the Malaria
Parasite Manipulates Its Hosts."
Article by Virginia Morell
Summary by Christine Nguyen
One of the oldest and most common human diseases is malaria. For
centuries, evolutionary biologists' have worked long hours to find
better ways to fight the disease. Any new discoveries related
to the
parasite leads to advancements in medicine to combat its deadly "sting".
The parasite does not literally sting, but it uses its host [the
mosquito] to increase its chances of being transmitted. Jacob
Koella
from the University of Aarhus in Denmark and his colleagues made a
new
discovery. Jacob Koella found that the malaria parasite has the
capability to manipulating its host [the mosquito] to bite insatiably,
thereby boosting the parasites' chance of being transmitted.
The
parasite is able to cause the mosquito to bite in an aggressive manner,
due to its capability to alter the neurochemistry controlling the
mosquito's abdominal stretch receptors.
Koella believed that the parasite could also caused infected mosquitoes
to move around much more than uninfected mosquitoes. He proved
this by
doing a research that involves using human volunteers (who had been
screened for distinct genetic differences) to spend a night in a house
in an area where malaria is rampant. In the morning, he collected
173
mosquitoes that had fed on the volunteers. Using the polymerase
chain
reaction technique, which distinguished the genetic patterns of each
volunteer. His team was able to identify which sleepers each
mosquito
had bitten. Only 18% of the 111 uninfected mosquitoes had feasted
on
more than one person. However, 34% of the 62 infected mosquitoes
had
feasted on more than one person.
Another gap in understanding malaria is that there's no predicting
how
virulent the disease may be. At this point in time, no research
has
proven this question. However, researchers suggest that extreme
form of
malaria caused by variations from genetic differences within the
parasite caused some strains to replicate at a higher rate. The
parasite's ability to replicate at a higher rate produces a more
virulent and more transmissible form of malaria. This parasite
continues to baffle researchers with its capability to manipulate its
hosts, and to adapt to its environment so easily.
Reference:
Morell, Virginia. (1997, October 10). How the Malaria Parasite
Manipulates Its Hosts. Science, vol. 278 pp. 223.