species, the causative agents of malaria.
There are a variety of different Plasmodium
that cause human malaria, Plasmodium falciparum
for example and this blood smear stained to
visualize two parasite containing red blood
cells, the pictures are slightly different
for each organism. Plasmodium vivax is another
malaria causing protozoan parasite. Plasmodium
malariae and finally Plasmodium ovale, the
diseases caused by these different Plasmodium
species have overall features in similar fashion,
but they do have some differences and there
are slight geographic differences as to the
location of the parasites. This global map
shows you the regions of the world in which
infection with the Plasmodia species occur.
The malarias, you can see most of Africa is
affected in red, a good part of Asia, Central
and South America. So the regions, essentially
border the equator, these are where the mosquitoes
are found that transmit the infection. The
malarias are responsible for 2 billion infections
every year, just think of that in the context
of the population of earth. This is huge and
3 million deaths mostly in Africa and mostly
in children less than five years of age. And
this is the real tragedy of malaria that it
targets children and makes them unable to
learn and have productive lives. As a consequence
of multiple infections with these parasites
and multiple bouts of malaria in the lifetime
of these individuals, the effect is a reduction
in both economic and social development.
If we could rid the globe of malaria, we’d
make so many more people able to have productive
lives and contribute to the human experience.
Humans are the only reservoir for those four
species of plasmodium that I showed you at
the beginning. There are animal variants of
these malarias and as far as we know they
don't cause human disease. There is some suggesting
that this may be changing, but for the most
part the four species I showed you, humans
are the only reservoir. They are transmitted
among humans by the bite of an infected female
anopheline mosquito, alright, female mosquito.
Now can you tell me, do male mosquitoes bite you?
I’ll give you a few seconds. The answer
is no. Whenever you're bitten by a mosquito,
it's a female mosquito doing that, and that's
because she needs the blood in order to lay
eggs. Interesting little observation. So all
the diseases transmitted by mosquitoes, whether
they be parasitic or viral, it's all spread
by female mosquitoes.