> Although many Indian children still die=
> of the disease, many adults seem to live with it, getting ill only once in=
> a while, probably when the immune system is stressed by other factors.

Adults who "live with malaria" can do so because they have developed
cell-mediated immunity to it by surviving numerous bouts during childhood.
If you grow up in a non-malarial area and move to a malarial region as an
adult, chances are you will die before your body can develop cell-mediated
immunity, as this works best in children.  As you age into your 60s and 70s,
you lose your cell-mediated immunity to malaria, such that many old people
die of malaria, as well as many infants and children under 5.  If you look
at a mortality rate curve by age, it forms a big wide flat-bottomed U --
high in the beginning of life, high in old age, very low in the middle.

Adults in malarial-ridden areas HAVE malarial parasites all the time, but
their immunity usually keeps the parasite levels below symptomatic levels.
The same is true of quinine-derived drugs -- they don't *prevent* you from
getting malaria, they merely keep the number of parasites below symptomatic
levels.  Infection with the parasite is probably universal in much of the
world, but having the frank "disease" is rare among older children and
adults.  It is my understanding that when a native adult gets symptomatic
malaria it is usually because (1) he has been infected with several
different strains at once or (2) his nutritional status has improved
somewhat -- malarial parasites thrive best in well-nourished people, and
don't fare very well in malnourished ones.

A typical course of malaria for an adult Malian (West Africa) is to have
fever and headache for 2-3 days, and then be fine again.  There are many
dietary treatments for malaria in different cultures around the world.

Kathy Dettwyler

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