Question:
When you have had typhus or malaria, you can get sick
from the disease without warning and without being
near any carriers. Why is this?
Replies:
Both typhus and malaria are infectious diseases.
Typhus is caused by bacteria called Rickettsia,
malaria is caused by a eukaryote micro-organism called
Plasmodium falciparum. Both diseases have in common
that they 'hide' in the body inside our cells, so that
our immune system can not sufficiently deal with them.
Plasmodium hide in red blood cells and in the liver.
Once the primary infection is over, there are no
symptoms but the micro-organisms are still present in
the body. Whenever the host is weakend (for isntance
by stress, a minor infection, sleep deprivation, etc)
the infection can pop up. A good information site on
malaria is the Travelers' Health fact sheet by CDC
(http://www.cdc.gov/travel/malinfo.htm).
Malaria parasites are passed from human to human by
mosquito's. Rickettsia bacteria are passed by lice,
ticks and sometimes fleas.
There are several types of Rickettsia that cause
different diseases. The Travelers' Health sheet on
typhus is found at
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