Parasites typically have several characteristics that allow them to survive in hosts, such as being highly reproductive, having morphological or physiological specializations, and showing site specificity. They are usually non-lethal to the host, more numerous than the host, and smaller than the host. Parasites also evolve ways to evade the host's immune system, such as antigenic variation, tough exteriors, or intracellular habitats. When a parasite infects a foreign host, it will often be killed immediately, may survive for a short time but not reproduce, or possibly develop to maturity without causing disease, but the most common fate is death.

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TYPICAL CHARACTERISTICS OF PARASITES
PRESENTED BY:
HAFIZ NAWAZ ALI

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TYPICAL CHARACTERISTICS OF PARASITES
1. Some parasites are highly reproductive;
eg. Multiple fission in Apicomplexa.
. Hermaphrodism of Trematodes.
2. Often have unique morphological or physiological specialization,
loss of structures,etc.
a. Loss of digestive track of Tapeworms
b. Loss of wings of fleas & lice
c. Loss of many sensory structures of Nematodes
d. Development of special hold fast organs; teeth , hooks , clamps
e. Production of anti-coagulation in Leeches

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3 – Often special site specificity
4 – Usually, but not always, non-lethal to host
5 – Generally much numerous than host
6 – Generally much smaller than host
7 – Evolve method of invading host immune system;
Antigenic variation of Trypnosomes
 Tough teguments of Acanthocephalans
 Intracellular habitat of Coccidia & Trichinella larvae
 Encystment
Ability to cleave antibodies or consume complement


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8 – many parasites are being shown to change the host behavior.
Scientists believe = ?

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FATE OF PARASITE IN FOREIGN HOST
When a parasite attacks on a foreign host one of the following may
happen;
a. it may be killed at once.
b. it may be survive for a longer or shorter duration but not multiply.
c. it may develop to maturity, if so ,may not cause disease.
OOOOOPssssss!!!!!!!
The commonest fate of parasite in foreign host is DEATH


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Thanks