JSS 1: Disease vectors
Disease vectors
A disease vector is any living thing that carries and transmits infectious pathogens from one organism to another.
Examples of disease vectors are mosquitoes, blackfly, tsetse fly, etc
Pathogens are disease-causing organisms e.g. Plasmodium, bacteria, viruses, filarial worms, trypanosomes, etc
Female anopheles mosquito
The mosquito carries the pathogen called plasmodium which causes malaria.
Black fly
The blackfly carries the pathogen called filarial worm which causes river blindness.
Tsetse fly
The tsetse fly carries the pathogen called Trypanosoma which causes sleeping sickness (trypanosomiasis)
Transmission of disease-causing organisms
Disease-causing organisms are transmitted or passed from one person to another through:
1. Direct contact
2. Air
3. Water
4. Food or objects
5. Vector
Characteristics of a vector
The characteristics of a vector are:
1. They are usually small animals
2. They transmit disease from one organism to another
3. The vector does not become infected with the disease.
4. The pathogen grows and develops inside the vector
Metamorphosis
Metamorphosis is a process by which animals undergo extreme, rapid physical changes.
Types of metamorphosis
There are two types of metamorphosis:
1. Complete metamorphosis
2. Incomplete metamorphosis
Complete metamorphosis
In complete metamorphosis, a larva completely changes its body plan to become an adult.
Egg → larva → pupa → imago (adult)
Examples of organisms that undergo complete metamorphosis are: butterflies, ants, fleas, bees, beetles, moths, flies, and wasp
Incomplete metamorphosis
In incomplete metamorphosis, only some parts of the animal’s body change during metamorphosis.
Egg → nymph → adult
Examples of organisms that undergo incomplete metamorphosis are cockroaches, termites, lice, grasshoppers, praying mantis, locusts, and crickets.
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