1. What is a disease vector? Discuss the roles and importance of disease vectors in the transmission of diseases. 25 pts.
A disease vector is any agent that transmits and carries an infectious pathogen into another living organism. These vectors have immunity to the pathogen and thus allows for the successful transport of the pathogen. Not every vector is able to carry every pathogen and ecological restrains also limit the spread of the disease due to the inability of the vector to survive in different kinds of environments.
Arthropods can serve as vectors and play an important role in disease transmission. These vectors include mosquitoes, fleas, sand flies, lice, ticks, and mites. They are responsible for the transmission of several diseases. These vectors feed on blood at some or all stages of their life cycles. The hematophagous lifestyle of these arthropods allows the pathogens to enter the blood stream of the host. For example, the anopheles mosquito is a vector for malaria, filariasis,
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The transmission of pathogens from current to future host follows a repeating cycle. The cycle can be simple with a direct transmission or complex where it goes through multiple intermediate hosts or vectors. These cycles are called the disease transmission cycles. A cycle has many elements: the pathogen, the organism that causes the infection; the host, the infected organism carrying the pathogen; the exit, the method the pathogen follows to leave the body of the host; transmission, describes how the pathogen is transferred from host to susceptible organism; the environment, where the transmission of the pathogen takes place; the entry, the method followed by the pathogen to enter the body of the new host; and the susceptible organism, a person or animal who is receptive to the