Question

Briefly summarize the complex life cycle of a vector-borne pathogen of your choice. Describe the point in the life cycle at which we should intervene to halt disease progression.

Answer 1

The complex life cycle of a vector-borne pathogen - Malarial parasite

Malaria parasite (Plasmodium falciparum) needs two hosts for its growth (mosquito and growth). Within the mosquito, it is present in sporozoite phase. When a mosquito bites human, it releases the sporozoites into the circulation that infects liver cells. These sporozoites develop multiply into haploid merozoites within the liver and enter into the systemic circulation. Merozoites undergo asexual replication in the red blood cells and produce a number of infected cells, which is responsible for the illness. Some of the merozoites stop asexual multiplication and develop into sexual forms, means male and female gametes. These gametes again enter into a mosquito, if it bites an infected person.

Within the midgut wall of mosquito, gametes fuse to form an oocyte, which matures and release haploid sporozoites, the mosquito is now ready to infect again.

Summary: The parasite is spread by the bite of an infected female Anopheles mosquito, via the bloodstream. Then the sporozoites travel to the liver, where they grow and multiply (merozoites). The merozoites break open the liver cells and attack erythrocytes. Merozoites undergo asexual replication and produce a number of infected cells, some of the merozoites develop into sexual forms, which enter into a mosquito if it bites an infected person. Within the mosquito, the gametes matures and release haploid sporozoites, the mosquito is now ready to infect again.