Pathogen Management Strategies

Pathogen Life Cycle Disruption

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Ben Whitten


Pathogen life cycles: their impact

Understanding the life cycle of a pathogen is crucial knowledge for scientists in order to help them work out how to prevent and control the spread of the disease it causes. This includes the knowledge of things such as;

  • Portal of entry

  • Persistence in a reservoir

  • Portal of exit

  • How it is transmitted (mode of transmission)

  • Replication

Replication is the process of producing new pathogens from old pathogens. Viruses replicate by taking control of host cell enzymes for replication, bacteria replicate by binary fission (asexually) and fungi/protists may replicate through sexual or asexual means. Persistence refers to the ability for a pathogen to survive for longer periods in reservoirs; its viability outside a host.

If pathogen populations cease transmitting, infecting, replicating, persisting or gaining nutrients, or can't survive against the immune system of hosts, then the disease may stop spreading. The three main factors needed for the spread of disease include;

  1. A sufficient density of susceptible hosts

  2. Growth of a virulent pathogen population

  3. Sufficient amounts of transmission

Case Study: Plasmodium

Plasmodium has been studied by epidemiologists for decades with the main intention of targeting a stage in the life cycle as a measure of control.

Plasmodium causes the disease malaria and requires two types of hosts, being the intermediate host (the human) and the definitive host (Anopheles mosquito). Mosquitoes are a vector for the transmission of the protist, and have been targeted as a control measure. Adult mosquitoes however are highly active and have shown resistance to insecticides, creating difficulty in population control. It is important to target their larvae.

Killing both the asexual and sexual forms of the parasite has been made possible, however drug resistance has and continues to evolve. Prevention of transmission via blood feeds through barriers to infection (nets, clothing, closed windows, insect repellent) has reduced the rate of malaria.

Travellers to areas where malaria is endemic are encouraged to start chemoprophylaxis prior to travel, a preventative treatment with drugs against malaria. Its actions are to suppress malaria.

Topic Menu
Introduction to Pathogen Management
Immunisation and Herd Immunity
Pathogen Life Cycle Disruption
Physical Preventative Measures
Monitoring Disease Activity
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