This week we begin studying modes of transmission and transmission dynamics – foundational concepts in the epidemiology of infectious diseases. Malaria is what first caught my interest for infectious disease epidemiology and definitely ranks as one of my favorite diseases. The malaria parasite is transmitted from person to person (or animal to person) via the bite of the Anopheles species of mosquito. One of the cool things about the malaria parasite (Plasmodium, see malaria “Featured Disease” on this blog for more info) is that the parasite completes part of its life cycle in the human/animal host, and a different part of its life cycle in the mosquito vector. Both creatures are necessary for the propagation of the parasite.
As you may deduce from your studies of the interaction between agent, host, and environment, there are many ways one can go about interrupting transmission of the vector-borne parasite. Drugs reduce the parasite load and treat the individual. Insecticides sprayed on interior walls kill the vectors as they “rest,” after they have taken one blood meal but before they can infect another person. Bednets prevent transmission from the insect to the person, and insecticide treated nets kill the insect as well. Decades-long efforts toward a vaccine for this challenging multi-stage parasite are also showing some success.
Some scientists promot the sterile insect technique (SIT) for controlling malaria and other diseases transmitted by vectors. This involves releasing a large quantity of sterile male mosquitoes into an endemic area, thus reducing the vector population drastically when females cannot produce offspring. While this technique has its critics, it has been sucessfully used to control disease and reduce insect populations. Read more about SIT in this nice article from the journal Vector-Borne and Zoonotic Diseases.
How Malaria is Transmitted (1943)