Manipulation by Plasmodium Parasites of Anopheles Mosquito Behavior and Human Odors

Purpose

The phenomenon of parasites manipulating host phenotypes is well documented; the best-known examples are manipulations of host behavior. More recently, there has been interest in whether parasites can manipulate host odor phenotypes to enhance their attractiveness to vectors. We review here evidence that Plasmodium-infected mosquitoes have enhanced attraction to human hosts, especially when the parasite is sufficiently developed to be transmissible. We also review evidence suggesting that malaria-infected host odors elicit greater mosquito attraction compared to uninfected controls.

Methods

We reviewed and summarized the relevant literature.

Results

Though evidence is mounting that supports both premises we reviewed, there are several confounds that complicate interpretation. These include differences in Plasmodium and mosquito species studied, stage of infection tested, age of human participants in trials, and methods used to quantify volatiles. In addition, a key requirement to support the hypothesis of manipulation by parasites is that costs of manipulation be identified, and ideally, quantified.

Conclusions

Substantial progress has been made to unlock the importance of odor for enhancing transmission of Plasmodium. However, there needs to be more replication using similar methods to better define the odor parameters involved in this enhancement.