Fighting the Feverish Flyers

It has been estimated that 50 million to 100 million people are infected by dengue fever each year, a number that is larger than the UK’s population [1]. Dengue fever is a disease that is mainly transferred through mosquito bites, and the number of epidemics in the world has increased in recent years. A British company, Oxitec, has recently manufactured a method to help address the problem of dengue fever. Oxitec’s invention is based on the idea of creating a genetically modified mosquito. Similar to their modifications to plants, genetic engineers have discovered a way to genetically engineer mosquitoes to help prevent deadly diseases such as dengue and yellow fever. However, as with many other GMOs (genetically modified organisms), these human-made mosquitoes are generating controversy because of ethical issues. Critics question humans’ right to alter nature and to essentially “play God” [2]. Another cause for concern is that the potential results are unknown. Unlike traditional GMOs, such as plant seeds or farm animals, these mosquitoes are the first of their kind, which means that research into how these organisms could affect their environment is relatively slim. In addition, these mosquitoes cannot be recalled in the event of a failure of the project. Therefore, the ethics of creating and releasing genetically modified mosquitoes has been heavily debated in the scientific and public communities. Using genetically modified mosquitoes, despite the potential effectiveness in eradicating disease, should not be considered a viable option at this time because of the unknown environmental effects.

The idea of the genetically modified mosquito lies in an age-old method of pest suppression and eradication: that a group of sterile pests, when released into the environment, will mate with their wild counterparts. Because one of the mating partners is sterile, there is no possible production of offspring. Thus, the population of the pests will be lowered two-fold. However, “this technique has not been successfully used for mosquitoes because the radiation used to sterilize the insects also injures them, making it difficult for them to compete for mates against wild counterparts” [3]. Therefore, since introducing sterile mosquitoes was not a viable option, scientists were forced to create a different method of eradicating these mosquitoes.

Scientists have found the main breed of mosquitoes that transmit dengue and yellow fever and have genetically engineered this species to contain a self-killing gene. The only cure for these mosquitoes is a common antibiotic called tetracycline [3]. While in the lab, these genetically engineered mosquitoes are bred and given the antibiotic until they have reached a sizable number. Then, they are “released into the wild, where tetracycline is not available. They live long enough to mate but their progeny will die before adulthood” [3]. Instead of creating a breed of mosquitoes that cannot produce offspring, scientists have slightly altered the course of action. Although offspring are produced, they do not live long enough to produce harm in their environment. This process has recently been tested in the field as well as in a controlled cage. The results of the experiments were overwhelmingly positive. All three cages eventually reached extinction and proved that the principle behind this idea was in fact applicable. However, the field tests did lead to some ethical concerns, primarily the unknown effects of these genetically modified mosquitoes on other species in the environment, including humans.

One concern is that this experiment might lead to a growth in disease-carrying mosquitoes instead of a decrease in the population. A contributor to this concern is the fact that the process might not be 100% effective. Oxitec, the company who created this organism, admitted “that a small percentage of its altered mosquitoes, including biting females, can survive in the lab without tetracycline” [4]. This means that although these mosquitoes were given this self-killing gene, they managed to survive and develop resistance to it. In addition, it was also found that tetracycline allowed the “survival rate of next generation genetically engineered mosquitoes to increase from 3 percent up to 18 percent” [5]. When the genetically engineered mosquitoes (RIDL) were unable to mate with a wild female, the RIDL survived 18 percent of the time. As a result, releasing these mosquitoes could potentially pose a safety risk because of the increases to the population of mosquitoes.

Another ethical dilemma is presented as we explore scenarios that have never been encountered before in science. One such instance is the result of the eradication of the current disease-carrying mosquitoes. After careful study, “Panamanian researchers have warned that a competitor species, the Asian tiger mosquito, could move in and be harder to eradicate” [4]. The Asian tiger species also is known to spread dengue fever and would thus present more risk to humans living in the area. Furthermore, engineers must also be wary of introducing “antibiotic resistant bacteria into the environment” [4]. The use of tetracycline could cause bacteria in the area to adapt and become resistant which would mean that food could also become contaminated. Another issue is the potential harm that would result from being bitten by one of these mosquitoes. As Helen Wallace from GeneWatch U.K. reports, “Oxitec has not provided sufficient evidence that being bitten by, or swallowing, these mosquitoes will be safe” [4]. Consequently, it is unknown if a bite from these insects would cause an allergic reaction or not.

The ethical questions are hard to tackle because the research is very much in flux. However, there are tools to aid the decision-making process. One way to address this question is to utilize the rights test. Because the rights test is based on respecting human rights, we must look to the right of health and well-being. Supporters of the release of genetically modified mosquitoes into the wild can claim that they are protecting people’s right to health because they are eradicating the main carrier of the dengue fever-causing virus. However, genetically modified mosquitoes may also represent a threat to human health. The results of the experiment suggest that the release of these mosquitoes could potentially lead to a larger population of dengue fever-carrying mosquitoes. This presents an inherent risk to humans and their right to health as they would be at greater risk of being bitten. Therefore, this experiment has the opportunity to be more harmful than helpful.

Another ethical issue that can be addressed with the rights test is that of the right to safety. People’s right to safety is affected because there currently is no way to recall the product. Unlike previous genetically modified organisms that can be easily recalled, these mosquitoes are microscopic and can fly away of their own free will. There is no way to track these mosquitoes to return them to the manufacturer. This presents a problem because if the mosquitoes cannot be controlled, they could affect the regions where they are released and violate the rights of the people who have not consented to the trials.

The utility test could also be used to test ethicality. The utility test, in this case, is based on maximizing the good and minimizing the bad for those impacted by this experiment. In this scenario, the good is represented by humankind’s ability to create a functioning genetically altered organism as well as provide an effective way to minimize the risk of dengue fever in a population. On the other hand, the negative aspect is represented by the potentially harmful effects. This test is much more difficult to provide evidence for because most of the bad is unknown due to lack of research. When considering a futuristic idea that has not been put into practice, “a long-term perspective is important because ecological deterioration not only harms the environment but can also present future risks to human health” [6]. For example, in the best case scenario, the mosquitoes could develop resistance at such a low rate that it would not affect the overall experiment’s success. However, a number of worst case scenarios must be considered. One such worst case scenario for genetically modified mosquitoes would be if the mosquitoes increase the wild population and cannot be captured. This would result in major harm to the human population because the risk of dengue fever would actually increase. Another possible scenario would be if the experiment were successful but a disease-carrying, more-difficult-to-eradicate species of mosquito came about. If this happened, there could be a plethora of harms caused to both humans and the ecosystem because of unknown effects of the new species.

Because of the possibility of great risk to human health and to the environment from genetically modified mosquitoes, the bad outweighs the good in this situation. Therefore, the utility test also agrees with the rights test that utilizing these modified mosquitoes would be a serious ethical offense.

All in all, though a seemingly great idea, genetically modified mosquitoes pose too great a risk towards human society because of unknown risks. One proposal for their future implementation would be to conduct more tests on the environmental and health effects that these mosquitoes can cause under careful observation of an international regulatory committee. As written by Georgetown lawyer Lawrence Gostin, if “the scientific evidence demonstrates significant disease reduction with low ecological risks, the precautionary principle should not impede meaningful benefits for human health” [6]. Therefore, Oxitec must continue testing and monitoring their product to ensure that it does not create an ethical violation. However, while this product is being developed, more can still be done to control the risk of dengue fever. Governments must educate their citizens on the ways to eradicate mosquito breeding areas from their places of residence as this is the only proven method to decrease the number of dengue fever infections. Only then can a positive step be made in the eradication of this horrific disease.

By Douglas Yuk, Viterbi School of Engineering, University of Southern California

Works Cited

[1] Dengue Fever – A Growing Problem [Online]. Available:

[2] T. Phillips. (2008). Genetically modified organisms (GMOs): Transgenic crops and recombinant DNA technology [Online]. Available:

[3] A. Pollack. (2011, Oct.11). Concerns are raised about Genetically Engineered Mosquitoes [Online]. Available:

[4] H. Wallace. (2015, Feb. 23). Genetically Modified Mosquitoes Have Few Proven Benefits, Too Many Risks [Online]. Available:

[5] K. Butler. (2012). Can GMO Mosquitoes Save You From Dengue [Online]. Available:

[6] G.R. Ostera, L.O. Gostin. (2011). Biosafety Concerns Involving Genetically Modified Mosquitoes to Combat Malaria and Dengue in Developing Countries [Online]. Available: