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 https://doi.org/10.47488/dhrp.v1iS3.13 

  

 
http://dhrproceedings.org 1 © DHR Health Institute for Research and Development 
 

 

EDITORIAL 

The Use of Transgenic Mosquitoes to Control Vertical Transmission of 

Arbovirus-related Illnesses 
The Rationale for Conducting a Field Trial in the Florida Keys and its Relevance to South Texas 

 
Globally, mosquitoes – the World’s Deadliest 

Animal, infect over 700 million and are responsible 

for the death of over one million people every year 

(1). It is estimated that mosquito-borne illnesses 

account for 17% of the estimated global burden of 

infectious diseases (2). Deadly arboviral diseases 

transmitted by mosquitoes include (among others) 

malaria, dengue, West Nile Virus, yellow fever, 

Zika fever and chikungunya (3). It is common 

knowledge that male mosquitoes do not bite but 

rather feed on nectar from flowers. On the contrary, 

female mosquitoes bite as they need blood to 

produce eggs (4). Of the many species of 

mosquitoes, Aedes aegypti is the primary vector that 

is responsible for vertical transmission of several 

arboviral diseases and has been most extensively 

studied (5). Aedes aegypti mosquitoes live in 

tropical, subtropical and some temperate climate 

and since they prefer to feed on people, they are 

most likely to spread arboviral illnesses (6). The 

efforts of World Health Organization and the Center 

for Disease Control and Prevention to prevent 

and/or control mosquito-borne illness have yielded 

success, but it remains a serious global challenge. 

More recently, several approaches to create 

transgenic mosquitoes with the ultimate objective 

of preventing and/or controlling mosquito-borne 

illness have undergone field studies. Infecting 

Aedes aegypti mosquitoes with different strains of 

Wolbachia resulted in the reduction of egg laying 

rates and transmission ability and shorter lifespan 

(7). Similarly, using genetic technology, a self-

limiting strain of Aedes aegypti male mosquitoes 

(OX513A) when released in the field have shown 

an 81%-95% suppression of population of this 

strain as compared to adjacent no-release control 

field (8).  

These encouraging results prompted the issuance of 

authorization by the U.S. Environmental Protection 

Agency for the use of second generation genetically 

modified Aedes aegypti mosquitoes (OX5034) in 

Florida and Texas (9). OX5034 has a self-limiting 

gene that prevents female Aedes aegypti offspring 

from surviving to adulthood. OX5034 is described 

as a species-specific female larvicide, or “male-

selecting” larvicide, that results in all-male progeny 

in the absence of tetracycline in the larval diet due 

to a female specific self-limiting gene. With 

continued field releases of OX5034 homozygous 

males, the Aedes aegypti population is expected to 

progressively decline due to the reduced number of 

females emerging in the area. Specifically, when 

OX5034 homozygous males are released into the 

environment and mate with wild Aedes aegypti 

females, their offspring inherit a single copy of the 

self-limiting gene. The self-limiting gene kills only 

female offspring while hemizygous males survive 

to pass on the OX5034 self-limiting gene further. 

As the self-limiting gene is inherited in a Mendelian 

fashion, half of the offspring resulting from a 

mating between an OX5034 hemizygous male, and 

a wild female would not inherit the self-limiting 

gene but would still inherit OX5034 strain genetics. 

This results in both male and female mosquitoes 

with OX5034 strain genetics (10). 

Despite public opposition, 750 million OX5034 will 

be ultimately released in the Florida Keys an area 

devastated by mosquito-borne illnesses (11). This 

will be the first-ever use of genetically modified 

mosquitoes in the United States. As an initial field 

experiment, in the week of May 03, 2021, an 

estimated 150,000 genetically modified eggs of 

Aedes aegypti will hatch in six small areas of 

Ramrod Key, Cudjoe Key and Vaca Key in Florida 

Keys (12). Since 2019, over one billion genetically 

modified mosquitoes have been successfully 

released in parts of Brazil, Cayman Islands, Panama 

and India to control Aedes aegypti (13). In all these 



DHRP, 2021, Vol. 1 (S3) 1-2  Editorial 

  

 
http://dhrproceedings.org 2 © DHR Health Institute for Research and Development 

    
 

studies, there has been no evidence of any harmful 

effects on humans, animals and or the environment. 

Considering the available safety data combined 

with the observed effectiveness of the genetically 

modified mosquitoes in reducing the burden of 

arboviral diseases in the community, the decision 

by the US Environmental Protection Agency was 

justified.  The implications for the success of the use 

of genetically modified mosquitoes are self-evident 

and its use must be seriously contemplated for other 

parts of the nation including South Texas the 

weather of which, is not dissimilar to Florida Keys.  

 

References  

 1. Caraballo H and King K. Emergency department management 

of mosquito-borne illness: malaria, dengue, and West Nile 

virus. Emerg Med Pract. 2014 May;16(5):1-23; quiz 23-4. 

PMID: 25207355 

2. Mosquitoes: World’s Deadliest Animal. Barcelona Institute of 

Global Health. https://www.isglobal.org/en/new/-

/asset_publisher/JZ9fGljXnWpI/content/mosquito-el-animal-

mas-letal-del-mundo  

3. Mosquito-borne diseases. The National Institute for 

Occupational Safety and Health, Centers for Disease Control 

and Prevention.  

https://www.cdc.gov/niosh/topics/outdoor/mosquito-

borne/default.html 

4. McBride CS, Baier F, et.al. Evolution of mosquito preference 

for humans linked to an odorant receptor. Nature. 2014 Nov 

13;515(7526):222-7. doi: 10.1038/nature13964. 

5. Kamal M, Kenawy MA, et.al. Mapping the global potential 

distribution of two arboviral vectors Aedes aegypti and Ae. 

Albopictus under changing climate. PLoS One. 2018 Dec 

31;13(12):e0210122. doi: 10.1371/journal.pone.0210122. 

eCollection 2018. 

6. Harrington LC, Edman JD and Scott TW. 2001. Why do 

female Aedes aegypti (Diptera:Culicidae) feed preferentially 

and frequently on human blood? Journal of Medical 

Entomology 38:411-422. 

7. Xue L, Fang Z, et al. Comparing the effectiveness of different 

strains of Wolbachia for controlling chikungunya, dengue 

fever, and zika. PLoS Negl Trop Dis. 2018 Jul 

30;12(7):e0006666. doi:10.1371/journal.pntd.0006666. 

eCollection 2018 Jul. 

8. Carvalho DO, McKerney AR, et. al. Suppression of a Field 

Population of Aedes aegypti in Brazil by Sustained Release of 

Transgenic Male Mosquitoes. PLoS Negl Trop Dis. 2015 Jul 

2;9(7): e0003864. doi:10.1371/journal.pntd.0003864. 

eCollection 2015. 

9. EPA approves experimental Use permit to test innovative 

biopesticide toll to better protect public health. May 01, 2020. 

https://www.epa.gov/pesticides/epa-approves-experimental-

use-permit-test-innovative-biopesticide-tool-better-protect. 

10.   Significant technology advancements set stage for targeted, 

multi-generation suppression of disease-transmitting 

mosquitoes. https://www.oxitec.com/en/news/oxitec-launches-

field-trial-in-brazil-for-next-generation-addition-to-friendly-

mosquitoes-platform 

11. Millions of genetically-modified mosquitoes will be deployed 

to save Floridians from bites. 

https://www.zmescience.com/science/genetically-modified-

mosqito-262345/ 

12. First-ever US release of genetically modified mosquitoes 

begins in Florida Keys. April 30, 2021. 

https://www.cnn.com/2021/04/30/health/genetically-modified-

mosquitoes-us-scn-wellness/index.html  

13. de Andrade PP, Aragao FJL, et. al. Use of transgenic Aedes 

aegypti in Brazil. Risk, perception and assessment. Bull World 

Health Organ 2016 Oct 1;94(10):766-771. 

doi:10.2471/BLT.16.173377. Epub 2016 Aug 31. 

  

 

Sohail Rao, MD, MA, DPhil 

Executive Vice President, DHR Health, 5501 S. McColl 
Road, Edinburg, Texas 

President & Chief Executive Officer, DHR Health 
Institute for Research & Development, 5323 S. McColl 
Road, Edinburg, Texas 

 

Corresponding author email: s.rao@dhr-rgv.com 

Disclosures: None 

ORCID: Sohail Rao: https://orcid.org/0000-0001-5027-

9992 

 

 

 

 

 

 

 

 

 

https://orcid.org/0000-0001-5027-9992
https://orcid.org/0000-0001-5027-9992

