In a recent development, genes from genetically-modified Aedes aegypti mosquitoes were discovered to have transferred to the naturally occurring population of the same species in Brazil. This occurrence was observed after the release of transgenic mosquitoes in the region. However, there is ambiguity regarding the impact of these transgenic mosquito genes on the natural population, particularly if it could influence the disease transmission capacity or complicate mosquito control activities.
Aedes aegypti mosquitoes are notorious for transmitting diseases including dengue, chikungunya and the Zika virus. The genetic strategy employed, named Release of Insects Carrying Dominant Lethal Genes (RIDL), was targeted to reduce the naturally occurring A. aegypti mosquito population. However, it wasn’t intended to affect or alter their genetics. Contrarily, the study detected transgenic genes in 10-60% of the naturally occurring mosquitoes. Additionally, it found that the natural A. aegypti mosquitoes carrying some genes of their transgenic counterparts were able to reproduce in nature.
Zika Virus: An Overview
Zika virus is a mosquito-borne flavivirus originally identified in Uganda back in 1947 within monkeys. It was later detected in humans in 1952, in Uganda and the United Republic of Tanzania. Outbreaks of Zika virus disease have been documented in Africa, the Americas, Asia, and the Pacific. The Zika virus disease primarily transmitted by Aedes mosquitoes can also be passed from a pregnant woman to her foetus. Besides that, sexual transmission of Zika virus is also possible. Unfortunately, there is no vaccine or medicine for Zika as of now. Treatment focuses on relieving symptoms, which includes rest, rehydration and consumption of acetaminophen for fever and pain.
Dengue: A Persistent Threat
Dengue is another disease transmitted by several mosquito species within the Aedes genus. Symptoms of dengue include fever, headache, muscle, and joint pains, accompanied by a characteristic skin rash akin to measles. Dengvaxia, the first vaccine for dengue is yet to receive approval from the Indian drug controller. According to reports, India recorded 6,210 cases and six deaths from dengue until June 9, 2019.
Chikungunya: The Mosquito-Borne Scourge
Chikungunya is caused by a mosquito-borne virus that’s primarily transmitted by Aedes aegypti and Aedes albopictus mosquitoes. Its symptoms are characterized by abrupt fever and severe joint pain, often in hands and feet, which could be compounded by headaches, muscle pain, joint swelling, or rashes. At present, there is no specific antiviral drug treatment for chikungunya nor is there a commercial chikungunya vaccine.
| Disease | Symptoms | Transmission Mode | Treatment/Vaccine |
|---|---|---|---|
| Zika Virus | Fever, Rash, Joint Pain, Red Eyes | Aedes Mosquitoes, Sexual Transmission and Pregnancy | No specific treatment or vaccine available |
| Dengue | Fever, Headache, Muscle & Joint Pains, Skin rash | Aedes Mosquitoes | Treatment is symptomatic, Dengvaxia Vaccine (Not approved in India) |
| Chikungunya | Abrupt Fever, Severe Joint Pain, Headache, Muscle Pain, Swelling, Rash | Aedes aegypti and Aedes albopictus mosquitoes | No specific treatment or commercial vaccine available |
Genetic Impact: The Worrying Trend
The discovery of transgenic mosquito genes in naturally occurring A. aegypti mosquitoes raises concerns as it indicates that genetic modifications intended to reduce the mosquito population may instead result in their genetic alteration. This occurrence not only contradicts the primary objective of RIDL but also adds complexity to understanding the biological impact on the natural mosquito population. Clearly, more research is required to understand and manage the implications of genetic modification strategies in mosquito control.
