Context-Contrary to claims made, genes from genetically-modified Aedes aegypti mosquito were found to have been transferred to naturally-occurring A. aegypti mosquito population in three areas in Brazil where transgenic mosquitoes were released.

• It is unclear if the presence of transgenic mosquito genes in the natural population will affect the disease transmission capacity or make mosquito control efforts more difficult.
•  A.aegypti mosquitoes are responsible for transmitting dengue, chikungunya and Zika virus.

Concerns

• About 4,50,000 transgenic male mosquitoes were released each week for 27 months (June 2013 to September 2015) in three areas in Brazil.
• The genetic strategy employed to control A. aegypti population known as RIDL (the Release of Insects carrying Dominant Lethal genes) is supposed to only reduce the population of the naturally occurring A. aegypti mosquitoes and not affect or alter their genetics
• The genetic strategy works on the premise that the transgenic male mosquitoes released frequently in large numbers would compete with the naturally occurring male mosquitoes to mate with the females. Offspring from the mating of transgenic male mosquito and naturally occurring female mosquito do not survive to the adult stage. This is because tetracycline drug, which prevents the dominant lethal gene from producing the lethal protein during rearing in labs, is not present in sufficient quantity in nature. In the absence of tetracycline, there is overproduction of the lethal protein causing the larvae to die.
• The claim was that genes from the release strain would not get into the general population because offspring would die. That obviously was not what happened.

Dengue

• It is a mosquito-borne viral infection causing a severe flu-like illness and, sometimes causing a potentially lethal complication called severe dengue
• The Aedes aegypti mosquito is the main vector that transmits the viruses that cause dengue. The viruses are passed on to humans through the bites of an infective female Aedes mosquito, which mainly acquires the virus while feeding on the blood of an infected person.
• Once infected, humans become the main carriers and multipliers of the virus, serving as a source of the virus for uninfected mosquitoes. The virus circulates in the blood of an infected person for 2-7 days, at approximately the same time that the person develops a fever. Patients who are already infected with the dengue virus can transmit the infection via Aedes mosquitoes after the first symptoms appear (during 4-5 days; maximum 12).

Zika virus

• It is a mosquito-borne flavivirus that was first identified in Uganda in 1947 in monkeys. It was later identified in humans in 1952 in Uganda and the United Republic of Tanzania.
• Zika virus disease is caused by a virus transmitted primarily by Aedes mosquitoes, which bite during the day.
• Symptoms are generally mild and include fever, rash, conjunctivitis, muscle and joint pain, malaise or headache. Symptoms typically last for 2–7 days. Most people with Zika virus infection do not develop symptoms.
• Zika virus infection during pregnancy can cause infants to be born with microcephaly and other congenital malformations, known as congenital Zika syndrome. Infection with Zika virus is also associated with other complications of pregnancy including preterm birth and miscarriage.
• An increased risk of neurologic complications is associated with Zika virus infection in adults and children, including Guillain-Barré syndrome, neuropathy and myelitis.