Genetically Modified Sterile Mosquitoes Released in the Caribbean
Oxitec and the Mosquito Research and Control Unit of Grand Cayman (MRCU) announced, at the American Society of Tropical Medicine and Hygiene annual meeting in Atlanta, the results of their release of genetically modified sterile mosquitoes into the wild.
It is the first time genetically altered mosquitoes have been set loose in the wild, after years of laboratory experiments and hypothetical calculations. But while scientists believe the trial could lead to a breakthrough in stopping the disease, critics argue the mutant mosquitoes might wreak havoc on the environment.
Oxitec developed the sterile strain to control the dengue-carrying Aedes aegypti mosquito. This sterility can be suppressed with a dietary antidote, allowing the strain to be reared in large numbers. Sterile males are then released to seek out and mate wild females, competing for mates with the wild males. If a female mates with a sterile male she will have no offspring, thus reducing the next generation's population.
Oxitec claims that repeated releases of sufficient numbers of sterile males will result in a reduction in the target mosquito population below the minimum level needed to support dengue transmission.
Dr William Petrie of MRCU said ‘Dengue is a debilitating disease one can only get from the bite of an infected mosquito. The World Health Organization has stated that "the only way to prevent dengue virus transmission is to combat the disease-carrying mosquitoes."
Dr Luke Alphey, Chief Scientific Officer and Founder of Oxitec added ‘Oxitec considers that this approach could be used in many countries to help control the Aedes aegypti mosquito and hence prevent dengue fever.
Other researchers and critics of the operation are not so thrilled with the idea of releasing genetically modified mosquitoes into wild populations. "This is playing with fire as there have been no controlled long-term studies which demonstrate the safety of interfering with mating practices of mosquitoes," said Professor and entomologist Derek McAuley. "Despite any benefits relating to reduction in cases of dengue, this experiement could dramatically upset the delicate balance and ratio of mosquitoes necessary in these environments."
Other few points of interest:
1. The genetically engineered mosquitoes lifespan is considerably less when compared to natural mosquitoes.
2. Since the GM mosquitoes do not enter a reproductive cycle, when females mate with a sterile males, they will have no offspring disrupting the food chain cycle for higher level predators.
3. Releasing these mosquitoes into the environment may replace the natural mosquito population within a unspecified period of time..
4. The mosquitoes have no competitive advantage over natural mosquitoes.
5. GM mosquitoes would have to "take over" the naturally occurring, disease-spreading mosquitoes. This means giving the GM mosquitoes a competitive advantage, something that has not yet been achieved or tested.
"If we remove an insect like the mosquito from the ecosystem, we don't know what the impact will be," said Pete Riley, campaign director of GM Freeze, a British non-profit group that opposes genetic modification.
He said mosquito larvae might be food for other species, which could starve if the larvae disappear. Or taking out adult mosquito predators might open up a slot for other insect species to slide in, potentially introducing new diseases.
Humans have a patchy track record of interfering with natural ecosystems, Riley said. In the past, such interventions have led to the overpopulation of species including rabbits and deer. "Nature often does just fine controlling its problems until we come along and blunder into it."
Others are convinced the biotechnology presents an opportunity for positive change. "This test in the Cayman Islands could be a big step forward," said Andrew Read, a professor of biology and entomology at Pennsylvania State University, who was not involved in the project. "Anything that could selectively remove insects transmitting really nasty diseases would be very helpful," he said.
Read said the bigger problem would be selling the idea of genetically altered mosquitoes to the public. In the Cayman Islands, officials said they worked closely with the local community and encountered surprisingly little resistance.
"We still have people who don't believe in vaccines," Read said. "How are we going to convince them it's OK to let scientists release genetically altered mosquitoes into the wild?"
What is Dengue?
The WHO says some 2.5 billion people, two fifths of the world's population, are now at risk from dengue and estimates that there may be 50 million cases of dengue infection worldwide every year. The disease is now endemic in more than 100 countries.
The disease manifests as fever of sudden onset associated with headache, muscle and joint pains (myalgias and arthralgias—severe pain that gives it the nickname break-bone fever or bonecrusher disease), distinctive retro-orbital pain, and rash.
Dengue fever has been the intense focus of U.S. army and CIA biological warfare researchers for over fifty years. As early as the 1950s, the army’s Fort Detrick in partnership with the CIA launched a multi-million dollar research program under which dengue fever and several addition exotic diseases were studied for use in offensive biological warfare attacks. Indeed, as several CIA documents, as well as the findings of a 1975 Congressional committee reveal that 3 sites in Florida, Key West, Panama City, and Avon Park, as well as 2 other locations in central Florida, were used for experiments with mosquito borne dengue fever and other biological substances.
The experiments in Avon Park, about 170 miles from Miami, were covertly conducted in a low-income African American neighborhood that contained several newly constructed public housing projects. CIA documents related to Project MK/NAOMI clearly indicate that the mosquitoes used in Avon Park were the Aedes aegypti type. Interestingly, at the same time experiments were conducted in Florida there were at least two cases of dengue fever reported among civilian researchers at Fort Detrick in Maryland. Avon Park residents still living in the area say that the experiments resulted in “at least 6 or 7 deaths". One elderly resident told this journalist, “Nobody knew about what had gone on here for years, maybe over 20 years, but in looking back it explained why a bunch of healthy people got sick quick and died at the time of those experiments.”
A 1978 Pentagon publication, entitled Biological Warfare: Secret Testing & Volunteers, reveals that the Army’s Chemical Corps and Special Operations and Projects Divisions at Fort Detrick conducted “tests” similar to the Avon Park experiments in Key West, but the bulk of the documentation concerning this highly classified and covert work is still held by the Pentagon as “secret.” One former Fort Detrick researcher says that the army “performed a number of experiments in the area of the Keys” but that “not all concerned dengue virus.”
In the spring and summer of 1981, Cuba experienced a severe hemorrhagic dengue fever epidemic. Between May and October 1981, the island nation had 158 dengue-related deaths with about 75,000 reported infection cases. Prior to this outbreak, Cuba had reported only a very small number of cases in 1944 and 1977. At the same time as the 1981 outbreak, covert biological warfare attacks on Cuba’s residents and crops were believed to have been conducted against the island by CIA contractors and military airplane flyovers. Particularly harmful to the nation was a severe outbreak of swine flu that Fidel Castro attributed to the CIA.
In 1985 and 1986, authorities in Nicaragua accused the CIA of creating a massive outbreak of dengue fever that infected thousands in that country. CIA officials denied any involvement, but army researchers admitted that intensive work with arthropod vectors for offensive biowarfare objectives had been conducted at Fort Detrick in the early 1980s, having first started in the early 1950s. Fort Detrick researchers reported that huge colonies of mosquitoes infected with not only dengue virus but also yellow fever were maintained at the Frederick, Maryland installation, as well as hordes of flies carrying cholera and anthrax, and thousands of ticks filled with Colorado fever and relapsing fever.
A review of declassified Army Chemical Corps documents reveal that the army may have also been engaged in dengue fever research as early as the late 1940s. Several redacted Camp Detrick and Edgewood Arsenal reports indicate that experiments were conducted on state and federal prisoners who were unwittingly exposed to dengue fever, as well as other viruses, some possibly lethal. Freedom of Information requests filed months ago for details on these early experiments remain unanswered.