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By Elizabeth Bravo
Naomi Klein in her book The Theory of Shock analyzes how capitalism takes advantage of extreme situations to create propitious scenarios to influence decisions that favor power groups, and that would otherwise be impossible to implement. That is happening with the emergence of vector-borne diseases like Zika and dengue. In 2015 it happened with Ebola and before with the “swine” flu. In all these cases, great fortunes were made without actually addressing the causes of these epidemics, or giving them a solution.
In recent weeks the media were flooded with news of the emergence of this new epidemic, because it is assumed that the virus has the ability to affect babies in the womb. In Brazil, the media has insisted that the Zika virus is related to an increase in cases of microcephaly.
Zika is a viral disease transmitted by several species of mosquitoes, including Aedes aegypti, also a vector of dengue and chikungunya. To transmit the disease, one of these mosquitoes must first bite a sick person and then a healthy person.
The virus was isolated for the first time in 1947 in Uganda in monkeys, when a group of scientists was investigating yellow fever. Despite the havoc it is wreaking in our region, there have only been two cases in Uganda in 70 years, perhaps because people there developed immune defenses to the virus. The first human infections were detected in 1952 in Uganda and Tanzania. Starting in 2007, cases were reported in Oceania. Now it presents itself as an epidemic in Latin America.
On March 3, 2016, the World Health Organization produced a document mapping the research and development portfolio to attack Zika, and convened the Vector Borne Diseases Advisory Group (VCAG) to assess the new proposed tools, including diagnostic methods, prophylactic medicines, vaccines and vector control. Behind most of them, there are pharmaceutical companies. The ultimate goal is for WHO to prioritize medical products and approaches that should be taken in a fast track, for development and adoption.
Many of these proposals are based on vector control.
A disease-fighting approach focused on controlling the mosquito at the cost of everything, involves the use of dangerous chemicals, such as the larvicide pyriproxyfen, which was introduced in Brazil in 2014; a developmental inhibitor that produces endocrine disorders and is teratogenic. Another chemical used is malathion, an organophosphate insecticide considered by the International Agency for Research on Cancer (IARC) to be potentially carcinogenic to humans. In other words, the poor population is being poisoned to control the mosquito, and without our having certainty that the incidence of the disease will decrease.
Following this same approach, one of the issues that the Advisory Group on Vector Borne Diseases will evaluate is the use of the transgenic mosquito OX513A to reduce the vector population.
The transgenic mosquito OX513A was developed by Oxitec, a company formed with researchers from the University of Oxford, and was acquired in 2015 by Intrexon, a company specializing in synthetic biology.
Oxitec has genetically manipulated strains of the mosquito so that the male leaves nonviable offspring when crossed with a wild female. It is a kind of "terminator mosquito". Theoretically, only the male is released (who does not transmit the virus because it does not bite). The separation between females and males in the laboratory is manual, based only on the size of the mosquitoes, so the possibility of transgenic females infiltrating and being released is high.
In a test carried out in the Cayman Islands with the transgenic mosquito, it was found that 0.5% of the mosquitoes released were female. Although these percentages are low, the total number of transgenic female mosquitoes released or the number of offspring that survive may be high. In Brazil, more than 2,500,000 transgenic adult mosquitoes are produced per week, 0.5% of these mosquitoes will be female: 12,500 female mosquitoes, with the ability to bite, could be released each week. This number will increase in each season.
On the other hand, if the transgenic mosquito succeeds in eliminating or reducing the wild populations of Aedes aegypti, it will leave the niche unoccupied so that another mosquito that is also a vector of Zika and dengue, Aedes albopictus, can occupy it, since competition for the sites of reproduction and food.
Another problem is that the OX513A mosquito survives in the presence of tetracycline. In their presence, mosquitoes can reproduce and persist for several generations. Remember that tetracycline is an antibiotic widely used in the poultry, aquaculture, human and veterinary medicine industries, so there is an additional risk there.
The company has already carried out experiments with these mosquitoes in Panama, in the Cayman Islands, in Malaysia and in the state of Bahia in Brazil. Its results are highly debatable. In a report made on the releases of the OX513A mosquito in Panama, it was evidenced that this is not an area where dengue is an epidemiological problem, because according to the director of the Nuevo Chorrillo Health Center (the place where the release of the transgenic mosquito), the last dengue outbreak had occurred five years earlier, and in 2014 only five cases had been recorded, so it is difficult to ensure that the transgenic mosquito has been a success in the fight against dengue.
In any case, the evaluation carried out by the WHO vector control group, at its meeting in March 2016, concluded that the transgenic mosquito is not ready for commercialization, as it has not been proven that this technique truly reduces the disease (see http://www.who.int/neglected_diseases/news/mosquito_vector_control_response/en/)
According to expert Julius Lutwama, the chief virologist at the Uganda Virus Research Institute, another problem with disease control strategies based on vector control is that there are 3,500 known species of mosquitoes and most of them it does not bother humans at all: they live on plants and fruit nectar. Only 6% of females suck blood from humans, and of these, only half are carriers of parasites that can cause disease.
Furthermore, strategies based on combating the vector do not address the underlying causes that give rise to these epidemics.
The Brazilian Association of Collective Health Abrasco, when referring to the problem of microcephaly, an epidemic in that country, evaluates that the dengue disease control strategies have failed, since there was an exponential growth of the dengue epidemic (in 2015, the Ministry of Health registered 1 million 649 thousand 008 probable cases of the virus in the country and there was an increase of 82.5% in deaths compared to the previous year).
According to Abrasco scientists, the majority of mothers of children with microcephaly live in the poorest areas where environmental sanitation systems are deficient, there is increasing environmental degradation, an immense presence of solid waste from homes and deficiencies in the drainage of rain water. Their access to water is intermittent, and that is why families have to store it, which not only damages its quality, but is also an ideal niche for the reproduction of the Aedes aegypti mosquito.
Diseases such as Zika, dengue, malaria will increase as the El Niño phenomenon worsens, which is another factor that has influenced the proliferation of these epidemics. As long as the system that prioritizes the generation of capital at the expense of health and nature is maintained, it will be difficult.