Some of the most dangerous and life-threatening diseases seen worldwide today are spread by parasites known as ‘vectors’, such as mosquitoes. Pest-borne diseases such as malaria – an infection of the liver and red blood cells – affect an average of 200 million people every year, claiming the lives of 600,000 annually (Lovett, 2018.). Over 90% of these cases occur in the sub-Saharan region of Africa, causing them to carry a disproportionately large share of the global malaria burden. Due to this, one child dies every minute from their sufferings of the disease. (Lovett, 2018.)
Furthermore, in 2017, 181 million people worldwide suffered from the Zika virus – another pest – borne disease. (Laporte, 2017.) Zika is notorious for severely weakening the nervous systems of its victims, as well as causing major birth defects in pregnant women, including microcephaly (abnormal smallness of the head) and other acute neurological problems. The majority of these cases were reported throughout the Americas. (CDC, 2017)
Through the implementation of vaccines and early diagnosis treatments, the threat of insect-borne viruses in today’s society is being taken under control. As a result of this, malaria mortality rates have reduced by 29% since 2010. (Hoibak, 2018.) It is critical that the impacts of these viruses and diseases be controlled as they affect millions of people around the world every year and this rate will climb unless a sustainable method of prevention is brought into action.
Despite the exemplary success of naturally manufactured tools in preventing these horrific viruses, the true success in this field could most likely be seen in the use of GMOs (genetically modified organisms), through their extremely effective and economically beneficial methods which evidentially work in better ways than the previous ones. In the efforts of preventing these diseases and reducing the number of cases of all pest-borne viruses worldwide, GMOs are leading the fight through the development of new treatments to eradicate the infection and mortality rates of citizens across the globe. Their developments can be seen in that of a genetically engineered mosquito species, transgenic symbiotic bacterium and a model foreseeing weather conditions in which disease-bearing parasites dwell. These advancements are seen and proven to have a benevolent effect on those infected and in preventing others from catching or acquiring these life-threatening viruses.
Genetically Modified Mosquito Cohort
An experiment conducted by American scientists gives hope to eradicating the infection and mortality rates of malaria. Researchers from California Universities have genetically engineered a species of mosquito whose genes are altered to improve its reaction against diseased parasitic microorganisms. They inserted genes from mice – who have extremely strong immune systems – into the mosquitoes, giving them an immensely stronger immune response to malaria-bearing parasites. Progressively, the scientists constructed a series of mosquito genes that produced a cohort of mosquitoes, 99% of which had malaria resistance and therefore would not transmit the disease to humans. (Burnett, 2015.) This is extremely advantageous in the way that by reproducing this mosquito species, the infection rate of malaria will inevitably decrease as the malaria-bearing mosquitoes die out and are replaced by the new species.
However, in the creation of a new class of animal to cause the extinction of another, a minor disruption in the mosquitoes’ ecosystem could be caused. Through this, harmful changes in the ecosystem’s food chain may occur, and in turn, even possibly physical alterations in the species’ biome could occur as well. (Cleland, 2018.)
Transgenic Symbiotic Bacteria
Due to the extensive use of pesticides in agriculture nowadays, insects have developed “an array of resistance mechanisms by which they can inactivate toxic substances.” (Durvasula, et al. 1997) In this way, they have become incredibly competent in carrying disease-causing or disease-bearing microorganisms. A study conducted by the PNAS (Proceedings of the National Academy of Sciences of the United States of America) has aimed to terminally affect one or two specific properties of insect vectors. By doing this, they aim to identify and eliminate the component of their biology which allows them to harbour harmful viruses. In this way, the suggested method is sustainable as it prevents the extinction of a species but encourages its improvement at the same time in a minor change of their anatomy. To bring this method into action, the researchers found an area where the inhabiting species of insect vectors fed off of a relatively restricted diet (that of mostly tree sap and blood). By consuming a diet which restricts their nutritional intake, the vectors were seen to harbour thousands of symbiotic microorganisms – ones which interact with other species – which “synthesize the needed nutrients” (Durvasula, et al. 1997) for the development. This symbiotic bacterium showed competence in being genetically altered to “express and release” transgene products into the vectors’ tissues to inhibit the pathogenic microorganisms’ ability to transmit disease. This method sustains a steadily increasing rate of successful hindrance of disease transmission while also decreasing the population of vectors that carry viruses. However, as would be a risk with the previous concept, inserting genes from a foreign body into a new one could cause major defects in the species’ anatomy as the organisms reproduce. Therefore, in producing transgene insects, much caution should be shown to ensure the experiment’s success and the organisms’ safety in doing so.
Linthicum Model
Rift Valley fever (RVF) is an acute insect-borne virus, notorious for causing painful fevers, muscle pains and headaches in its victims. Transmitted by vectors between livestock and humans, the disease commonly leads to neurological infections and bleeding in the liver. As well as this, 50% of cases suffer permanent loss of central vision (ECDC, 2018); a result of severe unilateral or bilateral damage to the retina. In recent years, the continent of Africa has recorded almost 15,000 cases of the disease, as the result of a viral epidemic, with 8,111 recorded deaths due to coming to these stages without medical treatment. (CDC, 2017)
While its effects are not seen worldwide, the increasing prevalence and seriousness of its harm shows its ability to become a more prominent issue around the world. Kenneth Linthicum, America’s leading expert on disease prevention, has developed a model which hopes to eradicate these rates where the virus is most prominent, in Africa and the Middle East. Linthicum has invented “a surveillance system which predicts the onset” (O’Connell, 2013) of RVF through observing global climate data and vegetation changes. Because the virus is “commonly associated with mosquito-borne epidemics during years of unusually heavy rainfall”, (O’Connell, 2013) the model predicts weather conditions that will lead to floods. Floods cause mosquito eggs to hatch in the soil, promoting the emergence of virus in vectors. By predicting these conditions, Linthicum provides “governments and international organisations with early notice and an opportunity to deploy resources” (O’Connell, 2013) accordingly to treat and prevent viral outbreaks.
Before Linthicum’s model was developed, RVF had torn through Africa’s society and economy. In the Horn of Africa in 1997, 100,000 human cases of Rift Valley fever and “an estimated $100 million in economic losses in Kenya alone due to the devastation of livestock” (The Partnership for Public Service, 2013) were recorded. In 2006, subsequent to the development of Linthicum’s model, only 1,000 human cases were reported, and the countries’ economic loss was reduced to $65 million.
Figure 2: Recorded Rift Valley Fever Cases in the Horn of Africa 1997 – 2007
Figure 3: Economic loss as a result of Rift Valley Fever in the Horn of Africa 1997 – 2007
Figure 1 and 2 depict the substantial decrease in recorded Rift Valley Fever cases and the drop in economic loss between 1997 and 2007 in the Horn of Africa. This progress in such a short time span is exemplary and the method has no apparent side effects either. By using an observation method to prepare for a virus influx rather than retaliating against its occurrence, its vectors remain unharmed but those at risk of contracting the disease are safe, therefore making for a sustainable method in preventing the virus. As quoted by Steven Kappes, ARS’ (Agricultural Research Service) deputy administrator, “His work has provided the research findings needed to protect literally millions of people from disease and to save agriculture billions of dollars.” (O’Connell, 2013)
As seen in the evidence presented above, it is clear that in preventing insect-borne diseases, the benefits of using GMOs far outweigh the risks, for the risks have very little impact on their environment and if kept under control, should have no effects at all. Through this, researchers can complete their experiments in a benevolent manner and minimally affect the ecosystems and species involved with their studies. This is evident in the studies of the GM mosquito cohort, transgenic symbiotic bacteria and the Linthicum model. By continually advancing these developments and ensuring the safety of the organisms involved, further progress can be made and insect-borne diseases may be completely eradicated.