Malaria Epidemics and a Rising Climate: A Correlating Relationship?
With a climate change crisis on our hands, the world is scurrying to find ways to minimize the issue, but what if that wasn’t the only thing that can keep us awake at night? Exotic diseases have always been a hot topic in the news, usually pertaining to third world countries overseas; far, far away from us. Exotic disease epidemics have always been an “oh, that’s awful!” subject, but we go on eating our dinners and return to our malaria-free lifestyles within seconds. I experienced these very feelings about many news stories about the epidemics of various exotic diseases in Africa, Israel, and Iraq. The haunting images of the victims did not stick in my mind for long, for I knew that these diseases could never touch me. That was until December 2012 when I read an article online about an outbreak of West Nile virus in the New England area. First there was one, then two, and before long there were about 16 cases. I suddenly felt defenseless; every bug was a pathogen-carrying monster. I was doomed.
So why care? I’m an athletic training major so ailments of the muscoskeletal and organ systems intrigue me. Within my major we learn how to treat, cure, and prevent injury and illness. Naturally, exotic diseases and climate change struck me as a prevention issue that needed solving. I asked myself what research could I do that could answer my questions about the relationships between vector prosperity and the climate changes, and how to stop the exotic diseases from spreading? Also, I try my hardest to stay healthy in day-to-day life, which is normally an easy task because I have a tough-as-nails immune system. My concern for this issue is obvious, I don’t want the spread of exotic diseases to the U.S. jeopardizing my health, and I’m sure much of America feels the same way.
Before I began my research, I approached my topic like any other student would, as simply as possible. I studied and read up on diseases that migrated outside native areas. I never thought of researching migrations patterns of organisms that act as carriers of the diseases and how exotic ailments spread that way. But it made sense; in order to travel, the diseases needed a host. Most of them couldn’t travel through the air (contagiously), so they needed a vector. What better than a human? I asked myself. A mosquito! Of course, they were more numerous and don’t possess the morals we do in the prevention of spreading diseases. They are virtually unstoppable!
But, these diseases could never reach us, could they? The infectious mosquitoes were oceans away. Well, with the climate rising, the mosquitoes, a primary carrier of exotic diseases such as malaria, have begun migrating to the U.S. Because the climate from their native area is so warm, and the climate is changing globally they are able to thrive with less adaptation causing epidemics of diseases that before were mostly isolated to particular areas (Fernando & Wickremasinghe). In short, we are welcoming the mosquitoes with open arms, and there is nothing we can do to stop them.
The concern of this issue is growing with not only the temperature affecting the migration patterns of the mosquitoes, but also because the temperature increase also acts as a steroid for the pathogen-carrying insects. The warmer and more humid the climate, the stronger the mosquitoes become. Their populations increase due to the shortening of their growth cycle, and increased biting rates and in correlation the success of disease transmission, and frequent reproduction. (Balbus). “Pathogens inside the mosquito mature faster in heat, increasing transmission efficiency and the likelihood of the disease being spread” (Andreadis). As disease transmission success rates increase, malaria cases become more prominent in areas where they have been scarce in the past.
Also “going-green” campaigns have become more commonplace over the years. But in my opinion, the threat of a disease seems more real to the public than say the ozone layer, which is farther away than just across the ocean. The significance of this problem has raised awareness of the link between malaria and climate change. The threat of the disease coming to the U.S. catches the public’s attention, and they empathize for the areas where the infectious mosquitoes are native. I chose this topic because I too, am frightened of malaria and feel powerless in the fight against prevention and isolation of the disease because I feel any immediate changes or efforts will only delay the inevitable.
Swatting at mosquitoes is common now, but if the climate rise continues on this dangerous path, the U.S. will soon be enveloped in a cloud of malaria-infested blood-sucking monsters (Fernando & Wickremasinghe). Their growth cycles have accelerated and the populations are increasing as a result. Granted, only the females suck/inject infected blood for obtaining protein for egg production. There has to be a considerable amount of female mosquitoes to cause such damage and spreading of malaria (Bobechko & Stockton). Also, the warm temperatures fuel the mosquitoes and they become like super bugs with their increased potency and disease transmission rate. They have also become more adaptable to different environments making malaria a risk for almost all areas with a temperate-hot climate season.
Other factors as a result of climate change are influencing the mosquito’s migration patterns as well: for example, the melting of ice caps causing the sea level to elevate “approximately 2 mm per year,” globally allows the mosquitoes to thrive (Andreadis). This is because although they are comfortable anywhere from sea level to high altitudes, the moist air from the rise in sea level is favorable to them. Going along with the moist air and rise in sea level, the increased rainfall as a result of climate change hasn’t helped the problem much. Mosquitoes not only thrive in the wet/humid conditions; they breed during it. With the high amount of precipitation the mosquitoes have been breeding more frequently due to the higher quality and number of breeding sites in wet conditions. Lastly, in addition to the increased rainfall as a result of climate change; “climate change greatly influences the El Nino cycle” minimizing the time between storms (Fernando & Wickremasinghe). Due to the high waves and winds from the storms and their increased frequency of late the distribution of the mosquitoes, and indirectly the diseases they transmit has spread out geographically.
However, the U.S. is at an advantage because we are aware of the rising climate and are able to predict our own risk of possible outbreaks of malaria and West Nile virus (CDC). We can plan accordingly, and have treatment and prevention plans ready. Prevention plans already set in motion include recycling, and reducing wastes and greenhouse gas emissions (CDC). The only downfall is that we are unsure how effective global changes to reduce climate change will be, so it becomes a waiting game against the threat of exotic diseases. Hopefully when and if they strike we will be ready.
In short, my early research answered my original question about exotic diseases and climate change. My question is: is there a relationship between the rising climate and the migration of mosquitoes? Indeed there is; there is a linear relationship between the rising climate and the spread of exotic diseases through the mosquito host. As the climate increases the migration of mosquitoes to the U.S. increases because they can adapt to our environment easily because it is not much different from their native conditions. Because this was more of an assumption rather than a question, I knew I had to take my research deeper. I decided to see how other countries coped with the problem and how the U.S. could possibly stop the spreading of the diseases or isolating the vectors. So my new questions are “how have other countries dealt with the exotic diseases? Will their methods prove to be successful for the U.S.? Can we possibly isolate the vectors and at an extension the diseases?”
To my surprise, the U.S. has seen malaria outbreaks in the past, but not so recent that the current generation would remember. From 1882-1949 the U.S. was battling malaria and attempting to eliminate it which they were able to do successfully (CDC). Granted this was an easier task then because the climate was not exactly feeding the mosquitoes existence. Dr. L. L. Williams of the CDC suggested “DDT application to the interior surfaces of rural homes or entire premises in counties where malaria was reported to have been prevalent in recent years” (CDC). By 1949, “the country was declared” malaria free! (CDC). This method worked, yes, but this becomes a problem to the present time. Because the use of DDT is now illegal, what other methods can we use to control the mosquitoes? We turn to other countries for ideas, but unfortunately they have little preventative measures as well. This is due to fact that exotic diseases occur mostly in developing countries in the tropics where medicine has not advanced as quickly as the U.S. A prime example being Africa.
Evidence of the migration of exotic diseases is the epidemic of West Nile Virus in Greece in the summer of 2010. “Human cases of WNV disease had not been previously reported in Greece,” (CDC). 262 patients were reported and of those 262 people 197 of them had the neuroinvasive disease while the other 65 had the West Nile fever (CDC). The significance of this epidemic is that WNV was never previously reported in livestock let alone humans in Greece. To control the issue, scientists began researching how vector control could be executed and regulated those who were donating blood at the time of the incident to ensure their blood was not infectious so the disease would not be spread that way. (CDC)
Since the only remedy (DDT) that seemed to work is now illegal, it leaves us with little hope of eliminating the disease once it reaches us. We will have to rely on the few preventive measures we can take. Personal preventive steps include using bug spray, and avoiding humid environments where mosquitoes thrive. Incorporating the use of insecticide treated nets to block possibly infected mosquitoes is one such step. Also taking measures to protect those who are most at risk for contracting the exotic diseases if bitten. These individuals include pregnant women whose immune systems are suppressed during their pregnancy, children whose immune systems are still developing, those who have diseases that hamper their immune system’s ability to defend their body, and the elderly who have deteriorating immune systems that do not function as well as they should anymore (CDC). Lastly, even though it may not be DDT the use of IRS (indoor residual spraying) may prove to be successful. The insecticide will hopefully be lethal enough to combat mosquitoes that are infectious and even those that are not. Also wearing light colored clothing, long sleeves and pants, and the insertion of screens on one’s door and windows are highly recommended. Preventive measures are always an option, but sometimes stricter actions need to be executed (CDC).
As for vector control (i.e. Greece’s method), there is much you can do, but with little success. The weak stage for the mosquitoes is their larval stage. A variety of intervention methods during this stage of life have been used including source reduction, which basically just limits or eliminates the mosquitoes’ resources by destroying their breeding sites. When destroying their homes and breeding grounds fails, what better way to go then the traditional chemical insecticide? They can either be applied directly to the area or oil can be applied to the water which will “suffocate the larvae and pupae” (CDC). Other methods of this include exposing the area to a toxin from the “bacterium acillus thuringiensis var. israelensis (Bti),” or using an “insect growth regulator,” these work in the same way a traditional insecticide would (CDC). Moving onto biological control we can use certain fungi such as “Laegenidium giganteum or mermithid nematodes to kill the larval mosquitoes”; a little less successful then other methods, but still an option (CDC). These fungi are harmless to humans, but when ingested by mosquitoes they become lethal. They can slow the growth process of the diseases the mosquitoes carry, hamper their flying ability, and even kill them (Bobechko & Stockton).
In the event that the migration of mosquitoes gets worse than we thought, fogging and spraying (insecticide) of large areas may become necessary. Releasing sterile males into the country may also prove to be effective, because it eliminates breeding with the females causing populations to decrease (CDC). Also, in the future scientists hope to have the technology to genetically modify mosquitoes so that they are no longer susceptible to the parasite that causes the exotic diseases they carry; eliminating the disease for good.
Also we can continue with the going green projects that will hopefully halt climate change before it gets any worse and that way when the mosquitoes migrate here the epidemics and outbreaks of the diseases they carry will not be nearly as bad as they could be.
Based on my research, other developed countries have dealt with the epidemics and spread of exotic diseases the same way the U.S. has in the past and will hopefully not have to do again in the future; through the use of insecticides and various methods of vector control, and primarily personal preventative measure to limit the risk of being bitten. Unfortunately, developing countries are limited in their resources, so they must rely on aid from other countries, which is not always an option, so personal preventative actions are primarily their method of disease control. In addition, I have discovered that the easiest way to limit the spread of exotic diseases is not through vector isolation, it is through diminishment of their populations (insecticide, sterile males, biological control, and destruction of breeding sites) , and in the future, genetically modifying mosquitoes so that they are not susceptible to the parasites they carry.
My research did not leave me with unanswered questions, although what the future holds in unknown to everyone. I am unsure if the public’s efforts will be enough to delay/reverse the effects of climate change so that mosquitoes will no longer migrate to the U.S. or other places that will soon have ideal conditions for them. So, I can only hope that the technologies that scientists expect to have for altering the genetic makeup of mosquitoes so they will not be able to carry pathogens will be available soon because this method seemed like the best and most effective method of eliminating exotic diseases if it is successful. However, there is much left to explore in the realm of exotic diseases and climate change. For example, will the climate cause known diseases to warp into something more dangerous? Will mosquitoes start carrying new diseases that require vectors to spread and thrive? These two questions still press in my mind and I hope for everyone’s sake that I’m not the only one who has been asking myself these questions, but I’m sure that scientists from disease control units are already one step ahead than they are letting on.
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