The Impact of Mosquitoes on World Health
In the medical field, mosquitoes are perhaps the greatest scourge of any insect pest. In much of the world, mosquitoes are the number-one public health menace, it being estimated that they transmit disease to more than 69 million people every year. They are a common pest in virtually every corner of the world, since they have evolved to adapt to virtually any climate and condition.
But there’s one piece of good news: AIDS is among the diseases they do not transmit. HIV virus is specific to human bodily fluids; it requires blood, sexual fluids, or breast milk to live. That’s one disease off the list, but a small comfort when the mosquito is able to give you an astounding array of other diseases, infections, and parasites.
The mosquito-borne diseases are mostly of the zoonotic variety. “Zoonotic” means a disease can be transmitted across multiple species, as opposed to being restricted to one species. Mosquitoes stand alongside fleas, ticks, lice, and other blood-sucking parasites as nature’s handiest methods of porting diseases from one creature to the next. It could even be argued that if there were no blood-sucking vermin, there would be no such thing as a zooanotic disease!
The one getting the most attention currently in the United States is the West Nile virus. Almost anything with warm blood seems to be able to play host to a West Nile virus. It’s preferred hosts are birds, but it is transmittable to humans, horses, dogs, cats, bats, chipmunks, skunks, squirrels, and rabbits, and we’re probably going to discover more before the story’s over. And of course, the main carriers of West Nile are mosquitoes. West Nile Virus, like HIV, has no known human vaccine at this time. It was first discovered in Uganda in 1937, and first appeared in North America in the year 1999. An interesting fact is that crows are particularly susceptible to it, and so the sudden deaths of many crows in an area is a sign that there could be a local West Nile outbreak. Thus, crows serve as a kind of “canary in a coal mine” warning of a West Nile outbreak.
The list of other diseases that you can catch from a mosquito bite seems to go on forever. Take a deep breath and get ready to say: yellow fever, dengue fever, epidemic polyarthritis, Rift Valley fever, Ross River Fever, and don’t forget to mention malaria. Malaria, a historically dangerous menace to the human population, has always been linked to mosquitoes. One historic epidemic in particular was the Panama Canal project, which had trouble with a malaria outbreak. This incident alone contributed to the 27,000 deaths associated with that project.
Now here’s one fact that should be on the final exam: What is the link between mosquitoes and elephantiasis? Lymphatic Filariasis, the parasite, is transmitted by mosquito bite as well. This particular infection is limited to tropical regions, and causes symptoms reminiscent of the famous “Elephant Man”, although the disease actually affecting the Elephant Man was something different.
The dramatic threat posed by mosquitoes to humans has led to all varieties of drastic measures to ward them off. The things that work are mosquito netting, repellents containing the chemical DEET (N,N-diethyl-meta-toluamide), clothing treated with Permethrin repellents, and citronella candles and torches. Now that we’ve taken care of what works, the following is a list of urban legends for repelling mosquitoes which most definitely do not work. If you catch a patient relying on one of these methods, inform them that it’s been de-bunked.
ULTRASONIC DEVICES: They do not work, not only for mosquitoes, but for repelling anything at all. There is not a single shred of scientific evidence anywhere to show that any living creature on Earth consistently avoids the source of an ultrasonic noise. The U.S. Environmental Protection Agency recently conducted a series of tests spanning two years trying many types of ultrasound devices which are purported to repel mosquitoes. Their testing grounds were the mosquito-ridden area around Chesapeake Bay. Their findings were that not one of the devices had any effect on mosquitoes at all. Various studies have been done in universities which produced the same results. Both the EPA and the U.S. Postal Service have begun prosecuting manufacturers of ultrasonic repelling devices because they are making unsupported claims for their products.
VITAMIN B: Even though vitamin B, particularly B6, has been shown to be effective against other kinds of blood-sucking vermin like fleas, it doesn’t work against mosquitoes. Vitamin B works to protect your pet against fleas because it makes the dog’s blood and skin taste bad to the fleas. Mosquitoes aren’t fazed in the least, even if you douse yourself in a barrel of brewer’s yeast.
GARLIC: Why is it that every time you go to look up ways to repel something, garlic always pops up? Why did it have to be the garlic clove at the center of so many legends? Why not celery or oranges or corn syrup? But anyway, garlic doesn’t repel mosquitoes either. It is a tasty seasoning, however.
BATS: While bats are marvelous, misunderstood, and endangered species and building a bat house is something you shouldn’t discourage, bats, sadly, do not make an effective mosquito-killer. Bats do help farmers by gobbling up a wide range of other destructive insect pests, but mosquitoes constitute less than one percent of a bat’s diet. This is because a mosquito simply isn’t big enough to satisfy a bat-sized appetite.
INCENSE: Now this is just plain silly. Incense, at least the stick kind which you can buy at the store, attracts mosquitoes rather than repels them. This myth arises from the confusion with citronella candles and torches, which do repel mosquitoes.
BUG ZAPPERS: Oh, no, I hear you cry, those electric purple bug zappers really do kill mosquitoes, I’ve seen them! Yes, along with completely innocent and even beneficial species such as moths, bees, ladybugs, and dragonflies, and it’s the dragonflies which, by the way, really are the greatest natural predators of mosquitoes! If a bug zapper gets a mosquito, it was pure luck that the mosquito just happened to blunder into it. You would need about a hundred of them around you to keep from being bitten.
Good luck in fighting them. Remember that eradicating the mosquito menace is difficult because they were here at least 165 millions years before we were!
Josh Stone
http://www.articlesbase.com/health-articles/the-impact-of-mosquitoes-on-world-health-136895.html
February 22nd, 2010 at 4:27 am
tell me what you think about my explanation of global warming.?
What Is Climate Change?
Global climate change is caused by the accumulation of greenhouse gases in the lower atmosphere. The global concentration of these gases is increasing, mainly due to human activities, such as the combustion of fossil fuels (which release carbon dioxide) and deforestation (because forests remove carbon from the atmosphere). The atmospheric concentration of carbon dioxide, the main greenhouse gas, has increased by 30 percent since preindustrial times.
Projections of future climate change are derived from global climate model or general circulation model (GCM) experiments. Climatologists of the Intergovernmental Panel on Climate Change (IPCC) review the results of these experiments for global and regional assessments. It is estimated that global mean surface temperature will rise by 1.5° to 3.5° C by 2100. This rate of warming is significant. Large changes in precipitation, both increases and decreases, are forecast, largely in the tropics. Climate change is very likely to affect the frequency and intensity of weather events, such as storms and floods, around the world. Climate change will also cause sea level rise due to the thermal expansion of the oceans and the melting of the mountain glaciers. Global mean sea level is anticipated to rise by 15 to 95 centimeters by 2100. Sea level rise will increase vulnerability to coastal flooding and storm surges. The faster the climate change, the greater will be the risk of damage to the environment. Climatic zones (and thus ecosystems and agricultural zones) could shift toward the poles by 150 to 550 kilometers by 2100. Many ecosystems may decline or fragment, and individual species may become extinct. The IPCC Second Assessment report concludes that climate change has probably already begun.
Impacts on Health
To assess the potential impacts of climate change on health, it is necessary to consider both the sensitivity and vulnerability of populations for specific health outcomes to changes in temperature, rainfall, humidity, storminess, and so on. Vulnerability is a function both of the changes to exposure in climate and of the ability to adapt to that exposure.
Science classically operates empirically, via observation, interpretation, and replication. However, having initiated a global experiment, it would not be advisable to wait decades for sufficient empirical evidence to describe the health consequences. Risk assessment must therefore be carried out in relation to future environmental scenarios. The traditional "top-down" approach is to answer the question, "If climate changes like scenario X, then what will be the effect on specific health outcomes?" In contrast, "bottom-up" approaches begin with the question, "How much climate change can be tolerated?"
It is important to distinguish between "climate and health" relationships and "weather and health" relationships. Climate variability occurs on many time scales. Weather events occur at daily time scale and are associated with many health impacts (e.g., heatwaves and floods). Climate variability at other time scales also affects health. In particular, the El Niño Southern Oscillation has been shown to influence interannual variability in malaria, dengue, and other mosquito-borne diseases. Climate change is the long-term change in the average weather conditions for a particular location. Climate change will become apparent as a change in annual, seasonal, or monthly means. Thus, incremental climate change will be superimposed upon the natural variability of climate in time and space.
Natural Disasters. Climate change will increase the risk of both floods and droughts. Ninety percent of disaster victims worldwide live in developing countries, where poverty and population pressures force growing numbers of people to live in harm’s way—on flood plains and on unstable hillsides. Unsafe buildings compound the risks. The vulnerability of those living in risk-prone areas is perhaps the single most important cause of disaster casualties and damage.
Water Quality and Quantity. Human health depends on an adequate supply of potable water. By reducing fresh water supplies, climate change may affect sanitation and lower the efficiency of local sewer systems, leading to increased concentrations of pathogens in raw water supplies. Climate change may also reduce the water available for drinking and washing. In developed countries, the anticipated increase in extreme rainfall events, which may be associated with the outbreaks of diarrheal diseases, may overwhelm the public water supply system. Flooding is likely to become more frequent with climate change and can affect health through the spread of disease. In vulnerable regions, the concentration of risks with both food and water insecurity can make the impact of even minor weather extremes (floods, droughts) severe for the households affected. The only way to reduce vulnerability is to build the infrastructure to remove solid wast
February 22nd, 2010 at 9:29 am
Impressive, nice balanced approach to the issues. Perhaps add some more about sea level rise making costal cities vulnerable, lots of valuable real estate becoming unusable, populations having to move. Especially Bangladesh. Frankly, couldn’t have written better myself, no obvious scientific bloopers. No mention of tipping points?
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February 22nd, 2010 at 9:31 am
You’ve missed out the important impact of one billion cattle breathing out methane having a greater effect as a greenhouse gas than all the CO2 emitting cars.
There is hope on the horizon with a new portable water filter which is cheap to produce good for 6,000 litres before losing effectiveness, and filters out all bacteria and even the tiny smallpox virus.
In other words, you’ve missed some important facts, painted a rather black picture with no hope, and there may even be benefits to global warming which you haven’t touched upon. People need some optimism if this article is aimed at improving the situation.
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February 22nd, 2010 at 9:33 am
Good job – just a few details are a little bit off.
The increase in CO2 has been closer to 40% (280 ppm to 388 ppm).
http://climate.nasa.gov/
The IPCC warming projections are a bit out of date. Based on recent studies, it’s more like 2-7 degrees Celsius by 2100, depending on how much we reduce CO2 emissions in the meantime.
http://climateprogress.org/2008/12/21/hadley-study-warns-of-catastrophic-5%C2%B0c-warming-by-2100-on-current-emissions-path/
http://globalchange.mit.edu/resources/gamble/
Similarly, the IPCC sea level rise estimates are a bit out of date and conservative. Recent studies show it could be as high as 2 meters by 2100, but most likely it will be around 1 meter.
http://www.sciencemag.org/cgi/content/abstract/321/5894/1340
http://www.nature.com/ngeo/journal/v1/n1/full/ngeo.2007.28.html
http://www.pik-potsdam.de/~stefan/Publications/Nature/rahmstorf_science_2007.pdf
But other than those few details, you did a nice job.
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February 22nd, 2010 at 9:35 am
Ya its pretty good… if global warming was real, but it is a JOKE!
Summer in Arizona is 115 degrees, it was last summer and it will be next summer. And FYI last winter was as cold as I’ve felt it in a long time!
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February 22nd, 2010 at 9:37 am
Can you explain to me how they predict a rise in mean temperature by 2100 when weather forecasters can only give 10 day forecasts and they are still sometimes wrong? I would really appreciate it. Thanks!
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February 22nd, 2010 at 9:39 am
Good keep it up . You can also add how the green house effect is essiansial for our lives and how is it harmfull .
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February 22nd, 2010 at 9:41 am
It was simplistic and not accurate. The part about greenhouse gases accumulating in the lower atmosphere was meaningless and completely untrue relative to any other portion of the atmosphere. In spite of what socialist political activists say, the IPCC always overestimates and they overestimate in a manner that renders them a joke and a bad joke at that.
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February 22nd, 2010 at 9:43 am
Very well written and generally accurate synopsis of what the issue is all about. A few details could be reconsidered as suggested above, but some of these are not etched in stone anyway.
CO2 is not the main greenhouse gas. Water Vapor is. CO2 is the greenhouse gas with the most relevant Global Warming Potential (GWP)
NOTE:
Weather forecasting is an initial condition problem, climate prediction is a boundary condition problem. Very different. That weather forecasting skill deteriorates rapidly with advancing time beyond 3 days says nothing about the skill of climate prediction decades into the future.
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February 22nd, 2010 at 9:45 am
its long but nice, if you look back you can see what has happened on earth in history from accumulations of green house gasses, we are not the first to throw carbon in the air.
the earth has been through far worse extrenes than we will ever produce, and it has always stabalized back to pretty much what we have now.
i think conditions will become tough enough some day for us to become concerned enough to take actions, but people need to realize the earth likes to be hot and wet, it was like that when the dinosaurs were here, for millions of years, but the planet took about a billion years of stabalizing to that point, a million years is not much if you think the planet, has been through major upheavles and always came back to be stable, and it has done so for maybe 2 billion years
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February 22nd, 2010 at 9:47 am
Global warming isn’t caused by gasses in the atmosphere, it’s caused by the sun.
It’s been warmer than now in recorded history, and those times were very prosperous for the people.
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February 22nd, 2010 at 9:49 am
lMost people’s explanation or understanding of global warming comes from a non-scientific point of view like the one you cut and pasted.
http://www.answers.com/topic/climate-change
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