Parasites

Naegleria fowleri

Description: Naegleria fowleri is a free-living excavate form of protist typically found in warm bodies of fresh water, such as ponds, lakes, rivers, and hot springs. It is also found in soil, near warm water discharges of industrial plants, and minimally chlorinated swimming pools.

Life Cycle: It exists in nature in three forms: a flagellate, an ameboid and a cyst:

• Flagellate stage: A biflagellate form occurring when trophozites are exposed to a change in ionic concentration such as placement in distilled water. The transformation of trophozoites to flagellate form occurs within a few minutes.


• Trophozoite stage: The reproductive stage of the protozoan organism, which grows fastest at around 42°C and proliferates by binary fission. The trophozoites are characterized by a nucleus and a surrounding halo. The trophozoites travel by pseudopodia, temporary round processes which fill with granular cytoplasm. The pseudopodia form at different points along the cell, thus allowing the trophozoite to change directions. In their free-living state, trophozoites feed on bacteria. In tissues, trophozoites phagocytize red blood cells and white blood cells and destroy tissue.




• Cyst Stage: Trophozoites encyst due to unfavorable conditions. Factors that induce cyst formation can include food deprivation, crowding, desiccation, accumulation of waste products, and cold temperatures. N. fowleri has been found to encyst at temperatures below 10°C.
  

Infection and Treatment: In humans, N. fowleri can invades the central nervous system via the nose. The penetration initially results in significant bleeding of the nasal passages. From there, amoebae climb along nerve fibers and into the brain. The amoebae begin to consume the cells of the brain using a unique sucker apparatus. It then becomes pathogenic, causing primary amoebic meningoencephalitis (PAM). PAM is a syndrome affecting the central nervous system, characterized by changes in olfactory perception (taste and smell), followed by vomiting, nausea, fever, headache, and the rapid onset of coma and death in two weeks. PAM usually occurs in healthy children or young adults with no prior history of immune compromise who have recently been exposed to bodies of fresh water. Amphotericin B is effective against N. fowleri in vitro, but the prognosis is not good for those that contract PAM, and survival remains less than 1%.

Video showing the Naegleria Flowleri in action: http://animal.discovery.com/videos/monsters-inside-me-the-brain-eating-amoeba.html

Schistosoma mansoni

Description: Schistosoma mansoni is a significant parasite of humans, a trematode that is one of the major agents of the disease schistosomiasis. The schistosomiasis caused by Schistosoma mansoni is intestinal schistosomiasis. Schistosomes are atypical trematodes in that the adult stages have two sexes and are located in blood vessels of the definitive host. Most other trematodes are hermaphroditic and are found in the intestinal tract or in organs, such as the liver. The lifecycle of schistosomes includes two hosts: a definitive host (i.e. human) where the parasite undergoes sexual reproduction, and a single intermediate snail host where there are a number of asexual reproductive stages.

Life Cycle: Eggs of the parasite are emitted in the feces and into the water, where the eggs hatch. The hatching happens in response to temperature, light and dilution of feces with water. Once hatched, it searches for a suitable freshwater snail to act as an intermediate host and penetrates it. Following this, the parasite develops via a so-called mother-sporocyst and daughter-sporocyst generation to the cercaria. The purpose of the growth in the snail is the numerical multiplication of the parasite. From a single hatched egg, results a few thousand cercaria, every one of which is capable of infecting humans.
The cercaria emerge from the snail during daylight and they propel themselves in water and actively seek out their final host. When they recognize human skin, they penetrate it within a very short time. This occurs in three stages, an initial attachment to the skin, followed by the cercaria creeping over the skin searching for a suitable penetration site, often a hair follicle, and finally penetration of the skin into the epidermis using proteolytic secretions from the cercarial post-acetabular, then pre-acetabular glands. On penetration, the head of the cercaria transforms into an endoparasitic larva, the schistosomule. Each schistosomule spends a few days in the skin and then enters the circulation starting at the dermal lymphatics and venules. Here they feed on blood, regurgitating the haem as haemozoin. The schistosomule migrates to the lungs (5–7 days post-penetration) and then moves via circulation through the left side of the heart to the hepatoportal circulation (>15 days) where, if it meets a partner of the opposite sex, it develops into a sexually mature adult and the pair migrate to the mesenteric veins. Such pairings are monogamous.

Treatment: Diagnosis of infection is confirmed by the identification of eggs in stools. Currently there are two drugs available, Praziquantel and Oxamniquine, for the treatment of schistosomiasis.

Ascaris lumbricoides

Description: Ascaris lumbricoides is the giant roundworm of humans, belonging to the phylum
Nematoda. An ascarid nematode, it is responsible for the disease ascariasis in humans, and it is the largest and most common parasitic worm in humans. A quarter of the human population is estimated to be infected by this parasite. Ascariasis is prevalent worldwide and more so in tropical and subtropical countries.

Life Cycle: Roundworm infections in humans occur when an ingested infective egg releases a larval worm that penetrates the wall of the duodenum and enters the blood stream. From here, it is carried to the liver and heart, and enters pulmonary circulation to break free in the alveoli, where it grows and molts. In 3 weeks, the larvae pass from the respiratory system to be coughed up, swallowed, and thus returned to the small intestine, where they mature to adult male and female worms. Fertilization can now occur and the female produces as many as 200,000 eggs per day for a year.

Treatment: Most diagnoses are made by identifying the appearance of the worm or eggs in feces. Due to the large quantity of eggs laid physicians can diagnose using only one or two fecal smears. Infections can be treated with drugs called ascaricides. The treatment of choice is Mebendazole.

Nuclear Energy

Karen Silkwood (February 19, 1946 – November 13, 1974) was an American labor union activist and chemical technician at the Kerr-McGee plant near Crescent, Oklahoma, United States. Silkwood's job was making plutonium pellets for nuclear reactor fuel rods. She discovered what she believed to be numerous violations of health regulations, including exposure of workers to contamination, faulty respiratory equipment and improper storage of samples. She also believed the lack of sufficient shower facilities could increase the risk of employee contamination. In the summer of 1974, Silkwood testified to the Atomic Energy Commission (AEC) about these issues, alleging that safety standards had slipped because of a production speedup which resulted in employees being given tasks for which they were poorly trained. She also alleged that Kerr-McGee employees handled the fuel rods improperly and that the company falsified inspection records. On November 5, 1974, Silkwood performed a routine self-check and found almost 400 times the legal limit for plutonium contamination. She was decontaminated at the plant and sent home with a testing kit to collect urine and feces for further analysis. The next morning, as she headed to a union negotiation meeting, she again tested positive for plutonium. This was surprising because she had only performed paperwork duties that morning. She was given a more intense decontamination. The following day, November 7, 1974, as she entered the plant, she was found to be dangerously contaminated — even expelling contaminated air from her lungs. A health physics team accompanied her back to her home and found plutonium traces on several surfaces — especially in the bathroom and the refrigerator. The house was later stripped and decontaminated. Silkwood, her partner and housemate were sent to Los Alamos National Laboratory for in-depth testing to determine the extent of the contamination in their bodies. Silkwood herself asserted that she was the victim of a malicious campaign, and that the testing jars she had been given were laced with plutonium. Kerr-McGee's management asserted that she had contaminated herself in order to paint the company in a negative light. None the less, Silkwood said she had assembled a stack of documentation for her claims. She now decided to go public with this evidence, and made contact with a New York Times journalist prepared to print the story. On November 13, 1974 she left a union meeting at the Hub Cafe in Crescent. Another attendee of that meeting later testified that she did have a binder and a packet of documents at the cafe. Silkwood got into her car and headed alone for Oklahoma City, about 30 miles (48 km) away, to meet with New York Times reporter. However, later that evening, Silkwood's body was found in her car, which had run off the road and struck a culvert. The car contained no documents. She was pronounced dead at the scene from a "classic, one-car sleeping-driver accident".
…Later, Silkwood's father and children filed a lawsuit against Kerr-McGee on the behalf of her estate. The jury rendered its verdict of US $505,000 in damages and US $10,000,000 in punitive damages.

Similar to Karen Silkwoods controversial story that gives light to large corporation corruption, Erin Brockovich is an American legal clerk and environmental activist who, despite the lack of a formal law school education, was instrumental in constructing a case against the Pacific Gas and Electric Company (PG&E) of California in 1993. The case alleged contamination of drinking water with hexavalent chromium, also known as chromium(VI), in the southern California town of Hinkley. At the center of the case was a facility called the Hinkley Compressor Station, part of a natural gas pipeline connecting to the San Francisco Bay Area and constructed in 1952. Between 1952 and 1966, PG&E used hexavalent chromium to fight corosion in the cooling tower. The wastewater dissolved the hexavalent chromium from the cooling towers and was discharged to unlined ponds at the site. Some of the wastewater percolated into the groundwater, affecting an area near the plant approximately two miles long and nearly a mile wide. The case was settled in1996 for $333 million, the largest settlement ever paid in a direct action lawsuit in US history.

Aside from these two influential ladies stories, The Three Mile Island is best known for having been the site of the worst civilian nuclear accident in United States history on March 28, 1979. The accident was a result of a cooling system malfunction that caused a partial melt-down of the reactor core. This resulted in the release of a significant amount of radioactivity into the environment. Athough the accident did not induce any adverse health effects, it did encourage federal changes. Public reaction to the event was probably influenced by the release of the movie The China Syndrome 12 days before the accident, depicting an accident at a nuclear reactor. Communications from officials during the initial phases of the accident were felt to be confusing. The accident further influenced anti-nuclear safety concerns among activists and the general public, resulted in new regulations for the nuclear industry, and has been cited as a contributor to the decline of new reactor construction that was already underway in the 1970s.

In all three of these stories, environmental movement and responsibility (or lack there of) can be seen as a detrement to our society and to our environment. Not only are environmental companies influencing our standard of living, as seen above, but they are also influencing our environment and in turn responsible for global warming as a result. It can be said that the Three Mile Island accident, which tainted the public's opinion and "fueled" activists rants regarding fossil fuel vs. Nuclear energy, and the two individual stories above regarding environmental corporation corruption, has ignited a society dependent solely on coal and oil and has petrified society away from other energy sources. These factors are the largest contributors to global warming in our environment today and are proven very detrimental to our way of life.

Global Warming- Fact or Fiction?

Global warming can be defined loosely as Earth's increase of near surface air and water temperature since the mid 20th century. Greenhouse gases, radiative forcing, and atmospheric CO2, as well as aerosols and soot and solar variation are known external forces that effect climate response. There are several views and controversies with global warming which stem through politics, public opinion and scientific knowledge. Many believe that population and humans in general show a direct link to the effect of climate change. While others feel that climate change is a natural effect that has no bearing on human interference.

Carbon Footprint

America Going Green

NY Times- Global Warming

Chapter 1
Rachel Carson describes a town that once was pristine and harmonious, but now is ravaged with death and misfortunes. The story is fictional, but has attributable scenarios to various towns in America over the years related to pollution and human interference of the environment.

Chapter 2
She gives a good introduction to the use of pesticides and the causes of problems that pesticides account for in the United States. You also get a good sense of history with respect to bugs and why people have intervened in this relationship of crops and insects.

Chapter 3
Carson describes the contamination of humans to harsh chemicals in this chapter. She also goes into detail about specific chemicals and their properties explaining the damage that they can cause.

Chapter 4
In this chapter, water and water sources are described as far as how they are affected by pesticides. She presents water as a fundamental natural resource and describes the path of chemical contamination from a simple microorganism, to fish, all the way to human consumption.

Chapter 5
This chapter deals with soil, talking about how it is made up from both organic and non organic material. Plants and vegetation needs soil to grow and contamination of this fundamental substance can throw off the entire cycle of the system itself.

Chapter 6
This chapter describes plants and how weed killers and herbicides affect them. Humans depend on plants in the big scheme of things and she explains that although humans try to control certain sagebrush while growing crops, grass, etc, that they are actually hurting plants that were not meant to be. She explains various alternatives to using these harsh methods to control weeds, etc.

Chapter 7
"Needless Havoc" was described in this chapter and is decided as massive spraying of insecticides to kill target insects but which kills a variety of life in its path. She gives an example of the Japanese beetle in the Midwest where massive spraying was done which "needlessly" killed huge numbers of wildlife.

Chapter 8
This chapter talks about birds and how they are killed and effected by mass spraying operations since birds directly eat plants and insects. She talks specifically about Dutch elm disease with respect to DDT because many birds were killed in this process without the success of DDT to stop the elm disease significantly at all.

Chapter 9
A description of efforts in Canada to stop the spruce budworm that was threatening forests. However all river life was effected as a result. A massive killing of salmon took place when this effort to kill the budworm took place. She gave examples of alternatives that would have prevented this situation: natural parasites of the insect or introduction of a natural disease to the insect.

Chapter 10
This chapter discusses aerial campaigns against the gypsy moth. Massive spraying of insecticides took place from airplanes, however the effect of this was not good. It effected farms and produce that were in harms way as well as Innocent bystanders who had to endure the spraying as well. This event seems to be one of the reasons people have changed their viewpoints on insecticide spraying methods.

Chapter 11
This chapter discusses the individuals responsibility and the lack of understanding people have about pesticides and chemicals in their own homes. A lot of the contamination comes from small amounts from individuals as well. People are encouraged to use these chemicals and are not made aware of the detrimental effects.

Chapter 12
This chapter talks about the human body and how poisons and chemicals effect its "ecology." Carson discusses diseases and compares them to that of human introduced chemical and radiation problems that increase risk and Public Health issues that already exist.

Chapter 13
Carson discusses cells in this chapter with respect to how chemicals can disrupt and manipulate cell structure and function in living organisms. This can cause mutation, deletion, etc, in cells that are vital to our existence. She links cancer and other mutations to this kind of damage caused by chemicals.

Chapter 14
Carson discusses the link between cancer and insecticides, pesticides, and herbicides that are used in our environment. Adaptation and evolution happens very slowly, however with the introduction of chemicals that cause cell mutation, etc, this process must happen relatively rapidly. It is for this reason that cancer causing effects are discussed.

Chapter 15
This chapter discusses how nature has the ability to "fight back" when chemicals are introduced into the environment. Nature already has certain insecticides in place and introducing synthetic ones proves to not always be successful. Insects have the ability to quickly develop resistance to certain chemicals. She suggests scientists take note of these natural controls to deal with pests, insects, and other interferences.

Chapter 16
This chapter discusses the danger of insects developing select resistance to insecticides. The problem with insecticides is that not only do they kill the target but also possibly its natural predetor. If this is proven to be the case and the target insect develops a resistance to the chemical being used, the problem of control might turn into an ''avalanche" like issue.

Chapter 17
Carson concludes the book with the notion of alternative methods to chemical control of our environment. We do not know the long term effects or overall outcome of what we are injecting into our world.