Preventing infection

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Preventing Infections

2.2 Study Guide [ 2.2 Sequence Assessment 1/21 and 1/22] Ecosystems and Ecological Relationships Invasive Species ● An invasive species is a plant, animal, or organism that is not native to a specific area and causes harm to the environment or human health. Why are they harmful? Invasive species often outcompete native species for food, water, and space. They can spread quickly because they lack natural predators in the new environment. What is their impact on the ecosystem? Invasive species can reduce biodiversity by pushing native species to extinction or by changing the habitat in which native species live. Biodiversity and Its Importance to Ecosystems Biodiversity refers to the variety of life in a specific area, including different species of plants, animals, and microorganisms, and the ecosystems they form. ● Stability: Biodiversity makes ecosystems more resilient to changes such as climate change, diseases, and natural disasters. ● Food chains and webs: A greater variety of species means more sources of food for different animals, helping maintain a balanced food web. For example, a forest with many species of plants and animals can recover from a drought more easily than a forest with fewer species. Predator-Prey Relationships In a predator-prey relationship, one organism (the predator) hunts and eats another organism (the prey). The predator benefits by getting food, while the prey loses its life.The population sizes of predators and prey are often linked. If there are more prey, the predator population may grow, but if too many predators eat the prey, the predator population will decrease. This relationship can be shown in the graph below. ● For example: Lions hunt zebras for food. When there are many zebras, lions have more food and their population can grow. However, if too many lions eat the zebras, the zebra population can decrease. Predator-prey relationships help keep animal populations balanced, preventing one species from becoming too numerous and harming the environment. Ecological Relationships There are several types of relationships between organisms in an ecosystem. These include commensalism, parasitism, and mutualism. Commensalism In commensalism, one organism benefits from the relationship while the other is neither helped nor harmed. An example would be Barnacles and Whales. Barnacles attach to the skin of whales. The barnacles get access to nutrient-rich water while the whale swims, but the whale is not affected by their presence. Parasitism In parasitism, one organism (the parasite) benefits at the expense of the other organism (the host), which is harmed. For example, fleas live on dogs and feed on their blood. The fleas benefit, but the dog may suffer from itching, infections, or even anemia. Another example are tapeworms and humans. Tapeworms live in the intestines of humans and absorb nutrients, leaving the human host malnourished. Mutualism In mutualism, both organisms benefit from the relationship. An example would be bees and flowers: Bees collect nectar from flowers to make honey, while helping the flowers by transferring pollen, which helps them reproduce.

When Europeans met American Indians in the late 15th century, the people of two continents exchanged many beneficial customs and goods. Europeans received New World crops such as potatoes and corn. American Indians acquired cloth and horses. However, besides the beneficial exchanges, Europeans and American Indians often traded deadly germs–bacteria and viruses–for which they had no immunity. Smallpox and Indians Image 1: Smallpox epidemics helped Europeans conquer the Aztec and Incan Empires of Mexico and South America. North American Indians quickly concluded that contact with Europeans often resulted in devastating diseases that caused widespread death. This drawing, made in the 1500s in Mexico, shows how the disease was passed from a European to an American Indian through simple contact. Many of the diseases that were common in Europe were entirely new to the peoples of North America. Diseases such as tuberculosis and measles could be fatal, but Europeans had developed resistance to the disease, so many people survived. However, when European diseases infected American Indians with no previous exposure, the people suffered terribly. The most devastating of these diseases was smallpox which is caused by a virus (Variola major). Smallpox, like many other diseases, had a latent period of about one week between the time the person was exposed to the disease and the time when signs of the disease became apparent. During this time, the sick person might begin a journey and carry the germs along with him. Anyone the person met would be exposed to smallpox. Anything the victim touched including clothing, bedding, or unwashed dishes carried living germs of smallpox. Cotton Mather Image 2: Cotton Mather was a Boston minister. When smallpox threatened Boston, he remembered reading about how the Turks inoculated people with dried material from smallpox blisters. The inoculation usually gave the person a mild case of the disease and future immunity. The procedure was highly controversial, but it helped save the lives of 274 people who were inoculated during the Boston smallpox epidemic of 1721. Symptoms of the disease began with fever, chills, and aches. The fever might raise a person’s temperature from the normal 98.6o to a dangerous 106o. After four days of misery, the victim entered the second stage when large pustules (fluid-filled bumps) appeared on the body. The rash made the person feel as if their skin were on fire. After suffering with the rash for nine days, the victim entered a new stage-if he or she had survived this long. The pustules opened and dried up. Each pustule formed a scab that turned into a scar that marked the person’s face for the rest of his or her life. Complications of smallpox for those who survived might include loss of vision or damage to the lungs, heart, or liver. Waterhouse Image 3: Dr. Benjamin Waterhouse of Harvard University brought Jenner’s smallpox preventative to the United States. It was called vaccination and used cowpox as the infective material. This much milder form of pox gave immunity to smallpox with fewer complications. Dr. Waterhouse encouraged President-elect Thomas Jefferson to promote vaccination. Jefferson responded, “Every friend of humanity must look with pleasure on this discovery, by which one evil more is withdrawn from the condition of man.” (T. Jefferson 12/25/1800 to Benjamin Waterhouse, December 25, 1800) Historians have found evidence of smallpox as far back as 1157 B.C. when the Egyptian pharaoh Ramses V apparently died of smallpox. From Egypt, where scientists believe smallpox began, the disease spread to Asia. Europeans began to experience periodic epidemics of smallpox in the14th century when Crusaders returning from the Middle East brought smallpox to Europe. People who survived the disease were immune and could not get smallpox again. This fact explains why epidemics struck periodically and the disease was not a constant threat to European societies. Smallpox Vaccination 1803 Image 4: Dr. Edward Jenner’s new smallpox vaccination (from cowpox) was widely accepted. This medical image was published by a Spanish physician to teach colonial doctors how to apply the vaccine to native Mexicans. The scratches were supposed to go through several stages of development as evidence that the vaccine had given the patient immunity. Vaccination was very effective in preventing smallpox epidemics among those who received the vaccine. In 1520, while Cortés was trying to conquer the Aztecs, smallpox broke out among the Spaniards and was transferred to the Aztecs. By 1527, the disease had migrated through Central America to Peru where it helped Pizarro conquer the Incas. (See Image 1.) In 1633, smallpox infected American Indians living near the English colony of Plymouth, Massachusetts. The disease traveled very quickly to tribes living far inland from the English colonies. In 1721, a smallpox epidemic threatened the English colonists of Boston. (See Image 2.) Cotton Mather, a Boston minister, wanted to inoculate people against the disease. He knew that Turkish healers took material from a dried smallpox scab and injected it into the body of a healthy person by scratching the surface of the skin. The patients developed a mild form of the disease from which they recovered. The procedure was highly controversial in Boston where about 280 Bostonians accepted inoculation. The epidemic infected more than half of the people living in Boston at the time. About 15% of those who got sick died of the disease. Among those who were inoculated, only six (2%) died of smallpox. The practice of inoculation spread to other English colonies, but not to the American Indian tribes living near the colonies. Late in the 18th century, British doctor Edward Jenner recognized that people who milked cows never came down with smallpox. They had already been infected with cowpox, a similar, but much milder disease that gave them immunity to smallpox. In 1796, Jenner inoculated a young man with cowpox virus he had collected from a milkmaid. The young man had a mild infection for less than 24 hours and recovered. Jenner’s efforts resulted in a widespread acceptance of vaccination (vaccine comes from Latin words meaning “taken from a cow”). By 1800, many Americans were receiving smallpox vaccinations. (See Image 3.) President Thomas Jefferson supported and encouraged the vaccination program in major American cities. (See Image 4.) By the middle of the 19th century, smallpox was under control, but broke out from time to time among unvaccinated people. Bismarck, Dakota Territory, experienced a small outbreak of smallpox in 1882. American Indians, however, were still subject to the disease in its most dangerous form.

Marine and Coastal Processes.What are the hazards that usually occur along marine and coastal areas? Coastal processes, such as waves, tides, sea level changes, crustal movement, and storm surges will result to coastal erosion, submersion, and saltwater intrusion. Coastal Erosion. Coastal erosion is the wearing down of the coastlines by the movement of wind and water. It is not a constant process; instead, the rate of erosion depends on other events such as cyclones. When cyclones occur along coastal areas, the winds and waves carry the sediment away from the shoreline. Shorelines play an important role to society. They are used in transportation, fishing, and tourism. Therefore, preventing coastal erosion is of utmost priority. There are three main classifications of stabilizing the shoreline: hard stabilization, soft stabilization, and retreat. 1. Hard stabilization is done by building structures that will slow down the erosion on areas that are prone to erosion. Examples of hard stabilization structures are jetties, sea walls, and breakwaters. Though they may slow down the erosion in one area, it may hasten the erosion in other areas. 2. Soft stabilization includes the process of beach nourishment, wherein sand from an offshore location is brought to an area with a receding shoreline. It does not make use of structures like the ones used in hard stabilization. 3. Retreat is the option taken by residents near areas where coastal erosion is already severe. At this point, the authorities no longer attempt to save the shoreline but rather limit the amount of human interference in the area. Submersion. Coastal erosion happens because of the interaction of the winds and waves on the shoreline. Submersion, on the other hand, happens because of the changes in the sea level, specifically, when it rises dangerously above the normal level. This is all due to the increase in the global temperature, which, in turn, melts the glacial deposits and increases the overall sea level. Another factor that may cause submersion is the vertical movement of the plates. Landmasses can be uplifted, which can also cause changes in the sea level. It can also be caused by tsunamis and storm surges. Submersion will most likely occur in reclaimed lands. These are the areas that were originally part of oceans, riverbeds, or lakebeds. They are low-lying flatlands, so even a small rise in sea level can cause great damage on the land. To prevent this from happening not only in reclaimed lands but also in coastal areas, a hard stabilization technique is used. Sea walls are built along the coastline to protect the land from being easily flooded. Aside from sea walls, dikes can also help prevent flooding. The government can also upgrade the infrastructures built in coastal areas, regenerate mangroves, or relocate the people. There are also other proposed strategies to mitigate coastal submersion, such as imposing of setback policies and construction regulations and creating adaptive plans for coastal management. Saltwater Intrusion. In coastal areas where there is an interaction between saltwater and fresh water, saltwater intrusion is one of the hazards that are evident in that area. Saltwater intrusion is the movement of saltwater into the freshwater aquifer. The natural flow is that the fresh water, which is less dense, moves towards the denser saltwater. But if the fresh water is being withdrawn faster than it is being replenished, then there will be a change in pressure and saltwater intrusion will occur.There are a few ways of preventing saltwater intrusion. One is to stop using the well where fresh water has been depleted and let the groundwater replenish naturally via the water cycle. The other method is to build two wells: a pumping well-built farther inland and an injection well-built closer to the coast. Using the injection well, fresh water is pumped into the aquifer to prevent the saltwater from intruding. The different marine and coastal hazards often occur in the Philippines, being an archipelago with the longest coastline. Manila Bay is one of the coastal areas of the Philippines that is facing various threats from both natural and anthropological causes. Saltwater intrusion occurs due to uncontrolled withdrawal of groundwater to be used by residential, commercial, and industrial areas built around the bay. It is also frequently flooded due to poor drainage systems and improper disposal of waste. Since Manila Bay is shared by four coastal provinces, four noncoastal provinces, and the National Capital Region, each local government unit and national agencies need to collaborate in planning, developing, and managing its marine and coastal resources. And it is not only Manila Bay but other parts as well, for as long as they are in coastal areas, hazards will mostly likely occur if not immediately addressed.

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