Monday, February 29, 2016

Public Health and Infectious Disease Discussion 4

Half of all people live in cities and due to urbanization and overpopulation face challenges in these urban settings. Although there is a network of community assistance, there is a lot to consider. Humans need to handle complications due to water (sanitation and availability) and food safety, food security (availability). There is a risk of diseases both communicable and non-communicable. Violence, traffic injury and the possibility of being hurt through injury may be increased in urban settings. Humans may abuse animals. Humans may make negative diet choices as they consume food which may be unhealthy. People may exercise less in an urban location. They may gather in larger groups, or travel the world, propagating the spread of disease. Diseases like tuberculosis may increase in large cities like New York City.
Humans are not in contact with nature as much with many living close to urban areas. Because of this, there is a general lack of education regarding animals, even common or local animals. Pollution affects the breathing of humans and animals. Smog may propagate breathing and respiratory issues. Chemical changes in the soil change what can grow in a given area. This is due to stripping of the natural resources such as local flora and detritus. Global warming leads to some strains of bacteria, mold or pathogen becoming abundant.
Keeping animals in large groups, such as large scale cattle, chicken or pig farming propagates disease. Many animals live together in close quarters may provide more opportunity for exposure. This is because there are more animals coming in, so proper isolation procedures and quarantine procedures should be identified and adhered to. Additionally, the animals should be kept on a healthy immunization schedule. They should be kept in sanitary conditions. There are tests and monitoring as well as veterinary services, dewormings, insect repellants and other products that may be used on animals to keep them healthy and disease free. Monitoring the health of animals may not always be done however. Additionally not all locations are strict on their laws regarding food animal production.
Teaching people to properly handle, store and prepare food is vital. People should be educated on proper sanitary conditions, such as hand washing techniques and procedures. Food should be cooked to the proper temperature and maintained as well as later stored as appropriate to the product to prevent disease, mold or other contamination. This provides a more educated populace where programs are in place, however, urbanization in areas where sanitation or proper food preparation is not propagated may not be able to keep as strict a measure over pathogens from food sources.
In the environment urbanization creates many issues, primarily due to development. Habitat loss occurs for animals due to development which leads to a reduced shelter, food availability and other necessities for wild animals. Local extinction rates are high. Many native species are lost. Many groups and organizations seek to reclaim lost wildlands or to preserve what is available but still, urbanization eliminates land available to animals. Weeds, animals, bugs, birds, pathogens, and plants from other regions infect new areas as invasive species. Some local areas enact strict laws to restrict the arrival of invasive species, such as the glassy winged sharp shooter in Napa Valley. Some states, like California, monitor and restrict the incoming plants and animals.
Some animals such as raccoons, sea gulls and pigeons adapt to a life living around humans and may cause issues in an urban environment such as spreading disease, overwhelming amounts of excrement, nesting locations or methods inconvenient to humans or volatile excrement that damages things and more. Some areas preserve nesting areas for wild birds in locations convenient to human locations, provide sanctuaries and promote native bird watching or preservation such as in Lake County California. Opportunistic pests often move in to urbanized areas, leading to potentially more disease propagation and unsanitary conditions. Animals are no longer living in their “cleaner” outdoor environments, rather they are making their homes in human areas. They are exposed to pathogens from humans and the environment. Invasive species bring with them their own internal pathogens, flora and fauna which will spread.
Hunting and fishing can lead to extreme imbalances in the environment. This may include bringing in an invasive species to hunt or provide nourishment for humans and it overruns an area. This can impact the local species. Dogs brought with humans may eliminate local species. Feral and pet outdoor cat populations devastate local birds and other small wildlife.
Humans impact our ocean waters. They promote overacidity of the ocean by producing carbon which is absorbed by the ocean. It leads to the suffering of large scale ecosystems as damaged reefs are unable to sustain life as they once were. Through the oceans changing temperature due to climate change, animals cannot eat or breed as well as they once were. With the loss of kelp beds and reefs wild fish and other oceanic creatures loose area they can survive, as these provide “oasis” within the ocean where life can flourish.
Overfishing by humans especially in urbanized areas leads to a devastating loss of ecosystem stability. The loss of one fish or shark species can have devastating effects in ecosystems on large and small scales. For instance, the loss of sea otters may lead to an overabundance of sea urchins. This leads to an area where only sea urchins thrive with no predator to keep their numbers in check. These barrens or deserts eliminate the ability for certain ecosystems to thrive. Eventually the sea urchins will be the only thing in these areas and we have lost biodiversity. Equipment, boats, sound contamination and debris from humans causes damage to local species. This can be in the form of nets catching dolphins and manatees being damaged by boat propellers.
The ocean is a delicate balance, the loss of one species may lead to another taking over reducing biodiversity and eventually reducing the oceanic health. This may lead to lowered overall production of ocean species and a lowered production of oxygen through marine life oxygen production processes.. Unsanitary keeping conditions or surviving conditions of species can infect it with pathogens which can be passed on. For instance, an animal which consumed a sick fish will pass that sickness onto a human which consumes it. This is especially dangerous in sushi where parasites and pathogens can more easily be passed.
This is not limited to the ocean, in fact, it can certainly happen in lakes and creeks inland. If sanitation is released into the water sources and it is not properly cleaned it can infect the local aquatic life with pathogens and contaminate the food chain. For instance, hepatitis being released near bivalves such as oysters may be absorbed by those animals. When a human later consumes the oyster if it is not properly prepared, it could pass hepatitis to the human. Proper sanitization is key to keeping down disease in large populations. Immunization to help reduce or eliminate certain diseases will also help. Educating the population on how to correctly prepare a variety of foods is vital. Large populations may mean large resources to invest in education for public health and disease prevention.
Humans release poisons, sometimes intentionally, sometimes not. This can have positive and negative effects. For instance, spreading pesticide may kill all the insects in the area, even beneficial ones. However, spreading poisons geared to eliminate ticks in a park may reduce the spread of pathogens such as Lyme disease. In the past, birds have suffered from the effects of DDT and other chemicals. This may lead to a reduced bird population. Other chemicals may reduce their immune system leading to an increased incidence of disease and loss of life.

SOURCE
Urbanization, Biodiversity, and Conservation. Michael L. McKinney. Oxford Journals. Science & Mathematics. BioScience. Volume 52, Issue 10. Pp. 883-890.https://bioscience.oxfordjournals.org/content/52/10/883.full

Oyster-Associated Hepatitis. JAMA Journal of the American Medical Association. September 8, 1975, Vol 233, No. 10 . Benjamin L. Portnoy, MD; Philip A. Mackowiak, MD; Charles T. Caraway, DVM; John A. Walker, MD; Thomas W. McKinley, MPH; Calvin A. Klein Jr, MD. http://jama.jamanetwork.com/article.aspx?articleid=340640

Urbanization and health. Bulletin of the World Health Organization (BLT). http://www.who.int/bulletin/volumes/88/4/10-010410/en/

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