Epidemiology According to John Snow and William Farr Research Paper

Epidemiology According to John Snow and William Farr - Research Paper Example When the second cholera pandemic broke out and reached London in 1832, a number of theories on the causation of such catastrophic spate were proposed, including miasma or â€Å"bad air† and changes in environmental conditions (Morabia, 2001, 150th Anniversary, 2004). However, John Snow, who was a respected medical practitioner specializing in anesthesia and respiratory physiology, questioned the correctness of those theories. He observed that the symptoms were intestinal in nature, abdominal pain is one of the first complaints of the afflicted, accompanied by vomiting, diarrhea, and dehydration (Eyler, 2001). At the same time, treatments that acted specifically in the digestive tract seemed to alleviate early symptoms. From these observations, he proposed that cholera could not be a blood or respiratory infection but an infection of the gut. Snow proposed that the main proponent of transmission was not the soil, nor climate change or miasma as originally suggested, but the ing estion of water contaminated with fecal matter. But this did not convince the medical community. Without definitive data, Snow’s analogy was not good enough. In 1854, another wave of cholera plagued the Soho district yet again. This time, Snow suspected that an infected water pump located in Broad Street brought upon the outbreak. Following his earlier proposal that the cholera infection was from the ingestion of contaminated water and bearing a record of death from Cholera from the General Register Office, he traced the deaths attributed to cholera within the vicinity and found that they drank water from a common water pump in Broad Street. Snow elucidated this by plotting a Cholera spot map showing the areas collectively affected by the epidemic, as well as its proximity to the specific pump in question.  

The Molecular Detection Methods For Plasmodium Falciparum Essay

The Molecular Detection Methods For Plasmodium Falciparum - Essay Example This travels through the blood into the liver where it attacks the liver cells. Here, it matures into a mother cell which also produces other daughter cells within a period of six days. This daughter cells the releases themselves from the mother and attacks the red blood cells (Guerra, Snow and Hay, 2006). Plasmodium Falciparum sometimes prevents the destruction of these red blood cells which have been affected by the virus causing more trouble to the body. This is achieved by sending proteins to the cell membrane of the red blood cell which causes the red blood cells to stick to the walls of the small blood vessels. The cluster of red blood cells may cause blockage in the circulation system The symptoms of malaria usually begin to show after about 10 to 30 days after a mosquito bite. These can either be severe or a little complicated to the person. Small children and expectant mothers are the most vulnerable to the disease. Diagnosis of malaria is, therefore, an important factor in the determination of the presence of the disease. This should be then followed by a correct treatment of the disease. However, the causative virus is still a problem due to its ability to be resistance making malaria a threat to medicine. Several molecular detection methods can be applied to establish the existence of plasmodium falciparum in the body. ... The parasite can also be observed from the smear. A drop of blood is usually placed on a slide and then spread uniformly throughout the slide length to make sure that the cells are spaced up properly in the slide. A definite layer where the cells are spaced far enough to be counted and differentiated is always the best to examine. This layer is referred to as monolayer. It is usually found on the slide’s edge. The slide is then left to air dry and then fixed into the slide by immersing into methanol. It is the stained. Staining helps to differentiate the cells from each other. Romanowsky Wright`s, or Giemsa, is usually the stain that is used to stain the cells. The slide is then viewed under a microscope under a high magnification e.g. x1000. The abnormalities in these cells which in the case of plasmodium falciparum are usually red blood cells are observed and recorded. The parasites appearance can also be observed from the film. Each of the plasmodium species portrays distin guishing characteristics hence can, therefore, be differentiated from each other. The parasites’ appearance is usually preserved in a thin film; this is unlike in thick films, which are mostly used when large volumes of blood are to be observed. They have been found to be more sensitive than the thin films of blood, but separating the parasites here is usually hard. However, it poses its own limitation especially in the diagnosis of malaria in early stages. This is because, in these stages all the parasites appear in a ring like shape hence distinguishing them becomes a problem. This is the trophozoites stage which is a ring shape. Another problem also arises when the amount of time between the blood collection