On page 119, Maolem begins to discuss how microbes move around from host to host, and how some microbes such as the cold virus need their host to be relatively healthy in order to survive and continue to spread to new hosts, while others such as malaria can attack with no limits at its host. This is a technique used by the microbe to ensure that it has the best chance of spreading. Expanding on the microbes that do not care for the host's condition, Maolem states that evolution favors parasites who can exploit the host to the fullest. This relates to Big Idea 4 as the microbes are interacting with the host.
Research another virus, and state to what extent the virus attacks the host. Also, how can the virus be contained? In the text Maolem also states that outbreaks such as Cholera 1991 in South America can be contained with simple procedures such as water safety, or malaria with mosquito nets. While this definitely sounds possible, given the current state of some areas, is it viable/possible to truly contain these outbreaks if and when they happen?
(Name- Ray Lee, Email- rclee4@students.d125.org )
When looking at different pathogens and their effect on the host, it is important to identify what the characteristics of the pathogen are. For example, different types of viruses cause colds. Viruses cannot reproduce on their own, which means the viruses need a host cell to survive and reproduce. If the host is dead, a virus cannot use the machinery of the host cell to replicate. (http://www.prism.gatech.edu/~gh19/b1510/virus.htm) The antigen that causes malaria, however, is eukaryotic parasite that can reproduce on its own. The parasite does not need a host cell to surive and reproduce.
ReplyDeleteTherefore, when looking at the evolutionary history of various pathogens, we need to identify how much the pathogen needs the host cell. To survive and reproduce, viruses need the host cell. Pathogens, like malaria, don’t need the host cell--- even though the host cell helps the pathogen. Malaria can have a high virulence.
As Dr. Moalem also notes, malaria does not need humans to find new host cells. Malaria can use other organism, such as mosquitoes, to spread. The common cold, however, is transmitted through sneezing and close contact--- so if the human host dies, the cold can no longer spread.
Another virus is HIV, which attacks the helper T cells of the immune system. (Campbell 950) Because helper T cells are what signal cytotoxic T cells and B cells, HIV can destroy a human’s whole immune system. (Campbell 942) However, HIV is not the cause of death. It is a selective advantage for HIV to let the host live and use the host cells to reproduce. Most often, the body is unable to fight of another disease because the immune system is impaired. Because HIV is a virus, much like the common cold, HIV needs a host cell to replicate.
The best way to contain HIV is to prevent the transmittance of HIV infected fluids, which means having protected sex and making sure needles are clean. HIV can also be transmitted from mother to child. While there is no cure for HIV, there are drugs that reduce the risk of getting HIV.
In terms of containing diseases like cholera and malaria in developing countries, the first step is to make sure governments are willing to help. While the solutions sound simple, it is difficult to contain outbreaks when the infrastructure of a region is bad. Non-profit organizations like the Red Cross need the help of the governments in these regions if we want to contain and eliminate disease in regions like Africa and Southeast Asia. While it is difficult, I do think it is viable--- collaboration between governments and outside organizations would make containment of malaria and cholera outbreaks possible.
(Dhruv Luthra, dluthra4@students.d125.org)
As we have learned in class and as Dhruv has mentioned in his response, viruses cannot reproduce on their own and, therefore, must hijack host cells in order to reproduce. On page 119, Moalem briefly discusses the importance of a healthy host cell. Moalem states that there is “evolutionary pressure against virulence” (Moalem 119) because if a virus attacks a host cell and kills the host, the virus is no longer able to reproduce.
ReplyDeleteOne example of a virus that relies on healthy host cells to reproduce is the rotavirus. Rotavirus causes severe diarrhea in infants and children mostly under the age of 5. The complex interaction between rotavirus and the human host cells of infants relates to Big Idea 4 (Biological systems interact, and these systems and their interactions possess complex properties). The complex interaction begins when rotavirus enters the body either orally or anally and makes its way to the gut and small intestine where the virus begins to replicate through the lytic cycle. The virus breaks down the DNA of the host cell, produces between 100 and 200 new virus phages, and releases the new phages through lysis of the cell. The new viruses are able to survive and reproduce in the acidic environment of the gut due to the rotavirus’s triple protein coat.
In order to contain rotavirus, children receive a rotavirus vaccine at a very young age. The vaccine consists of attenuated live virus. According to the article “Vaccinating Children Against Rotavirus May Indirectly Protect Adults Too, Study Finds” of Science Daily, ever since the introduction of the rotavirus vaccine in the United States, “declines in the disease have been seen in both vaccinated and unvaccinated children.” More vaccinated children results in fewer children capable of passing on the virus which explains the decrease in both vaccinated and unvaccinated children.
However, as Dhruv also mentioned in his response, pathogens such as malaria and cholera are capable of reproducing without a host cell. These two diseases can have higher virulence because they do not need to rely on healthy host cells to reproduce. Malaria and cholera can be minimally contained with the use of mosquito nets and water safety, respectively. Underdeveloped countries in Africa and Southeast Asia cannot contain these outbreaks without help from organizations such as the Red Cross (as mentioned by Dhruv) who are willing to provide the required tools necessary for containment of the diseases. Containment of malaria and cholera is possible, but with the knowledge and tools at hand, containment and elimination of these diseases will take decades.
(Christine Fanning, cfannin4@students.d125.org)
When looking at different pathogens and their effect on the host, it is important to identify what the characteristics of the pathogen are. For example, different types of viruses cause colds. Viruses cannot reproduce on their own, which means the viruses need a host cell to survive and reproduce. If the host is dead, a virus cannot use the machinery of the host cell to replicate. The antigen that causes malaria, however, is eukaryotic parasite that can reproduce on its own. The parasite does not need a host cell to surive and reproduce.
ReplyDeleteTherefore, when looking at the evolutionary history of various pathogens, we need to identify how much the pathogen needs the host cell. To survive and reproduce, viruses need the host cell. Pathogens, like malaria, don’t need the host cell--- even though the host cell helps the pathogen. Malaria can have a high virulence.
As Dr. Moalem also notes, malaria does not need humans to find new host cells. Malaria can use other organism, such as mosquitoes, to spread. The common cold, however, is transmitted through sneezing and close contact--- so if the human host dies, the cold can no longer spread.
Another virus is HIV, which attacks the helper T cells of the immune system. (Campbell 950) Because helper T cells are what signal cytotoxic T cells and B cells, HIV can destroy a human’s whole immune system. (Campbell 942) However, HIV is not the cause of death. It is a selective advantage for HIV to let the host live and use the host cells to reproduce. Most often, the body is unable to fight of another disease because the immune system is impaired. Because HIV is a virus, much like the common cold, HIV needs a host cell to replicate.
The best way to contain HIV is to prevent the transmittance of HIV infected fluids, which means having protected sex and making sure needles are clean. HIV can also be transmitted from mother to child. While there is no cure for HIV, there are drugs that reduce the risk of getting HIV. According to Science Daily on March 29, 2011, one of the ways to prevent the spread of infection is to stop transmission from mother to child. In research conducted by the Center of Disease Control, it was found that antiretroviral treatment during pregnancy and the breastfeeding period are essential in stopping the transmission of HIV from mother to child. Identifying and understanding how the virus is transmitted is how we can prevent the spread of HIV--- similar to the way the transmission from mother to child is being reduced. Knowing when the virus is transmitted will give researchers targets as to when to interrupt the infection process.
Christine noted one of the ways to contain a virus: stopping people from getting infected in the first place through vaccines. We need to research how to make vaccine cheaper and more accessible in poorer countries. However, prevention is also something we should take towards fighting bacterial infection in poorer countries. Ensuring clean water is vital, considering how many pathogens enter the body through drinking. Basic hygiene would help stop the spread of disease, regardless of pathogenic type. One way to prevent a disease like malaria is through mosquito nets, which is a cheap solution that is universal.
In terms of containing diseases like cholera and malaria in developing countries, the first step is to make sure governments are willing to help. While the solutions sound simple, it is difficult to contain outbreaks when the infrastructure of a region is bad. Non-profit organizations like the Red Cross need the help of the governments in these regions if we want to contain and eliminate disease in regions like Africa and Southeast Asia. While it is difficult, I do think it is viable--- collaboration between governments and outside organizations would make containment of malaria and cholera outbreaks possible. ‘