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Infectious Diseases in Humans

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Infectious Diseases in Humans Assignment Two - Coursework Essay Introduction One hundred and six years after the discovery that the malaria parasite was transmitted by mosquitos to humans via their bite the struggle against malaria is far from over. An estimated 3000 children a day die of the diseases in Africa and between one and two million die each year (1). In addition malaria claimed a staggering 42,280,000 DALYs (disability adjusted life years) in 2002 (2), a 10 million increase from the 1998 statistics. During this discussion I will focus upon each side of the complex interactions between host, agent and environment. Initially I will consider the interaction between the two hosts, the human and the anopheles mosquito, then the hosts and the malaria agent, followed by the connection between the environment and the host and agent. Attention will be paid to how better understanding between them is providing new opportunities to intervene to combat this disease but also how understanding of this knowledge is paramount in the successful design of any intervention programme with the ultimate aim of eradicating malaria or reducing the burden it causes on many developing nations. Main Body Malaria (Mal aria: Bad air) is a disease whose name literally describes its previous aetiological explanation. It was widely known that the disease was commonly found around swamps and poorly drained areas and this subsequently led to the belief that it was caused by bad air, the product of decaying matter (3). ...read more.


The potential of greater understanding between the human and the four types of malaria parasite, plasmodium falciparum, p. vivax, p. malaire, and p. ovale holds the key in the development of future anti-malarial drugs and potential vaccines. Unfortunately as we have begun to understand more about the stages of the parasites lifecycle that occurs in humans, we have come to realise its true complexity is far beyond the complexity of any the parasites we currently possess vaccines for, and thus many attempts have been confounded. The two phases of the parasites development in humans, i.e. Hepatic schizogony and Erythrocytic schizogony, and the blocking of transmission of the parasite back to the mosquito have all been targeted as potential sites for vaccine development. Pre-erthtocytic, blood-stage and transmission blocking vaccines have recently been developed by a number of groups (8). Most development has been in Pre-erthrocytic stages of development where there are currently 12 vaccines in clinical trails (9). It has already been mentioned that drugs which possess anti-malarial properties been present for a considerable time yet in recent years there has been a spreading development of resistant malarial parasites to many of the first line drugs, namely chloroquine and sulfadoxine/pyrimethamine. The recent ability to isolate and structurally analysis the protein DHFR that has been identified as responsible for changing itself to protect the parasite against pyrimethamine - a chemical used in anti-malarial drugs, is of great significance in developing a new generation of drugs which makes it possible to overcome resistant strains of malaria. ...read more.


In addition, knowledge of the resistance levels of the anopheles is imperative (19). Residually spraying an area with a certain pesticide which the local anopheles population has acquired resistance to will be largely ineffective. Conclusion It has been stated that knowledge is the most powerful remedy for all diseases (20). This essay has drawn attention to the implications of how greater understanding between the host, agent and environment with regards to malaria has provided greater opportunities to intervene and aided in the design of intervention programmes. Increased knowledge of the interaction between the hosts has lead to many measures aimed at interrupting the transmission of the disease. Through better understanding the agents' activity in the human we have been able to identify areas to target anti-malarial drugs and vaccines and through knowledge of the environments interaction, opportunities to reduce the mosquito's reproduction have been possible. Genome sequencing of the host, Anopheles gambiae, and the most deadly of the four types of malaria parasite, plasmodium falciparum will undoubtedly reveal awareness and vastly add to our knowledge of mosquito biology, breeding patterns and many of the factors which make the mosquito an excellent vector for the malaria parasite. Undoubtedly it will have an unprecedented impact in the development of new generation resistant pesticides, drugs and ultimately led to genetically modified anopheles unable to act as a vector. However, in the mean time better understanding of the host, agent and environment will continue to assist and improve current interventions and influence new avenues of opportunity. ...read more.

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