Biological Pathogen and Characteristics of Malaria Research Paper

Introduction Malaria is a key public health predicament and cause of much distress and untimely death in the poorer areas of tropical Africa, Asia and Latin America. In many endemic areas it is becoming increasingly complex to control because of the resistance of the parasite to anti- malarial drugs and the failure of vector control measures. Malaria is mainly caused by plasmodium species of the Coccidia family of Parasites. The most pathogenic species of the plasmodium species is plasmodium falciparum which is responsible for almost 90% of malarial infections in the world. The Coccidia are intracellular parasites that reproduce asexually by a process called schizogony and sexually by sporogony. They are normally found in the liver and red cells, and are transmitted by anopheline mosquito vector. Characteristics of the pathogen Four distinct Plasmodium species infect humans: P. falciparum, P. vivax, P. malariae, and P. ovale. P. falciparum is the most pathogenic of the human malaria species, with untreated infections causing severe disease and death, particularly in young children, pregnant women and non-immune adults (Caraway, 1959). The pathogenicity of P. falciparum is mainly due to: The cytoadherence of falciparum parasitized red cells, causing the cells to adhere to one another and to the walls of capillaries in the brain, muscle, kidneys and elsewhere and in pregnant women, in the placenta. The Sequestration of parasitized cells in the microcirculation causes congestion, hypoxia, blockage and rupturing of small blood vessels. And Due to high levels of parasitaemia, the activation of cytokines prompts and the destruction of many red cells occur (WHO, 2000). Falciparum malaria parasitaemia can go beyond more than 250 000 parasites per liter of blood. And about up to 30–40% of red cells may become parasitized resulting to severe falciparum malaria which is associated with cerebral malaria, haemoglobinuria, severe anemia, hypoglycaemia, and complications in pregnancy (2000). P. falciparum is found mainly in the hotter and humid regions of the world. It is the main species found in tropical and subtropical Africa and parts of Central America and South America, Bangladesh, Pakistan, Afghanistan, Nepal, Sri Lanka, South East Asia, Indonesia, Philippines, Haiti, Solomon Islands, Papua New Guinea and many islands in Melanesia (WHO, 2000). It also occurs in parts of India, the Middle East, and eastern Mediterranean. According to WHO, the species Plasmodium falciparum contains several varieties which show differences in geographical distribution, vector susceptibility, human infection pattern, drug susceptibility, morphology and antigenic composition (2000). Transmission Malaria parasites are transmitted when an infected female Anopheles mosquito bites a host. Sporozoites contained in the saliva of the mosquito are inoculated into the blood of a human host when the mosquito takes a blood meal (Webster, 2003). Infection can also occur by transfusion of infected donor blood, by injection through the use of needles and syringes contaminated with infected blood, and very occasionally congenitally, usually when a mother is non-immune. Following inoculation, the Sporozoites rapidly, within 8 hours, leave the blood and enter liver cells. Within 5–15 days, depending on species, they develop into liver schizonts and are referred to as pre-erythrocytic (PE) schizonts. Mature PE schizonts contain many merozoites (2003). When mature, a PE schizont ruptures from the liver cell, releasing its merozoites into the blood circulation. The merozoites infect red cells by binding to receptors on the red cell membrane. Entry of the parasites into red cells starts a cycle of schizogony in the blood which to complete takes 48 hours for P. falciparum.P vivax and P. ovale and 72 hours for P. malariae (2003). During this time the intracellular merozoites develop into trophozoites which feed on the contents of the red cells. As the trophozoite feeds, malaria pigment, known as haemozoin, is produced as an end product of hemoglobin breakdown. This accumulates in the trophozoite, appearing as brown-black granules (Webster, 2003). When the trophozoite is fully developed, the nucleus begins to divide, followed by a division of cytoplasm, resulting in the formation of a schizont containing 8–24 merozoites (2003). The mature schizont ruptures from its red cell releasing merozoites, malaria pigment, and toxins into the plasma which is the cause of a typical malaria attack. Merozoites released from schizonts enter the blood circulation and those which are not destroyed by the host’s immune system infect new red cells, beginning a further cycle of schizogony with more red cells being destroyed. After several erythrocytic schizogony cycles, some of the merozoites entering red cells deve lop into male and female gametocytes. For the life cycle to be continued, the gametocytes must be ingested by a female Anopheles mosquito in a blood meal. If they are not taken up by a mosquito they die. Symptoms The characteristic feature of malaria is fever caused by the release of toxins, when erythrocytic schizonts rupture, which stimulate the secretion of cytokines from leucocytes and other cells. In the early stages of infection the fever is irregular or continuous. As schizogony cycles synchronize, fever begins to recur at regular intervals particularly in quartan malaria, every 72 hours, vivax and ovale malaria, every 48 hours (Beales, 2002). Splenomegaly occurs in all forms of malaria with repeated attacks causing a greatly enlarged spleen. Anemia and jaundice are also features of malaria, particularly falciparum malaria. Malaria caused by P. falciparum is referred to as falciparum malaria, formerly known as sub tertian (ST) or malignant tertian (MT) malaria. It is the most widespread, accounting for up to 80% of malaria cases worldwide (2002). Diagnosis The diagnosis of malaria is by done routinely though detecting and identifying malaria parasites microscopically in blood films, concentrating parasites in venous blood by centrifugation when they cannot be found in blood films, using a malaria rapid diagnostic test (RDT) to detect malaria antigen (WHO,2000). Measurement of hemoglobin or packed cell volume (PCV) is done due to presence of malaria with heavy parasitaemia particularly in young children and pregnant women. The measurement of blood glucose to detect hypoglycaemia is usually done particularly to diagnose young children and pregnant women off severe falciparum malaria. Also with suspicion of Falciparum Malaria, the total white cell count and platelet count is done. Coagulation tests if abnormal bleeding is suspected in falciparum malaria. A thick blood film is the most suitable for the rapid detection of malaria parasites, particularly when they are few. In areas where P. malariae is found, unless a thick film is examined, infection is likely to be missed because parasitaemia is normally low with this species. In a thick film the blood is not fixed. The red cells are lysed during staining, allowing parasites and white cells to be seen in a much larger volume of blood .A thin blood film is required to confirm the Plasmodium species if this is not clear from the thick film. The blood cells are fixed in a thin film, enabling the parasites to be seen in the red cells. Parasitized red cells may become enlarged, oval in shape, or stippled. These features can help to identify Plasmodium species. Examination of a thin film greatly assists in the identification of mixed infections. By counting the percentage of parasitized red cells before and after treatment, thin films are also of value in assessing whether a patient with fa lciparum malaria is responding to treatment in areas where drug resistance is suspected. Examination of a thin film also gives the opportunity to investigate anemia and white cell abnormalities, and in the absence of malaria parasites, suggest an alternative diagnosis, e.g. sickle cell disease (WHO, 2000). Treatment The treatment of Malaria parasites is now tricky due to intense drug resistance. Artemisinin-based combination therapies are combinations in which one of the components is artemisinin and its derivatives, artesunate, artemether, dihydroartemisinin. The artemisinins produce rapid clearance of parasitaemia and rapid resolution of symptoms, by reducing parasite numbers 100- to 1000-fold per asexual cycle of the parasite, which is more than the other currently available anti- malarials can achieve (Webster, 2003). Prevention Reducing the suffering and loss of life caused by malaria is possible, providing the financial, political, and technical commitment to achieve this is strengthened. The WHO/UNICEF/UNDP and World Bank Roll Back Malaria Partnership, the Global Fund to fight AIDS, Tuberculosis, and Malaria, the Medicines for Malaria Venture, the Gates Malaria Partnership and the Multilateral Initiative on Malaria have been established to reduce the burden of malaria by: implementing malaria control strategies, improving health infrastructures, raising awareness of malaria and its effects on poverty and development, mobilizing communities to combat malaria, raising and monitoring funds to effect and sustain malaria control programmes and the development of anti-malarial drugs and vaccines. References Beales, P. F, and Gilles, H .M, (2002). Â  Rationale and technique of malaria control. Ch. 6 in 4th ed. Essential Malariology, pp 107–190 Caraway, W.T., (1959). American Journal of Clinical Pathology, 32. Webster D et al., (2003) Progress with new malaria vaccines. Bulletin World Health Organization, 81(12), pp 902–909 WHO, (2000). Severe falciparum malaria. Transactions Royal Society Tropical Medicine and Hygiene, 94, Supplement

The Correlation between Population Grown and Economic Growth

1.0 Introduction Population growth and economic development have been intertwined since historic times. The question of these two detrimental factors being correlated with one another has been the topic for debate time and time again, but even today controversies among them exist. Our economy has withheld the impact of war, immigration, and depressions and stands today at a much higher point than it did decades ago. The concern is not with where the economy stands today, but where it will be in the long run. The long run can be anywhere from one year to a substantial time gap. When considering long run economic growth we must also take into account population growth. In order to further understand this relationship we must define the term long run economic growth. Long run economic growth refers to rise in GDP per capita, which measures individuals’ material standard of living. 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Happiness Is Real When Shared Free Essays

This is one book which I have just finished reading. I don’t normally read biography, but came across the story while doing some random search on wikipedia (where one link can lead to another). I really got very interested in the true story of this young man who ended up dying in Alaska. We will write a custom essay sample on Happiness Is Real When Shared or any similar topic only for you Order Now I went to buy the book at Kinokuniya. In 1992, a young man by the name of Christopher McCandless from a well-to-do family in the US abandoned everything he possessed after graduating with honours from University. For the next two years, he lived off the streets, travelling from place to place, living on the bare minimum. Finally, he hitchhiked to Alaska with little food (only 5 pounds of rice) and equipment as he wanted to be in total isolation from human contact and go into the wild, in his words â€Å"to live off the land† – eating the animals he hunted and plants grown there. He actually managed to survive for more than 100 days in Alaska with this way until a series of unfortunate accidents that caused him to die slowly (and painfully) of starvation on an abandoned bus. His decomposed body was found more than two weeks later. He was only 24 at the time of demise. All this while, his family didn’t know his whereabouts and was searching for him, until they received this piece of unfortunate news. In this book, Jon Krakauer explored the life of Christopher McCandless and try to understand the thoughts behind this young man who gave up everything he has in search of a life of adventure and meaning (to him), and also how the people around him were affected. He must had been a very charismatic person, as people he met along the way during his years on the streets really liked this guy a lot. Some actually asked him to settle down at the place he was at. But then his ultimate aim was to really live in the wild with only nature (and nothing else, human relationships was worthless to him) and commitment was the last thing on his mind. This story left a very deep impression in me, not just because of the tragic circumstances surrounding it, but I could identify with Christopher McCandless in that at his age, I was also sort of like him. Well, I might not have given up all my wealth (I admit, my family wasn’t as well-to-do as his) and go all the way out into the wild, but I did have certain anger or unhappiness about the way my life turned out and wanted to live a different sort of life. That was why at that time my results sort of fumbled (as I was half-hearted about the whole studying affair – to me, studying what I had no interest in was an â€Å"insult to my integrity†. ). I also wanted to get away from my family (which was one of the catalysts which caused Christopher McCandless to make such a decision, he was very upset by certain things he found out about his parents), so for a period of time I was staying in the hostel. During that time, I really planned to eventually leave my family once I have the financial means and stay outside. In fact, after I graduated from university, I went to Malacca for a few days all by myself to enjoy the isolation. Ha ha, until now, my parents weren’t aware this was what I did – and I can’t yet find the courage to inform them. (This is probably a secret I will bring to my grave). Okay, this was probably not so much of an adventure, but I did derive certain excitement out of this trip. Imagine me on a free and easy trip carrying just the map and walking around (and people who know me know I’ve a very, very poor sense of direction). I would not say I managed to find my sense of purpose in life during that very short trip. In fact, it was years after I graduate before I realised what was really important in my life. For Christopher McCandless, towards the end of his life, realised that â€Å"happiness only real when shared† which is what he wrote on his journal. When he finally got the isolation he yearned for in Alaska, somehow, he must have finally realised the importance of human relationships and that real happiness lies with being able to spend time with the one you care. Of course, the sad part is it came too late too as he was trapped in the wilderness which he had yearned for previously. Given time, I believe he would eventually return to his family and friends. For me, after years of working (and probably maturity over the years), I also realised the importance of treasuring the time with my familiy and friends. You do not have to go to the extreme (in my case, escape from my family) to change the state of your life. In fact, all that matters is your perception. I have to be responsible in what I do as it is not just about me, but whatever I do have repercussions on my loved ones too. I had probably hurt the people around me as much as they have hurt me. I remember there was one saying I read somewhere – people may not love you the way you want them to, but that doesn’t mean they don’t love you. Recently, I did have the urge to go backpacking alone somewhere (of course, with the intention of not letting my parents know), but I admit I did have second thoughts after reading the book, ha ha! But don’t think that will last for long, as by nature, I do like to â€Å"wander around† – I can’t be trapped for too long. In the end, I guess Christopher McCandless did manage to find peace with himself. His final note written on his journal was â€Å"I HAVE HAD A HAPPY LIFE AND THANK THE LORD. GOODBYE AND MAY GOD BLESS ALL! † Although he didn’t manage to go back to his loved ones, he appreciated all the love bestowed upon him by them. I would like to think that he did not leave this world with any regret. Currently, I am reading another book by Jon Krakauer about his experience during the 1996 Mount Everest climb. Another tragic tale of how harsh nature can be. I might want to catch the movie version of â€Å"Into The Wild† directed by Sean Penn. Not sure if the film will evoke the same emotions in me (sometimes film adaptations can be disappointing). How to cite Happiness Is Real When Shared, Essay examples