History and Current Understanding of Malaria - Essay Example

? Malaria s I. History of Malaria a. Romans first called it mal aria, which means “bad air” In many parts of the world Malaria, remains a life threatening disease which are primarily caused by parasites that enter the body through mosquito bites. The disease is endemic in almost 107 countries. According to the reports of WHO, there were about 219 million cases of malaria in the year 2010 alone. “Malaria infection causes significant economic losses and can decrease gross domestic product (GDP) by as much as 1.3% in countries with high levels of transmission” (Jadhav et al,2012,p111). The existence of the disease can be traced back to the Roman times. The name malaria comes from the “mal”aria which means bad air in medieval Italy. When the term was coined it was believed that malaria was caused by breathing in bad air. Louis Pasteur was the first to discover that several diseases were caused by microbial germs. This discovery helped researchers gain insight into diseases such as malaria. In fact it was Pasteur idea of microbial-caused infection that helped Laveran conduct his research on malaria parasites (The Cambridge Historical Dictionary of Disease). One of the pioneering malaria related research is Robert Koch. In 1883, Koch visited India and witnessed the plight of the people inflicted with malaria. He was hooked and upon his return to Italy he conducted several experiments to try and prove that malaria was caused by mosquito bite. Later, Italian researchers Grassi and Feretti gave a nomenclature malaria parasite. They named the malaria parasite in honor of Laveran as Laverenia which was deemed zoologically accurate. II. Current understanding of the disease a. Anopheles mosquitoes Worldwide the Anopheles mosquito is known as malaria mosquito because it is considered to be the primary vector for malaria. It is caused by one-celled parasites of the genus Plasmodium that are transmitted to humans by the bite of Anopheles mosquitoes (Britannica Encyclopedia).  The anopheles mosquito is found worldwide except for in Antarctica. The disease is transmitted by the female anopheles. All of the important vectors of this species have a tendency to bite at night .The mosquito sucks human blood to grow its eggs but it is this phenomenon that is the most important part of the malarial microbe lifecycle. Anopheles plays a pivotal role in the development of Plasmodium. The growth of the microbe from the gametocytic stage to the sporozoite stage takes place inside the body of the female Anopheles. The body of the mosquito provides ambient temperature and humidity to the developing microbe and the female survives long enough to allow the parasite complete its lifecycle in the mosquito body. Anopheles breed on water and each species has its own preference when it comes to selection of breeding place for example some like puddles, shallow water, fresh water or even hoof prints. b. Apicomplexa protozoa: Plasmodium Apicomplexans are also known as sporozoans. All apicomplexans are obligatory and intracellular microbes i.e. they need to spend at least some part of their life cycle within an animal host. Important characteristics of apicomplexans include the presence of tiny organ like structures which are present at the very tips of the cells. These tiny organ-like structures contain enzymes which helps the microbe penetrate into the host tissue. One of the most well known and pathogenic genera of apicomplexans includes Plasmodium- which causes malaria. Plasmodium’s lifecycle is spent in two stages- in the body of mosquitoes and that of humans. It ultimately affects humans and causes rupture in the blood vessels. There are more than 100 Plasmodium species which can infects living organisms however only 4 of these species cause infection in humans- Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale and Plasmodium malariae. The lifecycles of the four species affecting humans are similar. Lifecycle: The lifecycle begins when a female Anopheles carrying malaria parasite sucks human blood. While sucking the parasites in form of sporozoites are injected into the blood stream. These sporozoites are carried to the liver where they invade hepatocytes. They grow within the liver cells for a certain time period during which they produce tens and thousands of merozoites which are then released into the bloodstream. The merozoites invade the red blood cells and undergo trophic period. During the trophic period the merozoite enlarges and often engages in asexual reproduction leading to formation of thousands of infected blood cells. In fact, this stage is associated with the pathology symptoms of malaria. The intermittent fever which is seen in malarial patients is a result of lysis of the red blood cells infected with the parasite. Some merozoites do not reproduce asexually and hence produces both male and female gametocytes. These gametes circulate in the human blood stream. When a mosquito sucks this blood, it ingest some gametocytes along with the blood. The human blood cells burst open and release the gametocytes into the mosquito’s body. The male and female gametes fuse and form a zygote. The zygote develops into motile ookinete which then penetrates the epithelial cells of the gut of the mosquito and forms an oocyst. This oocyte undergoes a number of asexual stages or multiplication and finally forms sporozoites. The sporozoites that are formed migrate to the salivary glands of the mosquito thereby completing the lifecycle of the plasmodium microbe. c. Diagnosis and treatment Malaria if left untreated can become fatal. In fact, according to the WHO reports of 2010, almost 660,000 deaths were reported and each of these deaths was caused by this disease. It has been seen that since the year 2000, the mortality associated with malaria has risen by a little more than 25%.However it must be noted that this disease is not only treatable but is also preventable. Early detection, diagnosis and treatment are essential in order to prevent fatality. It also prevents further spread of this disease. The first step towards prevention of the disease, proper management and proper treatment is accurate diagnosis. The currently available tools for the control of malaria are largely, early diagnosis and prompt treatment of clinical episodes with effective anti-malarial drugs (Mwangoka et al,2013, 1480).Diagnostic tests with high sensitivity can not only prevent unnecessary treatment but can also reduce the cost involved in mislead treatments. The two most widely used tests for confirming malaria are- microscopy and rapid diagnostic tests. Microscopy: Microscopic observation of suspected infected blood remains the golden standard for detection and confirmation of the presence of malaria parasite in the blood stream. For this, a blood smear is taken from the patient, it is stained and the slide is observed under the microscope. Owing to the high sensitivity of the observation, it is possible to detect presence of parasites even at fairly low densities. Microscopy can also help in calculating the total parasite load. Another major advantage of microscopy is that the different parasite species can be differentiated at their different life stages. Rapid Diagnostic Tests: These tests are preferred over microscopy since they can be performed by the staff with only a basic training. RDT are based on detection of parasite antigens that circulate in the body. Different kits are available today that can detect only one or more than one species of parasite. Owing to the costs involves the prices of the kits is high and therefore the entire procedure is slightly more expensive. Treatment: proper treatment can be given if the parasite presence is confirmed by standard techniques such as microscopy or rapid diagnostic tests. WHO recommends the usage of artemisinin-based combination therapies to treat uncomplicated cases of malaria. By saying uncomplicated malaria it is meant that the diseases did not cause any major organ dysfunction in the patient and the symptoms of which are non-specific. Previously non-artemisinin based combination therapies i.e. therapy without using artemisinin or its derivatives was given. However, it is no longer recommended since it is less effective and much inferior to the combination therapy using artemisinin or its derivatives as major components. Artemisinin-based combination therapy- This therapy involves usage of artemisinin as one of the components or the usage of artemisinin derivatives such as artesunate, artemether and dihydroartemisinin. Both artemisinin and its derivatives have the ability of reducing parasite numbers 100-1000 fold per asexual cycle. The components produce rapid clearance of the parasites and also help in controlling the associated symptoms. A normal 7 day course of artemisinin or its derivatives must be given as they are eliminated rapidly when given alone or with compounds such as tetracycline etc. In case the artemisinin is given in combination with antimalarials that are not eliminated fast, the course duration can be reduced to just 3 days. Use of this therapy also helps control of malaria since it drastically brings down the gametocyte carriage. Severe or complicated forms of the disease can be either treated with ACT or quinine maybe employed. In order to avoid cardiac complication related to severe malaria, intravenous quinine must be given slowly over a time period of 8 hours. This injection of quinine needs to be followed with oral quinine tablets for a whole week. Quinine is also the recommended treatment for malaria in children. III. Breakthrough a. Development of a vaccine Since malaria is worldwide public health problem, researchers have been trying to develop vaccines against the disease to lend protection against the parasites. The development of a vaccine would mean lower mortality, morbidity and economic costs involved with the treatment of the disease, awareness programs etc. the aim of the researchers are to wipe the disease from the earth. It was first in 1960, that it was thought that the development of a vaccine for malaria was feasible. It was seen that IrSp (irradiated sporozoites) rendered rodents immunized. Next the IrSp vaccine was tested on human volunteers with anopheles bite and it was seen that the vaccine was highly species specific. The multifactorial protection given by the vaccine involves direction of neutralized antibodies against circumsporozite and it is this idea that is today being researched upon to develop a better and much effective vaccine. The most important malaria vaccine candidate is RTS,S vaccine. “RTS,S conferred approximately 50% protection from clinical Plasmodium falciparum disease in children aged 5-17 months, and approximately 30% protection in children aged 6-12 weeks when administered in conjunction with Expanded Program for Immunization (EPI) “ (Birkett et al,2013,p233).This vaccine is composed of the fusion protein of a portion of CS or circumsporozite protein along with hepatitis B surface antigen, which are incorporated together in a mixture of only three adjuvants. RTS,S is now in its third trial phase. The vaccine showed low efficacy of about 50%-60% in the trial II phase. However, candidates for a second generation malaria vaccine is under research and a trial of the polymorphic blood stage vaccine is still to p[rove its efficacy (Gray,2013,p2) b. Advanced prophylaxis Given to the fact that malaria is a cause of a number of problems for the public health in general prophylaxis is the most effective way to prevent and restrain the problem. However, advancement in prophylaxis has been made and includes the concept of chemoprophylaxis. Chemoprophylaxis involves the usage of some antimalarials drugs to prevent the disease for example malarone, doxycycline and lariam. This is needed especially when one is travelling from one country to another. All travelers to the countries where malaria is common need to understand the importance of chemoprophylaxis and gain a good understanding of using them. Most recent progress has been seen in the field of genetics where researchers reported genetic manipulation of mosquitoes which would impair their ability to transmit the disease (Bite on Malaria, 2002, p761). Conclusion It is needless to say that malaria has been a curse on human health. However, the recent advances in development of vaccination are quite promising. Efforts need to be made to spread awareness about diagnosis and treatment to people who may not have access to them especially in the poor tropical countries. Future research should aim at not only developing vaccines but also developing better chemoprophylaxis agents. REFERENCES Birkett, A. J., Moorthy, V. S., Loucq, C., Chitnis, C. E., & Kaslow, D. C. (2013). Malaria vaccine R&D in the Decade of Vaccines: Breakthroughs, challenges and opportunities. Vaccine, 31(s2), B233-B243. doi:10.1016/j.vaccine.2013.02.040 D. Gray, H. (n.d). Review: The malaria vaccine – Status quo 2013. Travel Medicine And Infectious Disease, 11(Special Issue : Malaria Reviews), 2-7. doi:10.1016/j.tmaid.2013.01.006 Jadhav, P., Shah, R., & Jadhav, M. (2012). Important advances in malaria vaccine research. Chronicles Of Young Scientists, 3(2), 111-120. Malaria. (2003). In The Cambridge Historical Dictionary of Disease. Retrieved from http://vlib.excelsior.edu/login?url=http://www.credoreference.com.vlib.excelsior.edu/entry/cupdisease/malaria Malaria. (2013). In Encyclopaedia Britannica. Retrieved from http://www.britannica.com.vlib.excelsior.edu/EBchecked/topic/359534/malaria Mwangoka, G., Ogutu, B Msambichaka, B., Mzee, T., Salim, N., Kafuruki, S., & Abdulla, S. (2013). Experience and challenges from clinical trials with malaria vaccines in Africa. Malaria Journal, 12(1), 1-9. doi:10.1186/1475-2875-12-86 Tenenbaum, D. J. (2002). Breakthroughs Put the Bite on Malaria. Environmental Health Perspectives, 110(12), A 760. Tortora, G. J., Funke, B. R., & Case, C. L. (2013). Microbiology: An Introduction (11thth ed.). Glenview, IL: Pearson. Towie, N. (2006). Malaria breakthrough raises spectre of drug resistance. Nature, 440(7086), 852-853. Read More