Malaria

Taxonomical Classification
Ovale, Vivax, Kmowlesi ||
 * Kingdom || Protista ||
 * Sub-kingdom || Protozoa ||
 * Phylum || Apicomplexa ||
 * Class || Sporozoasida ||
 * Order || Eucoccidiorida ||
 * Family || Plasmodiidae ||
 * Genus || Plasmodium ||
 * Species || Falciparum, Malariae,

Background
Malaria is an infectious disease caused by the protozoan of the genus Plasmodium. According to the Center of Disease Control, it is a major problem in third-world countries, with hundreds of millions infected and countless fatalities annually (2014). Malaria is a mosquito-borne pathogen that is transmitted by a bite from an infected female Anopheles, which presents the Parasite into the host’s blood stream through a bite (CDC, 2014). The parasite travels through the circulatory system and makes a home in the liver till it reaches maturity. Malaria causes symptoms mimicking the flu and can often be over looked that can lead to coma and death. Most deaths come from P. falciparum and P. vivax, while P.ovale and P.malariae are milder forms and rarely cause death. P. knowlesi hails from Southeast Asia and primarily infects Macaques (primates), but as of late is has crossed over to humans. Specific geographical locations with vast amount of rainfall, warm weather, and stagnant water are ideal breeding grounds for Mosquitoes which are known to carry the malaria pathogens. Since the common signs and symptoms of malaria mimic flu-like symptoms, it not easily diagnosed, especially in the absence of a lab like environment. Doctors and other healthcare practitioners rely on clinical diagnoses of malaria because they often have limited resources. Diagnostic tools vary from microscopic examination to the more modern polymerase chain reaction (Wongsrichanalai, 2007). These techniques are expensive and are not amenities that a third world country would have readily available.

** Cell Structure **



Malaria's asexual stage adheres to an accessible host and invades the red blood cells via transmission by a mosquito bite, for example using a human host. The malaria parasites hijacks the available red blood cells and eventually acquire a new set of directions and properties from the pathogen, and create new eukaryotic cell structures in the red blood cell cytoplasm. This affected red blood cell undergoes significant cell structure alterations and its original properties are altered. These dramatic changes appear as red blood cells but with ridge membranes, and increase in adhesiveness to other cells.

= Methods of Identification =



Upon physical examination of an individual who has been effected by malaria, a physician or trained medical expert may find an enlarged liver or enlarged spleen. Blood samples are obtained at 6 and 12 hour intervals to confirm a positive diagnosis of malaria, and hemoglobin levels are monitored for signs of anemia.

It is heavily recommended by the World Health Organization, that parasite-diagnosed by microscopy weigh heavily on proper identification of malaria. Malaria Rapid Diagnostic Testing (RDT) is a rapid form of testing using an individuals finger stick of blood to detect malaria antigens (proteins), and results in a positive color change on the strip paper. Another form of testing using blood smears on 2 glass slide and stained. The specimens are viewed under a microscope to compare the number of parasites seen. Blood smears collected at 8 to 12 intervals over 2 to 3 days are obtained to rule out any possible missed parasites. Thick smears are more sensitive for testing for malaria, where a greater amount of blood specimen is collected and the increased amount of parasites detected indicates the degree of infection, also known as parasite load. Molecular testing amplifies the parasite's DNA and allows the microbiologist to identify the Plasmodium species of malaria, on a microscopic level. Antibody tests detects antibodies in a possible exposed host, to determine if they had been previously infected.

= Metabolism =

Plasmodium falciparum is an obligate human parasite that is the causative agent of the most lethal form of human malaria. Transmission of P. falciparum to a new human host requires a mosquito vector within which sexual replication occurs. P. falciparum replicates as an intracellular parasite in man and as an extracellular parasite in the mosquito, and it undergoes multiple developmental changes in both hosts. Changes in the environment and the activities of parasites in these various life-cycle stages are likely to be reflected in changes in the metabolic needs and capabilities of the parasite (Key, 2014).

= Infectious Diseases =

Malaria is caused by the plasmodium parasite. This parasite can be spread to humans through the bites of infected mosquitoes.There are many different types of plasmodium parasite, but only five types cause malaria in humans. These are:
 * **Plasmodium falciparum** – mainly found in Africa, it is the most common type of malaria parasite and is responsible for most malaria deaths worldwide.
 * **Plasmodium vivax** – mainly found in Asia and South America. This parasite causes milder symptoms than Plasmodium falciparum, but it can stay in the liver for up to three years, which can result in relapses.
 * **Plasmodium ovale** – fairly uncommon and usually found in West Africa. It can remain in your liver for several years without producing symptoms.
 * **Plasmodium malariae** – this is quite rare and usually only found in Africa.
 * **Plasmodium knowlesi** – this is very rare and found in parts of South East Asia. (CDC, 2014)

**How Malaria is Spread** The plasmodium parasite is spread by female Anopheles mosquitoes, which are known as 'night-biting' mosquitoes because they most commonly bite between dusk and dawn. If a mosquito bites a person already infected with malaria, it can also become infected and spread the parasite on to other people. However, malaria cannot be spread directly from person to person. Once you are bitten, the parasite enters the bloodstream and travels to the liver. The infection develops in the liver before re-entering the bloodstream and invading the red blood cells.The parasites grow and multiply in the red blood cells. At regular intervals, the infected blood cells burst, releasing more parasites into the blood. Infected blood cells usually burst every 48-72 hours. Each time they burst, you will have a bout of fever, chills and sweating. Malaria can also be spread through blood transfusions and the sharing of needles, but this is very rare (Medline Plus, 2014).

CDC, 2014


 * Malaria in the Mammalian Immune System **

The parasite is primarily protected from attack by the host body's immune system because for most of its human life cycle it resides within the liver and blood cells, and is relatively invisible to immune surveillance system. However, the body eventually detects the circulating infected blood cells are sent to the spleen to be destroyed. To avoid this action, the malaria P. falciparum parasite displays sticky proteins on the surface of the infected blood cells it has hijacked, therefor causing the blood cells to stick to the walls of small blood vessels, and eventually stopping the parasite from circulating into the spleen. The blockage of the microvasculature causes symptoms such as in placental malaria. Hijacked red blood cells can breach the blood-brain barrier and cause cerebral malaria (CDC, 2014).

** Resistance **

Several genetic factors provide some resistance for a host to prevent infection from malaria. These include sickle cell trait, thalass anemia trait, glucose-6 phosphate dehydrogenase deficiency, and the abcense of Duffy antigens. Sickle cell trait causes a defect in the hemoglobin molecule in the blood, so instead of retaining the biconcave shape of a normal red blood cell, the modified hemoglobin S molecule causes the cell to sickle or distort into a curved shape. Due to the sickle shape, the molecule is not as effective in taking or releasing oxygen, so they are removed from circulation sooner. This process reduces the frequency with which malaria parasites continue their life cycle and harm the host.

According to the CDC, the development of resistance to drugs poses one of the greatest threats to malaria control and results in increased malaria morbidity and mortality (2014). Resistance to currently available antimalarial drugs has been confirmed in only two of the four human malaria parasite species, Plasmodium falciparum and P. vivax. It is unknown if P. malariae or P. ovale has developed resistance to any antimalarial drugs. P. knowlesi, a zoonotic monkey malaria that infects humans in forest fringe areas of Southeast Asia, is fully susceptible to chloroquine and other currently used drugs (WHO, 2014).

**Treatment and Prevention **



Malaria is treated with antiviral medications and the ones used depends on the type and severity of the disease. Fever is also addressed aggressively with oral antipyretics. Uncomplicated malaria may be treated with oral medications. The most effective treatment for //P. falciparum// infection is the use of artemisinins in combination with other antimalarials which decreases resistance to any single drug component. These additional antimalarials include: amodiaquine, lumefantrine, mefloquine, or sulfadoxine/pyrimethamine (CDC, 2014; WHO, 2014).

Recommended treatment for severe malaria is the intravenous use of antimalarial drugs. For severe malaria, artesunate is superior to quinine in both children and adults. Treatment of severe malaria involves supportive measures that are best done in a critical care unit. This includes the management of high fevers and the seizures that may result from it. It also includes monitoring for ineffective breathing, low blood sugar, and low blood potassium.

The number one way to prevent a malaria exposure is to prevent mosquito bites. Bug repellents, netting, sprays, insecticides, and avoiding standing water around your area. According to the CDC, there is no active form of vaccination for malaria on the market. With the complex life cycle of malaria, thousands of antigens produced by the parasite, and fewer pharmaceutical developers to take on the challenge, the prevention in future risks is not viable. Exposure to the parasite does not confirm life long protection, and a host can go months without any symptoms.

The link provided provides simplified information by type of malaria, each countries prevalence, and the type of medicines used to combat malaria exposure for current and future travelers. [|Malaria Information and Prophylaxis by Country] (CDC, 2014)

<span style="font-family: Arial,Helvetica,sans-serif;">Center for Disease Control, CDC. (2014). www.cdc.gov <span style="font-family: Arial,Helvetica,sans-serif;">Key, L. (2014). Studying the metabolism of the malaria-causing parasite plasmodium falciparum. Medical Xpress. <span style="font-family: Arial,Helvetica,sans-serif;"> Retrieved from http://medicalxpress.com/news/2014-03-metabolism-malaria-causing-parasite-plasmodium-falciparum.html <span style="font-family: Arial,Helvetica,sans-serif;">Medline Plus. (2014). Malaria. U.S. National Library of Medicine, National Institutes of Health. Retrieved from http://www.nlm.nih.gov/medlineplus/ency/article/000621.htm <span style="font-family: Arial,Helvetica,sans-serif;">Wongsrichanali, C. (2007). A review of malaria diagnostic tools: Microscopy and rapid diagnostic test (RDT). The American Journal <span style="font-family: Arial,Helvetica,sans-serif;"> of Tropical Medicine and Hygine. 91 (2). World Health Organization, WHO. (2014). www.WHO.org
 * <span style="font-family: Arial,Helvetica,sans-serif;">References: **