Malaria Spread By Certain Mosquitoes Biology Essay

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Malaria can cause several different concerns to the human body. It is a serious, infectious disease spread by certain mosquitoes. It is most common in tropical climates and is characterized by recurrent symptoms of chills, fever, and an enlarged spleen. The disease can be treated with medication, but it often recurs. Malaria is endemic (occurs frequently in a particular locality) in many third world countries.

Life Cycle

When a female Anopheles mosquito penetrates human skin to obtain a blood meal, it injects saliva mixed with an anticoagulant (blood clot preventer). If the mosquito is infected with Plasmodium, it will also inject elongated sporozoites (motile, spindle shaped asexual cells) into the bloodstream of its victim. The sporozoites travel to the liver where they enter liver cells and rapidly divide asexually. This asexual division, which is called schizogony, generates the next life cycle form, called merozoites. The released merozoites invade other liver cells and enter the host's bloodstream, where they invade erythrocytes. Once inside the erythrocyte, the merozoite begins to enlarge as a uninucleate cell termed a ring trophozoite. The trophozoite's nucleus then divides asexually to produce a schizont which contains several nuclei. The schizont then divides and produces mononucleated merozoites. The erythrocyte then ruptures and releases toxins throughout the body of the host, bringing about the well-known cycle of fever and chills that is characteristic of malaria. Plasmodium enters a sexual phase when some merozoites in the erythrocytes develop into gametocytes, cells capable of producing both male and female gametes. Erythrocytes containing gametocytes do not rapture. Gametocytes are incapable of producing gametes within their human hosts and do so only when they are extracted from and infected human host by a mosquito. Within the gut of the mosquito, the gametocytes form male and female gametes. The resultant diploid zygotes develop within the mosquito's intestinal walls and ultimately differentiate into oocysts. Within the oocysts, repeated mitotic divisions take place, producing large numbers of sporozoites. These sporozoites migrate to the salivary glands of the mosquito, and from there are injected by the mosquito into the bloodstream of a human, thus starting the life cycle of the parasite again.C:\Users\Georgio\AppData\Local\Temp\ch40f1.jpg

Taxonomy

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Malaria is caused by protozoan parasites of the genus Plasmodium. Four species of Plasmodium can produce the disease and affect humans in its various forms:

Plasmodium falciparum

Plasmodium vivax

Plasmodium ovale

Plasmodium malariae

P. falciparum

P. malariae

P. ovale

P. vivax

Location

Tropical and Subtropical areas of C. & S. America, Africa, and S.E. Asia

Tropical and subtropical areas of C. & S. America, Africa, and S.E. Asia

Primarily in Sub-Saharan Africa

C. & S. America, India and S.E. Asia

Taxonomic Classification

Kingdom

Sub-Kingdom

Phylum

Class

Order

Family

Genus

Species

Plasmodium belongs to the family Plasmodiidae, order Eucoccidiorida and phylum Apicomplexa. Currently, there are 450 recognised species in this order. Many species of this order are undergoing re-examination of their taxonomy with DNA analysis. It seems likely that many of these species will be re-assigned after these studies have been completed.

Symptoms/Pathology and Current Treatment

Symptoms can appear any time from six days after you are bitten by a mosquito carrying the malaria parasite. The time it takes your symptoms to appear - the incubation period - can vary with the type of parasite that the mosquito was carrying (falciparum, ovale etc.).

The classical malaria attack lasts 6-10 hours. It consists of

a cold stage (sensation of cold, shivering)

a hot stage (fever, headaches, vomiting; seizures in young children)

a sweating stage (sweats, return to normal temperature, tiredness).

If bitten by a mosquito containing the P. falciparum parasite, the symptoms will usually develop within three months of the bite, but, most generally start between seven and 30 days.

If a mosquito carrying the P. vivax, P. ovale or P. malariae parasite bites you, it is possible for the symptoms to emerge a year or more after the bite. This is because the parasite can lay dormant in your liver and become active months later. These parasites may also cause you to have the symptoms repeat.

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The most typically used medicine when travelling, to prevent malaria, is the Chloroquine Drug:

Issues and Concerns

there is no drug that is completely safe and effective either for prevention or for treatment, nor is there a vaccine. The optimum regimen is an attempt to balance the risk of side effects against the risk of disease. You must consider where you are going and when, how you will travel, the types of malaria present, types of drug resistance, the prevalence of risk, how long you will be exposed, and also your personal condition: as with many other drugs, pregnant women are especially constrained, as are young children. The two major issues are which areas you will be visiting (especially what drug resistance has developed), and how long you will be there. After that come the complications caused by what drugs you cannot take.

The disease is endemic in 91 countries currently, with small pockets of transmission in a further eight. Malaria is generally endemic in the tropics, with extensions into the subtropics.

Countries which have regions where malaria is endemic as of 2003 (coloured yellow). Countries in green are free of indigenous cases of malaria in all areas.

Human Impact

To fight malaria, we already have a set of tools that can prevent malaria's spread, keep people from dying and (in the process) demythologize the disease. Early efforts at treatment focused on the development of medicines to fight the disease. This resulted in the parasite developing resistance to the drugs. Subsequently, disease prevention has focused primarily on treatment of stagnant water since mosquitoes breed and develop in such places. So far, these precautions have been put in place by humans thus far:

1.     Using mosquito nets to avoid being bitten by the insects

2.     Using prescribed malaria drugs to kill the parasite before it incubates

3.     Eradicating mosquito breeding sites

4.     Wearing long-sleeved clothing

5.     Applying insect repellent creams when outdoors

With these safety measures established, human have provided a much safer and preventable environment. With more processes developing, it is only a matter of time before this disease has become completely avoidable; scientists are trying to institute a vaccine which will be able to immune the disease. Overall it has been a success and human endeavours will continue to proceed.

Source Analysis

After researching different articles on the web on Plasmodium and malaria, four sources were selected and analysed. The articles were very variable in the fact that some were well-written reliable sources, but some not so dependable. Wikipedia was purposely chosen as a poor source, because it would be a good choice of article to compare to one like the Tulane article. The Tulane article was composed by the Tulane University, one of the most highly regarded research universities in the United States. The other two articles were the averagely dependable sources which comprised of well-written information but not as reliable as the Tulane source. In general there is a wide range of resources that are offered on the net. It is being able to distinguish the reliable and dependable ones from the inadequate, substandard ones.

How can human further help the situation? If we educate families on how to ensure a malaria vector-free environment, as well as provide families with insecticide treated bed-nets, we will be able to reduce the number of malaria illnesses and deaths in children by at least 50%. Other possible solutions could be to make sure of sanitation in the community. Keeping clean surroundings could be a possible method to excluding these blood-sucking pests. As for medication, all that can be done at this moment is being conducted and further precautions are at commencement. The parasite itself is uncontrollable and out of our reach at this very moment, but surely future procedures will take place to prevent this issue. It's just up to the travellers to remember the travelling safety precautions, and for those who live in a malaria endemic region, must take further actions if it be medication, sanitation, eradication, or education.