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The Medicine Of Malaria Changed Biology

Essay add: 24-11-2017, 17:48   /   Views: 20

Malaria is an intermittent and remittent fever caused by a protozoan parasite that invades the red blood cells. malaria is transmitted to humans by mosquitoes. Mosquitoes are any of various two-winged insects of the family Culicidae, in which the female of most species is distinguished by a long proboscis for sucking blood. Some species are vectors of diseases such as malaria and yellow fever.

Life cycle of Malaria.

The plasmodium parasite is spread by female anopheles mosquitoes. When the mosquito bites a person infected with malaria, it can then carry the parasite and spread it to other people after it has developed in the mosquito.

 So the mosquito becomes infected when it takes a blood meal from an infected vertebrate. Once ingested, the parasite gametocytes taken up in the blood will further differentiate into male or female gametes and then fuse in the mosquito's gut. This produces an ookinete that penetrates the gut lining and produces an oocyst in the gut wall. When the oocyst rip open, it releases sporozoites that migrate through the mosquito's body to the salivary glands, where they are then ready to infect a new human host.

When the parasite enters your blood through a bite, it migrates straight to your liver where they infect hepatocytes (A hepatocyte is a cell of the main tissue of the liver), multiplying asexually and asymptomatically for a period of 8-30 days. After a potential dormant period in the liver, these organisms differentiate, specialise to yield thousands of merozoites (when a cell that arises from the asexual division of a parent sporozoan during its life cycle) , which, following rupture of their host cells, escape into the blood and infect red blood cells to begin the erythrocytic stage of the life cycle. The parasite escapes from the liver undetected by wrapping itself in the cell membrane of the infected host liver cell.

Once in the red blood cells, the parasites grow and multiply. Eventually, the infected red blood cells burst and release even more parasites into your blood. The infected cells usually burst every 48-72 hours. Each time this happens, you will experience an attack of chills, fever and sweating.

Symptoms of Malaria

Symptoms of malaria usually appear 10-15 days after you are bitten. However, depending on the type of parasite that infected you with, it can take a year for symptoms to show. Symptoms of malaria are similar to flu symptoms and include:

A high  temperature (fever) of 38°C (100.4F) or above.

Sweats and chills.

Generally feeling unwell.

Muscle pains.

Headaches.

Cough.

Diarrhoea.

With some types of malaria, the fever occurs in 4-8 hour cycles. You feel cold at first with shivering that lasts for up to an hour. You then develop a fever that lasts for 2-6 hours, accompanied by severe sweating.

Defences against Malaria

Today's prevention against malaria include taking anti- malaria tablets and sleeping in mosquito nets and in some cases vaccines.

Anti malaria Tablets

Recommendations for drugs to prevent malaria differ by country of travel.

No anti malarial drug is 100% protective and must be combined with the use of personal protective measures, (i.e., insect repellent, long sleeves, long pants, sleeping in a mosquito-free setting or using an insecticide-treated bed net).

Some anti malaria tablets are taken daily while others are taken weekly. Some anti malaria tablets are made for shorter trips where you will have to continue taking the medicine 7 days after travelling than four weeks or more. Some anti malaria tablets are can be taken during pregnancy while others cant.

Popular Malaria tablets

Name

How quickly it works

How to take it

Side effects

Other malaria tablets

Malarone

Protection starts one to two days after starting your course. As with all malaria tablets you still need to take steps to avoid being bitten by mosquitoes because Malarone doesn't guarantee protection

One tablet a day. Start taking the tablets one to two days before you enter a malaria area and continue until one week after you leave the area.

Uncommon and usually mild, but can cause stomach pain, headache, nausea, diarrhoea, coughing or mouth ulcers. You may experience vivid dreams

Depending upon where you're travelling, other malaria pills might also be appropriate.

Doxycycline

Protection starts two days after starting your course. As with all malaria tablets you still need to take steps to avoid being bitten by mosquitoes because doxycycline doesn't guarantee protection.

One tablet a day. Start taking the tablets two days before you enter a malaria area and continue until fours week after you leave the area

Uncommon but can cause nausea, diarrhoea, sore throat and, even more rarely, inflammation of the liver or bowel. Can make skin more sensitive to sunlight. Can reduce the effectiveness of the combined contraceptive pill.

Depending upon where you're travelling, other malaria pills might also be appropriate

Lariam

Protection starts two and half weeks after starting your course. As with all malaria tablets you still need to take steps to avoid being bitten by mosquitoes because Lariam doesn't guarantee protection.

One tablet a week, always on the same day. Start taking the tablets two and half weeks before you enter a malaria area and continue until fours week after you leave the area

Can cause nausea, vomiting, depression, mood changes, anxiety, confusion, panic attacks or a general feeling of agitation. Side-effects can last a number of weeks. It's best not to take Lariam if you're trying to get pregnant or might become pregnant when taking the medicine or within three months of stopping the course.

Mefloquine can also cause dizziness or disturbed sense of balance so be alert to this if you intend to drive, dive, pilot aircraft or operate machines.

Depending upon where you're travelling, other malaria pills might also be appropriate.

Mosquito Nets

Properly used, a mosquito net offers protection against mosquitoes, flies, and other insects, and thus against the diseases they may carry. Examples include malaria, dengue fever, yellow fever, and various forms of encephalitis, including the West Nile virus

there are different types of mosquito nets like the self supporting mosquitoes.  Self supporting mosquito nets use special flexible wire hoops or metal or plastic wands to make a stiff frame that suspends the net over the user much like a tent. They don't require any other form of support. Some self supporting mosquito nets also have a sewn-in base so that the interior of the net is completely enclosed.

Advantages: Do not require net frames, hooks, string, ladders, improvisation or clips in order to be erected. Can be set up quickly or packed away. Can be used on a bed, in a tent or on the ground, indoors or out. Some have sown in groundsheets and so give all round protection from crawling bugs, small snakes and scorpions as well as flying insects. They can also be used outdoors in windy conditions

Disadvantages: because they include poles or hoops to support the net they are heavier, bulkier and generally more expensive than smaller sized conventional nets. the poles or hoops don't squash or bend easily so packing, particularly in a rucksack is harder. the poles or hoops can be damaged and are hard to repair. Tend to have smaller volume than bell and box nets so there is less air circulation, making it relatively warmer to sleep in.

Vaccines

Malaria vaccines are an area of intensive research. However, there is no effective vaccine that has been introduced into clinical practice.

In the Guardian they have posted an article on a new malaria vaccines that could save millions of children's lives.

This new vaccine shown to halve the risk of malaria in the first large-scale trials across seven African countries.

The long-awaited results of the largest-ever malaria vaccine study, involving 15,460 babies and small children, show that it could massively reduce the impact of the much-feared killer disease. 

Small-scale studies, in a few hundred children, have shown promising results in the past, but a trial of this size is needed to prove the vaccine's usefulness across populations. It is being carried out in Burkina Faso, Gabon, Ghana, Kenya, Malawi, Mozambique and Tanzania.

The early data from five- to 17-month-old children is the first of three important results; the outcome from the vaccination of newborn babies will be published next year. These figures are crucial, because the malaria vaccine needs to be incorporated into the infant immunisation schedule, alongside the usual diphtheria and measles jabs. Earlier small-scale trials suggest the results in six- to 12-week-old babies will also show around 50% protection.

The third important outcome, on how well the protection lasts, will not be known until 2014. The data so far, over 22 months, suggests there may be a drop in the numbers protected from severe malaria.

The WHO has said that if the results are satisfactory, it will recommend its use and the vaccine may begin to be rolled out as early as 2015, but it will need to be used in conjunction with all the other existing tools of malaria prevention, such as bed nets and insecticide spraying on the inside of homes.

Yesterdays defences against malaria

there have been many defences against malaria in the past, below there are two defences that have been known to act against malaria.

DDT- Dichlorodiphenyltrichloroethane (DDT) (1939)

A German chemistry student, Othmer Zeidler, synthesized DDT in 1874, for his thesis. The insecticidal property of DDT was not discovered until 1939 by Paul Müller in Switzerland. Various militarilies in WWII utilized the new insecticide initially for control of louse-borne typhus. DDT was used for malaria control at the end of WWII after it had proven effective against malaria-carrying mosquitoes by British, Italian, and American scientists. Müller won the Nobel Prize for Medicine in 1948

Chloroquine (Resochin) (1934, 1946)

Chloroquine was discovered by a German, Hans Andersag, in 1934 at Bayer I.G. Farbenindustrie A.G. laboratories in Eberfeld, Germany. He named his compound resochin. Through a series of lapses and confusion brought about during the war, chloroquine was finally recognized and established as an effective and safe anti malarial in 1946 by British and U.S. scientists.

Chloroquine prevents the development of malaria parasites in the blood. Doctors use it to both prevent and treat malaria. Chloroquine does not destroy the Plasmodium (P.)vivax and P. ovale parasites that may remain in the liver. Chloroquine is a drug that is still used today.

People would take this medicine because

Some people would rather take medicine weekly

Good choice for long trips because it is taken only weekly

Some people are already taking hydroxychloroquine chronically for rheumatologic conditions. In those instances, they may not have to take an additional medicine

Can be used in all trimesters of pregnancy

To treat malaria, you take chloroquine at several-hour intervals and at a higher dosage than when it's taken to prevent malaria.

The reasons to avoid taking this drug is because

Cannot be used in areas with chloroquine or mefloquine resistance

May exacerbate psoriasis

Some people would rather not take a weekly medication

For trips of short duration, some people would rather not take medication for 4 weeks after travel

Not a good choice for last-minute travellers because drug needs to be started 1-2 weeks prior to travel

Malaria around the world

Approximately half of the world's population is at risk of malaria. Most malaria cases and deaths occur in sub-Saharan Africa. However, Asia, Latin America, and to a lesser extent the Middle East and parts of Europe are also affected. In 2010, 99 countries and territories had ongoing malaria transmission.

The Anopheles species of mosquitoes located in Africa have an exceptionally long lifespan, which results in more time for the parasite to develop inside of the mosquito. Malaria is an epidemic is a broad band around the equator, including much of Africa, Asia, and parts of the Americas (See the map below). Malaria is prevalent in tropical regions because of environmental factors such as rainfall, consistent high temperatures, and stagnant waters which are necessary for continuous breeding.

http://malariasocgen180.files.wordpress.com/2012/01/places-affected-by-malaria.gif

Sickle cell anaemia

Sickle cell anaemia is a disease passed down through families in which red blood cells form an abnormal sickle or crescent shape. Red blood cells carry oxygen to the body and are normally shaped like a disc.

Sickle cell anaemia is caused by an abnormal type of haemoglobin called haemoglobin S. Haemoglobin is a protein inside red blood cells that carries oxygen.

Haemoglobin S changes the shape of red blood cells. The red blood cells become shaped like crescents or sickles.

The fragile, sickle-shaped cells deliver less oxygen to the body's tissues.

They can also get stuck more easily in small blood vessels, as well as break into pieces that can interrupt healthy blood flow. These problems decrease the amount of oxygen flowing to body tissues even more.

Sickle cell anaemia is inherited from both parents. If you inherit the sickle cell gene from only one parent, you will have sickle cell trait. People with sickle cell trait do not have the symptoms of sickle cell anaemia.

Sickle cell disease is much more common in people of African and Mediterranean descent. It is also seen in people from South and Central America, the Caribbean, and the Middle East. There have been instances where Caucasians, Asians and Europeans have also inherited this defective gene and no, it is not necessarily a result of being from a mixed African or Caribbean background.

So the people who carry just one sickle cell allele are less likely to get malaria. they have an improved chance of survival. so the frequency of the sickle cell allele has increased in places where malaria is a problem.

Symptoms

Symptoms usually do not occur until after age 4 months.

Almost all patients with sickle cell anaemia have painful episodes (called crises), which can last from hours to days. These crises can cause pain in the bones of the back, the long bones, and the chest.

Some patients have one episode every few years. Others have many episodes per year. The crises can be severe enough to require a hospital stay.

When the blood cells go out of shape causing these symptoms

Severe pain, when the sickled red blood cells block tiny blood vessels

Anaemia as damaged cells can't be replaced fast enough

Tiredness caused by the lack of oxygen.

Anti malaria tablets and sickle cell anaemia

Having Sickle Cell disorder does not make one immune to Malaria. If a Sickler is infected with the Malaria parasite, it increases the sickling in the blood which can lead to serious illness. This is why it is important for a Sickler to take anti-malarial tablets when travelling to areas where Malaria is prominent. It is thought that individuals who carry the Sickle Cell trait have some protection against Malaria; however it is also imperative that anti-malaria tablets are taken when necessary.

Article name: The Medicine Of Malaria Changed Biology essay, research paper, dissertation