General information on malaria

Malaria is a preventable infection that has the capability of affecting anybody at any age. The infected female anopheles mosquito transmits malaria, when it settles on a person to take a blood meal.

Malaria can be contracted when visiting a malaria-risk area or through "airport malaria" - which is not very common. Airport malaria is contracted through the coincidental introduction of the anopheles mosquito in an airport, luggage or any type of closed vehicle / container.

It was originally thought that malaria originated in marshes and swamps and was transmitted through the air, hence the name "mal" "aria" - meaning "bad air", but the real cause was discovered in 1880, when scientists discovered that malaria is caused by a single cell parasite called plasmodium.

The mosquito transfers this parasite to a human through its bite, as blood is required by the mosquito to nurture its eggs.

Affected areas

Malaria usually occurs in tropical and sub-tropical countries, and is one of the largest scourges in third world countries, infecting approximately 300 - 500 million people, and killing one million people annually.

Malaria is present in sub-Saharan Africa, southern and eastern Asia, India, Haiti, Mexico, the Middle East, Dominican Republic, Oceania, Central and South America, Vanuatu the Solomon Islands as well as Papua New Guinea.

The population of Africa suffers the most from malaria, and it is reported that 90% of malaria cases are diagnosed in Africa - mainly among young children and pregnant mothers. It is reported that malaria causes the death of an African child every 30 seconds.

Types of malaria

There are 4 types of malaria that infect humans:

Symptoms of malaria infection

Malaria can occur despite taking anti-malarial drugs and symptoms of malaria infection usually occur within 9 to 14 days.

The general symptoms include headache, nausea, fever, vomiting and flu-like symptoms, although these symptoms may differ depending on the type of plasmodium that caused the infection.

Time for symptoms to develop

Plasmodium falciparum normally take 7 to 14 days to show symptoms while Plasmodium vivax and ovale normally take 8 to 14 days (but in some cases can survive for some months in the human horst) and Plasmodium malariae 7 to 30 days.

These figures are as indication only - the onset of symptoms varies tremendously and people should not try and diagnose themselves by using any time-frame figures as these listed above.

Symptoms of malaria infection are not always dramatic, and can easily be dismissed as unimportant.

Should the infection not be attended to deterioration is normally sudden and drastic as the parasites rapidly increase in the blood stream.

Symptoms may appear and disappear in phases and may come and go at various time frames. These cyclic symptoms of malaria are caused by the life cycle of the parasites - as they develop, mature, reproduce and are once again released into the blood stream to infect even more blood and liver cells.

When this happens a high swinging fever can develop, with marked shivering and intense perspiration. Further serious complication involving the kidneys and brain can then develop leading to delirium and coma.

There are cases reported where symptoms of malaria infection developed 12 months after the patient was bitten by a mosquito, as the plasmodia may remain dormant in the liver for a long period.

List of symptoms

Malaria causes a flu-like illness and these would include

Fever in the first week of travel in a malaria-risk area is unlikely to be malaria; however, any traveler feeling ill should seek immediate medical care.

Although malaria is unlikely to be the cause, any fever should be promptly evaluated. If you or your child becomes ill with a fever or flu-like illness while traveling in a malaria-risk area and up to 1 year after returning home, seek immediate medical care. Tell your health care provider where you have been traveling.

The normal treatments for malaria infection are drugs based on quinine, or a combination drug therapy known as ACTs, based on artemisinin (which is expensive).

Symptoms may develop later

It is possible, but not very general, to develop a relapsing type of malaria months for even years after being infected by malaria - even if anti-malarial drugs were taken.

While anti-malarial drugs can prevent symptoms of acute malaria from developing, by suppressing the infection in the bloodstream, they however do not prevent relapses of the infection caused by certain strains of the plasmodium parasite which have a persistent liver phase.

The most common type of malaria infection is that of Plasmodium falciparum and this strain does fortunately NOT have a relapsing phase. The other strains such as Plasmodium vivax, ovale, or malariae can infect the liver and persist in a dormant state for months, or even years after exposure to the infection.

Should a relapse develop it can be treated by restraining the acute symptoms with chloroquine and then overcome the liver infection with medication called primaquine. This medication is more toxic and has more side effects than chloroquine but is a very effective form of treatment.

People with a deficiency of the blood enzyme G6PD are predisposed to reactions from primaquine treatment but such an enzyme blood deficiency is easy to ascertain with a simple blood test before treatment with primaquine is started. Prevention is better than cure in the case of malaria, however, as the infection is becoming increasingly resistant to prescribed drugs.

Various insecticides, which are used to spray areas favored by mosquitoes, are also no longer effective, and a constant struggle is under way to develop new anti-malarial drugs and insecticides, to keep the disease at bay.

Malaria from Plasmodium falciparum

Plasmodium falciparum is known to be the most lethal form of the plasmodium parasite, with most malaria infections and deaths being due to falciparum.

Plasmodium falciparum is common to the southern regions of Africa, but it is reported that cases are now being reported in other areas, where this type was thought to have been eradicated.

Although P. falciparum is a dangerous infection to contract, the three other types of infection also needs to be treated, as their untreated progress can also cause a host of health problems.

Lifecycle of the plasmodium parasite

The plasmodium parasite which causes human malaria can be divided into four different species, namely

Transmission of the parasite

The parasite is transmitted to the human host when an infected anopheles mosquito bites the human to feed of human blood

Plasmodium falciparum occurs in almost all areas affected by malaria and it is classed in most cases resistant to chloroquine. Plasmodium vivax infection is predominantly located in South America as well as the Middle East, but is uncommon in sub-Saharan Africa. Plasmodium ovale as well as Plasmodium malariae is mostly found in Africa.

In order to plan effective treatment of malaria infection, the identification of the infecting species is important and testing may be required to ascertain it.

The plasmodium parasite has an extremely complex lifecycle, and on entering the human host, goes through a series of changes until it reaches a sexual stage.

It is in this stage of sexual maturity that the parasite can be transmitted to another person through the vector agency of the mosquito, as the mosquito will feed on the infected human host and then feed again, within 10 to 14 days, on a different person.The various stages in the lifecycle of the plasmodium parasite allow it to confuse the body's immune system, and to invade and infect the liver and red blood cells.

The plasmodium parasite multiplies in the human body, spreading from the liver, destroying red blood cells, which also results in anemia (anaemia).

If the infection reaches an advanced state the plasmodium start to clog the capillaries that carry blood to the brain, (this is called cerebral anemia (anaemia)) and various other organs of the body. Malaria can be life threatening and must be treated by a competent health practitioner as soon as possible.

Preventing malaria infection

The best way to prevent malaria is to avoid being bitten by a mosquito, since the disease is transmitted by the bite of the malaria. Apart taking measures to prevent being bitten in the first place, anti-malarials drugs must also be taken before entering a high risk area.

The time that you are most susceptible to be bitten is between dusk and dawn - outdoors and inside, but some preventative measures can be used to avoid the bite of the mosquito.

Various ways can be followed to reduce the risk of being bitten, but following all available recommendations will help reduce the risk.

Anti-malarial drugs

People traveling to areas such as South America, Mexico, Africa, Indian, Asia, and the South Pacific should consult their health practitioners well in advance before traveling in order to facilitate the prescription of drugs to prevent malaria.

The choice of drug/s will depend on your personal medical history and health condition as well as the duration and itinerary of your travels as some drugs work better in certain areas than others.

Although these anti-malarial drugs are taken as a preventative measure, they are potent drugs and overdose can be fatal, and for this reason, store them in childproof containers out of reach of children.

Timing is very important with this type of drug, and for this reason the medication must be taken in the prescribed manner and at the precise times as indicated, without missing any doses.

Guarantee

Taking anti-malarial drugs does not carry a 100% guarantee and people that has returned from a malaria infected area should be aware of any malaria symptoms that may develop, and should this happen, a health practitioner must be contacted immediately for the appropriate medication, since malaria is a serious disease and should be treated without delay.

Other measures

Although being on an anti-malarial drug treatment course is a must when entering a high-risk malaria area, it is still the best to take other precautions as well to avoid being bitten in the first place. Click here for some ideas.

Different types of drug therapies

Depending on your personal health history, as well as the area being visited, your health practitioner may prescribe any of the following drugs

Compiled by Dr. F.I. Biswas, Otoawa, Canada.

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