Defining malaria and its causes
What is malaria?
A disease which mostly affects tropical and subtropical areas, malaria is one of the world’s biggest killers. When contracted, malaria can be a life-threatening disease if left untreated or if severe complications occur.
An infection is typically caused by parasites (Plasmodium parasites) in the bloodstream after being bitten by an infected female Anopheles mosquito. This is the only mosquito known to carry the parasite and spread the disease. Carriers of this parasite, a bite from an infected mosquito quickly transmits it through the bloodstream to the liver.
Once the parasite reaches the liver, it matures and begins to target a person’s red blood cells within a matter of days. Once the red blood cells have been infected, they multiply (reproduce) and burst open. A person will begin to feel unwell within 48 to 72 hours of infection and experience symptoms in cycles that last a few days at a time as red blood cells are continuously targeted by the parasite. Chills and fever are typical symptoms associated with this recurrent cycle.
The plasmodium parasite thrives in tropical and subtropical climates (such as Africa, Southern Asia, South and Central America), making these areas of the world incredibly high-risk. Billions of people are at risk of malaria every day and up to half a million people die from the disease each year.
Preventative measures to help reduce the occurrence of mosquito bites in high-risk areas are one way many are trying to gain control of the disease. Bed nets (mosquito nets) which help to protect people from bites while they sleep are somewhat effective.
Another means of prevention is medication (although drugs cannot offer 100% protection due to parasites consistently becoming immune), which travellers, in particular, are encouraged to take before entering high-risk areas (during and after their trip too).
There are 5 known species of the Plasmodium parasite:
- P.falciparum: This parasite species mostly occurs in the tropics and subtropics (close to the equator) and can lead to life-threatening complications within a matter of days following infection. This species is known to be resistant to antimalarial medications and an infection with this parasite typically requires combination treatment.
- P. vivax / P. malariae / P. ovale / P. knowlesi: The species, P. vivax and P. malariae occur in tropical areas. The species P. knowlesi is typically found in Southeast Asia. The malaria causing parasite P. ovale is typically seen in Western Africa, but can occur in other high-risk areas too. An infection with the parasite species P. knowlesi is often most life-threatening and may be fatal (but is not generally resistant to medication treatment). Infections with P.vivax, P. malariae or P. ovale aren’t usually life-threatening and have high recovery rates within a month of treatment (as they are generally not resistant to medications). Relapses are common with P.vivax, P. ovale and P.knowlesi parasite infections (as the parasite can remain in the liver) which may require further medication treatment.
How is malaria transmitted?
A malarial infection thrives in the bloodstream and it thus easily transmitted by blood. Here is a brief breakdown of how the transmission cycle works:
- An uninfected mosquito ‘feeds’ (bites or draws blood) on an infected person (who has malaria).
- The mosquito becomes infected with the parasite and bites the next person, transmitting the Plasmodium parasite to them.
- The parasite enters the blood stream of the now infected person and travels to the liver, as well as attacking the body’s red blood cells as it moves through the bloodstream.
- The parasite begins to mature and develops symptoms such as fever and body chills.
- If an uninfected mosquito bites an infected person, the cycle begins again, spreading the malarial parasite to another individual.
An infected person can also pass on their condition to others (though rare). Other means of transmission include blood transfusions, during an organ transplant, the sharing of needles (often used to inject drugs) or syringes and from mother to her unborn child during birth (known as congenital malaria).
How does malaria affect the body?
Signs and symptoms
The Plasmodium parasite typically begins attacking the body’s red blood cells within 48 to 72 hours. A person will start to feel the effects of the infection within a 10-day period.
It has been noted that some malarial parasites can lay dormant for certain periods of time and not develop any obvious symptoms for several months. This is one reason why travellers are encouraged to continue taking antimalarial medication after a trip to a high-risk area.
Typical symptoms of malaria are:
- A high fever
- Shaking and bodily chills (ranging from mild / moderate to severe)
- Profuse sweating
- Nausea and vomiting
- Muscle pain (Myalgia) and aches in the joints (Arthralgia)
- Bloody stools
- Anaemia (this can be severe)
- Coma (often seen with cerebral malaria)
The initial signs may be misinterpreted as the beginning stages of the flu (influenza) and typically come and go (cycles of fever, chills, sweating and muscle aches) every 48 to 72 hours.
In severe instances, malaria can lead to more serious complications where damage caused by the parasite affects the lungs (resulting in severe respiratory abnormalities, pulmonary oedema and impaired breathing function), kidneys (leading to renal failure and metabolic acidosis), heart and brain. If not sufficiently treated, this is life-threatening.
Risk factors and potential complications
The biggest risk factor associated with malaria is location. Where the malaria carrying mosquito is rife, many subtypes of parasites exist. The highest number of malaria cases with the deadliest of associated infection complications are most notably seen in the Asian subcontinent, African countries (south of the Sahara Desert), Haiti, the Solomon Islands and Papua New Guinea.
The CDC (Centers for Disease Control and prevention) consistently updates their world map with areas known to be high-risk. This is especially useful for those who frequently travel or who live in these locations. You can view the map here.
Those at highest risk include:
- Travellers coming from lower risk areas or countries where malaria is not a concern
- Infants and young children
- Pregnant women (and their unborn babies)
A lack of knowledge, particularly in areas with high poverty rates and little to no access to sufficient health care can also lead to high numbers of fatalities as a result of malarial infections.
It is also possible that people, who are exposed to the condition so frequently (in high risk areas), become partially immune and sometimes experience milder symptoms when infected with malaria. Still, all cases of malaria must be treated by a medical professional.
It is also possible for malarial infections to relapse, causing an infected person to experience symptoms again. This is most commonly noted in some parasite varieties causing milder symptoms.
When complications happen, the results can be severe. The biggest concern in all malaria related diagnoses is preventing another fatality.
The highest number of fatalities related to malarial infections happen in Africa (almost 90%). Children under the age of 5 make up the largest portion of those who have lost their lives as a result of malarial infection. When the parasite in the bloodstream results in damage to the organs of the body (in particular), serious life-threatening complications occur.
Serious complications include:
- Breathing problems: A serious complication is pulmonary oedema where a build-up of fluid accumulates in the lungs. This causes problems with breathing.
- Cerebral malaria: Swelling in the brain can cause severe brain impairment and damage due to parasite infected blood cells blocking small blood vessels. This can lead to coma.
- Low blood sugar: Severely low blood sugar levels can be dangerous, resulting in coma or even death. A malarial infection can cause low blood sugar levels, as can medications used to treat an infection.
- Anaemia: Damaged red blood cells can result in the development of anaemia in the blood (a lack of healthy red blood cells or haemoglobin).
- Organ failure: Damage that reaches the spleen, liver or kidneys can be life-threatening. The spleen can rupture and severe impairment to the function of the liver and kidneys can result in total failure thereof.
Diagnosis and treatment procedures
How is malaria diagnosed?
However mild or severe your symptoms, all cases of malaria are best diagnosed and treated by a medical doctor or infectious diseases specialist. Your doctor will want to determine the following during the initial consultation:
- Have you recently travelled to a high-risk area (often a remote location)?
- Your age and immune status
- Are you pregnant?
- Do you have any allergies or medical conditions?
- Are you currently taking any medications or supplements?
Once your overall health status is assessed and your medical history reviewed, your doctor will perform a physical exam. One of the main flags your doctor will be checking for is whether or not you may have an enlarged liver or spleen. Your doctor will also assess your neurological functions during the physical exam.
To confirm a diagnosis, your doctor will recommend blood tests. These tests will be used to determine:
- Whether or not you have a malarial infection
- The type of parasite involved
- Whether your infection is caused by known parasite which may be resistant to any medications currently being used
- Whether or not the infection has resulted in anaemia
- Whether or not the infection has caused any damage to any of your vital organs
A doctor will assess your blood culture, platelet count, haemoglobin concentration, electrolyte concentrations (especially sodium), and your liver and kidney function.
Although malaria can become life-threating, it can be effectively treated. Hospital care is necessary. Your doctor will need to monitor your treatment and keep an eye on the development of any potential complications.
Once determined through your blood tests, your doctor will treat your symptoms based on the type of parasite found to be causing your infection. In some cases, more than one kind of medication may be necessary to treat malaria due to the nature of the parasite and whether or not it is showing resistance. Sometimes, medications may be switched during treatment as well, for the same reason.
Medication types and length of treatment varies according to:
- The type of parasite causing the malarial infection
- A person’s age
- The nature of a person’s symptoms (mild or severe)
- If a woman is pregnant
Can malaria be prevented?
Antimalarial medications and mosquito-related precautions are currently your best means of prevention. Medications prescribed to help prevent the effects of an infection are typically the same as those used to treat malaria too. Medications are prescribed to be taken in set dosages before (up to several months ahead), during and after travel to a high-risk area. It is important that your doctor is aware of your intended travel location so that he or she may prescribe the medication that is currently showing the best results in preventing malaria in that area.
Bed nets (mosquito nets) are widely encouraged in areas rife with mosquito carrying parasites. These nets, which are often treated with insecticide, are effective in preventing bites from infected mosquitoes.
If you are in a high-risk area, it is also strongly advisable that you use repellent sprays that contain the chemical DEET (N,N-Diethyl-meta-toluamide or diethyltoluamide) and wear clothing that effectively covers your skin during active mosquito times (between dusk and dawn). You can also use insecticides in the home or places you are residing by spraying walls, window and door frames.
Is there a vaccine for malaria yet?
There is currently no licenced vaccine against malaria. A vaccine approved for human use is on the cards and is currently undergoing trials for safety. Over the years there have been many vaccine constructs tested in clinical trials, with several reaching advanced pre-clinical development stages.
The most successful vaccine trial currently taking place is in Queensland (Northwest Australia) by a team of scientists at Griffith University in collaboration with Gold Coast University Hospital. The research team is conducting a world-first ‘whole blood-stage malaria parasite vaccine trial’ in an attempt to assess human safety of the vaccine (testing the immune response in humans).
Researchers are testing the vaccine by involving the entire malarial parasite (not normally trialled in vaccine testing). The aim is to attempt ‘putting the parasite to sleep’ (i.e. killing it off) with the vaccine drug which binds to its DNA once the natural immune system response to infection has been stimulated.
Professor Michael Goode, Griffith University Institute for Glycomics, has been studying malaria extensively to determine how the malaria causing parasite evades the human immune system and rapidly multiplies its proteins into the bloodstream.
The majority of licenced vaccines available work with a single protein. The tricky part of developing a vaccine for malaria involves the typical mutation of the malaria parasite. When this happens, it changes and effectively becomes a moving target. The immune system then ‘dismisses’ the different strains created, not recognising them effectively in the body. The parasite can then easily cause the body more damage as it reproduces and mutates.
The researchers feel they have discovered the ‘key molecule’ (LFA-1) which will kill off the parasite as it infects the human liver, and prevent mutation in the bloodstream.
The initial group of volunteers tested amounted to 11 individuals, and Professor Goode himself. Researchers aim to expand testing on a larger group of 20 to 30 individuals.
Each individual will receive 3 doses of the vaccine. If the larger group trial is also successful, researchers will be headed to Uganda, where high rates of malaria occur, to trial the vaccine further. If successful, the public can potentially expect a vaccine (called PlasProtecT) to be made available within the next 5 to 10 years.
What is ‘sweet annie’ and can it cure malaria?
You may have heard a suggestion that a plant with small yellow flowers, called ‘sweet annie’ (Artemisia annua) contains compounds which can cure a variety of different health conditions, including cancer.
Native to China, ‘sweet annie’ is known to be used in traditional Chinese medicine practices. ‘Sweet annie’ is also known as ‘sweet wormwood’ or ginghao. The plant contains flavonoids, artemisinin and essential oils. The artemisinin content is what many believe capable of killing off parasites, including those that cause malaria.
A herbal remedy is made from the dried leaves of the plant and sold as a malaria treatment. Some approved antimalarial medications also contain artemisinin.
Still, the World Health Organisation (WHO) encourages the broader public to rather use clinically tested medications with this compound instead. Pharmaceutical medications include other compounds along with artemisinin. The concern with using one compound in a medicinal treatment is that parasites can become resistant to it, further complicating treatment of malaria.
Can malaria recur (come back)?
Unfortunately, yes. Recurrences depend on the parasite causing the infections and can happen at regular intervals for up to 2 years if treatment is insufficient.
Of the parasite species known to cause malaria recurrences, P. falciparum, P. vivax, P. ovale and P. malariae have been noted to bring back symptoms requiring treatment. Prescribed medications can be used to prevent recurrences where P. vivax and P. ovale parasites have been identified. P. malariae can remain in the bloodstream for up to 30 years and may not cause any malaria symptoms.
Should pregnant women take antimalarial tablets?
Pregnant women are considered extremely high-risk for malaria and should take every possible precaution to prevent an infection. A malarial infection can increase a pregnant woman’s risk of pregnancy complications (birth defects, premature birth, stillbirth or miscarriage) and in severe instances, cause death of both the expecting mother and her baby (foetus).
Antimalarial medications are essential for women who are pregnant or wish to fall pregnant if they intend to travel to high-risk areas (these will be prescribed by a medical doctor if you must travel). It is, however, not entirely clear as to whether these medications have a direct, harmful effect on a developing baby. Safety has not entirely been established as pregnant women (especially those in the first trimester of their pregnancy) are not typically used in clinical testing of medications.
Ideally, a pregnant woman is better off not travelling to a high-risk area and taking antimalarial medications. If you must, for whatever reason, it is essential that you consult your doctor well ahead of time so that he or she can best prescribe medication that may be most safe, in their opinion, to take. Prescribed medication will depend on where in the word you are headed to. Your doctor will likely prescribe one for the specific type of parasite known to cause malaria in the location and that has little to no current evidence of harm to a pregnant woman or her unborn baby.
Your doctor may discourage you from trying to conceive if you are to travel to a high-risk area where malaria is present, especially while taking antimalarial medications. In this instance, prevention is far better than cure.