Understanding Malaria: Should Australians be Concerned?
Published: 31 May 2020
Published: 31 May 2020
At least 200 million people are infected with malaria every year, with an estimated 400,000 deaths annually (WHO 2020).
Malaria is an infectious disease caused by the parasite Plasmodium, which is transmitted through the bite of a female Anopheles mosquito. Occasionally it is transmitted congenitally, by blood transfusion or by syringes (NSW DoH 2016).
When female Anopheles mosquitoes feed on blood to nurture their eggs, they can pick up Plasmodium parasites from humans infected with malaria. These mosquitoes will then become vectors (carriers) and transmit Plasmodium to other people they bite. You can not contract malaria directly from another person (CDC 2020; WHO 2016).
Australia was certified as being malaria-free by the World Health Organisation in 1981. (QLD DoH 2017).
Despite this, there are still reasons to be vigilant:
(QLD DoH 2017; NSW DoH 2016; Canna 2019)
If Australia is to remain free of malaria, it is imperative that all cases are diagnosed and treated appropriately. If you’ve been in an area where malaria has occurred within the previous 12 months and you develop a fever, you should be checked for malaria, both for your own sake and to prevent malaria getting into the community.
There are five main species of Plasmodium that cause malaria in humans. They differ somewhat in areas where they mainly occur, the symptoms they cause, and treatment required.
(MyDr 2012; Stanford Health Care 2019; The Walter and Eliza Hall Institute of Medical Research 2020)
After being bitten by an infected mosquito, the Plasmodium parasite enters the liver, where it begins to multiply. 7 to 18 days later (typically), the infection re-enters the bloodstream, invades red blood cells and reproduces (NHS 2018).
The initial flu-like symptoms are likely to include:
Some people may experience recurring ‘attacks’ of malaria, where they experience cycles of symptoms that last for around 6 to 12 hours.
(NHS 2018; Mayo Clinic 2018)
Plasmodium malariae may persist for several years and has been associated with nephrotic syndrome in children (Langford et al. 2015).
Severe malaria may cause symptoms such as:
(Severe Malaria Observatory 2017; RCHM 2012)
Laboratory diagnosis of malaria is by microscopy. A blood specimen is spread as a smear and examined to confirm the presence of Plasmodium and calculate the percentage of red cells containing the parasites (CDC 2020).
Where microscopy is not possible, ‘dipstick’ tests (malaria antigen immunochromatographic test) may be used. This can detect Plasmodium falciparum but not other species (CDC 2020).
Malaria is treated with antimalarial drugs to kill the Plasmodium. The exact drug will depend on the species of Plasmodium involved and the patient (some medicines are not suitable in pregnant women or infants) (Mayo Clinic 2018).
Increasing medicine resistance is a problem, especially in certain areas, and the area in which malaria was caught needs to be considered (Mayo Clinic 2018).
In severe malaria, treatment must be started urgently. Initially, it needs to be intravenous. If the attack is not classified as severe, oral medications may be used (CDC 2020).
Plasmodium vivax and Plasmodium ovale may have dormant stages (hypnozoites) that persist in the liver and are not killed by the medication used for the acute attack. The patient may need to take primaquine (Mikolajczak et al. 2015).
Anyone travelling to a malarious region should take precautions. This includes consulting a physician to prescribe preventative antimalarial drugs (NSW DoH 2016).
No antimalarial drug is 100% effective, so taking precautions to avoid mosquito bites is also crucial. These include:
(NSW DoH 2016; Malariasite 2015)
Question 1 of 3
Which type of <em>Plasmodium</em> parasite causes the most severe malaria?
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Phillip Petersen, BSc, FASM, has operated a writing and editing business for over twenty years. This follows a career as a microbiologist in hospitals and a pathology laboratory for over thirty years, during which he was also involved with the development and implementation of microbiology courses at Queensland University of Technology. He also conducted research on the in vitro study of infection and has had articles published as well as reference books on the diagnosis and management of infectious diseases and on antibiotics. Phillip ranks his greatest achievement as materially assisting several higher degree students and researchers to reach their goals. See Educator Profile