Understanding Malaria: Why Should Australians Worry About Malaria?
Published on the 28 February 2017
Published on the 28 February 2017
Malaria has been claimed responsible for half of all human deaths from disease since the Stone Age.
At least 200 million people are infected every year, with some 600,000 deaths.
It is a disease caused by a parasite (Plasmodium) transmitted through the bite of a female Anopheles mosquito and occasionally congenitally by blood transfusion or by syringes (especially in drug users).
The mosquito gets it from an infected human and remains infected for life. You can not contract malaria directly from another person.
Australia was certified as being malaria free by the World Health Organisation in 1981.
There are four good reasons:
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 occurs 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. Make sure you tell your doctor.
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.
Over 70% of infections are due to P. vivax, a significant cause of illness in the Asia-Pacific region. Its ability to lie dormant for months in humans makes it difficult to get rid of.
P. falciparum causes about 20% of cases, often a rapid and severe illness, and is the most likely species to kill you.
Malaria caused by P. malariae and P. ovale are usually less severe.
P. knowlesi occurs in South East Asia, and is associated with macaque monkeys, progresses rapidly and can be fatal. Very rare moderately severe cases due to other simian (monkey) species have been reported.
When the malaria parasite gets into your blood, it roams around for about an hour and then goes to the liver, where it multiplies but doesn’t cause disease.
Six to 16 days later (depending on the species), it gets back into the blood and into red blood cells and reproduces, and this is where the trouble begins.
First, you’re likely to feel cold and shiver. Then you will get a high fever, headache, backache, nausea and vomiting, and muscle and joint pains. Finally, sweat will pour out of you, your temperature will go back to normal and you will feel fatigued and lethargic.
You are likely to get bursts of fever and chills ending in profuse sweating every other day or at three day intervals in the case of malariae malaria.
If it is vivax malaria, ovale malaria or malariae malaria, you may get better without treatment, though you are likely to have repeat attacks. With malariae malaria, these can go on for many years.
In children, malariae malaria can also cause fatal kidney damage.
If you are unlucky enough to have falciparum malaria, there may be blockage of blood vessels in critical organs, such as the brain, organ failure (kidney, liver), anaemia, jaundice, rupture of the spleen, pulmonary oedema, and coma.
Laboratory diagnosis of malaria is by examination of blood films.
Thick films are used to confirm the presence of parasites and to calculate the percentage of red cells containing parasites.
A thin film is used to identify the Plasmodium species.
Three films should be taken 12-24 hours apart when the patient is febrile.
Where microscopy is not possible, ‘dipstick’ tests (malaria antigen immunochromatographic test) may be used. This is pretty good for P. falciparum but not for other species. A polymerase chain reaction test is also available, but is expensive.
Treatment depends on the species of Plasmodium involved and the patient (some medicines are not suitable in pregnancy or infants).
Increasing medicine resistance is a problem, especially in certain areas, and the area in which malaria was probably caught needs to be considered.
In severe malaria, treatment must be started urgently. Initially, it needs to be intravenous. If the attack is not classified as severe, only oral medications may be used.
P. vivax and P. ovale have a form of the parasite (hypnozoite) which persists in the liver and is not killed by the medication used for the acute attack. If you have one of these, you’ll have to take primaquine after you’ve finished the treatment to get rid of the blood forms.
If you are travelling to a malarious region, you need to take precautions. See a good travel doctor, who will advise you on the best medicines for you to take to prevent being infected and exactly how to take them, and give you the necessary prescriptions.
If you are pregnant, malaria is likely to be more serious for yourself and may also cause miscarriage, and some of the preventive medicines are not suitable, so you should ask yourself if your trip is absolutely necessary. The same applies to taking very young children into an area where there is malaria.
These medicines are never 100% effective, so you should also protect yourself from mosquito bites in the following ways:
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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.