Antimalarial medications

Malaria is a life-threatening disease caused by parasites that are transmitted to people through the bites of infected female Anopheles mosquitoes. It is preventable and curable.

Antimalarial medications are a key component of force health protection. Australian Defence Force (ADF) personnel are required to take them when they are deployed to malarious areas.

As the malaria parasite evolves over time and develops resistance to medications, development and trials of new medications are necessary. No single medication is fully effective in preventing malaria nor suitable for everyone. All medications have side effects and some individuals may demonstrate intolerance to certain drugs.

Defence works to ensure there is a range of preventative health options available for its personnel. The range of antimalarial medications described below are used in the ADF.

Doxycycline

Doxycycline has been the first line medication for malaria prevention in the ADF since 1990. It is an antibiotic widely used in Australia to treat a variety of infections and is effective in preventing malaria.

In 1989, a study involving troops deploying to Papua New Guinea, Malaysia and Thailand was conducted to determine doxycycline's effectiveness in preventing malaria compared to Maloprim (dapsone/pyrimethamine) and chloroquine, which were the antimalarial medications in use at that time. The study concluded that it was very effective and the outcomes are published in the Medical Journal of Australia.

A total of 388 ADF personnel took doxycycline as part of a mefloquine and doxycycline prophylaxis study conducted in East Timor from 2001 to 2002. This study was published in the Medical Journal of Australia.

Atovaquone/Proguanil

Atovaquone/Proguanil (trade name Malarone™) is a combination of 2 medications in one tablet. It has been the second line anti-malarial medication used in the ADF since 2006. It is used when doxycycline is either not tolerated or is not suitable.

Mefloquine

Mefloquine (trade name Lariam™) is used in the ADF when other anti-malarial medications are unsuitable. Commonly prescribed in the broader Australian community, mefloquine can be used for both prevention and treatment of malaria.

In 1989, a study involving troops deploying to Papua New Guinea, Malaysia and Thailand was conducted to determine mefloquine's effectiveness in preventing malaria compared to Maloprim and chloroquine. The study concluded that it was very effective and the outcomes are published in the Medical Journal of Australia.

A total of 1157 ADF personnel were provided mefloquine as part of the mefloquine and doxycycline prophylaxis study conducted in East Timor in 2001/2002. 162 ADF personnel took mefloquine as part of the tafenoquine prophylaxis clinical trial in 2000/2001.

Mefloquine is not the first choice for malaria prevention in the ADF. Mefloquine is prescribed when other antimalarials are not suitable. Outside of the Army Malaria Institute (AMI) studies, mefloquine use in the ADF has been very low. In the last 10 years, fewer than 100 ADF members have been prescribed mefloquine.

The Department of Veterans’ Affairs (DVA) offers a range of support services for current and former ADF personnel who are concerned about having taken mefloquine or tafenoquine.

Primaquine

Primaquine (trade name Primacin™) is an anti-malarial medication used to prevent relapses of malaria. ADF personnel who lack the glucose-6-phosphate-dehydrogenase (G6PD) enzyme are not prescribed primaquine. A personalised risk assessment and anti-malarial program is developed for these individuals.

Tafenoquine

Tafenoquine (trade names Kodatef and Kozenis) is chemically related to primaquine. The Australian Therapeutic Goods Administration (TGA) registered tafenoquine in 2018. It is now included in the suite of antimalarial medications available to ADF personnel. ADF personnel who lack the glucose-6-phosphate-dehydrogenase (G6PD) enzyme are not prescribed tafenoquine.

AMI conducted a clinical trial of tafenoquine for eradication (prevention of relapsing malaria) in 1999/2000 in 1017 ADF personnel deploying to Bougainville and Timor-Leste. The abstract of this study is available from the National Library of Medicine and the full text article can be requested from adf.malaria@defence.gov.au.

AMI conducted a larger clinical trial of tafenoquine for malaria prophylaxis in ADF personnel deploying to Timor-Leste in 2000 and 2001. This was a randomised controlled trial, with mefloquine as the comparator medication. In this trial, 492 participants took tafenoquine and 162 took mefloquine. This study has been published and is available on the American Society for Microbiology journals website.

A trial of tafenoquine for malaria treatment was undertaken in 2000/2001. ADF personnel who had a confirmed diagnosis of relapsing malaria were given the option of taking tafenoquine after previous treatments had failed. Because tafenoquine was not registered in Australia at that time, approval to use this medication was obtained from the Therapeutic Goods Administration (TGA). 31 ADF members participated in this trial. During treatment with tafenoquine, no adverse events were reported and the medication was well tolerated. One patient had a further relapse of malaria after completing treatment, meaning the cure rate recorded was 96%. The results of this trial have been published in the American Journal of Tropical Medicine and Hygiene. The abstract is available from the National Library of Medicine and a copy of the full article can be requested from adf.malaria@defence.gov.au.

The DVA offers a range of support services for current and former ADF personnel who are concerned about having taken mefloquine or tafenoquine.

Discontinued medications

Chloroquine

Chloroquine (trade name Chlorquin™) is no longer used by the ADF as an anti-malarial medication as malaria parasites have become resistant to the drug and it is no longer effective.

Dapsone/Pyrimethamine

Dapsone/Pyrimethamine (trade name Maloprim™) was phased-out by the ADF in 1990 after increasing resistance in malaria parasites made it ineffective.