Malaria: The story of a tiny parasite with a big impact

Malaria is a disease of global significance, usually spread through the bite of an infected mosquito. The World Health Organisation estimates there were 282 million malaria cases in 2024, and approximately 610,000 deaths. This direct health impact is predominantly in Africa, but the challenge for non-endemic countries like Australia is to protect transfusion recipients from a disease that is not present in Australia, but brought home via international travel.

With approval from the TGA and state, territory and federal governments, we’ve updated how we keep Australia’s blood supply safe from malaria. In this article we’ll explore what malaria is, why it matters to blood donations, and how we test donations for malaria. For more information about exactly why we’re changing our approach, visit our companion article, Malaria: How data drives our decision making.

What causes malaria?

Malaria is a disease caused by microscopic parasites from the Plasmodium family. While it is extremely uncommon in Australia, malaria remains widespread in many parts of Africa, Asia, South America and the Pacific. Nearly half of the world's population lives in areas where malaria is widespread.

Most people become infected after being bitten by a mosquito that’s carrying the Plasmodium parasite. Once inside the body, the parasites invade our red blood cells and begin to multiply. What’s interesting is that malaria may have even influenced human evolution. With the parasite life-cycle heavily reliant on red blood cell infection, some scientists argue that malaria could have shaped the distribution of blood groups on an evolutionary scale, with group O now known to be protective against cases of severe malaria. Of course, there are no eligibility criteria when it comes to blood groups – all blood groups are needed and can save a life.

Why does malaria matter in the context of blood donation?

Mosquito bites are not the only cause of infection; the parasite can also rarely be spread through blood transfusion. This is known as transfusion-transmitted malaria. Fortunately, this is extremely uncommon. A review of global cases identified around 100 cases in non-endemic countries between 1911 and 2017. In Australia, the last reported case occurred in 1991.

One of the challenges for blood services is that some people can carry malaria parasites without feeling unwell. People who have lived in malaria-endemic regions for long periods can sometimes develop partial immunity, allowing very low levels of parasites to remain in their blood without causing symptoms. This is one reason malaria risk must be carefully managed in blood donation settings.

How does Lifeblood test for malaria?

We use malaria antibody testing. This means that rather than looking for the parasite directly, we check for antibodies that have been produced by the body's immune system after exposure to malaria. Combined with donor eligibility rules, this testing has helped maintain an extremely low risk of transfusion-transmitted malaria in Australia.

Safety, science and continual review

Blood safety measures are never static. As we learn more about disease risks, donor populations and testing technologies, we review whether our approaches remain the best available.

Over the last twenty years, malaria testing has helped Australia maintain an extremely low risk of transfusion-transmitted malaria. At the same time, research has improved our understanding of who is most likely to pose a genuine risk.

That evidence increasingly points to a key conclusion: the greatest risk comes from people who have lived for extended periods in malaria-endemic regions, rather than short-term travellers. It’s this distinction that’s helped shape the latest evolution of malaria safety measures at Lifeblood. You can read about the rationale behind these changes in our companion article