Malaria

Malaria is a disease that is caused by a parasite. The parasite can get into our bodies when we are bitten by certain types of mosquitoes that are infected with the parasite. These mosquitoes are most common in hot, tropical regions like Africa and Asia.

While malaria is preventable and curable, it still claims the lives of more than 600,000 people worldwide every year. The disease is most deadly to pregnant women and children aged under five, particularly in poorer countries where malaria-fighting medicine is not always accessible.

Malaria is a major cause of death and loss of productivity in many countries in South-East Asia, the Pacific and Africa.

The parasite Plasmodium causes malaria. It is transmitted to humans through the bite of an infected Anopheles mosquito.

See this process in the WEHI.TV biomedical animation Malaria Lifecycle Part 1: Human Host

The malaria parasite has a complex lifecycle. When a malaria parasite enters the blood, via mosquito saliva, it travels to a person’s liver. Here it undergoes a ‘silent’ development stage. It multiplies in the liver cells but does not cause illness.

Parasites then move into the blood, where they infect red blood cells. This stage makes a person sick and causes symptoms of malaria, such as:

• fever and chills
• headache
• fatigue
• nausea and vomiting
• difficulty breathing
• blockage of blood vessels in critical organs like the brain
• organ failure
• anaemia (too few red blood cells)
• coma.

There are five species of parasite that can cause malaria in humans. Our research is focused on the two species that cause the greatest devastation:

• Plasmodium falciparum causes rapid and severe illness, and more deaths globally than any other type of malaria. It is most common in Africa.
• Plasmodium vivax is the most widespread type of malaria worldwide and is a significant cause of illness in the Asia-Pacific region. Its ability to lie dormant and undetectable for months in humans makes it tricky to treat and stop from spreading. It can reactivate, causing multiple episodes of sickness from a single bite. It also means the parasite has more opportunities to pass back to mosquitos, spreading the disease further.

If someone has malaria, there are antimalarial drugs that can help. Sometimes the drugs don’t work as well because the malaria is getting stronger and becoming resistant to the drugs. That’s why we need new drugs to fight it.

Vaccines could help stop malaria from spreading. Our scientists are trialling two different vaccines to see if they could be effective in treating malaria.

Malaria can be prevented by:

• avoiding mosquito bites by sleeping under bed nets, wearing long-sleeved clothing or using repellents
• taking antimalarial medicines to prevent malaria or stop mild cases from getting worse.

People who are at greatest risk of falling sick to malaria include:

• young children and travellers who have no immunity to malaria
• pregnant women or people with HIV/AIDS who have low or compromised immune systems
• people living in poor or remote locations who struggle to access doctors or medicines.

More information about malaria may be found on the following websites:

• World Health Organisation – Malaria
• Malaria – Patient information
• Malaria in Australia