Eliminating malaria: Can it be done?

Malaria remains a significant public health threat, especially in the tropics, but more countries than ever have been certified as malaria-free.

Nearly half the world’s population is at risk of malaria. According to the World Health Organisation (WHO), in 2016 there were 216 million cases of malaria in 91 countries – up from 211 million in 2015 – and an estimated 445,000 deaths occurred as a result of the infection.

Thankfully, total funding for malaria control and elimination has reached an estimated $US2.7 billion as the world’s top experts – including a team from James Cook University’s Australian Institute of Tropical Health & Medicine (AITHM) – continue to probe innovative strategies to prevent the transmission of malaria and improve treatment options.

What is malaria?

Malaria is an infection characterised by fever, shivering, chills, generally feeling unwell, headache and sweats. It can also present as a respiratory or gastrointestinal illness. These symptoms can lead to a range of complications including jaundice, rupture of the spleen, kidney failure, liver failure and, in very serious cases, death. Children under five and pregnant women are at higher risk of contracting malaria.  

Most cases and deaths occur in sub-Saharan Africa – indeed, 70 per cent of malaria cases are recorded in 10 African countries and India – because of strong local transmission by mosquito species with long lifespans and strong human-biting habits.

Crucially, malaria is not a virus – and its transmission is a lot more complicated than a virus. Malaria is caused by five species of parasite that are spread to people through the bites of infected mosquitoes.

How are experts working to reduce malaria?

Vector control – that is, reducing mosquitoes numbers – is one of the most effective methods of reducing malaria transmission, explains AITHM’s Professor Tom Burkot, a vector biologist who works with a team of 15 global malaria experts to provide independent advice to the WHO to develop policy recommendations for the control and elimination of malaria.

Crucially, he says it’s important to differentiate between malaria elimination and eradication. “Elimination refers to the removal or having zero level transmission in a region or country, while eradication refers to zero transmission globally,” says Prof Burkot. “A country needs to have three consecutive years with no indigenous cases of malaria to be classed as having eliminated local transmission of the parasite.”

Two elimination campaigns have had a lasting impact on malaria elimination around the world over the last 50 years. In the 1960s, a method called ‘indoor residual spraying’ –spraying the inside of homes with insecticide to kill mosquitoes – resulted in 16 countries eliminating malaria by 1972, including Italy, the Netherlands and the US. Between 1972 and 1987, Australia and seven other countries eliminated transmission of the malaria parasite.

In the mid-1990s, insecticide treated nets – bed nets treated with insecticide that’s safe for humans and toxic for mosquitoes – were identified as a more effective strategy and replaced indoor residual spraying in most places.

“It was discovered that if you had high coverage of people sleeping under insecticide treated nets that you could have such a devastating impact on the mosquito population that you could actually protect people in adjacent villages,” says Prof Burkot. “So you're basically depressing the size of the entire mosquito population with insecticide treated nets.

“There's a lot of enthusiasm around insecticide treated nets because they are highly effective and have a lot to do with reducing malaria to the low levels we have today.”

Since 2007 nine countries have eliminated malaria – including the United Arab Emirates, Morocco and, most recently, Paraguay – and the WHO has identified 21 more countries with the potential to eliminate malaria by 2020.

Case study: Spotlight on Sri Lanka

Of course, eliminating malaria in the tropics is especially challenging – but not impossible. In 2016, Sri Lanka was certified by the WHO as having eliminated malaria. Prof Burkot says the achievement is particularly noteworthy given the country’s many challenges.

“They're in a tropical climate which is conducive to malaria transmission and they also have multiple mosquitoes that can transmit malaria,” he says. “Insecticide resistance developed and, not to mention, they had a civil war going on.”

The secret to Sri Lanka’s success? Prof Burkot says it came down to an effective strategy – insecticide treated nets, indoor residual spraying and a few other techniques – delivered by a motivated team of experts.

“Sri Lanka had a really good surveillance system where they did a lot of screening and looking for malaria cases,” he says. “Plus, they had a very motivated staff that was very competent in their approach to the problem. Despite the civil war they would take advantage of opportunities to move into areas that may not have been accessible for a while and run campaigns to distribute insecticide treated nets and look for malaria parasites.

“Ultimately, they understood the ecology of the mosquitoes and the epidemiology of malaria and they applied effective interventions.”

Professor Tom Burkot

Email: tom.burkot@jcu.edu.au

Phone: +617 4232 1867