The Cycle of Malaria Transmission

The good news is deaths from malaria have been cut by a third since 2005. The bad news is it still causes 250 million cases and 600,000 deaths a year, mostly among young children in sub-Saharan Africa.

We already have dirt-cheap ways to prevent and treat malaria, and the fraction of the Earth's surface where the disease exists at all has been halved since 1900. So why is it such a persistent problem in some places, even rebounding 15% since 2019?

That's one of many questions I put to today's guest, James Tibenderana — doctor, medical researcher, and technical director at a major global health nonprofit known as Malaria Consortium. James studies the cutting edge of malaria control and treatment in order to optimise how Malaria Consortium spends £100 million a year across countries like Uganda, Nigeria, and Chad.

Links to learn more, summary and full transcript.

In sub-Saharan Africa, where 90% of malaria deaths occur, the infection is spread by a few dozen species of mosquito that are ideally suited to the local climatic conditions and have thus been impossible to eliminate so far.

While COVID-19 may have an 'R' (reproduction number) of 5, in some situations malaria has a reproduction number in the 1,000s. A single person with malaria can pass the parasite to hundreds of mosquitoes, which themselves each go on to bite dozens of people each, allowing cases to quickly explode.

The nets and antimalarial drugs Malaria Consortium distributes have been highly effective where distributed, but there are tens of millions of young children who are yet to be covered simply due to a lack of funding.

Despite the success of these approaches, given how challenging it will be to create a malaria-free world, there's enthusiasm to find new approaches to throw at the problem. Two new interventions have recently generated buzz: vaccines and genetic approaches to control the mosquito species that carry malaria.

The RTS,S vaccine is the first-ever vaccine that attacks a protozoa as opposed to a virus or bacteria. It's a great scientific achievement. But James points out that even after three doses, it's still only about 30% effective. Unless future vaccines are substantially more effective, they will remain just a complement to nets and antimalarial drugs, which are cheaper and each cut mortality by more than half.

On the other hand, the latest mosquito-control technologies are almost too effective. It is possible to insert genes into specific mosquito populations that reduce their ability to reproduce. By using a 'gene drive,' you can ensure mosquitoes hand these detrimental genes down to 100% of their offspring. If deployed, these genes would spread and ultimately eliminate the mosquitoes that carry malaria at low cost, thereby largely ridding the world of the disease.

Because a single country embracing this method would have global effects, James cautions that it's important to get buy-in from all the countries involved, and to have a way of reversing the intervention if we realise we've made a mistake.

In this comprehensive conversation, Rob and James discuss all of the above, as well as most of what you could reasonably want to know about the state of the art in malaria control today, including:
• How malaria spreads and the symptoms it causes
• The use of insecticides and poison baits
• How big a problem insecticide resistance is
• How malaria was eliminated in North America and Europe
• The key strategic choices faced by Malaria Consortium in its efforts to create a malaria-free world
• And much more

Chapters:

• Rob’s intro (00:00:00)
• The interview begins (00:02:06)
• Malaria basics (00:06:56)
• Malaria vaccines (00:12:37)
• Getting rid of mosquitos (00:32:20)
• Gene drives (00:38:06)
• Symptoms (00:58:00)
• Preventing the spread (01:06:00)
• Why we haven’t gotten rid of malaria yet (01:15:07)
• What James is responsible for as technical director (01:30:52)
• Malaria Consortium's current strategy (01:39:59)
• Elimination vs. control (02:01:49)
• Delivery and practicalities (02:16:23)
• Relationships with governments (02:26:38)
• Funding gap (02:31:03)
• Access and use gap (02:39:10)
• The value of local researchers (02:49:26)
• Past research findings (02:57:10)
• How to help (03:06:30)
• How James ended up where he is today (03:13:45)

Producer: Keiran Harris
Audio mastering: Ryan Kessler
Transcriptions: Katy Moore