James Logan, a biologist at the School of Hygiene and Tropical Medicine also tried leeches and is thinking about maggot therapy
Interview by Josh Davis
Interview by Josh Davis
James Logan gets up close with mosquitos at the London School of Hygiene and Tropical Medicine. Photograph: Antonio Olmos for the Observer
A lot of people don't realise that just one metre below your feet walking along Gower Street or Malet Street in London, you have thousands upon thousands of very hungry, potentially dangerous insects.
In the basement we have our insectary colonies where we keep lots of different species of mosquitoes, found in all parts of the world. None of them are infected with malaria, but they are in very high numbers. We also have bed bugs, house dust mites, cockroaches, and house flies, among other insects.
I'm a senior lecturer at the London School of Hygiene and Tropical Medicine, where my speciality is medical entomology. I run a research group where we investigate new ways to control diseases spread by insects, such as malaria, dengue fever and other parasites. Out of pure interest – and because I like self-experimenting – I gave myselfhookworms.
Hook worm. Photograph: Sebastian Kaulitzki/Alamy
Hookworms are known to have surprising positive effects on your body. They modify the immune system, although this is a fine balance because if they modulate it too much you become ill, and if they don't modulate it enough, you'd get rid of them. But by suppressing the immune system, they have been shown to have a beneficial effect on diseases such as Crohn's, irritable bowel syndrome, asthma, and there's even a clinical trial looking at effects onMS. Maybe if we understand the science of how these worms do this, we could develop a drug which could mimic them.
For some years I've had a food allergy where I can't eat bread without feeling ill. So partly I just wanted to find out if the rumours were true and whether the worms would help me, but we also filmed them using a special camera which is usually used to look for skin cancer.
It's basically an ultrasound machine which allowed us to visualise a section through the skin, so we were able to see how the worms entered my arm, and moved through the layers. It was previously unknown how long they took to penetrate the skin, and it was thought that perhaps they hang around in the layers of the skin for some time.
When the worms enter the body they're microscopic. Normally you get them by walking around barefoot in infected areas, which is why children get them quite a lot in developing countries because they are often sitting on the ground. In the lab, we put them on to my arm in a droplet of water.
In no time at all, they started burrowing in, far quicker than anybody would have thought. While they were burrowing I could feel very slight nips. Using the camera we could see them move through the skin, and again, that happened much faster than people had thought, which was a new finding.
Then they make this incredible journey through the body. They go in the bloodstream, through the heart, to eventually burst through the lungs. You develop a bit of a cough, so you hack them up then you swallow them into your stomach. I kept thinking: "Am I coughing up worms?"
When they reach the stomach they develop into adults, where they hook on to the gut wall and suck your blood. They produce saliva which is injected into the bloodstream, which is what modulates the immune system so that you don't get rid of them.
Remarkably, the hookworm therapy actually worked. I had a good few weeks of scoffing pizza and garlic bread, which was just brilliant, but after about four weeks I started to develop really severe stomach pains. It was horrible, excruciating, and reached the point where I was unable sleep. It was making me feel ill and dizzy, and at one point I was on the verge of giving up and saying this is just enough.
A couple of days later I swallowed a pill-sized camera, so we were able to see the hookworms in place. But we were also able to see their path of destruction. There were lots of round, red wounds on the inside of my stomach wall in the shape of their mouth parts where they had been attached. This worried me, because some of them looked like ulcers. The specialist gastroenterologist we were speaking to said that if I went to him with all these symptoms, he'd be incredibly concerned.
Despite this, I actually spent a long time debating whether or not to get rid of them. I thought the likelihood was that this will all settle down eventually, my body will adjust and it will go back to how it should be – meaning I could continue to eat bread. However, my wife was unconvinced. She didn't really like the thought of sleeping in a bed beside somebody infested with worms. So after two months of being infected, I took the pill and got rid of them. I probably would do it again, but there would have to be a good reason, such as if there was a new aspect to hookworm biology that we didn't know about, or if I decided I wanted to eat bread again.
Leech therapy. Photograph: Hans-Joachim Schneider/Alamy
Since the hookworms, I've also tried leech therapy to help cure a muscle injury. There's anecdotal evidence that leeches can help by stimulating the flow of blood through the muscle, helping it to heal. So I gave it a go when after four months of physio a quad injury wasn't getting any better. I let three leeches feed on my leg for about an hour, until they were the size of big sausages, full of blood. Amazingly, about a week later my injury had disappeared. Whether it was coincidence or not, I don't know, but it certainly raises the possibility.
The next thing I want to experience is maggot therapy. I want to know what it's like, whether you can feel it, and how effective it actually is. I'm not sure how that'll work out.
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