It was about three days after I'd left Africa that the pain in my nose became too severe to ignore. Starting as a dull ache niggling at the edge of my consciousness, it had gradually built in intensity to the point at which I had to stop what I was doing to investigate further.

I'd been unpacking items from an expedition to western Uganda, where I'd been observing chimpanzees: I'm a patho-biologist and research infectious diseases in nature. It was partly deep revulsion that had led to my ignoring the symptoms at first. I had a pretty good idea what I was going to find, because I'd experienced a similar sensation before.

Using an angled mirror and moving my body awkwardly, I was able to peer up my nose with the help of a torch. There it was, half a pinkie's length up, right where the cartilage meets the bone: the smooth, rounded backside of a fully engorged tick.

No matter how long you've been studying nature, you can't train yourself out of the instinctive human response to seeing something like that. Scientists pride themselves on being objective and systematic, but when it's you with an arachnid in your nasal cavity, that sense of distance goes right out of the window. My scientific curiosity won out, but it still took all my willpower not to claw madly at my face.

I knew I had to remove the tick with great care. If any part of it was left behind, I might end up with a very nasty infection. I also needed to avoid killing the creature as I removed it, in case I caused it to release potentially disease-ridden saliva into my bloodstream.

I had all the tools I needed right there in the lab. Despite having to work at a contorted angle, I was able to use a pair of forceps to grasp the tick's mouth parts, which were buried deep in my flesh, and firmly yank the creature out. The pain was searingly intense. Nevertheless it was out, and all in one piece.

While part of me admired the way the creature had evolved, as if specifically to resist being removed with a fingernail, my initial reaction was that it looked pretty gross. It was really nothing more than a distended stomach, the diameter of a pencil eraser, with a proboscis and tiny legs at one end. I'd previously removed two similar creatures from my nose while travelling on a bus in Africa, but they'd been lost in the shock of the moment. Now I had an undamaged example I could study.

As I sealed the tick into a tube and put it in the freezer, I reflected on how it had come to stow itself away undetected. It must have been waiting in ambush on the forest floor as I passed, then made its way right up my body. Discovering it in my nose had been alarming enough, but thinking about it crawling across my face to get there was truly disturbing.

Once I got the genetics report back from the lab, though, my unease turned to excitement. The DNA sequence of the tick could not be matched with any existing database. At the very least, my specimen was a member of a species that had never been genetically tested before, but it could well be of a type previously unknown to science.

A colleague who'd been studying high-resolution photographs of the chimps I'd been researching found that many of them had ticks of the same type up their noses. No evidence of this phenomenon had been found before, and I now believe these particular ticks have evolved specifically to hide inside the nostril cavities of chimps, where they can feast in safety, away from their host's habitual grooming regimes.

It could well be that the Ugandan nostril ticks have yet to spread beyond the particular park where we conducted our research. We now have to return and set traps to catch more, so we can do further study. It's a tremendously exciting project for me, and could prove vitally important: we know my tick managed to latch on to me undetected, and we need to ensure others don't stow away on international flights and establish colonies in other countries, where they could potentially spread exotic diseases.

A biologist can spend a whole career hoping to make such a breakthrough, and there's a special kudos attached to being able to carry out a study on a subject of which you have personal experience. The discomfort and revulsion I went through is a very reasonable trade-off. I feel genuinely grateful to the tick for choosing me as its host.

• As told to Chris Broughton

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