Anxious and distracted, I gripped the table leg where I sat in a tea stall in Kathmandu's noisy central bazaar. A boy stepped from behind the counter balancing a tray load of tumblers of tea, set a glass at an adjacent table. Then, he looked at me.

The boy froze as if electrically shocked. Dropping the tray, he ran from the teashop as if fleeing the curse of Kali, Shiva's wrathful manifestation. Reflexively, I leaped up and found the boy trembling against the wall of a nearby building. "What did you see?" I asked him in Nepali. I felt as frightened as he. Shielding his eyes from mine, he ran from my voice through the alley.

Recently graduated from college, I was a Peace Corps volunteer posted in Nepal. It was the monsoon of 1975. As I relaxed in the office lounge reading my mail, a drop of blood splashed onto the aerogramme. I looked up, unable to see where it came from. More drips appeared-from my nose, bloodying my fingers. Not an early symptom of yet another exotic Asian disorder, I thought.

I had recently returned to Kathmandu from a trek to Everest base camp. In my mind I reviewed the trip-the 18,000 ft altitude, the thin, crystalline air, the simple meals and the cold, refreshing mountain spring water. At lower elevations, to drink untreated water would risk infection with hepatitis, typhoid fever, giardia, amoebae, roundworm and other parasites.

Perhaps Warren, a scholar friend who lived downstairs, would have an idea. Warren's guru was a Newari Buddhist priest who practiced Ayurveda and was descended from a 700-year lineage of royal physicians.

We set off for his office. The ageing doctor appeared in the vine-framed doorway and summoned me to his examining room. Dr Mana Bajra Bajracharya was puzzled by the duration of the bleeding. He prescribed aloe, an herbal astringent. That didn't work.

On the 18th day of nosebleeds, I bicycled down a cluttered side street of the central market. Thankfully, my nose hadn't dripped in several hours. But from the corner of my eye I thought I saw something emerge from my right nostril. I reached for my nose, which felt normal. I continued pedalling, presuming it to be a piece of coagulated blood.

There it was again. Then gone. Yes, something was in there, working its way out. A panic flushed over me. My nose grew large in my field of view, while the world beyond my face diminished. I needed to have this sighting confirmed by someone. But if this thing was part of a generalised, insidious infection, I feared, people might not tell me the truth. I pulled over to a teashop, ordered a glass of tea, and waited. That's when the boy in the teashop saw it too.

Back home I headed for my bedroom mirror. I drew up a chair, resolving to watch my nose until I saw the thing. For a quarter of an hour I focused. Then, as if trying to catch me unaware, a long, brown, eel-like creature slid out silently, offering no physical sensation at all. It scanned the air and retracted. I momentarily felt non-human, an alien sent to earth on reconnaissance to test the spiritual or intestinal fortitude of those who dared look at me.

I called the Peace Corps doctor, Barney, at home and described the events. Yes, a leech stuck its head out of my nose, I insisted. No, it always disappeared before I could touch it. "I don't know what to say," Barney finally responded, adding, "I'd like to make an appointment for you to see the embassy psychiatrist."

"I want you to take it out," I tried to say calmly.

Wearing the reluctant expressions of first-year anatomy students just introduced to their cadaver, Barney and a nurse greeted me with tentative nods in the driveway of the American medical compound. I sat on the examining table. Barney inserted the nasoscope but saw nothing. He flicked his head as if shaking off a dream then set the nasoscope down. Then he fished out a pair of hemostats, resigned to having a go at grabbing it.

I could tell that the leech appeared when Barney's body jerked. He hesitated, then bit his lower lip and approached, cautiously, as toward a dormant beast. Wait. Silently emerge. Clamp. Vanish. Wait. Emerge. Clamp. Missed again.

After several minutes, he nabbed the end of the leech, the head, on its way out for air. He cinched down the haemostats' miniature grippers and there the two of us paused, locked together in suspended animation. Then, with one palm on my forehead, he began to pull, slowly increasing the pressure.

For the first time I could now feel the thing-pulling vaguely from the interior of my head. It wouldn't let go. "Let me know if it hurts. Otherwise I'm just going to keep pulling until something happens," Barney stuttered, sounding unsure what that something might be.

The leech was now stretched out nearly a foot. My neck strained against the pull. I realized that I might never again experience this, nor again see such an expression on a doctor's face. I had been told to expect the unusual in this country but this was more like some altered, metaphysical dream.

Something snapped. Barney hit the wall directly behind him, while I fell over backward across the examining table. I couldn't see where the leech went, if in fact it came out, or if it had taken part of me with it. I wasn't sure Barney knew, either, until, with deliberation, he held up the trophy-a fidgeting, unattached leech, tightly seized in the clamps measuring four inches long, thick as a pencil, with a nickel-sized sucker on the host end.

Barney's mouth hung open, grinning at the same time. He had done the right thing. My nose dripped not a drop of blood. The leech was gone. I said thanks and shook hands with Barney and stepped from the clinic to again join the world of benign, unencumbered humans.

Broughton Coburn is author of Nepali Aama: Life Lessons of a Himalayan Woman and Aama in America: A Pilgrimage of the Heart and the US national bestseller Everest: Mountain Without Mercy (National Geographic Books). This article is excerpted from one that appeared in an anthology titled Nepal Travellers' Tales (O'Reilly and Associates) and another called No Shit, There I Was. Again.