A clinic on the back of a truck: Anna Pavord joined a medical team that matched Guyana's annual health budget in three weeks

The story of the frogs in the lavatory is one of my sister-in-law's best childhood tales. Born and brought up on a ranch in the Rupununi district of Guyana, she described how they always kept a big stick by the loo. Before you sat down you had to rattle the stick round the bowl, causing enough disturbance - you hoped - to persuade the frogs that lived inside to jump out, rather than attach their sticky suckered feet to your bottom.

Now a doctor, she went back to Guyana earlier this year as senior medical officer with Remote Area Medical (RAM), a charity that takes doctors, dentists, optometrists, nurses and other volunteers into places where medical staff have never been seen before. I joined her team as an assistant.

During a three-week tour in the savannahs, where Guyana borders Brazil, we saw more than 4,000 people, mostly Macushi and Wapaishana Indians, at a series of makeshift clinics held in small Amerindian settlements. The Amerindians have their own extremely effective cures for many illnesses. The medical team tackled what could not be cured by local medicine.

The places we visited could be reached by truck, but at each clinic there were families who had travelled miles from even more remote villages in the hope of seeing a doctor. One extended family travelled for two days in a bullock cart. Another man had packed his wife and three young children into a canoe and paddled for four days to reach the clinic at Yupakari, a village of mud-brick houses with palm thatch roofs. Others walked, carrying hammocks and the food they would need for the return journey.

Here, we take the business of being in touch for granted. There, in an area with no phones, no postal services, no roads and practically no transport (ours was the only truck we saw the whole time we were in the savannahs), you are back to basics in a way that John Major could not begin to imagine.

One day we decided to stop off at a small outstation that had once belonged to the Good Hope Ranch, where my sister-in-law was born and brought up. We left the truck, with most of the team and all the medical supplies, bumping its way to Rupununi's main town, Lethem, and looped up towards Good Hope in a borrowed Land Rover.

The outstation was planted with lemon trees, cashews and mangoes. Guinea fowl pottered through the compound. A child of about eight was slumped on the ground, limp with fever, the result of a wound on her leg that had turned dangerously septic. One of the nurses eased out a pool of pus from the badly swollen leg, but all the antibiotics were on the truck. Without them, the child was unlikely to recover.

In the time that it took my sister-in- law to write a prescription, the child's father, an Amerindian vaquero, had lassoed a horse from the corral. It was blanketed and saddled before she had finished giving him instructions.

He had to ride across country to try to intercept the truck, which we estimated would now be at least 12 miles away. He galloped off like a dervish.

Later that night, when we met up with the rest of the team, they described how the vaquero had caught up with the truck and ridden alongside it, waving the prescription. Being out of touch did not seem so romantic after that.

My job was strictly non-medical, taking down details of the hundreds of people who queued at the clinics each morning. Few spoke English - the village school teacher or the tuchau, the head man, usually acted as interpreter, rattling off names and ages; explaining which villages the patients came from.

As I tried to find out what they wanted, I crossed my fingers that it was something the medical team could sort out. Sometimes it wasn't. At Toka, a tough little Amerindian community on flat land at the feet of the Pakaraima mountains, we watched an old man ride in, his horse hung with lassoes and hunting tackle. He had a leather satchel over his shoulder and was wearing a round, fine straw hat pulled down over his eyes.

Our translator was a tall, imposing man, as much Indian as Amerindian you would guess, for few of the Macushi were more than 5ft tall. He told us the old man had been riding for four days in the hope of a cure for his failing sight. He could not hunt as well as he used to.

After examining him, the optometrist, a Belgian woman called Regine, discovered he had cataracts. To remove them would be simple in the West, but it was impossible there, in the field. As impassively as he had arrived, the old man left, and turned again into the mountains for the long, arduous journey home.

We all felt bad about that man - to have made such an effort for so little reward. That night Stan Brock, the founder of RAM, announced that if he could raise enough money, the next team to come into the area - in October this year - would be equipped to carry out cataract operations.

There is a small hospital in the area, built by the Dutch two years ago. It would be ideal for the job but it is not functioning because there is no money to run it. In its three weeks in the Rupununi, RAM spent the equivalent of Guyana's entire annual health budget.

Brock is a rock. He spent 15 years ranching in the savannahs, then presented a series of wildlife films - you may have seen him wrestling with an anaconda in The Natural World. He flies aircraft into improbable places and could sail himself round the world if he wanted. Instead he devotes himself to RAM.

The most frightening medical condition we saw was leishmaniasis, a disease spread by sandflies which causes ulcers that eat into the skin, especially on the face. The worst case was a Wapaishana Indian in the southern savannah. He had already lost his lower jaw and half his cheek. You would sometimes see the distinctive open sore on a baby that had been brought in for a different reason. Fortunately the doctors could treat it, as long as it was caught early.

The clinics started at eight in the morning and went on until there was nobody left to see. Among the older people, the same two questions always caused problems: their age and the number of their children. You would put an estimate on the age and then wait as the children were reckoned up, over the fingers of both hands. Then there would be a consultation with a daughter or a grandchild. The exact number seemed unimportant. They had sufficient.

If you asked a question the Macushi did not understand, they withdrew into a gentle sort of silence, looking calmly over your shoulder into the distance. When they spoke, it was on a curious inward breath, so the sounds were sucked back inside themselves even as they were trying to come out.

The tour ended at Annai, a small village with tall coconut palms shading the thatched huts and electricity from a wind generator laid on at the building to be used as a clinic. The owner of the local ranch house offered a place to sling hammocks. We even had a bed. And a shower.

In one of the open-sided thatched buildings there was a huge metal barbecue, big enough for a whole cow. Drink was invariably rum punch mixed up in a big plastic bucket: local rum, fresh lime and lemon juice, water and sometimes cinnamon or nutmeg.

At the end of the day, as I swayed quietly in a hammock, smelling the fresh herbs that Thomas the cook was throwing in handfuls on to the barbecue, and listening to Alan, the Guyanese truck driver's outrageous, macho stories, I almost forgot why I had come to Guyana. Then I remembered the figure with the round straw hat and the satchel, the old man hunched on his horse, making his slow, half-blind way back to his village.

Remote Area Medical needs money and fit, qualified volunteers, particularly medical staff. Volunteers must pay their own expenses. Contact Stan Brock at Remote Area Medical Volunteer Corps, 1016 Weisgarber Road, Suite 201, Knoxville, Tennessee 37909, USA. Tel: 010 1 615 588 2998. Fax 010 1 615 584 0175.

(Photographs omitted)