ILES DES SAINTES, Guadeloupe — The steep climb had barely started when Wolfy began to grumble.

“My foot,’’ he whined. “It hurts.’’

Our 3-year-old son demanded we carry him. We were coaxing him to walk, but his complaints crescendoed. So I lugged him up the winding path to an old fort at the top of the hill.

Wolfy had little interest in the sweeping views of the rocky coast or the light shimmering on the Caribbean Sea. His grousing continued as we descended, which is when we realized something was wrong.

Shortly afterward, we stopped at a pharmacy, and the pharmacist asked to look at his feet, which to our astonishment were swollen and covered in what appeared to be massive mosquito bites, some of which were spewing puss and looked like they could be infected.

“This is dangerous,’’ said the pharmacist, in the typically blunt way of the French.

My wife, Jess, and I grew anxious, convinced we were the worst parents. “You need to take him to the hospital,’’ he said.

We should have known better.

Before we had an inkling of the mosquito-borne virus Zika, we had decided to spend our winter vacation in Guadeloupe — a butterfly-shaped island southeast of Puerto Rico that is as much a part of France as Hawaii is of the United States — after we found a hard-to-believe deal. Norwegian Air, which had only recently started flying from Boston, had offered fares so cheap that the three of us could fly direct to this lush collection of small islands for little more than $500.

We had little interest in beach-oriented vacations, but after dragging our son to Thailand when he was 5 months old, where he got the flu, a frighteningly high fever, and took weeks to readjust to a normal sleep cycle, we opted for something closer to home and less exotic.

But before we left, we learned of a catch, or that was how we interpreted it. A colleague had sent me a newspaper story about how Guadeloupe the previous year had one of the Caribbean’s largest outbreaks of something called chikungunya, a painful, mosquito-borne virus that is similar to dengue and can be fatal. (We wouldn’t learn anything about Zika until January, a few weeks after we returned to Boston, when the Centers for Disease Control began issuing travel advisories about the dangers of the virus in Latin America and the Carribean.)

The article noted that few visitors had contracted the disease, and according to the CDC, the outbreak had subsided. So we invested in DEET and decided to stick with the plan to spend 10 days exploring the sugar-colored beaches, mist-shrouded volcano, and impressive waterfalls hidden in the rain forest, among other lures.

After a four-hour flight, we rented a car and drove to a small town near Saint-Francois on the eastern island of Grand Terre. We stayed at a bungalow that overlooked the water, watching warily for mosquitoes and any bites on our son’s doughy, rash-prone skin.

But after a few days, with little bother from mosquitoes, we let down our guard. We drove around the entire island, climbing a large, rocky hill overlooking the eastern tip of the island known as the Pointe des Chateaux, sipping coconut and passion fruit sorbet along the rocky cliffs in the north, and snorkeling off the touristy, topless beaches in the south. We feasted on croissants and pain chocolates, Camembert and other gooey cheeses, crepes and croque monsieurs, and all the other gustatory joys of being in France.

We never took the insect repellent out of our bags.

Things began to change after we crossed over to the western island of Basse Terre, which is dominated by a jungle at its center. We stayed in a riverside country house in the hills, where we noticed a few bites on our ankles. But our bed was covered with a mosquito net, and we were nearing the end of our trip. We weren’t worried.

So we explored the island’s hot springs and mountain-lined beaches, toured the renowned botanical gardens, and sampled local delicacies, such as rum punch and dark chocolate. Wolfy was a trooper, hiking up steep, rock-strewn trails, devouring mangoes that had fallen from trees, and lighting up with every new discovery.

Three days before we left, on Christmas Eve, we took a ferry across the choppy waters to Iles des Saintes, a breezy, lush retreat less than an hour south of Basse Terre.

Wolfy wasn’t always game for walking, so we brought a backpack to carry him. But after our hike up to Fort Napoleon, a stone-walled fortress rebuilt after British forces destroyed it in 1809, we began to worry about Wolfy.

The pharmacist suggested we call for an ambulance. With our ferry leaving in less than an hour, he gave us the address of a hospital on Basse Terre and urged us to drive there directly.

We gave Wolfy strawberry-flavored ibuprofen and eased it down with ice cream. He was uncomfortable and kept scratching his foot. His dimples, his mischievousness, had vanished — until we were doused by a series of big waves, which he still found hysterical, despite the pain.

After docking, we followed a weak GPS signal around the island’s narrow, curving roads to a small hospital, where the pharmacist said we should expect a wait of several hours. Wolfy now looked catatonic.

We found our way to the entrance of the emergency room, and I went to speak to a receptionist behind a window. My French could be better, but the transaction was quick and clear. He asked for our address, Wolfy’s birthday, and a few other basic details. Unlike in the States, however, he never asked for a credit card or insurance.

After a few minutes, he pointed to a door and told me to press a button beside it. When the door opened, a nurse asked to see Wolfy, who was now squirming. He began to scream as a doctor tried to take his temperature.

We tried our best to soothe him. The doctor was undaunted. “He’s crying because he’s 3 years old,’’ she said. “When he’s 7, he’ll stop.’’

She examined his foot, which now looked as if it had been filled with air and covered with lesions. A nurse blotted the puss with an antiseptic and then wrapped his tiny foot in gauze and a bandage. The doctor told us not to worry. He most likely had an allergic reaction to mosquito bites — not chikungunya. She prescribed an antibiotic, just in case. Zika wasn’t even mentioned.

We left without paying a euro.

The doctor had drawn us a map to find the only pharmacy in the area likely to be open on Christmas Eve, but when we arrived, it was closed. I asked a few people there where we could find another pharmacy, and they said there was one a few towns away, but their directions were vague.

When we found the right town, we flagged down a man driving the other way to see if he could point me in the right direction. Instead, he turned around and told us to follow him. We breathed deeply when we saw the flashing green lights of the pharmacy. The lights inside were still on.

I handed the prescription to the pharmacist, and he spent a while searching for the medicine. He didn’t have what was prescribed. He tried to call the doctor, but she couldn’t be reached. So he offered us a similar antibiotic, and we decided to give it a try.

It was a long night, but Wolfy was ready to play again in the morning, especially after opening a Christmas gift from the owner of the bed and breakfast. We drove back to the hospital to check whether we should continue using the antibiotic, and within five minutes, we were waved in to see the doctors.

They examined Wolfy’s foot again and said the swelling had improved, assuring us he would be fine.

So we went on with our plan, driving to the base of the volcano for a dip in the hot springs (Wolfy napped instead), snorkeling near Jacques Cousteau’s underwater reserve, and hiking to see Les Chutes du Carbet, a series of three impressive waterfalls that together drop more than 800 feet.

Wolfy continued to scratch, but he was back to making us chase him around, jumping in puddles, and playing with his new toys. His dimples had returned and he seemed to be having the time of his life.

When he awoke on the final morning of our trip, we noticed red bumps and other bites lining his hands and arms.

We were leaving behind the rainbows and turquoise waters for the dreary grays of winter, but it was good to be heading home.

David Abel can be reached at dabel@globe.com. Follow him Twitter @davabel.