Sand flies get Phu Quoc's reviews. Dengue sets its daily routine.

Yes, and on Phu Quoc the beach biters get the reviews. Sand flies on Sao Beach and the quieter northwest beaches are the island's signature complaint, worst in the early evening. Dengue is the disease to plan for, in a 2026 season running at about twice last year's pace in An Giang province, which now includes the island.

A busy dengue year in An Giang

Phu Quoc, once part of Kien Giang province, is now a special zone of An Giang province. An Giang reported about twice as many dengue cases by mid-October 2026 as in the same period of 2025, and Phu Quoc had more outbreak sites than any other locality in the province, Vietnamese state media VOV and Dai Bieu Nhan Dan reported. No case count for the island alone has been published. Provincial health officials call October and November the yearly peak, driven by heavy rain and humidity.

Nationally, the World Health Organization puts about 71% of Vietnam's 2026 cases in the south, in a year running about 37% above 2025, and Vietnam is on CDC's global dengue list. The Aedes mosquito bites by day, with peaks after sunrise and before sunset, so the exposure is in Duong Dong, around the night market, in resort gardens and around An Thoi. Put repellent on over sunscreen after breakfast, again after a swim and before the late afternoon, and choose an air-conditioned or screened room. Our dengue & Zika routine has the full schedule.

CDC's Vietnam page places malaria in "Rural areas only; rare cases in the Mekong and Red River Deltas," and for the deltas it says "No chemoprophylaxis recommended (insect bite precautions and mosquito avoidance only)." Phu Quoc belongs to the Mekong Delta region administratively, though CDC doesn't name the island or say how its wording applies to the forested north around Phu Quoc National Park. If you plan to camp or trek there, see a travel clinic 4–6 weeks before departure; the same visit can cover Japanese encephalitis vaccine. Zika has circulated in Vietnam, so pregnant travelers should talk to a healthcare provider before the trip.

Sand flies on the sand

Sao Beach, the white-sand bay on the southeast coast, draws the most sand fly warnings in reviews, and posters say they're worst in the early evening. The quieter bungalow beaches around Ong Lang, north of Duong Dong, get them too, on the sand and on verandas. Which tiny biter it is hasn't been identified, and the routine is the same either way. Treat ankles, calves and feet before an afternoon on the beach, use a lounger or a mat, and cover up or leave the sand around sunset. If they're biting midges, the Caribbean's no-see-ums, our Barbados sand fly guide explains how they behave.

The forested north tends to be evening mosquito country. Some "bites" after a swim are stings from jellyfish or sea lice, which repellent won't stop.

When to go

December to April, roughly the dry season, is the easier stretch for bites. The southwest monsoon brings rain from about May to October, and August to November, the end of the rains, tends to be the hardest. The sand fly reports carry no months, so plan on the evening routine in any season.

Where you're going

Coming from Saigon? The Vietnam briefing covers the rest of the route, and Hoi An has its own page.

What travelers report

Paraphrased from TripAdvisor reviews and linked so you can read them in full. None is dated, and sand flies vary from beach to beach and evening to evening.

• Sao Beach, Phu Quoc

  A Sao Beach reviewer warned other visitors about sand flies in the sand there. TripAdvisor ↗

• Mango Bay Resort, Ong Lang, Phu Quoc

  A guest was still recovering from bites picked up on the beach and on the bungalow veranda, and suspected sand flies. TripAdvisor ↗

• Sao Beach (Bai Sao), Phu Quoc

  A Sao Beach reviewer headlined the review 'Be wary of sand flies!' as a warning to other visitors. TripAdvisor ↗

Any fever during or within two weeks after your trip means a prompt doctor visit, and you tell them you were on Phu Quoc, in southern Vietnam. Bitten and worried? Bitten in a dengue zone has the 14-day calendar.

Traveler questions