Kerala's houseboats moor at dusk. That's the hour to plan for.

Yes, and the overnight houseboat is the main bite window, because boats on the backwaters moor for the night around dusk. The CDC recommends prescription malaria medicine for India below 6,500 feet, which covers Kochi, the backwaters and the beaches, so the trip starts with a travel-clinic visit.

Kerala and the CDC's malaria line

The CDC places malaria transmission in India "Throughout the country, including the cities of Bombay (Mumbai) and New Delhi (the capital)," with "No malaria transmission in areas >2,000 m (>6,500 ft) elevation." The CDC lists Kerala among the states with such areas. Kochi, the backwater towns and the Thiruvananthapuram coast are low-lying, inside the recommendation.

Yellow fever vaccine isn't needed when you fly from the US, though India requires proof from travelers 9 months or older arriving from countries it lists as having yellow fever risk.

Dengue and chikungunya in 2026

Kerala's dengue follows the southwest monsoon, and 2026 ran true to form. WHO's South-East Asia office wrote that cases "increased steadily from week 16 but started to decline from week 29," roughly mid-April to mid-July, and in October that they "have continued to fluctuate."

Chikungunya came next. The European Centre for Disease Prevention and Control reported 167 more cases from Kerala in August 2026, "most of them concentrated at Thiruvananthapuram city," and local authorities pointed to the monsoon. The CDC says there is elevated chikungunya risk in India and suggests the vaccine only for stays of about six months or more.

Both viruses travel with Aedes, which bites in daylight with peaks after sunrise and in the late afternoon, so in Fort Kochi's lanes and at beach restaurants repellent goes on over sunscreen in the morning and again before sunset. Our dengue & Zika routine has the schedule. Nipah, back in the news with a case in Kozhikode district in June 2026, spreads from fruit bats and close contact rather than insects; WHO recommends no travel restrictions and advises avoiding bat roosts and fruit with bat bite marks.

The houseboat hour

Overnight boats on the Alleppey and Kumarakom backwaters stop cruising and moor around dusk, sometimes at a bank where guests can't go ashore, just as malaria mosquitoes start their dusk-to-dawn shift. Boats vary, and an air-conditioned bedroom that closes fully tends to be the best defense. Put on repellent and long sleeves before the boat moors and shut doors and windows early, or book a day cruise, which ends before the worst hours.

Where you're going

Adding Delhi or Goa? The India briefing covers the rest of the country, and the Goa briefing the beaches up the coast.

What travelers report

Paraphrased from two TripAdvisor reviews of Alleppey houseboats and linked so you can read them in full. Neither is dated, and they disagree, which says a lot about how much the individual boat matters.

• Alleppey (Alappuzha) houseboat, Kerala · evening

  A reviewer advised against an overnight houseboat stay: the boat docked early in the evening at a spot where guests could not get off, and mosquitoes and other insects kept them from enjoying the evening. TripAdvisor ↗

• 21-hour houseboat tour, Alleppey

  A reviewer of an overnight houseboat tour through the Alleppey canals reported no mosquito bites and put it down to the boat being spotlessly clean. TripAdvisor ↗

One more rule outlasts the trip. Any fever during your trip or in the year after it means a doctor visit, right away, and you tell them you were in Kerala, India. Dengue usually shows up within two weeks; malaria can take much longer.

Traveler questions