Nepal's mosquitoes mostly stay below the trekking trails. Here's the routine for the valleys and Chitwan.
CDC reports no malaria in Kathmandu, Pokhara or on typical Himalayan treks. Dengue is the valley risk, climbing with the June–September monsoon after the country's largest outbreaks on record from 2022 to 2024, and Chitwan's jungle lodges call for repellent and long sleeves at dusk.
Yes, though rarely where trekkers spend their days. Mosquitoes tend to thin out fast as the trails climb, and CDC reports "no malaria transmission in Kathmandu (the capital), Pokhara, or on typical Himalayan treks." The insects to plan for are the day-biting dengue mosquito in Kathmandu, Pokhara and the lowlands, busiest in the June–September monsoon, and the jungle biters at Chitwan after dark.
Dengue follows the monsoon
Nepal's largest dengue outbreaks on record came back to back, from 2022 to 2024. The peak year, 2022, brought 54,784 cases and 88 deaths in a peer-reviewed count, and the World Health Organization's South-East Asia office counted 41,865 cases in 2024. In Gandaki Province, home to Pokhara, a 2025 study found the dengue rate rose from 4.56 to 431 per 100,000 people between 2021 and 2024, with Pokhara a named hotspot. Then 2025 dropped to 8,563 cases nationwide.
This year is following the usual monsoon curve. WHO counted 918 cases in July 2026, 1,776 in August and 1,908 in September. It reports national totals only, with no separate count for Kathmandu or Pokhara.
The Aedes mosquito that spreads dengue bites by day, with peaks after sunrise and in the late afternoon. In Kathmandu and Pokhara from June through October, put repellent on over sunscreen in the morning and again in the afternoon. Our dengue & Zika routine has the full schedule.
Chitwan: rare malaria, buggy evenings
Chitwan National Park is lowland jungle outside the two far-western provinces where CDC recommends malaria medicine. It falls under CDC's wording for the rest of the country, "Rare cases in other areas throughout the country in areas <2,000 m (~6,500 ft) elevation," and for those areas the advice is "No chemoprophylaxis recommended (insect bite precautions and mosquito avoidance only)." Medicine is recommended only for "Sudurpashchim and Karnali provinces in areas <2,000m (~6,500 ft) elevation." If your trip reaches those far-western lowlands, see a travel clinic 4–6 weeks before departure; our malaria-zone checklist covers the preparation.
In Chitwan, bite precautions mean an evening routine. Jungle mosquitoes and sand flies are busiest from dusk to dawn, the hours of dusk safaris and lodge dinners. Put repellent on before you head out, wear long sleeves and long pants, ideally treated with permethrin at home, and sleep under a net or in a screened, air-conditioned room. CDC also lists leishmaniasis for Nepal, a parasite spread by sand flies, one more reason to cover up after dark.
If you'll spend rural nights in the lowlands, ask a travel clinic about Japanese encephalitis vaccine too. CDC says to consider it for rural stays and for nights without air conditioning, screens or bed nets.
When to go
October–November and March–May are the main trekking seasons. After a heavy monsoon, dengue can still run high in Kathmandu and Pokhara in October, so keep the daytime habit then. December–February has the fewest mosquitoes of the year, at the cost of cold days at altitude. The June–September monsoon is the hard stretch, with dengue climbing in the valleys and the lowlands and wet trails that have a reputation for leeches.
On the trek itself, altitude is the health question to plan for, and it's beyond this page. Adding India? CDC's malaria advice there covers travel throughout the country below 6,500 feet, Delhi included, and our India briefing has the details.
Where you're going
How the four usual stops compare.
Kathmandu
CDC reports no malaria transmission in the capital. Dengue is the issue, highest from June to October, so the daytime repellent habit matters most then.
Pokhara & Lakeside
No malaria transmission, per CDC, but Pokhara was a named dengue hotspot when Gandaki Province's rate reached 431 per 100,000 in 2024. Lakeside's gardens draw mosquitoes, so keep the daytime repellent habit before and after a trek.
Chitwan National Park & Sauraha
Covered by CDC's wording for other lowland areas, where it reports rare cases and recommends no malaria medicine. Repellent and long sleeves for dusk safaris and lodge evenings, and a net or screened room at night.
Everest & Annapurna treks
CDC reports no malaria "on typical Himalayan treks," and mosquitoes tend to drop away as the trail climbs. The lowest trailheads and the Pokhara-side approaches can be buggy in the monsoon.
The Nepal kit
- Picaridin 20% travel sprays: odorless, layers over sunscreen for daytime dengue protection in Kathmandu and Pokhara, and the 3.4 oz size rides in a carry-on to the trailhead. One bottle covers about a week of daily use for one person.
- Permethrin 0.5% for safari clothes: treat a long-sleeved shirt, trousers and socks at home 48 hours before you fly. Treated fabric repels and kills mosquitoes on contact through several washes. It goes on clothing, never on skin.
What travelers report
Paraphrased from forum threads and a review and linked so you can read them in full. Only one is dated, to 2019, and the others may be as old, so read them for where bites happen and use the figures above for this year.
- Kathmandu and Pokhara · 2019
A 2019 forum post warned that dengue was circulating in Kathmandu and Pokhara; replies recommended repellent and long clothing. TripAdvisor ↗
- Jiva Spa, Pokhara Lakeside
In an otherwise glowing review, the reviewer noted that mosquitoes can be a nuisance because of all the plants around the spa. TripAdvisor ↗
- Nepal (spring trip) · spring
Asked about dengue for a spring trip, a poster said transmission mainly happens in the June to September monsoon and that spring travel is fine. TripAdvisor ↗
One more rule outlasts the trip. Any fever during or after your trip means a doctor visit, and you tell them you were in Nepal and whether you spent time in the lowlands.
Traveler questions
Do I need malaria pills for Nepal?
CDC doesn't recommend them for the usual route. It reports "no malaria transmission in Kathmandu (the capital), Pokhara, or on typical Himalayan treks." Chitwan falls under CDC's wording for other lowland areas, where it reports rare cases, and for those areas its advice reads "No chemoprophylaxis recommended (insect bite precautions and mosquito avoidance only)." CDC recommends prevention medicine only for travel below 6,500 feet (2,000 m) in Sudurpashchim and Karnali provinces in the far west. If that's on your route, see a travel clinic 4–6 weeks before departure.
Are there mosquitoes on the Everest Base Camp or Annapurna treks?
Usually very few once you gain height. Mosquitoes tend to thin out quickly with altitude, and CDC reports no malaria on typical Himalayan treks. The lowest trailheads and the approaches from the Pokhara side can be buggy in the monsoon, so keep repellent in your pack for the first days and for the nights in Kathmandu or Pokhara on either side of the trek.
When is dengue season in Nepal?
The June–September monsoon, and after a heavy monsoon it can still run high in Kathmandu and Pokhara in October. In 2026 the World Health Organization counted 918 cases nationwide in July, 1,776 in August and 1,908 in September. The biggest years were 2022 to 2024, with tens of thousands of cases each year; 2025 was far lower, at 8,563. Last year cases fell sharply by December.
Do I need a Japanese encephalitis or yellow fever vaccine for Nepal?
CDC doesn't recommend the yellow fever vaccine for Nepal, and it isn't required when you fly in from the US. Nepal does require proof of vaccination from travelers 9 months or older arriving from a country with yellow fever risk, including airport transits or layovers of more than 12 hours there. For Japanese encephalitis, CDC recommends the vaccine for stays of a month or more and says to consider it for shorter trips with rural stays, hiking or camping, or nights without air conditioning, screens or bed nets. Bring your Chitwan and lowland plans to a travel clinic and ask.
Sources
Health authorities, surveillance reports and news coverage of official bulletins used for this briefing, last checked October 2026. Traveler reports are linked where they appear. This page summarizes public-health guidance and is not medical advice.
- World Health Organization
- World Health Organization
- World Health Organization
- European Centre for Disease Prevention and Control
- Peer-reviewed study (PubMed Central)
- Peer-reviewed study (PubMed Central)
- Peer-reviewed study (PubMed Central)
- CDC destination page for travelers
- European Centre for Disease Prevention and Control
- Peer-reviewed study (PubMed Central)
- Peer-reviewed study (PubMed Central)