{ "slug": "dengue-travel", "question": "What are the odds of contracting dengue fever as a traveler?", "category": "health", "tags": [ "travel" ], "no_reliable_estimate": false, "perceived": { "description": "Dengue sits in a strange corner of the traveler’s risk imagination. Most Likelier readers heading to Bali or Cancun don’t carry a specific fear of dengue the way they carry a specific fear of malaria or Japanese encephalitis; they carry a vague “tropical mosquito disease” worry that folds dengue, chikungunya, Zika, and malaria into one bucket. That intuition is roughly calibrated for the wet-season urban traveler — symptomatic attack rates on a two-week trip to peak-season Southeast Asia or the Caribbean sit in the low-single-digit-per-thousand range, which is neither negligible nor alarming. We haven’t found a rigorous recent survey that isolates “fear of catching dengue on a trip” from general travel-health anxiety, so the perceived side of this entry is marked as editorial intuition rather than polled data.\n", "rough_estimate": "most travelers file dengue under 'tropical mosquito disease, unlikely but real'", "kind": "intuition" }, "native": { "display": "~1 in 200 per 2-week trip to an endemic region in peak transmission season", "numerator": 1, "denominator": 200, "unit": "per traveler-trip", "population": "reference traveler: 2-week leisure visit to a dengue-endemic urban area during peak transmission season" }, "normalized": { "lifetime_us_adult": 0.005, "display": "~1 in 200 per reference trip", "log_value": -2.3, "assumptions": "The headline is an order-of-magnitude estimate for a reference traveler: a two-week leisure visit to a dengue-endemic urban area (Southeast Asia wet season or Caribbean / Latin America peak season), with baseline precautions but no vaccine. It is NOT a lifetime figure for a US adult; travel dengue risk is overwhelmingly a per-trip, per-destination, per-season question, so this entry uses scope “activity_specific_lifetime” to mean “per traveler-trip.” Off-peak travel to the same destinations is roughly an order of magnitude lower. An estimated 40–80% of dengue infections are asymptomatic (CDC Yellow Book), so the true infection rate is higher than the symptomatic attack rate this figure represents — but asymptomatic infections still count toward the antibody-dependent enhancement (ADE) risk on a future trip, which is why the personal_factor_multipliers call out prior infection. Severe dengue occurs in roughly 5% or fewer of symptomatic cases (CDC Yellow Book); per-trip severe-dengue risk is therefore on the order of 1 in 4,000 at the headline figure, and per-trip mortality is lower still given modern supportive care. The uncertainty band reflects the spread across destinations, seasons, and serosurvey-vs-case-report methodology.\n", "uncertainty": { "low": 0.0005, "high": 0.01 }, "scope": "activity_specific_lifetime" }, "sources": [ { "url": "https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/dengue.html", "title": "Dengue — CDC Yellow Book (Health Information for International Travel)", "publisher": "US Centers for Disease Control and Prevention (CDC)", "source_type": "govt_report", "statistic": "~390 million DENV infections and ~96 million symptomatic cases per year globally; 7,528 travel-related US dengue cases reported 2010-2021 with 3,135 hospitalizations and 19 deaths; >1,400 travel-associated US cases in 2019 and 2022-2024; 40-80% of DENV infections asymptomatic; up to 5% of symptomatic cases develop severe disease.", "excerpt": "\"The incidence of dengue among travelers to the tropics has increased in recent years, and dengue burden continues to grow in Sub-Saharan Africa, Latin America, and Asia, with estimates of 390 million DENV infections and 96 million symptomatic cases per year. … During 2010–2021, a total 7,528 travel-related dengue cases were reported in the United States; a total of 3,135 patients required hospitalization, and 19 died. … Travel-associated dengue case numbers also increased during 2019, and 2022–2024, with >1,400 cases reported each year, compared to a previous peak of 919 cases in 2016. … An estimated 40–80% of DENV infections are asymptomatic. … ≤5% of all people experiencing symptoms from dengue develop severe, life-threatening disease.\"\n", "source_date": "2024-05-01", "source_accessed": "2026-04-11", "archive_url": "http://web.archive.org/web/20260324150921/https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/dengue.html", "calculation_notes": "CDC Yellow Book is the authoritative traveler-facing guidance. The ~96 million symptomatic infections per year across the ~4 billion people living in dengue-endemic areas implies a roughly 2% annual per-capita symptomatic rate averaged across endemic regions; travelers undersample the high-transmission rural pockets and over-sample urban areas and shorter exposure windows, so the per-trip figure for a two-week stay in a peak-season urban area lands roughly an order of magnitude below that (0.3–1%). CDC’s observation that US travel-associated cases jumped from ~919 in 2016 to >1,400 in 2019 and each year 2022–2024 anchors the “risk is rising, not falling” note in the body text. The 40–80% asymptomatic share is the basis for the ADE personal factor, and the ≤5% severe-dengue share is what takes the ~1-in-200 per-trip infection risk to ~1 in 4,000 per-trip severe-dengue risk.\n", "independence_note": "CDC Yellow Book is the primary US traveler-facing clinical guidance, built from CDC dengue surveillance (ArboNET) and the peer-reviewed travel-medicine literature. Shares the Bhatt et al. 2013 modelled 390M/96M estimate with the WHO fact sheet below — treat the CDC/WHO modelled figures as one upstream; GeoSentinel (Duvignaud/Huits) is the genuine independent traveler-case stream.\n" }, { "url": "https://www.who.int/news-room/fact-sheets/detail/dengue-and-severe-dengue", "title": "Dengue and severe dengue — Fact sheet", "publisher": "World Health Organization", "source_type": "reputable_reference", "statistic": "100-400 million dengue infections per year globally; modelling estimate of 390 million infections with 96 million symptomatic; 2024 historic high of >14.6 million cases and >12,000 deaths reported to WHO; 308 locally-acquired cases in France, Italy and Spain reported in 2024.", "excerpt": "\"About half of the world’s population is now at risk of dengue, with an estimated 100–400 million infections occurring each year. … One modelling estimate indicates 390 million dengue virus infections per year, of which 96 million manifest clinically. … During 2024, ongoing transmission, combined with an unexpected spike in dengue cases, resulted in a historic high of over 14.6 million cases and more than 12 000 dengue-related deaths reported. … Dengue is spreading to new areas, including the European and Eastern Mediterranean regions. In 2024, 308 cases were reported to WHO from three European countries (France, Italy and Spain). … From January to July 2025, over 4 million cases and over 3000 deaths have been reported to WHO from 97 countries.\"\n", "source_date": "2025-08-01", "source_accessed": "2026-04-11", "archive_url": "https://web.archive.org/web/20260413171233/https://www.who.int/news-room/fact-sheets/detail/dengue-and-severe-dengue", "calculation_notes": "WHO provides the global denominator and the 2024-2025 trajectory. The >14.6 million reported cases in 2024 — more than triple a normal year — is the main empirical basis for the “per-trip risk in 2024–2025 is higher than a decade ago” framing in the body. WHO case reports undercount the true infection total by roughly an order of magnitude (modelling gives ~96 million symptomatic vs ~14.6 million reported), but the year-over-year growth signal is robust. Independent of CDC: WHO pulls country-level case reports and the modelled Bhatt et al. burden estimate; CDC Yellow Book quotes the same modelled figure but uses its own US surveillance stream for the traveler-case counts.\n", "independence_note": "WHO and CDC both cite the Bhatt et al. (2013) modelling estimate for the 390M / 96M figure, so that number is not independent between them. WHO’s 14.6M 2024 reported cases and CDC’s US travel-associated case counts come from different surveillance pipelines and corroborate each other on the 2024 spike.\n" }, { "url": "https://pubmed.ncbi.nlm.nih.gov/38951998/", "title": "Epidemiology of travel-associated dengue from 2007 to 2022: A GeoSentinel analysis", "publisher": "Journal of Travel Medicine (Duvignaud, Stoney, Angelo, et al.)", "source_type": "peer_reviewed", "statistic": "5,958 confirmed or probable dengue cases in travelers evaluated at GeoSentinel sites 2007-2022; 50.4% acquired in Southeast Asia, 14.9% South Central Asia, 10.9% Caribbean, 9.2% South America; ~2% had complicated dengue; median travel duration 21 days; 67.3% tourism, 12.2% visiting friends and relatives.", "excerpt": "\"This analysis included 5,958 travellers with confirmed (n = 4,859; 81.6%) or probable (n = 1,099; 18.4%) dengue. The most frequent regions of acquisition were South East Asia (50.4%), South Central Asia (14.9%), the Caribbean (10.9%) and South America (9.2%). … In Southeast Asia, annual proportionate morbidity increased from 50 dengue cases per 1000 ill returned travellers in non-epidemic years to an average of 159 cases per 1000 travellers during epidemic years. … the median travel duration was 21 days … the most frequent reasons for travel were tourism (67.3%), visiting friends or relatives (12.2%) and business (11.0%).\"\n", "source_date": "2024-10-19", "source_accessed": "2026-04-11", "archive_url": "https://web.archive.org/web/20260413171315/https://pubmed.ncbi.nlm.nih.gov/38951998/", "calculation_notes": "GeoSentinel is the closest thing the travel-medicine literature has to a representative traveler case series. The 50 vs 159 dengue cases per 1,000 ill returned travelers (non-epidemic vs epidemic years) in Southeast Asia is a proportionate morbidity, not an attack rate — it describes what share of sick returning travelers have dengue, not what share of all travelers catch it — but the ~3× swing between epidemic and non-epidemic years is what anchors the regional_breakdown ordering and the seasonal personal factors. Median travel duration of 21 days in this case series matches the two-week reference trip used for the headline figure.\n", "independence_note": "GeoSentinel is a global network of travel and tropical medicine clinics with its own case-reporting pipeline, methodologically independent of CDC US surveillance and WHO country-level case reports. Genuine independent corroboration on the regional distribution of traveler dengue (SE Asia dominates, Caribbean and Latin America are next).\n" }, { "url": "https://pubmed.ncbi.nlm.nih.gov/37335991/", "title": "Clinical Characteristics and Outcomes Among Travelers With Severe Dengue: A GeoSentinel Analysis", "publisher": "Annals of Internal Medicine (Huits, Angelo, Leder, et al.)", "source_type": "peer_reviewed", "statistic": "Among 5,958 dengue cases in travelers 2007-2022, 95 (2%) had complicated dengue, of whom 27 (31%) were classified as severe; 91% hospitalized; one death (non-dengue-related).", "excerpt": "\"Of 5958 patients with dengue, 95 (2%) had complicated dengue. … 27 (31%) were classified as severe. … Seventy-eight (91%) patients were hospitalized. One patient died of nondengue-related illnesses.\"\n", "source_date": "2023-06-20", "source_accessed": "2026-04-11", "archive_url": "http://web.archive.org/web/20250206055418/https://pubmed.ncbi.nlm.nih.gov/37335991/", "calculation_notes": "The Huits et al. analysis found 2% of traveler dengue cases had complicated dengue, and 31% of those complicated cases (27/95) met WHO severe-dengue criteria — i.e., 27/5958 ≈ 0.45% of all diagnosed traveler dengue cases were severe. This is much lower than the CDC Yellow Book’s “up to 5%” ceiling for symptomatic cases globally. The gap is consistent with the two populations: GeoSentinel travelers are adults with access to modern supportive care, while the global figure includes endemic-country pediatric second infections, which dominate severe-dengue incidence. The sole death was attributed to non-dengue-related illness. Applied to the headline 1-in-200 per-trip infection risk, the traveler severe-dengue risk lands on the order of 1 in 20,000–40,000 per reference trip, and per-trip mortality is roughly another order of magnitude lower.\n", "independence_note": "Same GeoSentinel case pool as the Duvignaud et al. paper, so these two are not independent on the case count. They are cited for different purposes: Duvignaud for the regional distribution and traveler demographics, Huits for the severe-dengue and mortality fractions.\n" } ], "comparison_anchors": [ { "label": "Malaria per 2-week Sub-Saharan Africa trip with prophylaxis", "lifetime_us_adult": 0.0001 }, { "label": "Japanese encephalitis per short-term urban Asia trip", "lifetime_us_adult": 5e-7 }, { "label": "Death in a commercial plane crash (per flight)", "lifetime_us_adult": 7.3e-8 }, { "label": "Mosquito-borne disease death (lifetime, global average)", "lifetime_us_adult": 0.00525 } ], "regional_breakdown": [ { "region": "SE Asia wet season, urban, 2 weeks", "probability": 0.005, "notes": "Southeast Asia accounts for ~50% of GeoSentinel traveler dengue cases; wet-season urban risk in Thailand, Vietnam, Indonesia, and the Philippines dominates." }, { "region": "Caribbean / Latin America peak season, 2 weeks", "probability": 0.003, "notes": "The Americas reported >13 million dengue cases in 2024, more than triple a normal year. Caribbean and Latin America together account for ~20% of traveler cases in GeoSentinel." }, { "region": "Off-peak travel to an endemic area", "probability": 0.0005, "notes": "Dry-season or cooler-month travel cuts transmission roughly an order of magnitude; GeoSentinel reports ~3× lower proportionate morbidity in non-epidemic years." }, { "region": "Cruise ship port call only", "probability": 0.00001, "notes": "Short shore excursions with limited overnight exposure approximate non-endemic baseline." }, { "region": "Long-term expat in an endemic urban area", "probability": 0.05, "notes": "Year-round exposure in a peak-transmission city can push annual infection odds into the percent-plus range; repeat exposure across serotypes compounds." } ], "personal_factor_multipliers": [ { "factor": "Prior dengue infection (antibody-dependent enhancement risk)", "multiplier": 3, "notes": "A second infection with a different serotype raises the odds of severe disease, not the opposite. This is the reason WHO and CDC guidance treat prior dengue as a risk factor for severe dengue, not a protective factor." }, { "factor": "DEET or picaridin + permethrin-treated clothing + screened or air-conditioned accommodation", "multiplier": 0.3, "notes": "Aedes aegypti and Aedes albopictus are daytime biters concentrated in and around buildings; bite avoidance during daylight hours materially reduces exposure." }, { "factor": "Long-term expat in an endemic urban area", "multiplier": 20, "notes": "Duration of exposure is the dominant factor. A year in a peak-transmission city can approach local resident attack rates; two years can cycle through multiple serotypes." }, { "factor": "Wet-season travel vs dry-season travel to the same destination", "multiplier": 3, "notes": "GeoSentinel: proportionate morbidity for dengue tripled in Southeast Asia between non-epidemic and epidemic years; wet-season and post-monsoon travel carries most of the seasonal risk." }, { "factor": "Visiting friends and relatives (VFR) vs resort tourism", "multiplier": 2, "notes": "Longer stays, more time in residential neighborhoods, less screened accommodation. 12% of GeoSentinel traveler dengue cases were VFR travelers." } ], "short_label": "Dengue (travel)", "outcome_severity": "moderate_harm", "exposure_pattern": "acute", "outcome_type": "recoverable_injury", "valence": "negative", "caveats": "The headline ~1-in-200 per-trip figure is an order-of-magnitude estimate for a two-week leisure stay in a peak-season endemic urban area, not a precise rate. True attack rates vary by country, city, neighborhood, accommodation type, month, and prevailing serotype, and published traveler serostudies span roughly 0.2–2% per two-week trip depending on destination. An estimated 40–80% of dengue infections are asymptomatic, so the true infection rate is substantially higher than the symptomatic attack rate represented here; asymptomatic infections still carry forward the antibody-dependent enhancement (ADE) risk profile for any future trip, which is the main reason a “I had it once and it was nothing” traveler should not treat that as reassurance. Severe dengue (dengue hemorrhagic fever / dengue shock syndrome) occurs in up to 5% of symptomatic cases per CDC Yellow Book, with a lower ~0.45% figure specifically in GeoSentinel travelers who have access to modern supportive care (Huits et al. 2023). This entry measures the probability of contracting dengue, not of dying from it: per-trip mortality is roughly two orders of magnitude lower than the per-trip infection risk, and dominated by diagnostic delay in non-endemic emergency rooms. Returning travelers with fever within two weeks of an endemic trip should be evaluated for dengue alongside malaria. The sibling entry `malaria-travel` covers malaria specifically and `mosquito-borne-disease` covers the aggregate mortality figure across all mosquito-borne diseases globally.\n", "quality_score": { "d1": 5, "d2": 5, "d3": 4, "d4": 5, "d5": 5, "d6": 5, "d7": 4, "d8": 5, "avg": 4.75, "scored_by": "claude-code-8d", "scored_at": "2026-05-25", "methodology_version": "1.2" }, "reviewer": "likelier-phase-5-agent", "last_reviewed": "2026-04-11", "reviewed": true, "generated_at": "2026-04-11", "image": { "alt": "A single stylized hibiscus flower resting on a pale neutral background, flat vector illustration in muted tones." }, "attribution": "Likelier — https://likelier.app", "license": "https://creativecommons.org/licenses/by-sa/4.0/", "support": "https://buymeacoffee.com/kgluszczyk?via=likelier&utm_content=api-fear-single", "canonical_url": "https://likelier.app/dengue-travel" }