title: Possible association between recent migration and hospitalisation for dengue in an urban population: a prospective case-control study in northern Vietnam.
abstract: A prospective case-control study was conducted in urban districts in Hanoi, northern Vietnam to evaluate the effect of migration on the risk of hospitalisation for dengue in a Vietnamese urban population. We enrolled laboratory-confirmed dengue patients aged ≥ 18 years who were hospitalised in local hospitals in November and December 2010. Four neighbourhood-matched controls for each case were recruited within a week of hospitalisation. Sociodemographic data were collected by interviews, and the number of immature and adult mosquitoes within household premises was counted by entomological survey. Matched-pair analyses were conducted using conditional logistic regression models. Among 43 cases and 168 controls, 84% and 83% were migrants from rural areas, respectively. Although statistical significance was marginal, recent migration (residing in study area for ≤ 5 years) independently increased the risk of hospitalisation for dengue compared with inhabitants after controlling for potential confounders (adjusted odds ratio [aOR] = 3.78; 95% confidence interval [CI] = 0.99-14.27), whereas longer-term migration (residing in study area for ≥ 6 years) did not change the risk (aOR = 1.1; 95% CI = 0.30-4.05). Younger age (18-34 years) (aOR = 7.26; 95% CI = 2.39-22.06) and higher adult Aedes aegypti infestation level within household premises (aOR = 9.25; 95% CI = 1.68-51.09) were also independently associated with hospitalisation for dengue. Recent migration from rural areas seems to increase the risk of hospitalisation for dengue in urban populations in endemic areas. Further research including cohort study should be done to confirm the impact of migration on the risk of dengue in urban areas.
authors.affiliation: Department of Vector Ecology and Environment, Institute of Tropical Medicine, Nagasaki University, Nagasaki 852-8523, Japan.
authors.forename: Ataru
authors.initials: A
authors.lastname: Tsuzuki
authors.affiliation: National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.
authors.forename: Vu Trong
authors.initials: VT
authors.lastname: Duoc
authors.affiliation: Department of Vector Ecology and Environment, Institute of Tropical Medicine, Nagasaki University, Nagasaki 852-8523, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Sunahara
authors.affiliation: Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, Nagasaki 852-8523, Japan.
authors.forename: Motoi
authors.initials: M
authors.lastname: Suzuki
authors.affiliation: National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.
authors.forename: Nguyen Hoang
authors.initials: NH
authors.lastname: Le
authors.affiliation: Department of Vector Ecology and Environment, Institute of Tropical Medicine, Nagasaki University, Nagasaki 852-8523, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Higa
authors.affiliation: Department of Pediatric Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, Nagasaki 852-8523, Japan.
authors.forename: Lay-Myint
authors.initials: LM
authors.lastname: Yoshida
authors.affiliation: Department of Virology, Institute of Tropical Medicine, Nagasaki University, Nagasaki 852-8523, Japan.
authors.forename: Futoshi
authors.initials: F
authors.lastname: Hasebe
authors.affiliation: National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.
authors.forename: Tran Vu
authors.initials: TV
authors.lastname: Phong
authors.affiliation: Department of Vector Ecology and Environment, Institute of Tropical Medicine, Nagasaki University, Nagasaki 852-8523, Japan.
authors.forename: Noboru
authors.initials: N
authors.lastname: Minakawa
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D016022:Case-Control Studies; D003715:Dengue / Q000453:epidemiology*; D005260:Female; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D018570:Risk Assessment; D014171:Transients and Migrants; D014505:Urban Population; D014744:Vietnam / Q000453:epidemiology; D055815:Young Adult