title: Key traveller groups of relevance to spatial malaria transmission: a survey of movement patterns in four sub-Saharan African countries.
abstract: BACKGROUND
  As malaria prevalence declines in many parts of the world due to widescale control efforts and as drug-resistant parasites begin to emerge, a quantitative understanding of human movement is becoming increasingly relevant to malaria control. However, despite its importance, significant knowledge gaps remain regarding human movement, particularly in sub-Saharan Africa.
  
  
  METHODS
  A quantitative survey of human movement patterns was conducted in four countries in sub-Saharan Africa: Mali, Burkina Faso, Zambia, and Tanzania, with three to five survey locations chosen in each country. Questions were included on demographic and trip details, malaria risk behaviour, children accompanying travellers, and mobile phone usage to enable phone signal data to be better correlated with movement. A total of 4352 individuals were interviewed and 6411 trips recorded.
  
  
  RESULTS
  A cluster analysis of trips highlighted two distinct traveller groups of relevance to malaria transmission: women travelling with children (in all four countries) and youth workers (in Mali). Women travelling with children were more likely to travel to areas of relatively high malaria prevalence in Mali (OR = 4.46, 95% CI = 3.42-5.83), Burkina Faso (OR = 1.58, 95% CI = 1.23-1.58), Zambia (OR = 1.50, 95% CI = 1.20-1.89), and Tanzania (OR = 2.28, 95% CI = 1.71-3.05) compared to other travellers. They were also more likely to own bed nets in Burkina Faso (OR = 1.77, 95% CI = 1.25-2.53) and Zambia (OR = 1.74, 95% CI = 1.34 2.27), and less likely to own a mobile phone in Mali (OR = 0.50, 95% CI = 0.39-0.65), Burkina Faso (OR = 0.39, 95% CI = 0.30-0.52), and Zambia (OR = 0.60, 95% CI = 0.47-0.76). Malian youth workers were more likely to travel to areas of relatively high malaria prevalence (OR = 23, 95% CI = 17-31) and for longer durations (mean of 70 days cf 21 days, p < 0.001) compared to other travellers.
  
  
  CONCLUSIONS
  Women travelling with children were a remarkably consistent traveller group across all four countries surveyed. They are expected to contribute greatly towards spatial malaria transmission because the children they travel with tend to have high parasite prevalence. Youth workers were a significant traveller group in Mali and are expected to contribute greatly to spatial malaria transmission because their movements correlate with seasonal rains and hence peak mosquito densities. Interventions aimed at interrupting spatial transmission of parasites should consider these traveller groups.
authors.affiliation: Department of Infectious Disease Epidemiology, MRC Center for Outbreak Analysis and Modelling, Imperial College London, London, UK. john.marshall@berkeley.edu.|Divisions of Biostatistics and Epidemiology, School of Public Health, University of California, Berkeley, CA, USA. john.marshall@berkeley.edu.
authors.forename: John M
authors.initials: JM
authors.lastname: Marshall
authors.affiliation: Malaria Research and Training Center, University of Bamako, Bamako, Mali.
authors.forename: Mahamoudou
authors.initials: M
authors.lastname: Touré
authors.affiliation: Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso.|Institute for Disease Modeling, Bellevue, WA, USA.
authors.forename: André Lin
authors.initials: AL
authors.lastname: Ouédraogo
authors.affiliation: Chainama College of Health Sciences, Lusaka, Zambia.
authors.forename: Micky
authors.initials: M
authors.lastname: Ndhlovu
authors.affiliation: Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, Tanzania.
authors.forename: Samson S
authors.initials: SS
authors.lastname: Kiware
authors.affiliation: Department of Infectious Disease Epidemiology, MRC Center for Outbreak Analysis and Modelling, Imperial College London, London, UK.
authors.forename: Ashley
authors.initials: A
authors.lastname: Rezai
authors.affiliation: Chainama College of Health Sciences, Lusaka, Zambia.
authors.forename: Emmy
authors.initials: E
authors.lastname: Nkhama
authors.affiliation: Department of Infectious Disease Epidemiology, MRC Center for Outbreak Analysis and Modelling, Imperial College London, London, UK.
authors.forename: Jamie T
authors.initials: JT
authors.lastname: Griffin
authors.affiliation: Department of Infectious Disease Epidemiology, MRC Center for Outbreak Analysis and Modelling, Imperial College London, London, UK.|School of Life Sciences, University of Warwick, Warwick, Coventry, UK.
authors.forename: T Deirdre
authors.initials: TD
authors.lastname: Hollingsworth
authors.affiliation: Malaria Research and Training Center, University of Bamako, Bamako, Mali.
authors.forename: Seydou
authors.initials: S
authors.lastname: Doumbia
authors.affiliation: Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, Dar es Salaam, Tanzania.
authors.forename: Nicodem J
authors.initials: NJ
authors.lastname: Govella
authors.affiliation: Department of Infectious Disease Epidemiology, MRC Center for Outbreak Analysis and Modelling, Imperial College London, London, UK.
authors.forename: Neil M
authors.initials: NM
authors.lastname: Ferguson
authors.affiliation: Department of Infectious Disease Epidemiology, MRC Center for Outbreak Analysis and Modelling, Imperial College London, London, UK.
authors.forename: Azra C
authors.initials: AC
authors.lastname: Ghani
mesh_terms: D000293:Adolescent; D000328:Adult; D017954:Africa South of the Sahara / Q000453:epidemiology; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007407:Interviews as Topic; D008288:Malaria / Q000453:epidemiology* / Q000635:transmission*; D008297:Male; D008875:Middle Aged; D009068:Movement; D014195:Travel; D055815:Young Adult
keywords: Burkina Faso; Cluster analysis; Mali; Mobile phones; Plasmodium falciparum; Spatial transmission; Tanzania; Women with children; Youth workers; Zambia