title: High heterogeneity of malaria transmission and a large sub-patent and diverse reservoir of infection in Wusab As Safil district, Republic of Yemen.
abstract: BACKGROUND
  Yemen remains the country with the highest malaria transmission within the Arabian Peninsula and a source of imported cases to neighbouring countries.
  
  
  METHODS
  This study collected samples from individuals resident in a valley in Western Yemen as a baseline to examine infection prevalence for a future trial. As well as rapid diagnostic test (RDT) and microscopy, a filter paper blood spot was collected for molecular and serological analyses.
  
  
  RESULTS
  Samples were collected from 2261 individuals from 12 clusters across a study area of approximately 100 km(2). Plasmodium falciparum infection prevalence was 12.4, 11.1 and 19.6% by RDT, microscopy and polymerase chain reaction (PCR), respectively. RDT and microscopy did not detect 45% of infections present, suggesting many infections were low-density. Infection prevalence and seroprevalence were highly heterogeneous between clusters, with evidence of higher exposure in clusters close to the wadi. The mean multiplicity of infection (MOI) was 2.3 and high heterozygosity and allelic richness were detected.
  
  
  CONCLUSIONS
  This highly diverse parasite population suggests a high degree of transmissibility and coupled with the substantial proportion of low-density infections, may pose challenges for malaria control and elimination efforts.
authors.affiliation: MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK. jackie.cook@lshtm.ac.uk.
authors.forename: Jackie
authors.initials: J
authors.lastname: Cook
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Lynn
authors.initials: L
authors.lastname: Grignard
authors.affiliation: Department of Medical Parasitology, Faculty of Medicine and Health Sciences, Sana'a University, Sana'a, Yemen.
authors.forename: Samira
authors.initials: S
authors.lastname: Al-Eryani
authors.affiliation: Malaria Control Programme, Ministry of Public Health and Population, Sana'a, Yemen.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Al-Selwei
authors.affiliation: Global Malaria Programme, World Health Organization, Geneva, Switzerland.
authors.forename: Abraham
authors.initials: A
authors.lastname: Mnzava
authors.affiliation: Malaria Control Programme, Ministry of Public Health and Population, Sana'a, Yemen.
authors.forename: Hafed
authors.initials: H
authors.lastname: Al-Yarie
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Alison
authors.initials: A
authors.lastname: Rand
authors.affiliation: MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Immo
authors.initials: I
authors.lastname: Kleinschmidt
authors.affiliation: Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Drakeley
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D002648:Child; D002675:Child, Preschool; D002846:Chromatography, Affinity; D018562:Disease Transmission, Infectious; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016778:Malaria, Falciparum / Q000453:epidemiology* / Q000635:transmission*; D008297:Male; D008853:Microscopy; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D015995:Prevalence; D011795:Surveys and Questionnaires; D015006:Yemen / Q000453:epidemiology; D055815:Young Adult
keywords: Heterogeneity; Heterozygosity; Malaria transmission; Molecular; Multiplicity of infection; PCR