title: Transmission of malaria and genotypic variability of Plasmodium falciparum on the island of Annobon (Equatorial Guinea).
abstract: BACKGROUND
  Malaria transmission in Equatorial Guinea and its space-time variability has been widely studied, but there is not much information about the transmission of malaria on the small island of Annobon. In 2004, two transversal studies were carried out to establish the malaria transmission pattern on Annobon and analyse the circulating Plasmodium falciparum allelic forms.
  
  
  METHODS
  A blood sample was taken from the selected children in order to determine Plasmodium infection by microscopical examination and by semi-nested multiplex PCR. The diversity of P. falciparum circulating alleles was studied on the basis of the genes encoding for the merozoite surface proteins, MSP-1 and MSP-2 of P. falciparum.
  
  
  RESULTS
  The crude parasite rate was 17% during the dry season and 60% during the rainy season. The percentage of children sleeping under a bed net was over 80% in the two surveys. During the rainy season, 33.3% of the children surveyed were anaemic at the time of the study. No association was found between the crude parasite rate, the use of bed nets and gender, and anaemia. However, children between five and nine years of age were five times less at risk of being anaemic than those aged less than one year. A total of 28 populations of the three allelic families of the msp-1 gene were identified and 39 of the msp-2 gene. The variability of circulating allelic populations is significantly higher in the rainy than in the dry season, although the multiplicity of infections is similar in both, 2.2 and 1.9 respectively.
  
  
  CONCLUSIONS
  Based on the high degree of geographical isolation of the Annobon population and the apparent marked seasonality of the transmission, it is feasible to believe that malaria can be well controlled from this small African island.
authors.affiliation: National Centre for Tropical Medicine and International Health, Instituto de Salud Carlos III, Madrid, Spain. jcano@isciii.es
authors.forename: Jorge
authors.initials: J
authors.lastname: Cano
authors.forename: Pedro
authors.initials: P
authors.lastname: Berzosa
authors.forename: Aida
authors.initials: A
authors.lastname: de Lucio
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Descalzo
authors.forename: Leonardo
authors.initials: L
authors.lastname: Bobuakasi
authors.forename: Sisinio
authors.initials: S
authors.lastname: Nzambo
authors.forename: Melchor
authors.initials: M
authors.lastname: Ondo
authors.forename: Jesus N
authors.initials: JN
authors.lastname: Buatiche
authors.forename: Gloria
authors.initials: G
authors.lastname: Nseng
authors.forename: Agustin
authors.initials: A
authors.lastname: Benito
mesh_terms: D017677:Age Distribution; D000818:Animals; D001512:Bedding and Linens; D002648:Child; D002675:Child, Preschool; D016703:Equatorial Guinea / Q000453:epidemiology; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D005843:Geography; D006801:Humans; D007306:Insecticides; D016778:Malaria, Falciparum / Q000453:epidemiology / Q000469:parasitology* / Q000635:transmission*; D008297:Male; D010963:Plasmodium falciparum / Q000235:genetics*; D012621:Seasons; D012727:Sex Characteristics; D013997:Time Factors
chemical_list: D007306:Insecticides