title: Seasonal changes in the antibody responses against Plasmodium falciparum merozoite surface antigens in areas of differing malaria endemicity in Indonesia.
abstract: BACKGROUND
  The transmission of malaria in Indonesia is highly heterogeneous spatially and seasonally. Anti-malaria antibody responses can help characterize this variation. In the present study antibody responses to Plasmodium falciparum MSP-1 and AMA-1 were measured to assess the transmission intensity in a hypo-endemic area of Purworejo and a meso-endemic area of Lampung during low and high transmission seasons.
  
  
  METHODS
  Filter-paper blood spot samples collected from Purworejo and Lampung by cross-sectional survey during high and low transmission season were stored at -20°C. Indirect ELISA assays were carried out using PfMSP1-19 and PfAMA1 antigens. A positivity threshold was determined by samples from local unexposed individuals, and the differences in seroprevalence, antibody level and correlation between antibody level and age in each site were statistically analysed.
  
  
  RESULTS
  Prevalence of antibodies to either PfMSP1-19 or PfAMA1 was higher in Lampung than in Purworejo in both the low (51.3 vs 25.0%) and high transmission season (53.9 vs 37.5%). The magnitude of antibody responses was associated with increasing age in both sites and was higher in Lampung. Age-adjusted seroconversion rates showed an approximately ten-fold difference between Lampung and Purowejo. Two different seroconversion rates were estimated for Lampung suggesting behaviour-related differences in exposure. In both settings antibody responses to PfMSP1-19 were significantly lower in the low season compared to the high season.
  
  
  CONCLUSIONS
  Seasonal changes may be detectable by changes in antibody responses. This is particularly apparent in lower transmission settings and with less immunogenic antigens (in this case PfMSP1-19). Examination of antibody levels rather than seroprevalence is likely to be a more sensitive indicator of changes in transmission. These data suggest that sero-epidemiological analysis may have a role in assessing short-term changes in exposure especially in low or seasonal transmission settings.
authors: Center for Tropical Medicine, Faculty of Medicine, Gadjah Mada University, Jln Teknika Utara, Barek, Yogyakarta 55281, Indonesia. supargiyono@gmail.com.
authors: Supargiyono
authors: S
authors: Supargiyono
authors: Michael T
authors: MT
authors: Bretscher
authors: Mahardika A
authors: MA
authors: Wijayanti
authors: Inge
authors: I
authors: Sutanto
authors: Dian
authors: D
authors: Nugraheni
authors: Royhan
authors: R
authors: Rozqie
authors: Ayleen A
authors: AA
authors: Kosasih
authors: Sulistyawati
authors: S
authors: Sulistyawati
authors: William A
authors: WA
authors: Hawley
authors: Neil F
authors: NF
authors: Lobo
authors: Jackie
authors: J
authors: Cook
authors: Chris J
authors: CJ
authors: Drakeley
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000913:Antibodies, Protozoan / Q000096:biosynthesis / Q000097:blood* / Q000276:immunology; D000953:Antigens, Protozoan / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007214:Indonesia / Q000453:epidemiology; D007223:Infant; D016778:Malaria, Falciparum / Q000453:epidemiology* / Q000276:immunology* / Q000635:transmission; D008297:Male; D008565:Membrane Proteins / Q000276:immunology; D020066:Merozoite Surface Protein 1 / Q000276:immunology; D008875:Middle Aged; D010963:Plasmodium falciparum / Q000276:immunology*; D015800:Protozoan Proteins / Q000276:immunology; D012621:Seasons; D016036:Seroepidemiologic Studies; D055815:Young Adult
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D008565:Membrane Proteins; D020066:Merozoite Surface Protein 1; D015800:Protozoan Proteins; C090077:apical membrane antigen I, Plasmodium