title: Factors associated with malaria parasitemia, anemia and serological responses in a spectrum of epidemiological settings in Uganda.
abstract: BACKGROUND
  Understanding the current epidemiology of malaria and the relationship between intervention coverage, transmission intensity, and burden of disease is important to guide control activities. We aimed to determine the prevalence of anemia, parasitemia, and serological responses to P. falciparum antigens, and factors associated with these indicators, in three different epidemiological settings in Uganda.
  
  
  RESULTS
  In 2012, cross-sectional surveys were conducted in 200 randomly selected households from each of three sites: Walukuba, Jinja district (peri-urban); Kihihi, Kanungu district (rural); and Nagongera, Tororo district (rural) with corresponding estimates of annual entomologic inoculation rates (aEIR) of 3.8, 26.6, and 125.0, respectively. Of 2737 participants, laboratory testing was done in 2227 (81.4%), including measurement of hemoglobin, parasitemia using microscopy, and serological responses to P. falciparum apical membrane antigen 1 (AMA-1) and merozoite surface protein 1, 19 kilodalton fragment (MSP-119). Analysis of laboratory results was restricted to 1949 (87.5%) participants aged ≤ 40 years. Prevalence of anemia (hemoglobin < 11.0 g/dL) was significantly higher in Walukuba (18.9%) and Nagongera (17.4%) than in Kihihi (13.1%), and was strongly associated with decreasing age for those ≤ 5 years at all sites. Parasite prevalence was significantly higher in Nagongera (48.3%) than in Walukuba (12.2%) and Kihihi (12.8%), and significantly increased with age to 11 years, and then significantly decreased at all sites. Seropositivity to AMA-1 was 53.3% in Walukuba, 63.0% in Kihihi, and 83.7% in Nagongera and was associated with increasing age at all sites. AMA-1 seroconversion rates strongly correlated with transmission intensity, while serological responses to MSP-119 did not.
  
  
  CONCLUSIONS
  Anemia was predominant in young children and parasitemia peaked by 11 years across 3 sites with varied transmission intensity. Serological responses to AMA-1 appeared to best reflect transmission intensity, and may be a more accurate indicator for malaria surveillance than anemia or parasitemia.
authors.affiliation: Makerere University School of Public Health, College of Health Sciences, Kampala, Uganda; Infectious Diseases Research Collaboration, Kampala, Uganda.
authors.forename: Adoke
authors.initials: A
authors.lastname: Yeka
authors.affiliation: Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda; Infectious Diseases Research Collaboration, Kampala, Uganda.
authors.forename: Joaniter
authors.initials: J
authors.lastname: Nankabirwa
authors.affiliation: Child Health and Development Centre, Makerere University College of Health Sciences, Kampala, Uganda; Infectious Diseases Research Collaboration, Kampala, Uganda.
authors.forename: Arthur
authors.initials: A
authors.lastname: Mpimbaza
authors.affiliation: Infectious Diseases Research Collaboration, Kampala, Uganda.
authors.forename: Ruth
authors.initials: R
authors.lastname: Kigozi
authors.affiliation: Infectious Diseases Research Collaboration, Kampala, Uganda.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Arinaitwe
authors.affiliation: London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Chris
authors.initials: C
authors.lastname: Drakeley
authors.affiliation: Department of Medicine, University of California San Francisco, San Francisco, United States of America.
authors.forename: Bryan
authors.initials: B
authors.lastname: Greenhouse
authors.affiliation: Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda; Infectious Diseases Research Collaboration, Kampala, Uganda.
authors.forename: Moses R
authors.initials: MR
authors.lastname: Kamya
authors.affiliation: Department of Medicine, University of California San Francisco, San Francisco, United States of America.
authors.forename: Grant
authors.initials: G
authors.lastname: Dorsey
authors.affiliation: Infectious Diseases Research Collaboration, Kampala, Uganda; London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Sarah G
authors.initials: SG
authors.lastname: Staedke
mesh_terms: D000293:Adolescent; D000328:Adult; D000740:Anemia / Q000150:complications*; D000953:Antigens, Protozoan / Q000276:immunology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016778:Malaria, Falciparum / Q000150:complications / Q000453:epidemiology* / Q000276:immunology*; D008297:Male; D008565:Membrane Proteins / Q000276:immunology; D008875:Middle Aged; D018512:Parasitemia / Q000150:complications*; D010963:Plasmodium falciparum / Q000276:immunology / Q000502:physiology; D015995:Prevalence; D015800:Protozoan Proteins / Q000276:immunology; D012698:Serologic Tests; D011795:Surveys and Questionnaires; D014454:Uganda / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000953:Antigens, Protozoan; D008565:Membrane Proteins; D015800:Protozoan Proteins; C090077:apical membrane antigen I, Plasmodium