title: Surveillance for malaria elimination in Swaziland: a national cross-sectional study using pooled PCR and serology.
abstract: BACKGROUND
  To guide malaria elimination efforts in Swaziland and other countries, accurate assessments of transmission are critical. Pooled-PCR has potential to efficiently improve sensitivity to detect infections; serology may clarify temporal and spatial trends in exposure.
  
  
  RESULTS
  Using a stratified two-stage cluster, cross-sectional design, subjects were recruited from the malaria endemic region of Swaziland. Blood was collected for rapid diagnostic testing (RDT), pooled PCR, and ELISA detecting antibodies to Plasmodium falciparum surface antigens. Of 4330 participants tested, three were RDT-positive yet false positives by PCR. Pooled PCR led to the identification of one P. falciparum and one P. malariae infection among RDT-negative participants. The P. falciparum-infected participant reported recent travel to Mozambique. Compared to performing individual testing on thousands of samples, PCR pooling reduced labor and consumable costs by 95.5%. Seropositivity was associated with age ≥20 years (11·7% vs 1·9%, P<0.001), recent travel to Mozambique (OR 4.4 [95% CI 1.0-19.0]) and residence in southeast Swaziland (RR 3.78, P<0.001).
  
  
  CONCLUSIONS
  The prevalence of malaria infection and recent exposure in Swaziland are extremely low, suggesting elimination is feasible. Future efforts should address imported malaria and target remaining foci of transmission. Pooled PCR and ELISA are valuable surveillance tools for guiding elimination efforts.
authors.affiliation: Global Health Group, University of California San Francisco, San Francisco, California, United States of America. HsiangM@peds.ucsf.edu
authors.forename: Michelle S
authors.initials: MS
authors.lastname: Hsiang
authors.forename: Jimee
authors.initials: J
authors.lastname: Hwang
authors.forename: Simon
authors.initials: S
authors.lastname: Kunene
authors.forename: Chris
authors.initials: C
authors.lastname: Drakeley
authors.forename: Deepika
authors.initials: D
authors.lastname: Kandula
authors.forename: Joseph
authors.initials: J
authors.lastname: Novotny
authors.forename: Justin
authors.initials: J
authors.lastname: Parizo
authors.forename: Trevor
authors.initials: T
authors.lastname: Jensen
authors.forename: Marcus
authors.initials: M
authors.lastname: Tong
authors.forename: Jordan
authors.initials: J
authors.lastname: Kemere
authors.forename: Sabelo
authors.initials: S
authors.lastname: Dlamini
authors.forename: Bruno
authors.initials: B
authors.lastname: Moonen
authors.forename: Evelina
authors.initials: E
authors.lastname: Angov
authors.forename: Sheetij
authors.initials: S
authors.lastname: Dutta
authors.forename: Christian
authors.initials: C
authors.lastname: Ockenhouse
authors.forename: Grant
authors.initials: G
authors.lastname: Dorsey
authors.forename: Bryan
authors.initials: B
authors.lastname: Greenhouse
mesh_terms: D000293:Adolescent; D000328:Adult; D001800:Blood Specimen Collection / Q000379:methods; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D013541:Eswatini / Q000453:epidemiology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008288:Malaria / Q000097:blood / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods*; D011159:Population Surveillance; D012698:Serologic Tests / Q000379:methods; D055815:Young Adult