title: Comparison of three antigen detection methods for diagnosis and therapeutic monitoring of malaria: a field study from southern Vietnam.
abstract: OBJECTIVE
  To compare the sensitivity, specificity and post-treatment persistence of three commonly used rapid antigen detection methods.
  
  
  METHODS
  We studied 252 Vietnamese patients aged from 4 to 60 years, 157 with falciparum and 95 with vivax malaria and 160 healthy volunteers. An initial blood sample was taken for microscopy, and OptiMAL, immunochromatographic test (ICT) malaria P.f./P.v. and Paracheck-Pf tests. Patients with falciparum malaria were treated with an artesunate-based combination regimen and those with vivax malaria received chloroquine. Eighty-seven patients with falciparum malaria who were initially positive for one of the antigen tests and who remained blood smear-negative underwent follow-up testing over 28 days.
  
  
  RESULTS
  Paracheck-Pf was the most sensitive test for Plasmodium falciparum (95.8% vs. 82.6% for ICT malaria P.f./P.v. and 49.7% for OptiMAL). Specificities were all 100%. For vivax malaria, OptiMAL performed better than ICT malaria P.f./P.v. (sensitivities 73.7% and 20.0%, respectively), with 100% specificity in both cases. All tests had low sensitivities (< or = 75.0%) at parasitaemias < 1000/microl regardless of malaria species. During follow-up, Paracheck-Pf remained positive in the greatest proportion of patients, especially at higher parasitaemias (> 10,000/microl). Residual OptiMAL positivity occurred only in a relatively small proportion of patients (< 10%) with parasitaemias > 10,000/microl during the first 2 weeks after treatment.
  
  
  CONCLUSIONS
  Although microscopy remains the gold standard for malaria diagnosis, Paracheck-Pf may prove a useful adjunctive test in uncomplicated falciparum malaria in southern Vietnam. OptiMAL had the lowest sensitivity for P. falciparum but it might have a use in the diagnosis of vivax malaria and perhaps to monitor efficacy of treatment for falciparum malaria where microscopy is unavailable.
authors.affiliation: National Institute of Malariology, Parasitology and Entomology, Hanoi, Vietnam.
authors.forename: Nguyen Mai
authors.initials: NM
authors.lastname: Huong
authors.forename: Timothy M E
authors.initials: TM
authors.lastname: Davis
authors.forename: Sean
authors.initials: S
authors.lastname: Hewitt
authors.forename: Nguyen Van
authors.initials: NV
authors.lastname: Huong
authors.forename: Tran Thi
authors.initials: TT
authors.lastname: Uyen
authors.forename: Doan Hanh
authors.initials: DH
authors.lastname: Nhan
authors.forename: Le Dinh
authors.initials: le D
authors.lastname: Cong
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000953:Antigens, Protozoan / Q000302:isolation & purification*; D002648:Child; D002675:Child, Preschool; D006801:Humans; D016778:Malaria, Falciparum / Q000175:diagnosis / Q000276:immunology*; D016780:Malaria, Vivax / Q000175:diagnosis / Q000276:immunology*; D008875:Middle Aged; D010963:Plasmodium falciparum / Q000276:immunology*; D010966:Plasmodium vivax / Q000276:immunology*; D012680:Sensitivity and Specificity; D014744:Vietnam
chemical_list: D000953:Antigens, Protozoan