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Comparison of three antigen detection methods for diagnosis and therapeutic monitoring of malaria: a field study from southern Vietnam
Author(s) -
Huong Nguyen Mai,
Davis Timothy M. E.,
Hewitt Sean,
Van Huong Nguyen,
Uyen Tran Thi,
Nhan Doan Hanh,
Cong Le Dinh
Publication year - 2002
Publication title -
tropical medicine and international health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.056
H-Index - 114
eISSN - 1365-3156
pISSN - 1360-2276
DOI - 10.1046/j.1365-3156.2002.00869.x
Subject(s) - malaria , plasmodium vivax , plasmodium falciparum , medicine , rapid diagnostic test , parasitemia , immunology , gold standard (test) , gastroenterology , chloroquine
OBJECTIVES To compare the sensitivity, specificity and post‐treatment persistence of three commonly used rapid antigen detection methods. METHOD 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 (≤ 75.0%) at parasitaemias < 1000/μl regardless of malaria species. During follow‐up, Paracheck‐Pf ® remained positive in the greatest proportion of patients, especially at higher parasitaemias (> 10 000/μl). Residual OptiMAL ® positivity occurred only in a relatively small proportion of patients (< 10%) with parasitaemias > 10 000/μl 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.