title: Persistent histidine-rich protein 2, parasite lactate dehydrogenase, and panmalarial antigen reactivity after clearance of Plasmodium falciparum monoinfection.
abstract: We tested 240 patients with Plasmodium falciparum monoinfection for persistent parasite antigenemia after successful standardized antimalarial therapy by using the ICT Malaria Pf/Pv and OptiMAL-IT assays that detect the malaria antigens Plasmodium falciparum histidine-rich protein 2 (HRP2) and parasite lactate dehydrogenase (pLDH), respectively, as well as a panmalarial antigen (PMA). The patients were screened for antigenemia on days 0, 3, 7, and 14 of follow-up. On day 0, all 240 patients showed positive reactivity with both assays. Of the 229 cases with negative parasitemia on day 3, persistent antigenemia was observed in 207 (90.4%) of the cases: 188 (82.1%) for HRP2 antigen and 75 (32.8%) for PMA. There was a gradual decrease in antigenemia on follow-up to day 14; however, the drop in reactivity to PMA was less than that for HRP2 antigen. In contrast to HRP2 antigenemia, there was a significant decrease in pLDH antigenemia to 38.4% and to 14.8% (PMA) on day 3 (P < 0.03). The pLDH antigenemia level dropped further to 14.8% on day 7. There was no significant association of persistent antigenemia with gametocytemia. One case with gametocytemia was negative for both the antigens. In conclusion, the OptiMAL-IT assay is more sensitive than the ICT Malaria Pf/Pv test for monitoring therapeutic responses after antimalarial therapy since the LDH activity ceases when the malarial parasite dies.
authors.affiliation: Department of Microbiology, Faculty of Medicine, Kuwait University, P.O. Box 24923, Safat 13110, Kuwait. iqbal@hsc.kuniv.edu.kw
authors.forename: Jamshaid
authors.initials: J
authors.lastname: Iqbal
authors.forename: Ahmed
authors.initials: A
authors.lastname: Siddique
authors.forename: Mohammad
authors.initials: M
authors.lastname: Jameel
authors.forename: Persotum R
authors.initials: PR
authors.lastname: Hira
mesh_terms: D000328:Adult; D000818:Animals; D000953:Antigens, Protozoan / Q000032:analysis*; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000032:analysis*; D016778:Malaria, Falciparum / Q000175:diagnosis* / Q000276:immunology; D010963:Plasmodium falciparum / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D011506:Proteins / Q000032:analysis*; D015800:Protozoan Proteins / Q000032:analysis; D000099053:Histidine-Rich Glycoprotein
chemical_list: D000953:Antigens, Protozoan; D011506:Proteins; D015800:Protozoan Proteins; D000099053:Histidine-Rich Glycoprotein; D007770:L-Lactate Dehydrogenase