Tjitra E, Suprianto S, McBroom J, Currie B J, Anstey N M
Communicable Diseases Research Centre, National Institute of Health Research and Development, Jakarta, Indonesia.
J Clin Microbiol. 2001 Mar;39(3):1025-31. doi: 10.1128/JCM.39.3.1025-1031.2001.
A problem with rapid Plasmodium falciparum-specific antigen histidine-rich protein 2 (HRP2) detection tests for malaria is the persistence of antigen in blood after the disappearance of asexual-stage parasitemia and clinical symptoms, resulting in false-positive (FP) test results following treatment. The ICT P.f/P.v immunochromatographic test detects both HRP2 and a panmalarial antigen (PMA) found in both P. falciparum and Plasmodium vivax. To examine posttreatment antigen persistence with this test and whether persistent sexual-stage forms (gametocytes) are a cause of FP tests after treatment, we compared serial antigen test results with microscopy results from patients symptomatic with P. falciparum malaria in Indonesia for 28 days following treatment with chloroquine (CQ; n = 66), sulfadoxine-pyrimethamine (SP; n = 36), and artesunate plus sulfadoxine-pyrimethamine (ART + SP; n = 15). Persistent FP antigenemia following SP treatment occurred in 29% (HRP2) and 42% (PMA) of the patients on day 7 and in 10% (HRP2) and 23% (PMA) on day 14. The high rates of persistent HRP2 and PMA antigenemia following CQ and SP treatment were strongly associated with the presence of gametocytemia, with the proportion with gametocytes on day 7 posttreatment being significantly greater in those with FP results than in those with true-negative PMA and HRP2 results. Gametocyte frequency on day 14 post-SP treatment was also greater in those with FP PMA results. Following SP treatment, PMA persisted longer than HRP2, giving an FP diagnosis of P. vivax in up to 16% of patients on day 14, with all FP P. vivax diagnoses having gametocytemia. In contrast, PMA was rapidly cleared following ART + SP treatment in association with rapid clearance of gametocytemia. Gametocytes appear to be an important cause of persistent posttreatment panmalarial antigenemia in areas of endemicity and may also contribute in part to persistent HRP2 antigenemia following treatment.
疟疾快速检测恶性疟原虫特异性富含组氨酸蛋白2（HRP2）的检测方法存在一个问题，即无性期疟原虫血症和临床症状消失后，血液中的抗原仍会持续存在，导致治疗后出现假阳性（FP）检测结果。ICT P.f/P.v免疫层析检测法可同时检测HRP2和在恶性疟原虫和间日疟原虫中均存在的一种泛疟原虫抗原（PMA）。为了研究使用该检测方法治疗后抗原的持续存在情况，以及持续性的有性期疟原虫形态（配子体）是否是治疗后出现FP检测结果的原因，我们将印度尼西亚恶性疟原虫疟疾患者治疗后28天内的系列抗原检测结果与显微镜检查结果进行了比较，这些患者分别接受氯喹（CQ；n = 66）、磺胺多辛-乙胺嘧啶（SP；n = 36）以及青蒿琥酯加磺胺多辛-乙胺嘧啶（ART + SP；n = 15）治疗。接受SP治疗后，第7天有29%（HRP2）和42%（PMA）的患者出现持续性FP抗原血症，第14天分别为10%（HRP2）和23%（PMA）。CQ和SP治疗后HRP2和PMA抗原血症的高持续率与配子体血症的存在密切相关，治疗后第7天出现FP结果的患者中配子体的比例显著高于PMA和HRP2结果为真阴性的患者。接受SP治疗后第14天，出现FP PMA结果的患者中配子体频率也更高。接受SP治疗后，PMA持续的时间比HRP2长，在第14天高达16%的患者中出现间日疟原虫的FP诊断，所有间日疟原虫FP诊断的患者均有配子体血症。相比之下，ART + SP治疗后PMA迅速清除，同时配子体血症也迅速清除。在疟疾流行地区，配子体似乎是治疗后持续性泛疟原虫抗原血症的一个重要原因，也可能部分导致治疗后HRP2抗原血症的持续存在。
