Microbiology Department, Vall d'Hebron University Hospital, Autonomous University of Barcelona, PROSICS Barcelona, Barcelona, Spain.
Universitat Autònoma de Barcelona (UAB), Barcelona, Spain.
Parasit Vectors. 2024 Sep 11;17(1):384. doi: 10.1186/s13071-024-06467-3.
Malaria is the parasitic disease with the highest morbimortality worldwide. The World Health Organization (WHO) estimates that there were approximately 249 million cases in 2022, of which 3.4% were in Angola. Diagnosis is based on parasite identification by microscopy examination, antigen detection, and/or molecular tests, such as polymerase chain reaction (PCR). This study aimed to evaluate the usefulness of real-time PCR as a diagnostic method for malaria in an endemic area (Cubal, Angola).
A cross-sectional study was carried out at the Hospital Nossa Senhora da Paz in Cubal, Angola, including 200 patients who consulted for febrile syndrome between May and July 2022. From each patient, a capillary blood sample was obtained by finger prick for malaria field diagnosis [microscopy and rapid diagnostic test (RDT)] and venous blood sample for real-time PCR performed at the Hospital Universitario Vall d'Hebron in Barcelona, Spain. Any participant with a positive result from at least one of these three methods was diagnosed with malaria.
Of the 200 participants included, 54% were female and the median age was 7 years. Malaria was diagnosed by at least one of the three techniques (microscopy, RDT, and/or real-time PCR) in 58% of the participants, with RDT having the highest percentage of positivity (49%), followed by real-time PCR (39.5%) and microscopy (33.5%). Of the 61 discordant samples, 4 were only positive by microscopy, 13 by real-time PCR, and 26 by RDT. Plasmodium falciparum was the most frequent species detected (90.63%), followed by P. malariae (17.19%) and P. ovale (9.38%). Coinfections were detected in ten participants (15.63%): six (60%) were caused by P. falciparum and P. malariae, three (30%) by P. falciparum and P. ovale, and one (10%) triple infection with these three species. In addition, it was observed that P. falciparum and P. malariae coinfection significantly increased the parasite density of the latter.
RDT was the technique with the highest positivity rate, followed by real-time PCR and microscopy. The results of the real-time PCR may have been underestimated due to suboptimal storage conditions during the transportation of the DNA eluates. However, real-time PCR techniques have an important role in the surveillance of circulating Plasmodium species, given the epidemiological importance of the increase in non-falciparum species in the country, and can provide an estimate of the intensity of infection.
疟疾是全球发病率和死亡率最高的寄生虫病。世界卫生组织（WHO）估计，2022 年全球约有 2.49 亿例疟疾病例，其中 3.4%在安哥拉。诊断基于显微镜检查、抗原检测和/或分子检测（如聚合酶链反应（PCR））来识别寄生虫。本研究旨在评估实时 PCR 作为一种在安哥拉（Cubal）地方性疟疾地区的诊断方法的有用性。
在安哥拉 Cubal 的 Nossa Senhora da Paz 医院进行了一项横断面研究，纳入了 2022 年 5 月至 7 月间因发热综合征就诊的 200 名患者。从每位患者的指尖采集毛细血管血样进行疟疾现场诊断[显微镜检查和快速诊断检测（RDT）]和静脉血样进行实时 PCR 检测，PCR 检测在西班牙巴塞罗那的 Vall d'Hebron 大学医院进行。至少有三种方法之一呈阳性的任何参与者都被诊断为疟疾。
在 200 名参与者中，54%为女性，中位年龄为 7 岁。至少有一种三种技术（显微镜检查、RDT 和/或实时 PCR）诊断为疟疾的参与者占 58%，RDT 的阳性率最高（49%），其次是实时 PCR（39.5%）和显微镜检查（33.5%）。在 61 份不一致的样本中，只有 4 份仅通过显微镜检查阳性，13 份通过实时 PCR 阳性，26 份通过 RDT 阳性。最常见的是检测到间日疟原虫（90.63%），其次是恶性疟原虫（17.19%）和卵形疟原虫（9.38%）。在 10 名参与者（15.63%）中检测到混合感染：6 名（60%）由间日疟原虫和恶性疟原虫引起，3 名（30%）由间日疟原虫和卵形疟原虫引起，1 名（10%）由这三种疟原虫的三重感染引起。此外，还观察到间日疟原虫和恶性疟原虫混合感染显著增加了后者的寄生虫密度。
RDT 是阳性率最高的技术，其次是实时 PCR 和显微镜检查。由于在运输 DNA 洗脱液期间储存条件不理想，实时 PCR 结果可能被低估。然而，实时 PCR 技术在监测循环疟原虫种方面具有重要作用，因为该国非恶性疟原虫种的流行率增加具有重要的流行病学意义，并且可以提供感染强度的估计。
