The rapid and accurate diagnosis of malaria presents challenge in most countries where it is endemic. The conventional diagnostic method for malaria is microscopic examination of thin and/or thick blood smears. Although effective and inexpensive, this method is laborious and time-consuming, and its sensitivity is poor in cases of low parasitaemia. The assays employ lateral flow immunochromatographic method using antibody specific to malaria antigens are rapid but could not identify all human malaria species. Thus Nested PCR and real-time quantitative PCR have been developed. They demonstrate higher sensitivity and specificity than microscopic examination. However, their implementation in field clinics has been impeded by the requirement for expensive equipment. The introduction of loop-mediated isothermal amplification (LAMP) has allowed the development of rapid, sensitive, specific, and simple methods for the diagnosis of parasitic diseases. LAMP reaction is performed under one constant temperature and can be done in a water bath. Amplification and detection of genes can be completed in short time and amplified product can be visualized. LAMP assay for malaria diagnosis has been established in our laboratory with sensitivity and specificity comparable to nested PCR.
The aims of this study are to (1) optimize the LAMP assay condition and (2) evaluate LAMP assay for malaria diagnosis at field clinics. Optimization of LAMP will be done at Mahidol laboratory and then at Maesod malaria clinic in Tak province, Thailand. Evaluation of LAMP for malaria diagnosis will be carried out at the field clinics in Tak and Kanchanaburi provinces, Thailand. Blood samples will be collected from patients by finger pricking and will be used for 3 assays, (1) blood smear will be prepared for microscopic examination as a routine diagnosis, (2) blood will be tested by ICT malaria rapid diagnostic kit which detects P. falciparum-HRP2 antigens and panmalarial antigens expressed in P. falciparum and others, and (3) blood will be used for LAMP assay. Sensitivity, specificity and feasibility of LAMP for malaria diagnosis will be compared with microscopic examination and the ICT rapid diagnostic kit. Early diagnosis and appropriate treatment is a basic tenet of malaria policy to reduce morbidity and mortality in patients. Thus rapid and simple malaria diagnosis is needed in remote areas where sustainability of a microscopy service is limited by the capital investment, maintenance and the skill level required.
| Sattabongkot, Jetsumon; Tsuboi, Takafumi; Han, Eun-Taek et al. (2014) Loop-mediated isothermal amplification assay for rapid diagnosis of malaria infections in an area of endemicity in Thailand. J Clin Microbiol 52:1471-7 |
