Malaria diagnostics
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Links
- Malaria in Pregnancy
- MOT-TEST project
- National Center for Infectious Diseases - Malaria protocol
- Rapid diagnostics for malaria
- WHO - Malaria rapid diagnostic tests
Prompt and accurate diagnosis and effective treatment are the corner stones of effective malaria disease management. The clinical diagnosis is not always very easy, as the primary symptoms may resemble those of other diseases (like the flu). Therefore, laboratory diagnosis is also very important and this has up to now relied almost exclusively on microscopy.
Microscopy
This is a valuable technique when done properly, but unreliable when poorly performed. As the detection limit of microscopy is + 20 parasites/µl of blood, a substantial number of patients with low numbers of parasites may be missed using this technique. Furthermore, microscopy is time consuming and labour intensive (an experienced technician may need 30 – 60 minutes to examine a blood slide).
Alternative tests
Alternative test are becoming available that may be helpful in the diagnosis of malaria. So-called rapid diagnostic tests (RDTs) have been developed that allow for the detection of the parasites within minutes. A problem with these tests is that they may remain positive even after successful treatment for sometime. Furthermore, RDTs may also not detect low numbers of Plasmodium. Molecular tests, like quantitative nucleic acid sequence based amplification (QT-NASBA) which was developed by KIT Biomedical Research, are much more sensitive (100x more than microscopy) and allow for the quantification of parasites.
Approach
KIT Biomedical Research aims to improve the quality of the diagnosis of malaria in disease endemic and non-endemic countries. Therefore, it conducts, in collaboration with partners, research towards the development of new diagnostic tools that may eventually even be non-invasive. Although molecular tests are in principle the most sensitive methods to detect malaria, their complexity may hamper their implementation in developing countries. In order to circumvent this problem, KIT Biomedical Research invests in the development of simple molecular tests (isothermal amplification and easy read out system). By training and quality control, KIT Biomedical Research also contributes to the improvement of current malaria diagnosis that is relying on microscopy and other available methods like RDTs.
Focal points
- Development of novel sensitive diagnostic tests for malaria
- Evaluation and implementation of diagnostic procedures in disease endemic countries
- Development of molecular diagnostic tests that can be performed under field conditions
- Training in the diagnosis of malaria
- Quality control of diagnostic procedures
Example
KIT BR has conducted, in collaboration with Kenya Medical Research Institute (Nairobi, Kenya) and the Aga Khan Hospital (Dar es Salaam, Tanzania), a comparative study to assess the agreement of different diagnostic methods for the diagnosis and confirmation of the clinical suspicion of Plasmodium infection in children in Tanzania and Kenya.
Finger prick blood was collected from a total 338 children with the clinical suspicion of uncomplicated malaria in health clinics in Tanzania and Kenya. The presence of Plasmodium parasites was assessed with microscopy, rapid diagnostic tests (RDT’s) and the molecular assays Quantitative-Nucleic Acid Sequence Based Amplification (QT-NASBA) and PCR. The main conclusion from this study was that malaria might be overestimated if the diagnosis is based solely on clinical signs. Therefore, laboratory confirmation is essential.
Microscopy is a reliable method in rural areas where malaria is often seen, but RDT’s offer a good alternative with the advantage that it is an easy and rapid method. Molecular tests are more sensitive however difficult to implement in rural areas. In areas with lower incidence, molecular tests detect a significantly higher number of Plasmodium infections than RDT’s or microscopy. Although implementation of molecular tools in the detection of malaria parasites can be difficult, the prospect of development of an easy and cheap detection system makes it promising tools for the near future.
Projects
- Chloroquine and sulphadoxine/Pyrimethamine assessment outcome in the treatment of acute uncomplicated Plasmodium falciparum in Gezira-Sudan.
- Prevention, detection, monitoring and epidemiology of drug resistant P.falciparum, P.vivax and mixed infections in Vietnam
- PhD study in the field of malaria
- Novel magneto-optical Biosensors malaria diagnostics (MOT-Test)
Publications
- Schallig, H.D. - Usefulness of quantitative nucleic Acid sequence-based amplification for diagnosis of malaria in an academic hospital setting.
- Schneider, P. - Real-Time Nucleic Acid Sequence-Based Amplification Is More Convenient than Real-Time PCR for Quantification of Plasmodium falciparum
- Mens, P.F. - Molecular biology, the best alternative for the diagnosis of malaria to microscopy? A comparison between microscopy, antigen detection and molecular tests in rural Kenya and urban Tanzania.
- Schallig, H.D.F.H. - Molecular Tools for the Diagnosis of Parasitic Infections: Do We Really Need Them?
- Mens, P.F. - Detection and identification of human Plasmodium species with real-time quantitative nucleic acid sequence-based amplification
- Newman, D.M. - A magneto-optic route towards the in-vivo diagnosis of malaria:preliminary results and pre-clinical trial data.
- Mens, P.F. - Molecular diagnosis of malaria in the field: development of a novel 1-step nucleic acid lateral flow immunoassay for the detection of all 4 human Plasmodium spp. and its evaluation in Mbita, Kenya