Circulating antigen detection for diagnosis of schistosomiasis
The parasitology department of the LUMC is at the forefront in the development and implementation of immunodiagnostic assays based on the detection of Schistosoma circulating antigens, in particular CCA (Circulating Cathodic Antigen) and CAA (Circulating Anodic Antigen).
This line of research was initiated in the ’70 by prof. Deelder and colleagues and over the years highly sensitive and specific monoclonal antibody-based ELISA’s have been developed for improved diagnosis of active schistosomiasis by quantitative detection of CCA and CAA in serum or urine. These widely used and highly optimized ELISA’s can be used to diagnose active Schistosoma infections by all human as well as veterinary species (S. mansoni, S. haematobium, S. japonicum, S. intercalatum, S. mekongi, S. matthei, S. bovis, Heterobilharzia amercana, S. spindale, S. nasale, a.o.).
Since early 2000, the ELISA’s have been further refined and transformed into monoclonal antibody-based lateral flow (LF) assays which allow application in low-resource settings.
The assay for the detection of CCA in urine has been transformed by Dr. Govert van Dam and colleagues into a point of care (POC) test by which CCA could be detected in a single drop of urine in a highly sensitive and specific way. This POC-CCA strip test is now available from Rapid Medical Diagnostics in South-Africa (www.rapid-diagnostics.com). The POC-CCA is widely used as a rapid diagnostic test for mapping and monitoring of intestinal schistosomiasis (S. mansoni) in Africa by various control programmes and is increasingly used for the diagnosis of individual patients with active S. mansoni infection.
The assay for the detection of CAA has been further developed in collaboration with Dr. Paul Corstjens and colleagues from the Department of Molecular Cell Biology into a highly sensitive and specific strip assay utilizing UpConverting Phosphor (UCP) as a detection label. This ultrasensitive lateral flow assay allows diagnosis of very low worm infections based on CAA detection in serum or urine. The UCP-LF CAA assay is currently used in many immunoepidemiological studies in endemic areas, as well as experimental infections in animals and controlled human infection models.
Molecular diagnosis of parasitic infection via PCRs
The parasitology department of the LUMC has been one of the first research groups active in the development, improvement and implementation of (multiplex) real-time PCRs for the diagnosis of parasitic infections based on the detection of specific DNA in clinical samples.
Over the years our (multiplex) real-time PCRs have been employed to map the prevalence and distribution of parasitic infections in both the Netherlands and several low income countries.
The simple procedure for faecal sample collection without the need for a cold chain and the high throughput potential of the protocol provide additional value for epidemiological research. When mixed with ethanol, stool sampling can take place in rural and remote areas in the tropics without the need of cool storage or transportation.
The focus of our research has been on the detection of parasite specific DNA in faecal samples. All our tests are performed in a real-time multiplex format, including PhHV target as an internal control. Targets which are in use include (a.o.) the following helminths: Ascaris lumbricoides, Necator americanus, Ancylostoma duodenale, Strongyloides stercoralis, Trichuris trichiura, Schistosoma spp., Taenia saginata, Taenia solium, Hymenolepis nana; and (a.o.) the following protozoa: Entamoeba histolytica, Giardia lamblia, Cryptosporidium spp, Dientamoeba fragilis, Cyclospora cayeteanensis, Isospora belli, Enterocytozoon bieneusi and Encephalitozoon spp..
Besides stool samples, parasite specific DNA can also be detected in other clinical material. For example real-time PCR can be performed on tissue samples (Leishmania, Toxoplasma), blood samples (Plasmodium species) , urine samples (Schistosoma) and tissue samples (Leishmania, Schistosoma).
Quality assessment for the diagnosis of parasitic infections
The Leiden Clinical Parasitology Group is very active in the area of improving quality in the diagnosis of parasitic infections. Besides providing post-graduate teaching, both Dr. Lisette van Lieshout and Eric Brienen actively participate in the parasitology section of the national Dutch external quality assessment scheme (SKML)