Humanitarian Entrant Health Service (Migrant Health) patients from areas where malaria is present are screened prior to entering Australia, and are rescreened approximately one month after arrival. Current practice in our laboratory is to use a malarial antigen screening kit (BinaxNOW RDT) and to examine thick and thin blood films for the presence of malarial parasites. We evaluated a new rapid detection test (illumigene Malaria®) as an alternative to the current screening protocol.
The specificity and sensitivity of this technique was assessed by comparing known positive and negative samples and sample dilutions to achieve a level of parasitaemia at the lower level of detection of our current morphological detection methodology (approximately three parasites per thick film or 2 parasites per uL).
21 samples (P. falciparum n=13, P. vivax n=5 and P. ovale n=3 which had positive results by microscopy were chosen for the evaluation. 58 samples from malarial requests were run in parallel with the illumigene method. All of these were negative by thick and thin film examination, BinaxNow malaria kit, and by the illumigene method.
The correlation with blood films was 100% for 21 positive samples including three species of malaria and all negative samples.
Samples at the threshold of detection by microscopy with less than three parasites per thick film (2 parasites/uL) were identified by the illumigene platform. Dilutions of samples to less than 2 parasites/uL were also positive by the illumigene method.
The illumigene method has been demonstrated to be at least as sensitive as the currently employed morphological screening method and would be a cost efficient methodology to use as replacement for the current screening platform. Our costing estimate including labour, material costs and instrument depreciation is $47.86 (current protocol) versus $34.38 (illumigene testing).
This new test is less labour intensive to perform and is cost effective because its use obviates the need for labour intensive manual microscopy in cases shown to be negative.