Diagnosis of Malaria Infection Using Non Radioactive Malaria Diagnostic System (NOMADS)

Background: Malaria remains one of the leading causes of morbidity and mortality. A definitive and early diagnosis remains the biggest challenge world-wide. Light microscopy of blood smears has been the gold standard in diagnosis of malaria for decades. This routine microscopic diagnosis is often unreliable and may not be available at many peripheral health centers. Hence newer diagnostic techniques have been developed based on antigen detection.

Method: Microscopy and Non-radioactive Malaria Detection System (NOMADS) to diagnose falciparum malaria were compared. Specificity and sensitivity of this technique and applicability of the kit for rapid and reliable malaria diagnosis were evaluated. 2579 samples of blood were processed. Both thick and thin blood smear examination and NOMADS was carried out on each of them. All smear positive samples and highly suspicious clinical cases were also subjected to detection of HRP-2 antigen by ICT Malaria Pf test.

Results: The detection rate for malaria on smear examination (both vivax and falciparum) was highest at Dimapur (7.41%), followed by Tezpur (7.13%), Kolkata (7%), Guwahati (6%) and Changsari (3.6%). All centers had greater incidence of falciparum compared to vivax except Kolkata where only vivax was detected. The sensitivity of NOMADS was 0%, 4.8%, 13.5%, 42.9% and 52.8% at Kolkata, Tezpur, Guwahati, Changsari and Dimapur respectively. The specificity of the test ranged between 91.8% at Changsari to 95.9% at Dimapur. The specificity at Tezpur, Kolkata and Guwahati was 92.3%, 94% and 95.3% respectively.

Conclusion: The study revealed that the test kit developed needs to be standardised as regards calculation of cut off values for each of the test runs and reproductibility of optical density readings. Immuno-Chromatography Test (ICT) is helpful in early diagnosis, management and follow-up of cases of malignant malaria.