How well did rapid tests detect visceral leishmaniasis in southern Iran?

Details

To evaluate five alternative blood-based diagnostic tests, researchers compared serum samples from 100 confirmed visceral leishmaniasis (VL) patients, 197 healthy people from an endemic area, and 58 non-VL patients living in southern Iran. VL patients were defined as people with a positive immunofluorescent antibody test (IFAT), clinical signs and symptoms, and an appropriate response to treatment.

The tests evaluated were two direct agglutination tests, DAT-ITM (Institute of Tropical Medicine, Antwerp, Belgium) and DAT-KIT (Royal Tropical Institute, Amsterdam, The Netherlands), and three rapid diagnostic tests (RDTs): Kalazar Detect (InBios International Inc., USA), IT Leish (Bio-Rad, catalog 710124), and Leishmania test (Cypress Diagnostic Company, Belgium).

DAT-ITM and DAT-KIT had low sensitivities of 56% and 59%, respectively, while their specificities were considered acceptable at 98% and 93%, respectively. The observed sensitivities and specificities of the RDTs were higher: 71% and 99% for Kalazar Detect, 81% and 99% for IT Leish, and 70% and 98% for Leishmania test. Even at the maximum sensitivity of 81%, the RDTs missed almost one-fifth of VL patients who were positive by IFAT.

The researchers concluded that RDT performance in VL patients in southern Iran was inadequate and needed improvement, although the tests could still help diagnose and screen for the disease in the region because of their high specificity and speed.