Are We Now Well Prepared for Another Major Visceral Leishmaniasis Epidemic in Sudan?

Abstract

To minimize the chance for future visceral leishmaniasis (VL) epidemics such as the 1988–1991 epidemic in Sudan, several VL detection tools have been introduced. There are many VL diagnostics with excellent sensitivities, specificities, and ease of use reported. However, additional test characteristics should be considered for use in the detection of future VL epidemics. The potential for local production or uninterrupted availability, low production and application costs, and stability at ≥45°C are of the utmost importance. Of the antibody-, antigen-, or DNA-based methods introduced, only a liquid direct agglutination test (LQ-DAT) remains in routine use. The LQ-DAT test may be the ideal diagnostic for detection of VL epidemics due to its low cost ($0.50/patient), stability under frequent and long-duration electric failures, and high level of reproducibility. The improved reliability for VL detection achieved locally through incorporating autochthonous L. donovani strains in antigen processing and precluding toxicants in test execution provides optimal sensitivity and safety for routine and mass application.

Haematological malignancies as disorders negatively impacting specificities of the direct agglutination and rapid rK39 strip tests as reference diagnostics for visceral leishmanisis

“…No the current protocol for VL management, patients with typical disease symptoms and positive DAT and or rK39 outcome should be considered for treatment [1,2,[10][11][12][13]. In this study group of HM patients, symptoms highly similar to VL were recorded in 50-70 % of them.…”

“…Because of their invasive nature, lower sensitivity and the adequate expertise required to demonstrate the causative amastigotes, use of parasitological methods is rendered less important in routine and mass screening of VL. Following the current protocol for VL management, patients with typical disease symptoms and positive DAT and or rK39 outcome should be considered for treatment [1, 2, 10–13]. In this study group of HM patients, symptoms highly similar to VL were recorded in 50–70 % of them.…”

“…Based on merits here and previously enumerated included high diagnostic reliability, antigen stability under adverse conditions and the required safety for test execution, the new SDS-DAT is expected to comply with most of the criteria needed for an appropriate and safe management of VL [13,15].…”

Modifications in a Reference Freeze-Dried Direct Agglutination Test to Improve Visceral Leishmaniasis Detection

“…1 However, in the course of laboratory and field application during the past 25-28 years in Sudan, both tests revealed several drawbacks that negatively impacted their application on a routine basis. [2][3][4][5] The limited shelf-life (±30 days) of the rK39 at ambient temperatures and high application cost of the freezedried direct agglutination test (FD-DAT) (±$32.0/vial vs average income in Sudan of $70.0 a month) were the most important shortcomings. 2 The strict temperature range for the test kit (5-35°C) limited the use of the FD-DAT in Sudan, particularly during the hot season (April-October) when the mid-day temperatures of ±40°C are considered normal almost throughout the whole country.…”