Performance evaluation of nine reference centers for effective surveillance ofLeishmania-infected Phlebotomine sand flies and basis for technical recommendations
Authors: Prudhomme Jorian , Delabarre Aymeric , Alten Bulent , Berberoglu Umut , Berriatua Eduardo , Bongiorno Gioia , Cristovao José Manuel , Davidovich-Cohen Maya , Di Muccio Trentina , Kasap Ozge Erisoz , Fiorentino Eleonora , Kirstein Oscar D. , Kniha Edwin , Maia Carla , Mungan Mesut , Muñoz-Hernández Clara , Nalçaci Muhammed , Kaskan Gizem Oguz , Ozbel Yusuf , Toz Seray Ozensoy , Parreira Ricardo , Platzgummer Katharina , Polat Ceylan , Risueño José , Studentsky Liora , Varol Gamze , Walochnik Julia , Yetişmiş Kardelen , Robert-Gangneux Florence 
Published: September 2024

Background

Leishmaniasis, caused byLeishmaniaprotozoan parasites transmitted by Phlebotomine sand flies, is a significant public health concern in the Mediterranean basin. Effective monitoring ofLeishmania-infected sand flies requires standardized tools for comparing their distribution and infection prevalence. Consistent quantitative PCR (qPCR) conditions and efficient DNA extraction protocols are crucial for reliable results over time and across regions. However, there is currently a lack of technical recommendations forLeishmaniaDNA detection, which needs to be addressed. This study aimed to compare various DNA extraction protocols and conduct a qPCR based External Quality Assessment (EQA) through a multicenter study involving nine reference laboratories.

Methodology/Principal findings

EQA samples were prepared usingLeishmania infantumandL. majorstrains, at different concentration from 101to 104parasites/mL and distributed to participating centers. All centers, except one, detected allLeishmaniaconcentrations, demonstrating diagnostic proficiency. The ability to detect low concentrations highlighted the robustness of the qPCR assay used, although Cq value variations suggested differences in sensitivity due to technical capabilities and/or extraction kit performances.

Reported comparative analysis of seven DNA extraction methods identified the EZ1 DSP Virus® Kit and QIAamp® DNA mini-kit as the most efficient, supporting their use for standardized protocols. The study also evaluated the impact of lyophilization and shipment conditions, finding no compromise inLeishmaniadetection, despite slight Cq value variations. In addition to EQA samples, experimentally infected sand fly have been included to mimic sample field condition. All centers detected positive samples, with variable Cq values, reflecting differences in individual infection load.

Conclusion and significance

Overall, the study underscores the importance of standardized protocols and continuous quality assurance to maintain high diagnostic validity, crucial for effective surveillance of leishmaniasis, especially in field settings with low infection densities. Continuous training and calibration are essential to ensure uniform diagnostic performance across laboratories, enhancing epidemiological surveillance and disease control strategies.

Author Summary

Leishmaniasis is a disease caused byLeishmaniaparasites, transmitted by sand flies, and poses a major health risk in the Mediterranean region. Monitoring the spread of nfected sand flies is crucial for controlling the disease. This study focused on improving the methods used to detectLeishmaniain sand flies by comparing different DNA extraction techniques and assessing the accuracy of these methods across nine reference laboratories. All centers, except one, efficiently detected allLeishmaniaconcentrations, demonstrating proficiency in diagnostic protocols. Moreover, we found that two specific DNA extraction kits, the EZ1 DSP Virus® Kit and QIAamp® DNA mini-kit, were the most effective forLeishmaniadetection. We also tested how sample preparation and shipping conditions affected the results, ensuring that our methods would work in real-world settings. Even under these conditions, the detection methods proved reliable. This work helps to standardize the detection ofLeishmania, making surveillance more accurate and consistent. Continuous training and calibration are essential to ensure uniform diagnostic performance across laboratories, enhancing epidemiological surveillance and disease control strategies