Reliability of Rapid Diagnostic Tests to Assess Malaria Trends through a Fever Sentinel Surveillance Network in Madagascar, 2013-2015

Abstract

A fever sentinel surveillance network has been operational since 2007 in the island of Madagascar. In all 34 sentinel sites, all febrile patients are tested with malaria rapid diagnostic tests (RDTs) for pan-LDH and pfHRP2, and data are monitored for diagnostically-confirmed malaria trends. Quality assurances of on-site RDT results are managed by Institut Pasteur de Madagascar (IPM). Special attention is given to storage conditions and compliance with the manufacturer’s instructions for RDTs. Results of RDTs stored at facilities are compared with results from microscopy and also with the same RDT batch stored at 25°C and below 80% of humidity at IPM. From January 2013 to December 2015, 33/34 fever sentinel surveillance sites were visited regularly throughout the country. There were neither RDTs storage errors nor expired RDTs in stock at any sentinel sites. 81% of technicians (61/75) properly used RDTs in accordance with the manufacturer’s instructions. The results of 1,635 febrile patients were used for quality assurance. Results of on-site RDTs and those stored at IPM were 99.8% concordant. Comparison with microscopy resulted in sensitivity of 92.5%, specificity of 97.1%, positive predictive value of 86.0%, and negative predictive value of 98.5% (n=1,635). These results indicate the reliability of malaria RDT results from the fever sentinel sites. Thus, data collected at fever sentinel sites can be used by the National Malaria Control Program to better understand temporal and spatial trends in malaria transmission across Madagascar.