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Histidine-rich protein II (HRP2)-based malaria rapid diagnostic tests (RDTs) have shown high sensitivity and specificity for detecting Plasmodium falciparum malaria in a variety of study settings. However, RDTs are susceptible to heat and humidity and variation in individual performance, which may affect their use in field settings. We evaluated sensitivity and specificity of RDTs during routine use for malaria case management in peripheral health facilities. From December 2007 to October 2008, HRP2-based ParaHIT-f RDTs were introduced in 12 facilities without available microscopy in Rufiji District, Tanzania. Health workers received a single day of instruction on how to perform an RDT and thick blood smear. Job aids, Integrated Management of Childhood Illness guidelines, and national malaria treatment algorithms were reviewed. For quality assurance (QA), thick blood smears for reference microscopy were collected for 2 to 3 days per week from patients receiving RDTs; microscopy was not routinely performed at the health facilities. Slides were stained and read centrally within 72 hours of collection by a reference microscopist. When RDT and blood smear results were discordant, blood smears were read by additional reference microscopists blinded to earlier results. Facilities were supervised monthly by the district laboratory supervisor or a member of the study team. Ten thousand six hundred fifty (10,650) patients were tested with RDTs, and 51.5% (5,488/10,650) had a positive test result. Blood smear results were available for 3,914 patients, of whom 40.1% (1,577/3,914) were positive for P. falciparum malaria. Overall RDT sensitivity was 90.7% (range by facility 85.7–96.5%) and specificity was 73.5% (range 50.0–84.3%). Sensitivity increased with increasing parasite density. Successful implementation of RDTs was achieved in peripheral health facilities with adequate training and supervision. Quality assurance is essential to the adequate performance of any laboratory test. Centralized staining and reading of blood smears provided useful monitoring of RDT performance. However, this level of QA may not be sustainable nationwide.
Received August 2, 2009. Accepted for publication October 5, 2009.
We acknowledge the contributions of the field staff Bunzigwa Mbonde, Abdallah Bakari, and the field reference microscopist, Bakari Kissa. We also appreciate the cooperation of the Rufiji District Medical Officer (Said Mkikima) and the CHMT laboratory supervisor (Shaban Masoud). We are grateful for the collaboration of Christopher Membi and his colleagues at Muhimbili University of Allied Health Sciences who provided second and third readings of blood smears. And finally, we thank Peter McElroy, CDC PMI Resident Advisor in Tanzania, for his review of the protocol and training materials.
Financial support: This work was financially supported through the U.S. Centers for Disease Control and Prevention and the U.S. President's Malaria Initiative (PMI).
Disclaimer: The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of the Centers for Disease Control and Prevention.
Authors' addresses: Meredith L. McMorrow and S. Patrick Kachur, Malaria Branch, Centers for Disease Control and Prevention, Atlanta, GA, E-mails: mmcmorrow{at}cdc.gov and spk0{at}cdc.gov. M. Irene Masanja, Elizeus Kahigwa, and Salim M. K. Abdulla, Ifakara Health Institute, Dar es Salaam, Tanzania, E-mails: imasanja{at}ihi.or.tz, ekahigwa{at}ihi.or.tz, and sabdulla{at}ihi.or.tz.
*Address correspondence to Meredith L. McMorrow, Malaria Branch, Division of Parasitic Diseases, Centers for Disease Control and Prevention, 4770 Buford Highway, Mailstop F-22, Atlanta, GA 30341. E-mail: mmcmorrow{at}cdc.gov
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