Abstract:
INTRODUCTION
Establishing highly sensitive, affordable diagnostic test covering all
species of malaria is needed in countries like Pakistan that has significant
prevalence of this disease. Conventional tests, like microscopy are widely
used but it has certain performance related limitations. Rapid diagnostic
tests (RDTs) for plasmodium have not achieved greater sensitivity than
microscopy. Polymerase chain reaction (PCR) based methods have
shown lot of promise and these are replacing microscopy as gold
standard.
OBJECTIVES
To establish a real time PCR for malaria diagnosis and to compare its
accuracy with microscopy and an antigen based RDT.
STUDY DESIGN AND SETTING
This cross sectional analytical study was conducted at Military Hospital
and Armed forces Institute of Pathology Rawalpindi, Pakistan from
January 2011 to December 2011.
SUBJECTS
The study included 300 clinically suspected patients of malaria.
3
METHODS
Venous blood sample from each patient was tested for malarial parasite
by microscopy and antigen detection assay (OptiMal). Parasite index was
calculated. Plasmodium genus specific in house real time PCR, on all
specimens was performed targeting small subunit rRNA gene. Diagnostic
accuracy of three tests were compared and cost analysis done.
RESULTS
Out of 300 patients malaria parasite was detected in 110, 106 and 123
patients by microscopy, OptiMAL and PCR respectively. Real time PCR
was 100% sensitive while microscopy and OptiMal had sensitivity of
89.4% and 86.2% respectively. All methods were 100% specific. The cost
per test was 0.2, 2.75 and 3.30 US$ by microscopy, OptiMal and PCR
respectively, excluding the once capital cost on PCR equipment.
Conclusion:
Real time PCR for diagnosis of malaria was successfully established.
The technique is highly sensitive and affordable. It is recommended to be
incorporated in the diagnostic algorithm for malaria in Pakistan.
Key Words: Malaria, Microscopy, Rapid Diagnostic Tests (RDTs),
Polymerase Chain Reaction (PCR).
