Estimation of Plasmodium falciparum Transmission Intensity in Lilongwe, Malawi, by Microscopy, Rapid Diagnostic Testing, and Nucleic Acid Detection.
Estimates of malaria transmission intensity (MTI) typically rely upon microscopy or rapid diagnostic testing (RDT). However, these methods are less sensitive than nucleic acid amplification techniques and may underestimate parasite prevalence. We compared microscopy, RDT, and polymerase chain reaction (PCR) for the diagnosis of Plasmodium falciparum parasitemia as part of an MTI study of 800 children and adults conducted in Lilongwe, Malawi. PCR detected more cases of parasitemia than microscopy or RDT. Age less than 5 years predicted parasitemia detected by PCR alone (adjusted odds ratio = 1.61, 95% confidence interval = 1.09-2.38, Wald P = 0.02). In addition, we identified one P. falciparum parasite with a false-negative RDT result due to a suspected deletion of the histidine-rich protein 2 (hrp2) gene and used a novel, ultrasensitive PCR assay to detect low-level parasitemia missed by traditional PCR. Molecular methods should be considered for use in future transmission studies as a supplement to RDT or microscopy.
Division of Infectious Diseases, University of North Carolina, Chapel Hill, North Carolina.
Jonathan B
JB
Parr
Department of Biology, University of North Carolina, Chapel Hill, North Carolina.
Connor
C
Belson
Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina.
Jaymin C
JC
Patel
Division of Infectious Diseases, University of North Carolina, Chapel Hill, North Carolina. University of North Carolina Project-Malawi, Lilongwe, Malawi.
Irving F
IF
Hoffman
University of North Carolina Project-Malawi, Lilongwe, Malawi.
Portia
P
Kamthunzi
University of North Carolina Project-Malawi, Lilongwe, Malawi.
Francis
F
Martinson
University of North Carolina Project-Malawi, Lilongwe, Malawi.
Gerald
G
Tegha
University of North Carolina Project-Malawi, Lilongwe, Malawi.
Isaac
I
Thengolose
London School of Hygiene and Tropical Medicine, London, United Kingdom.
Chris
C
Drakeley
Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina.
Steven R
SR
Meshnick
Department of Obstetrics and Gynecology, University of Chicago, Chicago, Illinois.
Veronica
V
Escamillia
Department of Geography, University of North Carolina, Chapel Hill, North Carolina.
Michael
M
Emch
Division of Infectious Diseases, University of North Carolina, Chapel Hill, North Carolina. Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina. Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina. jjuliano@med.unc.edu.
Jonathan J
JJ
Juliano
D000328:Adult; D002648:Child; D015331:Cohort Studies; D016054:DNA, Protozoan / Q000235:genetics*; D003955:Diagnostic Tests, Routine / Q000592:standards; D005260:Female; D006801:Humans; D015994:Incidence; D016778:Malaria, Falciparum / Q000175:diagnosis* / Q000453:epidemiology / Q000469:parasitology / Q000635:transmission*; D008295:Malawi / Q000453:epidemiology; D008297:Male; D008853:Microscopy / Q000592:standards; D010963:Plasmodium falciparum / Q000235:genetics / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000592:standards; D013997:Time Factors
D016054:DNA, Protozoan