CHANGING PATTERNS OF PLASMODIUM BLOOD-STAGE INFECTIONS IN THE WOSERA REGION OF PAPUA NEW GUINEA MONITORED BY LIGHT MICROSCOPY AND HIGH THROUGHPUT PCR DIAGNOSIS

LAURIN J. KASEHAGEN Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH; Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea

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IVO MUELLER Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH; Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea

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DAVID T. McNAMARA Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH; Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea

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MOSES J. BOCKARIE Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH; Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea

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BENSON KINIBORO Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH; Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea

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LAWRENCE RARE Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH; Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea

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KERRY LORRY Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH; Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea

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WILL KASTENS Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH; Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea

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JOHN C. REEDER Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH; Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea

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JAMES W. KAZURA Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH; Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea

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PETER A. ZIMMERMAN Center for Global Health & Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH; Papua New Guinea Institute of Medical Research, Goroka, Papua New Guinea

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In Papua New Guinea (PNG), complex patterns of malaria commonly include single and mixed infections of Plasmodium falciparum, P. vivax, P. malariae, and P. ovale. Here, we assess recent epidemiologic characteristics of Plasmodium blood-stage infections in the Wosera region through four cross-sectional surveys (August 2001 to June 2003). Whereas previous studies performed here have relied on blood smear/light microscopy (LM) for diagnosing Plasmodium species infections, we introduce a newly developed, post-polymerase chain reaction (PCR), semi-quantitative, ligase detection reaction-fluorescent microsphere assay (LDR-FMA). A direct comparison of the two methods for > 1,100 samples showed that diagnosis was concordant for > 80% of the analyses performed for P. falciparum (PF), P. vivax (PV), and P. malariae (PM). Greater sensitivity of the LDR-FMA accounted for 75% of the discordance between diagnoses. Based on LM, the prevalence of blood-stage PF, PV, and PM infections was found to be markedly reduced compared with an early 1990s survey. In addition, there were significant shifts in age distribution of infections, with PV becoming the most common parasite in children < 4 years of age. Consistent with previous studies, prevalence of all Plasmodium species infections increased significantly in samples analyzed by the PCR-based LDR-FMA. This increase was most pronounced for PM, PO, and mixed infections and in adolescent (10–19 years) and adult age groups, suggesting that LM may lead to under-reported prevalence of less common Plasmodium species, infection complexity, and a skewed distribution of infections towards younger age groups. This study shows that the application of LDR-FMA diagnosis in large epidemiologic studies or malaria control interventions is feasible and may contribute novel insights regarding the epidemiology of malaria.

Author Notes

Reprint requests: P. A. Zimmerman, Center for Global Health and Diseases, School of Medicine, Case Western Reserve University, Wolstein Research Building 4-125, 2103 Cornell Road, Cleveland, OH 44106-7286, Telephone: 216-368-0508; Fax: 216-368-4825; E-mail: paz@case.edu.
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