Sains Malaysiana 37(2):  137-141(2008)

Detection of Malaria Parasites in Sabah by Nested Polymerase

Chain Reaction: A Focus of Naturally Acquired

Plasmodium knowlesi Infections

(Pengesanan Parasit Malaria di Sabah Menggunakan Tindakbalas

Berantai Polimerase: Tumpuan kepada Jangkitan Plasmodium

knowlesi Perolehan Semulajadi)

Fread Anderios, Zulaikah Mohamed

Seksyen Penyakit, Makmal Kesihatan Awam Kota Kinabalu

Jalan Kolam, Bukit Padang, 88850 Kota Kinabalu,

Sabah, Malaysia

Shanmuga Ratnam, Mohd Yusof Ibrahim  & Tajul Ariffin Mohd Awang

Jabatan Kesihatan Awam Negeri Sabah (Kesihatan Awam)

Tingkat 1, Rumah Persekutuan, Jalan Mat Salleh

88590 Kota Kinabalu, Sabah, Malaysia

Received: 4 July 2007 / Accepted: 6 September 2007

ABSTRACT

The emergence of primate malaria known as Plasmodium knowlesi in humans, which is always misdiagnosed by microscopy as P. malariae, has contribute to the needs of nucleic acid based technology to be applied in detection and differentiation of malaria parasites. The target DNA sequence of the 18SrRNA gene was amplified by a nested PCR assay for detection and identification of Plasmodium species in 31 Giemsa-stained blood smears examined as P. malariae. The assay demonstrated three samples identified as positive to genus-specific primers but negative to all species-specific primers. Three cases of misdiagnosed species were detected. The samples were diagnosed as P. malariae microscopically, but detected as P. falciparum by PCR assay. Twenty five out of 31 samples were detected as P. knowlesi. None of the samples diagnosed microscopically as P. malariae were identified as P. malariae with the nested PCR assay. Over 80.6% of all malaria cases in this study showed naturally acquired P. knowlesi infections.

Keywords: polymerase chain reaction; Plasmodium knowlesi; blood smear; malaria parasites

ABSTRAK

Kemunculan jangkitan malaria primat iaitu P. knowlesi pada manusia dan seringkali disalahdiagnos secara mikroskopik sebagai P. malariae, telah menyumbang kepada penggunaan teknologi berasaskan asid nukleik untuk pengesanan parasit malaria. Jujukan DNA bagi gen 18SrRNA diamplifikasi dengan menggunakan teknik tindakbalas polimerase berantai “nested” untuk mengesan dan mengenalpasti spesies malaria ke atas 31 calitan darah bercelup Giemsa yang didiagnos secara mikroskopik sebagai P. malariae. Keputusan asai menunjukkan tiga sampel dikenalpasti positif bagi primer genus-spesifik tetapi negatif kepada kesemua primer spesies-spesifik. Tiga kes kesilapan diagnos spesies telah dikesan. Sampel tersebut didiagnosa secara mikroskopik sebagai P. malariae tetapi dikenalpasti sebagai P. falciparum bagi asai tindakbalas berantai polimerase. Sejumlah 25 daripada 31 sampel  menunjukkan positif bagi P. knowlesi. Asai tindakbalas polimerase berantai menunjukkan semua sampel yang didiagnosa secara mikroskopik sebagai P. malariae adalah bukan jangkitan parasit P. malariae. Lebih 80.6% daripada kes malaria yang dikaji menunjukkan jangkitan P. knowlesi perolehan semulajadi.

Kata kunci:  tindak balas polimerase berantai; Plasmodium knowlesi; calitan darah; parasit malaria

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