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Molecular investigation of mixed malaria infections in southwest Saudi Arabia.

Bin Dajem SM - Saudi Med J (2015)

Bottom Line: The results obtained by the 2 methods were compared.Mixed malaria infections are currently overlooked when using microscopy.The PCR assays are essential complementary techniques that should be used with microscopic examination of blood smears.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Faculty of Science, King Khalid University, PO Box 9004, Abha, Kingdom of Saudi Arabia. Tel. +966 (17) 544804040. Fax. +966 (17) 2417851. E-mail. saad1426@gmail.com.

ABSTRACT

Objective: To investigate the incidence of mixed-species (MS) malaria infection, and compare the results with microscopically confirmed cases of malaria.

Methods: During 2010, blood spots collected from 371 clinically suspected cases of malaria were microscopically examined in a cross-sectional study. The DNA was extracted from the samples, and a nested polymerase chain reaction (PCR) was performed. The results obtained by the 2 methods were compared.

Results: From the microscopic analysis it was determined that 369 samples (99.5%) were positive for Plasmodium falciparum (P. falciparum) and 2 were Plasmodium vivax (P. vivax) mono-infections. There were no mixed malaria infections. The PCR analysis, however, showed that in 7 cases (1.9%) the infection was caused by MS malaria comprising of P. falciparum and P. vivax, 2 of these representing the cases that were microscopically diagnosed as P. vivax mono-infections. All cases were negative for Plasmodium malariae, Plasmodium ovale, and Plasmodium knowlesi.

Conclusion: Mixed malaria infections are currently overlooked when using microscopy. The PCR assays are essential complementary techniques that should be used with microscopic examination of blood smears.

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Related in: MedlinePlus

Second round of nested PCR to detect Plasmodium falciparum, indicating positivity at the expected size (205 bp). Lane 1- 50-bp DNA Step Ladder (Promega), lane 2 - negative control, lane 3 - positive control, lanes 4-9 - samples, lane 10 - control reagent; lane 11 - Gel Pilot Wide Range Ladder (100) (Qiagen).
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Figure 1: Second round of nested PCR to detect Plasmodium falciparum, indicating positivity at the expected size (205 bp). Lane 1- 50-bp DNA Step Ladder (Promega), lane 2 - negative control, lane 3 - positive control, lanes 4-9 - samples, lane 10 - control reagent; lane 11 - Gel Pilot Wide Range Ladder (100) (Qiagen).

Mentions: Microscopically, all specimens were positive for P. falciparum, except 2 that were diagnosed as P. vivax. When screened by molecular techniques using 18S rRNA-based nested PCR, 371 (100%) tested positive for P. falciparum (Figure 1), and 7 of them (1.9%) also tested positive for P. vivax (Figure 2), meaning that each case of P. vivax has P. falciparum parasites co-existing. This result contrasts with the health statistical report in Saudi Arabia in 2010,3 which showed that there were no cases of mixed malaria infection. Additionally, multiplex PCR assays proved that all samples were negative for P. malariae, P. ovale, and P. knowlesi.


Molecular investigation of mixed malaria infections in southwest Saudi Arabia.

Bin Dajem SM - Saudi Med J (2015)

Second round of nested PCR to detect Plasmodium falciparum, indicating positivity at the expected size (205 bp). Lane 1- 50-bp DNA Step Ladder (Promega), lane 2 - negative control, lane 3 - positive control, lanes 4-9 - samples, lane 10 - control reagent; lane 11 - Gel Pilot Wide Range Ladder (100) (Qiagen).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4375708&req=5

Figure 1: Second round of nested PCR to detect Plasmodium falciparum, indicating positivity at the expected size (205 bp). Lane 1- 50-bp DNA Step Ladder (Promega), lane 2 - negative control, lane 3 - positive control, lanes 4-9 - samples, lane 10 - control reagent; lane 11 - Gel Pilot Wide Range Ladder (100) (Qiagen).
Mentions: Microscopically, all specimens were positive for P. falciparum, except 2 that were diagnosed as P. vivax. When screened by molecular techniques using 18S rRNA-based nested PCR, 371 (100%) tested positive for P. falciparum (Figure 1), and 7 of them (1.9%) also tested positive for P. vivax (Figure 2), meaning that each case of P. vivax has P. falciparum parasites co-existing. This result contrasts with the health statistical report in Saudi Arabia in 2010,3 which showed that there were no cases of mixed malaria infection. Additionally, multiplex PCR assays proved that all samples were negative for P. malariae, P. ovale, and P. knowlesi.

Bottom Line: The results obtained by the 2 methods were compared.Mixed malaria infections are currently overlooked when using microscopy.The PCR assays are essential complementary techniques that should be used with microscopic examination of blood smears.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Faculty of Science, King Khalid University, PO Box 9004, Abha, Kingdom of Saudi Arabia. Tel. +966 (17) 544804040. Fax. +966 (17) 2417851. E-mail. saad1426@gmail.com.

ABSTRACT

Objective: To investigate the incidence of mixed-species (MS) malaria infection, and compare the results with microscopically confirmed cases of malaria.

Methods: During 2010, blood spots collected from 371 clinically suspected cases of malaria were microscopically examined in a cross-sectional study. The DNA was extracted from the samples, and a nested polymerase chain reaction (PCR) was performed. The results obtained by the 2 methods were compared.

Results: From the microscopic analysis it was determined that 369 samples (99.5%) were positive for Plasmodium falciparum (P. falciparum) and 2 were Plasmodium vivax (P. vivax) mono-infections. There were no mixed malaria infections. The PCR analysis, however, showed that in 7 cases (1.9%) the infection was caused by MS malaria comprising of P. falciparum and P. vivax, 2 of these representing the cases that were microscopically diagnosed as P. vivax mono-infections. All cases were negative for Plasmodium malariae, Plasmodium ovale, and Plasmodium knowlesi.

Conclusion: Mixed malaria infections are currently overlooked when using microscopy. The PCR assays are essential complementary techniques that should be used with microscopic examination of blood smears.

Show MeSH
Related in: MedlinePlus