Detection of malaria in blood bank

Detection of Malaria Infection in Blood Transfusion

  • Study aimed to compare the effectiveness of different diagnostic methods for detecting malaria in blood transfusions.

  • Methods compared: real-time polymerase chain reaction (real-time PCR), rapid diagnostic tests (RDT), and light microscopy.

Background

  • Malaria is a significant transfusion-transmitted disease worldwide.

  • Plasmodium falciparum can cause rapidly fatal malaria infections through blood transfusions.

  • The study involved collecting blood samples from both endemic and non-endemic regions in Iran (Bandar Abbas and Tehran).

Study Methods

  • Sample Collection: Two sets of 50 blood samples collected:

    • Bandar Abbas (Endemic): Located in a malaria-endemic area.

    • Tehran (Non-Endemic): Capital city with a low risk of malaria.

  • Diagnostic Techniques Used:

    • Light microscopy (thin and thick smears)

    • Rapid diagnostic tests (RDTs)

    • Real-time PCR for species confirmation

Results

  • Results from light microscopy and RDTs were negative for all samples.

  • Real-time PCR identified two positive cases from the endemic area, demonstrating higher sensitivity in detection.

  • Significance of Findings: Real-time PCR proved to be a more reliable method for confirming malaria infections in blood donations.

Malaria Persistence and Risks

  • Malaria parasites can remain in donor's blood for extended periods without symptoms:

    • P. malariae: 53 years

    • P. vivax: 27 years

    • P. falciparum: 13 years

  • All blood components containing erythrocytes can harbor viable parasites; this includes:

    • Whole blood

    • Red blood cell (RBC) concentrates

    • Platelets

    • Fresh frozen plasma

Diagnostic Challenges

  • Laboratory diagnoses primarily rely on the thick and thin blood smear techniques.

  • Diagnostic challenges include:

    • Induced morphologic alterations from staining

    • Low sensitivity of microscopy, typically around 500 parasites per µL.

  • Real-time PCR is more sensitive and specific, useful for detecting mixed infections.

    • However, it requires significant costs and specialized training.

    • Test Sensitivity: Detection of as few as 10 parasites per unit of RBCs necessary for transmission.

Location and Study Context

  • Bandar Abbas:

    • Major seaport, malaria-endemic.

    • Population approx. 520,000, high humidity and variable temperatures.

  • Tehran:

    • Free of malaria, with a larger population of over 8,500,000 and a semi-arid climate.

Study Design and Sampling Techniques

  • Sample size determined using a formula for a significant statistical outcome (n=100).

  • Blood samples gathered with participants' medical histories related to malaria and anti-malaria drug use.

Laboratory Procedures

  • Microscopy Examination:

    • Blood smears fixed and stained using the Giemsa method.

    • Examined for various fields to detect parasites.

  • Rapid Diagnostic Testing:

    • Utilizes dipstick assays that detect specific Plasmodium antigens.

  • Real-time PCR:

    • DNA extracted from blood samples and analyzed using specific primers for Plasmodium spp.

    • Assay optimization and confirmation through agarose gel electrophoresis.

Ethical Considerations

  • The study did not present ethical issues; blood samples were collected from donors voluntarily.

  • Results were provided to participants free of charge.

Conclusion

  • Emphasizes the importance of real-time PCR in blood banks located in endemic areas to detect asymptomatic malaria carriers.

  • RDTs can assist in rapid diagnostics amidst real-time PCR testing.

  • The study highlights ongoing need for proper training in blood banks to enhance detection capabilities.