Blood parasites: problems in diagnosis using automated differential instrumentation.

Area of Science:

• Hematology
• Parasitology
• Medical Laboratory Science

Background:

• Automated differential counters are widely used for blood cell analysis.
• These instruments are not primarily designed for intracellular parasite detection.

Observation:

• Two cases are presented where Plasmodium vivax and Plasmodium falciparum were initially missed by automated differential instruments.
• Diagnosis was confirmed later in a parasitology laboratory using manual smear review.
• Automated systems failed to detect low-level parasitemia due to limited field scanning.

Findings:

• Automated instruments failed to identify the presence of malaria parasites in red blood cells.
• The inability of automated systems to differentiate infected from uninfected red blood cells poses a diagnostic challenge.
• Missed diagnoses led to significant delays in initiating appropriate antimalarial therapy.

Implications:

• Relying solely on automated differentials can lead to missed diagnoses of blood-borne parasitic infections.
• Manual peripheral blood smear review remains crucial for detecting certain infections, especially with low parasitemia.
• Improved flagging or specific protocols for suspected parasitic infections may be needed for automated systems.