Laboratory Test Guide

Plasmodium 18S rRNA quantitative RT-PCR assay

General Information

Lab Name

Plasmodium 18S rRNA Quantitation

Lab Code

MAL18S

Description

The assay is a quantitative molecular reverse transcription PCR assay to detect and measure 18S rRNA from Plasmodium parasites and to specifically identify Plasmodium falciparum. The assay detects 18S rRNA from parasites in infected red blood cells and from gametocyte stage parasites.

Quantitative results are reported as 18S rRNA log10copies per milliliter of whole blood. For P. falciparum, the copies/mL result can be converted to estimated parasites/mL using a conversion factor of 7400 copies/ring-stage P. falciparum parasite. This conversion factor does not exactly apply to non-P. falciparum species (P. vivax, P. ovale, P. malariae, P. knowlesi) because of the presence of ring, trophozoite and schizont stage parasites in peripheral blood.

Note: If the test is negative for P. falciparum but positive for non-P. falciparum Plasmodium species, see the Plasmodium 18S Reflexive Sanger Sequencing [M18SEQ] will be performed at an additional charge.

Synonyms

Malaria molecular nucleic acid test

Components

Code	Name
M18SDE	Plasmodium 18S rRNA Specimen
PF18R	Plasmodium falciparum 18S rRNA Result
PAN18R	Pan Plasmodium 18S rRNA Result
M18INP	Plasmodium 18S rRNA Interpretation
M18MTH	Plasmodium 18S rRNA Method

Interpretation

Method

Real-time reverse transcription PCR

Reference Range

See individual components

Guidelines

Washington DOH Notifiable Conditions

Ordering & Collection

Specimen Type

EDTA blood

Collection

Preferred:

2 mL blood in EDTA lavender top tube.

Also acceptable:

2 mL blood in EDTA lavender top tube frozen at ≤-70°C within 48 hours of collection.

Note: Should be a dedicated tube (NOT shared with other tests except for MALP).

Unacceptable:

Green top (heparin) and red top tubes.
Blood in EDTA lavender top tubes frozen after 48 hours of collection.
Blood in EDTA lavender top tubes that have undergone freeze/thaw.

Handling Instructions

Whole blood may be shipped at ambient temperature or refrigerated at 4°C within 48 hours of collection.
If whole blood cannot be received by the testing lab within 48 hours of collection, store sample at ≤-70°C within 48 hours of collection and ship on dried ice. Do not freeze/thaw.
Specimen from external labs that were received frozen must remain frozen for delivery to the lab.

Quantity

requested: 2.0 mL EDTA blood.
minimum: 0.2 mL for infant; 0.5mL for adult.

Processing

If specimens can reach the lab at UWMC South Lake Union Campus within 48 hours of collection, ship the specimen with ice packs. If not, store the specimen in a ≤-70°C freezer within 48 hours of collection and then send the specimen on dried ice. Do not freeze/thaw.

Specimen(s) from external sites should be sent to UWMC-ML SPS.

SPS:

Notify Malaria Molecular Diagnostic Lab at 206-685-4599 about incoming specimen(s).
Print the Epic Order Requisition and package it with the sample.
Include text “Call recipient lab at 206-685-4599 upon delivery” on shipment label.
Send samples to Malaria Molecular Diagnostic Lab via Delivery Express courier to the address written exactly as below:

750 Republican St., Building F, Room 870, Seattle, WA 98109

If specimen is received by SPS after 12pm on Friday, freeze at ≤-70°C and hold until Monday or next non-holiday workday after 9am for delivery.
Specimen can only be received by lab during laboratory hours (M-F 9:00am – 4:30pm).

Performance

LIS Dept Code

Malaria Molecular Diag Lab (MMDL)

Performing Location(s)

Other	Malaria Molecular Diagnostic Laboratory Malaria Molecular Diagnostic Laboratory University of Washington Building F, Room # 870 (Call 206-685-4599 for access) 750 Republican St Seattle, WA 98109	206-685-4599 (Lab) 206-685-8212 (Office)