Parasitology Proficiency Testing Program

BBPO CRITIQUE 02 June 2003

The purpose of the New York State Proficiency Testing Program in the category of Parasitology Blood Borne Parasites is to monitor the performance of applicant laboratories in detecting and identifying parasites on blood films.

SAMPLE PREPARATION AND QUALITY CONTROL

All slides used in this test were prepared and stained by a commercial source. Numerous samples of each test specimen were selected at random by the Parasitology Unit of the David Axelrod Institute for Public Health, and were checked to confirm their contents. Extensive quality control tests were also conducted by the supplying vendor and a detailed quality control report was submitted to the New York State Parasitology Laboratory for inspection and verification. Samples were authenticated by 80% of participating laboratories and/or referee laboratories.

RESULTS OF PARTICIPATING LABS

** Unauthenticated

June 2003 DISTRIBUTION OF SCORES

ANSWER KEY

TOTAL POSSIBLE POINTS 100

*Unauthenticated

GRADING

The answer key was derived from the response of all participating laboratories as per CLIA Regulations, Part 493, Subpart I, Section 493.917. These regulations can be viewed at www.phppo.cdc.gov. These regulations state that 80% or more of participating laboratories or referee laboratories must identify the parasite for it to be correct. Similarly, less than 20% of the participating laboratories or referees finding parasites or ova is an incorrect response. Organisms reported by 20-80% of the participating laboratories or referees are "Unauthenticated", and are not considered for grading.

Each sample has a maximum value of 20 points. Credit is given according to the formula:

QUALITY CONTROL

04B-A This was a particularly difficult slide and participating laboratories failed to correctly identify this sample as Plasmodium ovale (08%). Quality control examination of 4% of this sample revealed an average of one organism per every 20-30 oil emersion fields. Cells are enlarged but Schüffner's stippling is not present. The majority of the organisms present are mature trophozoites but other stages are also seen.

04B-B Participating laboratories agreed that No Parasites Seen was the correct response (100%). Quality control examination of 4% of this sample showed erythrocytes of normal size and staining characteristics. Normal blood elements are present and exhibit typical staining characteristics. No inclusions are present.

04B-C Participating laboratories agreed that Plasmodium falciparum was the correct response (85%). Quality control examination of 4% of this sample showed infected erythrocytes in nearly every oil emersion field. The infected cells are normal in size and staining characteristics. Ring stage trophozoites are the only stage seen. There are typical signet ring and applique´ forms as well as double chromatin dots and multiple infected cells.

04B-D Participating laboratories agreed that Plasmodium malariae was the correct response (92%). Quality control examination of 4% of this sample showed an infected erythrocyte in every 6-10 oil emersion fields. The infected cells are normal in size and staining characteristics. The primary stage seen is the growing trophozoite which appears as a compact round, band, or basket form. Pigment is scattered and abundant and the cytoplasm is fairly dense.

04B-E Participating laboratories agreed that No Parasites Seen was the correct response (92%). Quality control examination of 4% of this sample revealed erythrocytes of normal size and staining characteristics. Normal blood elements are present and exhibit typical staining characteristics. No inclusions are present.

DIAGNOSTIC CHARACTERISTICS

	Plasmodium ovale infections occur primarily in Central West Africa and some South Pacific Islands and account for fewer than 5% of all malaria cases. P. ovale malaria is usually less severe than other malarias and often ends in spontaneous recovery. The infected cells are usually enlarged, fimbriate, and have Schüffner's stippling. The cytoplasm of the trophozoites is usually less amoeboid than then that of P. vivax and the schizonts have 4-12 merozoites compared to 12-24 for P. vivax. The chromatin is usually very pronounced and the pigment is coarse.
	Plasmodium falciparum is one of the four species of Plasmodium known to infect humans. It causes the most dangerous and severe form of malaria and is always considered to be a medical emergency. Death may occur rapidly if proper treatment is not started immediately. Its distribution is limited to the tropics, primarily Africa and Asia. P. falciparum invades all ages of RBC's and so the parasitemia can exceed 50%. The usual stages seen in the peripheral blood are rings and gametocytes. Schizogony occurs in the internal organs so it is rare to seen other stages although they may be present in cases of severe malaria. The infected RBC's are not enlarged nor do they contain Schüffner's dots. The rings are generally small, and may have one or two chromatin dots. Applique´ forms are also characteristic. Gametocytes are rounded to banana-shaped and contain a single well defined chromatin and coarse rice-grain like pigment.
	Plasmodium malariae is the least common species of malaria to infect humans, and is sporadic in distribution. It tends to infect older red blood cells and so the parasitemia is often low. The ring stage is short lived so it is not usually seen. The most common stages seen are mature trophozoites and schizonts. The infected cells are not enlarged and may actually be smaller than uninfected cells. There is no stippling. The trophozoites are not amoeboid and often appear as compact rounded or band forms. The schizonts contain 6-12 merozoites usually arranged in a rosette although they may be in an irregular cluster.

IMPORTANT REMINDERS

The next Parasitology Proficiency Test is scheduled for October 06, 2003. You are responsible for notifying us before October 13, 2003 if you do not receive your test. Proficiency test results must be postmarked by October 20, 2003 or you will receive a zero. These requirements are clearly stated in your NYS Proficiency Testing Handbook provided by the NYS Clinical Laboratory Evaluation Program or can be accessed via the internet at www.wadsworth.org/labcert/clep/ProgramGuide/WebGuide.pdf.

NEWS AND NOTES

Policy changes made by the Clinical Laboratory Evaluation Program now allow for the CQ holder for a particular category to sign the attestation statement instead of the Laboratory Director. Starting with the February 05, 2001 test event we will now accept Director's and/or CQ holder's signatures on the attestation statement.

The New York State Parasitology Laboratory now has available as an "investigational" tool a Polymerase Chain Reaction(PCR) assay for the detection and species identification of malaria. Please continue to submit EDTA whole blood samples with all requests for malaria confirmation so we can validate this new assay and make it available as routine diagnostic test.

The Clinical Parasitology Lab of the NYSDOH now offers two mailing kits for the submission of specimens. One kit contains vials of PVA and Formalin and the other does not. These kits can be ordered by calling 518-474-4175 and requesting kit DOH-2117. Please be sure to specify whether you need preservatives or not. Remember that the NYS Parasitology Lab only accepts specimens preserved in appropriate fixatives for the test requested.

Please check out our website at: http://www.wadsworth.org/parasitology/index.htm You can access information about our program, the current answer key and critique, past critiques, and information about upcoming workshops. You can also find links to related sites, contact information, and answers to frequently asked questions.

There will be a Molecular Workshop held in Albany on Monday November 3, through Friday November 7,2003. More information and registration forms will follow.

Web site questions or comments or to request a different file format (pdf.,doc.,wpd.) contact:
E-mail: Parasit@wadsworth.org.