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Parasitology Proficiency Testing Program

BBPO 06 February 2007

The purpose of the New York State Proficiency Testing Program in the category of 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.

ANSWER KEY

SAMPLE	CORRECT ANSWER	POINTS
07B-K	NO PARASITES SEEN	20
07B-L	NO PARASITES SEEN	20
07B-M	NO PARASITES SEEN	20
07B-N	Plasmodium malariae	20
07B-O	Plasmodium falciparum	20

TOTAL POSSIBLE POINTS 100

SAMPLE 07B-K

RESULTS OF PARTICIPATING LABS

ORGANISM	NUMBER REPORTED	PERCENT REPORTED	STATUS
NO PARASITES SEEN	14/15	93	Correct
Babesia sp.	1	7	Incorrect

QUALITY CONTROL

Participating laboratories agreed that No Parasites Seen was the correct response (93%). 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 although the staining quality was sub optimal. No inclusions are present.

SAMPLE 07B-L

RESULTS OF PARTICIPATING LABS

ORGANISM	NUMBER REPORTED	PERCENT REPORTED	STATUS
NO PARASITES SEEN	15/15	100	Correct

QUALITY CONTROL

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 although the staining quality was sub optimal. No inclusions are present.

SAMPLE 07B-M

RESULTS OF PARTICIPATING LABS

ORGANISM	NUMBER REPORTED	PERCENT REPORTED	STATUS
NO PARASITES SEEN	15/15	100	Correct

QUALITY CONTROL

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.

SAMPLE 07B-N

RESULTS OF PARTICIPATING LABS

ORGANISM	NUMBER REPORTED	PERCENT REPORTED	STATUS
Plasmodium malariae	15/15	100	Correct

QUALITY CONTROL

Participating laboratories agreed that Plasmodium malariae was the correct response (100%). Quality control examination of 4% of this sample showed parasites in every 2-3 100X oil emersion fields. The infected erythrocytes are not enlarged and no stippling was observed. The predominant stage seen was the mature trophozoite with compact cytoplasm and coarse pigment. Band and basket forms were present.

DIAGNOSTIC CHARACTERISTICS

Plasmodium malariae is the least common species of plasmodium 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 with coarse, scattered pigment. The gametocytes are round and compact with a single, well defined chromatin. The pigment is scattered and coarse and may appear to be peripherally distributed. The schizonts contain 6-12 merozoites usually arranged in a rosette although they may be in an irregular cluster. The pigment, in the schizont, is in a concentrated mass.

SAMPLE 07B-O

RESULTS OF PARTICIPATING LABS

ORGANISM	NUMBER REPORTED	PERCENT REPORTED	STATUS
Plasmodium falciparum	14/15	93	Correct
Plasmodium vivax	1	7	Incorrect

QUALITY CONTROL

Participating laboratories agreed that Plasmodium falciparum was the correct response (93%). Quality control examination of 4% of this sample showed parasites in almost every 100X oil emersion field. Infected cells are not enlarged and no stippling was noted. The only stage seen was the ring stage trophozoite.

DIAGNOSTIC CHARACTERISTICS

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 see 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. Appliqué forms are also characteristic. The mature trophozoites are compact with a mass or a few grains of coarse pigment. Gametocytes are rounded to banana-shaped and contain a single well defined chromatin and coarse rice-grain like pigment.

DISTRIBUTION OF SCORES

SCORE	NO. OF LABS	PERCENT
100	13/15	87
80	2	13

 

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:

Number of correct responses by lab # Correct Parasites Present + # Lab's Incorrect Answers

X 100

IMPORTANT REMINDERS

The mailout dates for Parasitology have been changed from the first Monday of February, June, and October to the first Tuesday.

The next Parasitology Proficiency Test is scheduled for June 5, 2007. You are responsible for notifying us before June 12, 2007 if you do not receive your test. Proficiency test results must be postmarked by June 19, 2007 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 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 Clinical Parasitology Lab of the NYSDOH 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.

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