Parasitology Proficiency Testing Program

BBPO CRITIQUE FOR 07 JUNE 2004

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.

RESULTS OF PARTICIPATING LABS

June 2004 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

05B-A 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.

05B-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. Some erythrocytes contain Howell-Jolly bodies which can be confused with parasites.

05B-C Participating laboratories failed to agree that Plasmodium malariae was the correct response (77%). Quality control examination of 4% of this sample showed infected erythrocytes in every 4-5 oil emersion fields. The infected cells are not enlarged and no stippling was observed. All stages except mature schizonts are seen but the prodominant stage is the mature trophozoite. Band and basket form trophozoites were observed.

05B-D Participating laboratories agreed that Plasmodium falciparum was the correct response (100%). Quality control examination of 4% of this sample showed infected erythrocytes in every 10-12 oil emersion fields. The infected cells are not enlarged and no stippling was observed. The only stage seen was the ring stage trophozoite which is characteristic for P. falciparum infection. Signet ring, headset and applique´ forms were all observed.

05B-E 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.

DIAGNOSTIC CHARACTERISTICS

	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 as shown in the images. 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. In contrast cells infected with P. vivax example in picture below are enlarged,pale staining, and usually exhibit stippling. Trophozoites are amoeboid and schizonts contain 12-24 merozoites.
	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. Applique´ forms are also characteristic. Gametocytes are rounded to banana-shaped and contain a single well defined chromatin and coarse rice-grain like pigment.

IMPORTANT REMINDERS

The next Parasitology Proficiency Test is scheduled for October 04, 2004. You are responsible for notifying us before October 11, 2004 if you do not receive your test. Proficiency test results must be postmarked by October 18, 2004 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

A Malaria Workshop will be held in the fall of 2004. Registration forms will be sent to all permitted laboratories. For further information or a registration form call 800-536-NLTN or visit NLTN web site.

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 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.

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.

Beginning with the next test event scheduled for October 2004 we will no longer routinely mail out critiques with the result reports. Parasitology critiques are available on the website at the above address. Critiques have been available in this format since June 2002. If you do not have access to the internet you can request a paper copy by calling Jill Ennis at 518-474-4177 or E-mail: jxe02@health.state.ny.us .

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