§ 493.917 Parasitology. ( a ) *Program content and frequency of challenge.* To be approved for proficiency testing for parasitology, the annual program must provide a minimum of five samples per testing event. There must be at least three testing events provided to the laboratory at approximately equal intervals per year. The samples may be provided through mailed shipments. The specific organisms included in the samples may vary from year to year. ( 1 ) The annual program must include, as applicable, samples for: ( i ) Direct parasite antigen detection; and
( ii ) Detection and identification of parasites which includes one of the following: ( A ) Detection of the presence or absence of parasites without identification; or
( B ) Identification of parasites.
( 2 ) An approved program must furnish HHS and its agents with a description of the samples it plans to include in its annual program no later than 6 months before each calendar year. Samples must include both formalinized specimens and PVA (polyvinyl alcohol) fixed specimens as well as blood smears, as appropriate for a particular parasite and stage of the parasite. The majority of samples must contain protozoa or helminths or a combination of parasites. Some samples must be devoid of parasites.
( 3 ) The content of an approved program must vary over time, as appropriate. The types of parasites included annually must be representative of the following major groups of medically important parasites, if appropriate for the sample sources: ( i ) Intestinal parasites; and
( ii ) Blood and tissue parasites.
( 4 ) The program must provide at least five samples per testing event that include challenges that contain parasites and challenges that are devoid of parasites.
( b ) *Evaluation of a laboratory's performance.* HHS approves only those programs that assess the accuracy of a laboratory's responses in accordance with paragraphs (b)(1) through (6) of this section. ( 1 ) The program determines the reportable parasites to be detected by direct parasite antigen detection, detection of the presence or absence of parasites without identification, and identification of parasites. It may elect to establish a minimum number of parasites to be identified in samples before they are reported. Parasites found in rare numbers by referee laboratories are not considered in a laboratory's performance; such findings are neutral. To determine the accuracy of a laboratory's response, the program must compare each response with the response which reflects agreement of either 80 percent or more of 10 or more referee laboratories or 80 percent or more of all participating laboratories. Both methods must be attempted before the program can choose to not grade a PT sample.
( 2 ) A laboratory must detect and identify or concentrate and identify the parasites to the highest level that the laboratory reports results on patient specimens.
( 3 ) A laboratory's performance will be evaluated on the basis of the average of its scores for paragraphs (b)(4) through (5) of this section as determined in paragraph (b)(6) of this section.
( 4 ) The performance criterion for direct parasite antigen detection is the presence or absence of the parasite antigen. The score is the number of correct responses divided by the number of samples to be tested, multiplied by 100.
( 5 ) The performance criterion for the detection and identification of parasites includes one of the following: ( i ) The performance criterion for the detection of the presence or absence of parasites without identification is the correct detection of the presence or absence of parasites without identification. The score is the number of correct responses divided by the number of samples to be tested, multiplied by 100.
( ii ) The performance criterion for the identification of parasites is the total number of correct responses for parasite identification submitted by the laboratory divided by the number of parasites present plus the number of incorrect parasites reported by the laboratory multiplied by 100 to establish a score for each sample in each testing event. Since laboratories may incorrectly report the presence of parasites in addition to the correctly identified principal organism(s), the scoring system must provide a means of deducting credit for additional erroneous organisms that are reported and not found in rare numbers by the program's referencing process. For example, if a sample contained one principal organism and the laboratory reported it correctly but reported the presence of an additional organism, which was not considered reportable, the sample grade would be 1/(1+1) × 100 = 50 percent.
( 6 ) The score for a testing event is the average of the sample scores as determined under paragraphs (b)(4) through (5) of this section.
[87 FR 41235, July 11, 2022]