Feasibility and comparative analysis of Dirofilaria immitis microfilaria freezing and fixation for student instruction and assessment of clinical parasitology skills

Table 1 Modified Knott’s test recovery comparison of D. immitis microfilaria, MO and JYD isolates, using Year 1 cryopreservation procedure

Day	Isolate	Recovery	Measurements	Size	Score
0	MO	> 1000	215.0–255.0 × 2.5–5	237.0 × 3	2.4
7	MO	> 1000	257.5–312.5 × 5	288.0 × 5	2.1
21	MO	1189	255.0–300.0 × 5	276.8 × 5	2.2
70	MO	897	222.5–270.0 × 2.5–5	240.5 × 4.8	2.1
0	JYD	> 1000	257.5–292.5 × 5	274.0 × 5	3
7	JYD	> 1000	257.5–302.5 × 5	275.5 × 5	2
21	JYD	> 1000	250.0–292.5 × 5	271.8 × 5	2
70	JYD	> 1000	237.5–270.0 × 5	253.0 × 5	1.9

Day 0, no cryopreservation added, Day 7, 21, and 70 cryopreservation added followed by freezing at − 20 °C
MO and JYD isolates from experimentally infected dogs
Modified Knott’s slide with 50-uL of sediment, number of microfilaria detected
Range for the 10 microfilaria measured in μm
Average length and width of the microfilaria measured in μm
Average Head Score- 1-3 scale, 3 = clear and distinguished head; 2 = stained head but lighter than body; 1 = stained same color as body or indistinguishable

ISSN: 1746-6148