Table 7.

Reported length and width measurements of microfilaria of Dirofilaria immitis, D. repens^a, Acanthocheilonema reconditum, and A. dracunculoides^a recovered by modified Knott (formalin fixed)

Measurement (μm)	Dirofilaria immitis	Dirofilaria repens a	Acanthocheilonema reconditum	Acanthocheilonema dracunculoides a	Reference
Length	295–325	268–360	250–288	189–230	[39]
	290–330	300–360	260–283	190–247	[42]
	295–308	359–380	259–270	253–266	[43]
	307–332	360	246–292	~ 300	[45]
	231–288b	302–344b	NR	NR	[46]
	≥ 315	NR	< 290	< 290	[68]
	280–320	NR	215–270	NR	[69]
Width	5.0–7.5	5.0–8.0	4.5–5.5	5.0–6.0	[39]
	5.0–7.0	6.0–8.0	4.0	4.0–6.5	[42]
	6.0–6.6	8.3–9.5	4.1–5.1	4.6–5.6	[43]
	6.8	12.0	4.7–5.8	NR	[45]
	6.1–7.2	NR	4.7–5.8	NR	[69]
	6.0–7.0	NR	< 5.6	NR	[70]

^aAutochthonous infections not documented to occur in North America

^bMicrofilaria recovered by thick smear (methanol fixed)