title: Morphometric analyses of canine blood microfilariae isolated by the Knott's test enables Dirofilaria immitis and D. repens species-specific and Acanthocheilonema (syn. Dipetalonema) genus-specific diagnosis.
abstract: BACKGROUND
  Considering the increasing importance of small animals travel medicine and the spread of filariae with zoonotic potential to non-endemic European areas, routine filarial diagnosis in dogs is becoming important. Dirofilaria immitis, D. repens, Acanthocheilonema dracunculoides and A. reconditum are the most common canine filarial nematodes presenting blood circulating microfilariae (mf) which can be differentiated to species level by the acid phosphatase activity patterns or by PCR. Available data on the size of the mf vary considerably in the literature. The aim of this study was to validate morphometric criteria for filarial identification in blood samples of dogs after concentration of mf with the modified Knott's technique.
  
  
  METHODS
  Morphometric analysis of 10 mf from samples identified to species level by acid phosphatase activity and partially confirmed by PCR were performed with specimens from 377 dogs.
  
  
  RESULTS
  The mean length and width of D. immitis mf from 60 dogs were 301.77 ± 6.29 μm and 6.30 ± 0.26 μm, of D. repens mf from 171 dogs 369.44 ± 10.76 μm 8.87 ± 0.58 μm, of A. dracunculoides mf from 133 dogs 259.43 ± 6.69 μm and 5.09 ± 0.47 μm and of A. reconditum mf from 13 dogs 264.83 ± 5.47 μm and 4.63 ± 0.52 μm.For a subset of 30 samples, morphometric analysis was repeated with identical results in two laboratories. Furthermore, the size of mf concentrated and fixed by the Knott's technique was shown to be stable over 105 days.
  
  
  CONCLUSIONS
  The Knott's test enables to clearly distinguish between D. immitis, D. repens and Acanthocheilonema spp. However, due to the overlapping size ranges of A. dracunculoides and A. reconditum, biochemical or molecular methods are required to distinguish these two species.
authors: Kleintierklinik in Iffezheim, An der Rennbahn 16a, 76473 Iffezheim, Germany.
authors: Johannes
authors: J
authors: Magnis
authors: Susanne
authors: S
authors: Lorentz
authors: Lisa
authors: L
authors: Guardone
authors: Felix
authors: F
authors: Grimm
authors: Marta
authors: M
authors: Magi
authors: Torsten J
authors: TJ
authors: Naucke
authors: Peter
authors: P
authors: Deplazes
mesh_terms: D063486:Acanthocheilonema / Q000033:anatomy & histology / Q000235:genetics / Q000302:isolation & purification*; D063485:Acanthocheilonemiasis / Q000175:diagnosis* / Q000469:parasitology; D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D049628:Body Size; D004183:Dirofilaria immitis / Q000033:anatomy & histology / Q000235:genetics / Q000302:isolation & purification*; D060348:Dirofilaria repens / Q000033:anatomy & histology / Q000235:genetics / Q000302:isolation & purification*; D004184:Dirofilariasis / Q000175:diagnosis* / Q000469:parasitology; D004283:Dog Diseases / Q000175:diagnosis* / Q000469:parasitology; D004285:Dogs; D005260:Female; D015801:Helminth Proteins / Q000378:metabolism; D008297:Male; D008842:Microfilariae / Q000033:anatomy & histology; D016133:Polymerase Chain Reaction; D013045:Species Specificity
chemical_list: D015801:Helminth Proteins; D000135:Acid Phosphatase