Influence of water temperature, sedimentation and fecal refrigeration times on the recovery of Dictyocaulus viviparus larvae by two diagnostic techniques

Influência da temperatura da água e dos tempos de sedimentação e de refrigeração fecal na recuperação de larvas de Dictyocaulus viviparus por duas técnicas diagnósticas

Bovine dictyocaulosis, caused by Dictyocaulus viviparus, is a respiratory infection that leads to economic losses in livestock farming. The objective of this study was to compare two techniques for the diagnosis of D. viviparus. Residual fecal samples from routine diagnostics known to be positive were homogenized and subjected to the techniques proposed by modified Rugai, and Ueno techniques. We verified the effects of fecal refrigeration time (+24h and +48h), sedimentation time (2h and 12h), and water temperature (22°C and 46°C) on the recovery and sensitivity of first-stage larva (L1) diagnosis. Fecal refrigeration time (24h vs. 48h) did not significantly affect the number of recovered larvae, demonstrating that samples can be safely stored for up to two days. Room temperature water demonstrated a sensitivity below 75% in the recovery of D. viviparus during the first two hours in both techniques, increasing to 100% with 12 hours of sedimentation. However, heating the water to 46ºC proved to be the key factor: larval recovery became equal between the techniques, achieving 100% sensitivity in both after only two hours. We conclude that both techniques have similar sensitivity, making both valid for the recovery and diagnosis of D. viviparus.

Keywords:
Ruminants; diagnosis; coproparasitological examination; dictyocaulosis