Prevalence and strain differentiation of Giardia intestinalis in calves inthe Manawatu and Waikato regions of North Island, New Zealand

Giardia intestinalis has been reported in newborn calves world-wide; howeve r, information on the extent of G. intestinalis in New Zealand calves has t o date been very limited. The current study attempted to establish the prev alence rate of G. intestinalis in calves up to 8 weeks old in New Zealand, More than 700 calf fecal specimens were collected during the spring calving seasons of 1998 and 1999 from two regions in North Island, New Zealand (Ma nawatu and Waikato) and tested for the presence of G. intestinalis. In addi tion to determining the presence of G. intestinalis in newborn calves, sequ ence analysis was performed using specific amplification primers developed to target a section of the ribosomal DNA (rDNA). This locus is considered t o be rapidly evolving, and therefore, suitable for use in the elucidation o f phylogenetic relationships between G. intestinalis isolates. Sequencing w as performed using G. intestinalis DNA extracted from cysts collected direc tly from the calf fecal matter. There was no culturing of the G. intestinal is isolates either in vivo or in vitro. Over 30% of all collected calf feca l specimens contained G. intestinalis cysts and rDNA sequence analysis reve aled two different sequences among calf isolates. These sequence difference s were not found to correspond to a particular season, geographical region or farming practice. Preliminary phylogenetic analysis suggests that these two rDNA sequence types are indicative of calf hosts. (C) 2000 Elsevier Sci ence B.V. All rights reserved.