Development and survival at low temperature of the free living stages of Trichostrongylus tenuis

Differential species traits of Trichostrongylus tenuis (Nematoda, Trichostrongylidae)

Trichostrongylus tenuis Mehlin, 1846 is a helminth species that parasitizes in the gastrointestinal tract of birds and causes trichostrongylosis. Research on the differential features of the pathogen at various stages of development facilitates timely finding of the foci of infection and providing recommendations for prevention and control. In the present study, the differential species traits of male and female Trichostrongylus nematodes parasitizing in the domestic goose were examined. The nematodes were obtained in helminthological dissection of the intestine of birds kept at farms and private households in Poltava region, Ukraine. It was revealed that the morphological features of T. tenuis females that should be considered in species identification include the structural specifics of the reproductive system and the tail end. 22 metric parameters were suggested for species identification, including the female body measurements for different parts, specifics of vulva and anus location, sizes of the ovijector, sphincter, ejector and vulval area. Differences were found in the metric parameters of the lateral crests of the cuticle in female nematodes in relation to the position of crests on the parasite’s bodies. The cuticular crests were absent at 0.1 mm from the head and tail ends, and the length of crests was 9.3 mm in total. The longest and widest crests were observed in the middle of the body, the shortest were found in the anus area, and the narrowest crests were from the anterior part of esophagus to its middle. The distance between crests varied 0.2–3.0 μm, the longest at the transition of esophagus into the intestine and the shortest in area between the vulva and the anus. The metric parameters of T. tenuis eggs obtained from bird feces and in the nematode uterus differed significantly by 5 characters. The collected data on the morphological and metric parameters of females and eggs of T. tenuis can be used in species identification and understanding of the taxonomic position of that species.

Comparison of single and split-dose flubendazole treatment for the nematode parasiteTrichostrongylus tenuisin experimentally infected grey partridgesPerdix perdix

Different therapeutic regimes using flubendazole for the treatment ofTrichostrongylus tenuisinfection in experimentally infected grey partridgesPerdix perdixwere examined. Flubendazole dosages of 4, 8 and 20 mg/kg were administered orally as a single dose or split into 3 or 9 parts given over 9 days. The efficacy against adult worms in the caeca improved with dose rate. Split doses were at least as effective as single doses, which removed up to 83% of adultT. tenuis. A dose of 20 mg/kg administered on a daily basis over 3 or 9 days gave the best clearance ofT. tenuis, resulting in a reduction of at least 95% in worm burden.

Further studies on the development and survival at low temperatures of the free living stages of Trichostrongylus tenuis

To assess the ability of the free living stages of Trichostrongylus tenuis, a pathogen of red grouse, to survive the winter in significant numbers, the temperatures prevailing during the autumn, winter and spring of 1991-92 on the North Yorkshire moors were simulated in an incubator into which replicate cultures of T tenuis eggs were placed at intervals. September and early October eggs developed into larvae which survived over winter and were infective the following spring. Few November to February eggs survived to become larvae but early March eggs were reasonably successful. Continuous temperatures of -15 degrees C were lethal to infective larvae within 12 days, but significant numbers of larvae survived temperatures of -10 degrees C or higher for up to three weeks and remained infective.