To investigate larval development of Acanthocheilonema reconditum in the cat flea Ctenocephalides felis, fleas were fed through an artificial feeding system with dog blood containing different concentrations of microfilariae (i.e. low, group L = 250; medium, group M = 500; high, group H = 1500 microfilariae per mL) or no microfilariae (group C). Fleas were sampled at 12 different time-points throughout the study period (D1–D28) and A. reconditum was detected by dissection, PCR and histology. Of 2105 fleas fed with infected dog blood, 891 (38·7%) died during the study before being sampled whilst the remaining (n = 1214) were examined for A. reconditum. Upon dissection, first-stage larvae (L1) were identified after 2 days post infection (D2), second-stage (L2) at D13 and infective third-stage larvae (L3) at D15. Eighteen (30%) of 60 pools of fleas molecularly examined tested positive. Histologically, L2 were detected at D13 in the sub-cuticle region embedded in the back muscle of one female flea. This study provides original data on larval development of A. reconditum in C. felis and reports on the usefulness of the artificial feeding system.

In spite of its wide distribution among dogs and the evidence of its implication as a zoonotic agent, scant information is available on the biology of Acanthocheilonema reconditum (Spirurida, Onchocercidae). In this study, blood samples from 152 Sicilian dogs were examined for A. reconditum microfilariae at the beginning of the study and 1 year later. The periodicity of microfilaraemia was investigated by bleeding 2 highly microfilaraemic dogs twice a day for 10 days and, later on, every 2 weeks for 1 year and a third animal every 3 h for 96 h. Fleas and ticks infesting dogs were collected and dissected for the detection of A. reconditum larvae. The prevalence of infestation was 11·2% (17/152) and 13·3% (16/120) at the beginning and at the end of the study, with a 1 year cumulative incidence of 5·9%. Although dogs bled twice a day showed a higher number of microfilariae in most of the morning samples, the absence of any circadian rhythm was suggested by data of the third experiment conducted by bleeding a dog every 3 h for 4 days. A. reconditum developing forms were detected in 5·1% (4/78) of dissected fleas, but not in any of the 272 ticks. The study provides new insights into the biology and ecology of this dog filarioid in its definitive and intermediate hosts.