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The study confirms earlier studies with regard to the age/sex distribution of scabies. We suggest a contagious pattern of spread of scabies infestation in the U.K. with an epidemic cycle length of 15-17 years.

Throughout the entire life of the fluke the spines anterior to the ventral sucker are arranged in approximately 60 rings each of 60 to 70 spines. The spines on the posterior body are scattered without any pattern of rings and by 1 week post infection (p.i.) their numbers have doubled (from 3,000 on the newly excysted juvenile) to 6,000 and by 3 weeks p.i. their numbers have multiplied by 8 to 24,000. Just prior to entry into the bile ducts, between 2 and 3 weeks p.i., all spines, anterior and posterior, have metamorphosed from single pointed to multipointed forms by division at the spine tips. Spines on the anterior body of mature flukes recovered from the bile ducts of mice 26 weeks p.i. have between 10 and 15 points whereas those on the posterior body have up to 30 points. The tegument forms a rectangular pattern of plateaux and valleys around each spine on the posterior body of mature flukes but this pattern is not present on the anterior body.

Three types of presumed sensory endings were distinguished by scanning electron microscopy: a ciliated type, a domed type, and a pit. The ciliated and domed type were also serially sectioned for transmission electron microscopy. Six of the pit type were observed, a group of 3 on each side of the oral sucker. The ciliated type were found only among the tegumental spines, and on the anterior ventrolateral surfaces except for an anterodorsal pair. The domed type resembled the ciliated type in that it had a ciliary basal body and rootlet but it lacked a cilium. It was found only in the tegument above the suckers where it probably serves as a pressure or contact receptor. Movement in vitro occurred by alternate attachment and release of the suckers with a vermiform peristalsis and the rings of spines between the suckers were considered to aid this movement in vivo.

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