Brachylaimids are parasitic trematode fluke worms that have a terrestrial life cycle involving land snails and slugs as the first and/or second intermediate hosts for the cercarial and metacercarial larval stages. A wide range of mammals, birds, reptiles and amphibians are the definitive hosts for the adult worm. Brachylaima spp. have been reported from most continents including Europe, Africa, Asia, North and South America and Australia. There are over 70 described species in the genus with

more »

... en species indigenous to Australia. Although Brachylaima spp. are a cosmopolitan terrestrial trematode they have not been recorded to infect humans other than the three Brachylaima cribbi infections reported in two children and an adult from South Australia. The publication of a new species of brachylaimid, Brachylaima cribbi by Butcher and Grove in 2001 was the culmination of a 12-year scientific journey that would not have been possible without a broad scientific network of colleagues and some 'scientific luck', which enabled the establishment of a laboratory life cycle using parasite eggs recovered from the stool of an infected human 1 . My long-term association, as an active member of the Australian Society for Microbiology and the special interest groups played a significant role in having a network of colleagues to help find techniques and data to assist in the study of this parasite. The publication of the first human Brachylaima sp. infections followed the detection of a fluke worm egg, in the stool of two South Australian children, who had never travelled overseas. The eggs were identified as belonging to a genus of trematode worm endemic in the local area 2 . After conversations with many local and interstate colleagues, a veterinary parasitology colleague Michael O'Callaghan remembered the post-doctoral work of Thomas Cribb in South Australia. He had studied and published work on a brachylaimid in South Australia that infected mice 3,4 . This provided the data on a local trematode that had an egg morphology matching the eggs detected in the children's stools. However, was this a true human infection that resulted in the establishment of mature gravid worms producing the eggs detected in their stool or was it a spurious infection? The answer to this question was resolved 18 months later when an elderly lady from the mid-north of South Australia presented with chronic diarrhoea. Microscopic examination of her stool detected Brachylaima eggs, which matched the morphology of the eggs detected in the two children. In addition, on the first day following treatment with praziquantel a gravid degenerate adult Brachylaima worm was recovered from her stool 5 . This provided the evidence that a Brachylaima sp. was infecting humans and completing its life cycle. (a) (b) Figure 1. (a) European helicid and hygromiid land snails aestivate over summer to escape the ground heat by attaching to fence posts, which presents an easy meal for natural definitive hosts like birds. (b) Fertile Brachylaima cribbi egg being smooth shelled with an inconspicuous operculum, an abopercular knob or thickening and measuring 26-32 mm (29.1 mm) long and 16-17.5 mm (16.6 mm) wide.