Fig 1.
Pathological signs of Spirometra erinaceieuropaei infection in Boiga irregularis.
(a) External blister-like nodules indicating presence of cestodes in subcutaneous space. (b) Internal lesions associated with the plerocercoid scolex revealed upon removal of the skin.
Fig 2.
Spirometra erinaceieuropaei Infection Prevalence Map of Guam.
(a) Locations of 77 samples of B. irregularis screened for parasite infection (N = 4 to 103 per site). White symbols denote locations where no infected snakes were found and black symbols represent locations with high infection rates. The two gray symbols represent samples of 100 snakes that contained a single infected specimen each. (b) Inset map depicting distribution of sampling sites within the area of high occurrence (Naval Ordnance Annex). Non-infected samples depicted by white spots are on an elevated limestone forest plateau, while the highly infected sites depicted by black symbols are in low-lying ravine forests. The low-infection gray symbol denotes a sample collected in savanna grassland habitat. The hatched polygon represents Fena Reservoir, the only large body of fresh water on Guam.
Table 1.
Top AICc model results for factors associated with Spirometra infection (models carrying 95% of model weights).
Fig 3.
Effect sizes for model terms under the top model.
(a) Effect of SVL at mean values of body condition and fat mass ratio; probability of infection = 0.5 at 880 mm SVL. (b) Effect of residual body mass at 880 mm SVL and mean fat mass ratio. (c) Effect of fat mass ratio at 880 mm SVL and mean residual body mass.
Fig 4.
Proposed Life Cycle Diagram of Spirometra erinaceieuropaei on Guam.
Blue arrows show hypothesized hosts’ geographic source population, green arrows indicate S. erinaceieuropaei life cycle stages as represented by hosts, and life history stages are labeled under each host. Eggs hatch in fresh water where they are ingested by copepods, which are in turn ingested by aquatic vertebrates such as frogs and fish. Spirometra mature into adult worms when a second intermediate host is consumed by a carnivorous mammal (typically feral cats (Felis catus) and dogs (Canis lupus familiaris), both of which occur on the Naval Ordnance Annex), and the life cycle is completed when mammals shed feces containing ova into fresh water. Photo credits listed in Acknowledgments.