Melanoides tuberculata as intermediate host of Philophthalmus gralli in Brazil

Abstract

SUMMARYMelanoides tuberculata that naturally harbored trematode larvae were collected at the Pampulha dam, Belo Horizonte (Minas Gerais, Brazil), during malacological surveys conducted from 2006 to 2010. From 7,164 specimens of M. tuberculata collected, 25 (0.35%) were infected by cercariae, which have been morphologically characterized as belonging to the Megalurous group, genus Philophthalmus. Excysted metacercariae were used for successful experimental infection of Gallus gallus domesticus, and adult parasites recovered from the nictitating membranes of chickens were identified as Philophthalmus gralli. This is the first report of P. gralli in M. tuberculata in Brazil.

Epidemiology of cercarial stage of trematodes in freshwater snails from Chiang Mai province, Thailand

“…Because, these cercariae have neither a collar-like thickening nor a crown of spines, they encyst on the surface of the bottom of the container. The metacercarial cysts are flask-shaped [26] . The snail intermediate host of these cercaria was similar to those reported in the same snail species [26][27][28][29] , while some were only found in Semisulcospira libertine in some study [29] .…”

“…The metacercarial cysts are flask-shaped [26] . The snail intermediate host of these cercaria was similar to those reported in the same snail species [26][27][28][29] , while some were only found in Semisulcospira libertine in some study [29] . Concerning the snail hosts, B. siamensis were shown to be the suitable intermediate hosts for harboring a wide spectrum of cercarial infection, where gymnocephalus cercariae and virgulate cercaria were found to have infected only in one snail species.…”

“…About 100 species of snails were reported to act as intermediate hosts for the trematode parasite, particularly in the family Thiaridae which harbor the larvae of the intestinal and eye flukes [26] . The species identification will be done for accuracy control in this area.…”

Outbreak of Philophthalmus gralli in four greater rheas (Rhea americana)

“…The life cycle of P. gralli begins when a fully embryonated trematode egg is shed into the water from the definitive host’s eye 5 . Miracidia hatch once immersed in water and are ingested by M. tuberculatus snails, which act as the intermediate host 4,41,42 . Snails then release cercariae, which are able to swim until they contact a solid structure, which is usually aquatic vegetation, and encyst becoming metacercariae 5 .…”

“…Water from the exhibit’s large stagnant pond was analyzed, and with the exception of moderately high level of ammonia (1–2 mg/L), from bird excrement, parameters were within normal ranges. Aquatic snails were plentiful and identified as Melanoides tuberculatus (M. tuberculatus), a known intermediate host for P. gralli 4,5,7,41,42 …”