Melanoides tuberculata (Mollusca: Thiaridae) as an intermediate host of Centrocestus formosanus (Trematoda: Heterophyidae) in Brazil

Abstract

SUMMARYPleurolophocercous cercariae emerged from naturally infected Melanoides tuberculata from Minas Gerais State, Brazil, were used to perform experimental infection of laboratory-reared Poecilia reticulata. Mature metacercariae were obtained from the gills of fishes and force-fed to Mus musculus. The adult parasites which recovered from small intestines of mice were identified as Centrocestus formosanus. This is the first report of M. tuberculata as intermediate host of this heterophyid in Brazil. Despite some studies related to the interaction between M. tuberculata and planorbid molluscs which transmit Schistosoma mansoni Sambon, 1907 in the country 13,14 , the possible damage on the native fauna as alien species and their potential to act as parasite vector in the country have not yet been evaluated. In this later aspect, some studies had already reported the finding of M. tuberculata harboring pleurolophocercous cercariae in Brazil 5,6,39 , but these larvae, characterized as Pleurolophocercous type, still remain without a specific identification. KEYWORDS:In the present study, malacological surveys were performed at Pampulha dam (an artificial lake located between 43 0 58' and 44 0 01'W and 19 0 50' and 19 0 52'S, in the northern region of the city of Belo Horizonte and 2 km away from the campus of "Universidade Federal de Minas Gerais") from March 2006 to July 2009. Molluscs were collected with a scoop net and long forceps. After a preliminary trial, molluscs were placed in a thermal box, labeled and shipped to the laboratory. Then they were placed individually in plastic recipients containing 5 mL of tap water and left overnight at room temperature. Thiarids were examined with a stereomicroscope before and after artificial photostimulation for two hours. Emerged larvae were collected with micropipette, transferred to glass slides and analyzed with vital stains (0.05% neutral red, 0.05% toluidine blue, 0.05% alizarin red) or fixed and then stained with acetic carmine and mounted in Canada balsam 23 .Cercariae were concentrated by filtration using a Buchner funnel 31 and one hundred larvae in 5 mL were used for individual infection of 30 adult specimens (2-3 cm of length) of laboratory reared Poecilia reticulata Peters, 1859 (Pisces: Poeciliidae). Thirty days after infection the surviving fishes were necropsied in order to recover metacercariae. Cysts obtained from gills of experimentally infected fish were administered per os to five mice of the AKR/J strain. Fifteen days after infection, mice were sacrificed by cervical dislocation according to the local animal experimentation ethics committee (CETEA/UFMG), and their intestines were thoroughly and longitudinally opened in Petri dishes containing 0.85% saline solution and adult parasites were recovered from the proximal third of the small intestine. Parasites were studied alive or then placed between the slide and the coverslip with slight pressure, fixed in cold 10% formalin, stained with acetic carmine, dehydrated, cleared in benchwood and mounted in C...

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

“…Haplorchis taichui, Haplorchis pumilio, Stellantchasmus falcatus, Centrocestus caninus and Procerovum sp. were reported to be as the cercarial stage of the intestinal trematode in family Heterophyidae [18][19][20][21][22][23][24][25] . The identification of the morphology of cercariae were similar to those described by previous reported [8,16,20] .…”

“…were reported to be as the cercarial stage of the intestinal trematode in family Heterophyidae [18][19][20][21][22][23][24][25] . The identification of the morphology of cercariae were similar to those described by previous reported [8,16,20] . In regard to this connection, previous surveys revealed that most metacercariae found in Mae Taeng district, Chiang Mai province belonged to the family Heterophyidae [3,6,18] .…”

The natural infection of Melanoides tuberculata (Müller, 1774) (Mollusca: Gastropoda) by Centrocestus formosanus (Nishigori, 1924) (Platyhelminthes: Trematoda) in Paranoá lake, Brasília, Brazil

“…Twenty-five adult parasites were recovered from the small intestine of the mice 15 days after infection. The morphological analysis of the developmental stages (cercariae, metacercariae and adult parasites) was performed as described in Pinto and Melo (2010a); this confirmed the presence of C. formosanus in M. tuberculata from Paranoá Lake. The studied snails and adult trematodes obtained in this study were deposited respectively in the collections of the Departments of Zoology (2688-2689 and 2692-2696) and Parasitology (5923a-d) at the Universidade Federal de Minas Gerais.…”

“…This is an artificial reservoir that was constructed in 1959 to provide recreational activities in Brasília (Monteiro and Dias, 1980;PadovesiFonseca et al, 2009). All procedures, such as collecting thiarids, detecting larval trematode, the experimental infection of fish Poecilia reticulata (Peters, 1859), the infection of mice (AKR/J strain), metacercariae recovery, and the fixation and colouration of the obtained parasites were performed as described by Pinto and Melo (2010a). Trematode larvae were found in 16 snails (33%) and were preliminarily identified as Pleurolophocercous cercariae.…”

“…However, only now, thirty years after the first reporting, their natural infection by trematodes has been investigated. C. formosanus is a trematode that originated from Asia, and there are several reports of its introduction and the involvement of M. tuberculata in its transmission in the Americas (Cortés et al, 2010;Pinto and Melo, 2010a;Pointier et al, 2011). Specimens of this thiarid were reported in several Brazilian states, presenting high densities in eutrophic and…”