www.cbpv.com.br/rbpv New host records and a checklist of fishes infected with Austrodiplostomum compactum (Digenea: Diplostomidae) in Brazil Novos registros de hospedeiros e “checklist” de peixes infectados por Austrodiplostomum compactum (Digenea: Diplostomidae) no Brasil Igor Paiva Ramos1,2*; Lidiane Franceschini3; Aline Cristina Zago3; Érica de Oliveira Penha Zica3; Alison Carlos Wunderlich3; Edmir Daniel Carvalho1; Reinaldo José da Silva3 1Departamento de Biologia e Zootecnia, Faculdade de Engenharia de Ilha Solteira, UNESP – Univ Estadual Paulista, Ilha Solteira, SP, Brasil 2Laboratório de Biologia e Ecologia de Peixes, Departamento de Morfologia, Instituto de Biociências, UNESP – Univ Estadual Paulista, Botucatu, SP, Brasil 3Laboratório de Parasitologia de Animais Silvestres, Departamento de Parasitologia, Instituto de Biociências, UNESP – Univ Estadual Paulista, Botucatu, SP, Brasil Received April 25, 2013 Accepted November 1, 2013 Abstract This study reports the infection of fishes by Austrodiplostomum compactum metacercariae in the Chavantes reservoir, medium Paranapanema River, municipality of Ipaussu, São Paulo State, Brazil. Twenty-three fish species were analysed, and 13 were infected with A. compactum metacercariae (56.5%) in their eyes. The following six fish species are new hosts for this metacercaria: Crenicichla haroldoi (1/1), Eigenmannia trilineata (11/6), Hoplosternum littorale (11/1), Iheringichthys labrosus (17/2), Leporinus amblyrhynchus (11/1), and Piaractus mesopotamicus (3/1). These new species increase the number of Brazilian fish species infected with this parasite to 36. Based on these findings, we hypothesise that the metacercariae larval stage of the parasite has a low specificity for the second intermediate host (fish). The majority of fish species infected in Brazil belong to the Loricariidae and Cichlidae families. For the fish species with higher mean abundances in Brazil, six are non-native species, and currently, Plagioscion squamosissimus has the highest mean abundance. The majority of fish species infected with A. compactum in Brazil are concentrated in the Paraná basin, although this may be related to the distribution of researchers. Keywords: Freshwater fishes, parasite, Trematoda, metacercariae, infection, Paraná basin. Resumo Este estudo relata a infecção por metacercárias de Austrodiplostomum compactum em peixes do reservatório de Chavantes, médio Paranapanema, Ipaussu, São Paulo, Brasil. Vinte e três espécies de peixes foram analisadas, e 13 estavam infectadas com metacercárias (56,5%) em seus olhos. Seis espécies de peixes foram registradas como novos hospedeiros: Crenicichla haroldoi (1/1), Eigenmannia trilineata (11/6), Hoplosternum littorale (11/1), Iheringichthys labrosus (17/2), Leporinus amblyrhynchus (11/1), and Piaractus mesopotamicus (3/1), aumentando para 36 o número de peixes brasileiros infectados por este parasita. Assim, inferimos que este estágio larval do parasita possui baixa especificidade parasitária em relação ao seu segundo hospedeiro intermediário (peixes). No Brasil, a maioria das espécies de peixes infectadas pertence às famílias Loricariidae e Cichlidae. Quanto às espécies de peixes com as maiores abundâncias médias no Brasil, seis são espécies não-nativas, sendo Plagioscion squamosissimus a espécie com a maior abundância média. Ainda, a maioria das espécies de peixes infectadas por A. compactum no Brasil, estão concentradas na bacia do Paraná, sendo este fato possivelmente relacionado com a distribuição de pesquisadores. Palavras-chave: Peixes de água doce, parasita, Trematoda, metacercária, infecção, bacia do Paraná. *Corresponding author: Igor Paiva Ramos Departamento de Biologia e Zootecnia, Faculdade de Engenharia de Ilha Solteira, Universidade Estadual Paulista – UNESP, Campus de Ilha Solteira, CEP 15385-000, Ilha Solteira, SP, Brasil e-mail: igor.paiva.ramos@gmail.com Original Article ISSN 0103-846X (impresso) / ISSN 1984-2961 (eletrônico) Rev. Bras. Parasitol. Vet., Jaboticabal, v. 22, n. 4, p. 511-518, out.-dez. 2013 Ramos, I.P. et al. Rev. Bras. Parasitol. Vet. Introduction Eye fluke diplostomids have complex life cycles, involving three hosts, of which two are intermediate and one is definitive (KARVONEN et al., 2006; VIOLANTE-GONZÁLEZ et al., 2009), and parasitise several fish species in the world (EIRAS, 1994). Austrodiplostomum compactum (Lutz, 1928) is widely distributed in the Neotropical region, and A. compactum metacercaria parasitise several species of Brazilian freshwater fishes. The A. compactum cercariae (first larval stage) infect aquatic snails and molluscs of the genus Biomphalaria Preston, 1910 in Mexico (VIOLANTE-GONZÁLEZ et al., 2009) and Brazil (PINTO; MELO, 2013). Diplostomum and Austrodiplostomum metacercariae are frequently found in the eyes of freshwater fishes, which are the second intermediate hosts during the life cycle of the parasite (SEPPÄLÄ et al., 2004). The adult stage parasitises the digestive tract of piscivorous birds, and Phalacrocorax brasilianus (Gmelin, 1789) [=Phalacrocorax olivaceus] is considered definitive host of this digenean in Brazil (TRAVASSOS et al., 1969; NORONHA et al., 2009; MONTEIRO et al., 2011). According to Eiras (1994) and Seppälä et al. (2005), the presence of Diplostomidae metacercariae in eyes of fishes can cause loss of vision, blindness and increases the coverage of cataracts of the lens area in fish with high rates of infection. This makes the fish more susceptible to predation and facilitates the transmission of the parasite to the definitive hosts (SEPPÄLÄ et al., 2004). However, a few Brazilian fish species were evaluated for the presence of A. compactum metacercariae and their possible effects. This study reports the occurrence of A. compactum in fish species from the Paranapanema River and its parasitological indexes, as well as several considerations regarding ecological aspects and a checklist for fishes parasitised in Brazil. Materials and Methods This study was conducted in the Chavantes reservoir (medium Paranapanema River), municipality of Ipaussu, São Paulo State, Brazil (23° 07’ 36” S and 49° 59.23’ 10” W) (Figure 1 and Table 1). Fish samples were collected monthly from March 2009 to February 2010 using gillnets (3 to 14 cm meshes between adjacent nodes) with 14 hours of exposure (from 5:00 PM to 7:00 AM). All Table 1. Physical and chemical characteristics (mean and standard error) of the sampling sites in the Chavantes Reservoir, municipality of Ipaussu, São Paulo State, southeast Brazil from Carvalho et al. (2012a). Sites Values ± SE Water temperature (°C) 23.8±2.5 Water transparency (m) 3.1±0.8 Dissolved oxygen (mg O2.L –1) 8.2±1.7 pH 7.1±0.3 Conductivity (µS.cm–1) 40.3±6.2 Depth (m) 11.7±0.4 Chlorophyll a (µg.L–1) 1.9±1.3 Total P (µg.L–1) 9.7±4.1 Total N (µg.L–1) 236.0±78.7 Figure 1. Map of the hydrographical network in São Paulo State highlighting the Chavantes reservoir and sampling location on the Paranapanema River in the municipality of Ipaussu, São Paulo State, southeast Brazil. 512 Austrodiplotomum compactum in Brazilian fishes captured fishes were frozen and transported to the laboratory where their eyes were removed and examined with a stereomicroscope. The metacercariae were collected from the vitreous humour, fixed in 70% alcohol under cover slip pressure and preserved in 70% alcohol (EIRAS et al., 2006). The metacercariae were stained with carmine and cleared with eugenol for identification. Morphological analyses were performed with a computerised system for image analysis (Qwin Lite 3.2 – Leica Microsystems, Wetzlar, Germany). Twenty-three fish species were analysed: ‘peixe-cachorro’, Acestrorhynchus lacustris n=33 (Lütken, 1875), ‘canivete’, Apareiodon affinis n=41 (Steindachner, 1879), ‘lambari-do-rabo-amarelo’, Astyanax altiparanae n=37 Garutti & Britski, 2000, ‘lambari-do- rabo-vermelho’, Astyanax fasciatus n=30 (Cuvier, 1819), ‘saguiru- do-rabo-vermelho’, Cyphocharax modestus n=1 (Fernández-Yépez, 1948), ‘peixe-cadela’, Galeocharax knerii n=32 (Steindachner, 1879), ‘traíra’, Hoplias malabaricus n=9 (Bloch, 1794), ‘piava’, Leporinus amblyrhynchus n=11 Garavello & Britski, 1987, ‘ferreirinha’, Leporinus octofasciatus n=1 Steindachner, 1915, ‘pacu’, Piaractus mesopotamicus n=3 (Holmberg, 1887), ‘ximborê’, Schizodon nasutus n=17 Kner, 1858, ‘piranha’, Serrasalmus maculatus n=21 Kner, 1858, ‘sardela’, Triportheus nematurus n=6 (Kner, 1858), ‘caborja’, Hoplosternum littorale n=11 (Hancock, 1828), ‘cascudo’, Hypostomus regani n=4 (Ihering,1905), ‘mandiuva’, Iheringichthys labrosus n=17 (Lütken, 1874), ‘mandi-guaçu’, Pimelodus maculatus n=34 Lacépède, 1803, ‘bagre’, Rhamdia quelen n=1 (Quoy & Gaimard, 1824), ‘tucunaré’, Cichla kelberi n=42 Kullander & Ferreira, 2006, ‘joaninha’, Crenicichla haroldoi n=1 Luengo & Britski, 1974, ‘acará’, Geophagus brasiliensis n=2 (Quoy & Gaimard, 1824), ‘corvina’, Plagioscion squamosissimus n=30 (Heckel, 1840), and ‘tuvira’, Eigenmannia trilineata n=11 López & Castello, 1966. The prevalence, mean intensity of infection and mean abundance were calculated according to Bush et al. (1997) for fish species with at least nine specimens collected. Parasite voucher specimens were deposited in the Coleção Helmintológica do Departamento de Parasitologia (CHIBB 6723, 6974-6985) at the Instituto de Biociências, Universidade Estadual Paulista (IB/UNESP), municipality of Botucatu, São Paulo State, Brazil. Fish voucher specimens were identified and deposited by Dr. Cláudio de Oliveira in the Coleção do Laboratório de Biologia e Genética de Peixes (LBP 4797, 9192, 9174, 9179, 9181, 9183, 9184, 9185, 9186, 9191, 9194) at IB/UNESP and the Coleção Ictiológica do Nupélia (NUP 6117), Universidade Estadual de Maringá, municipality of Maringá, Paraná State, Brazil. A review of the fishes infected with A. compactum in Brazil was performed using books (EIRAS et al., 2010) and by searching databases (SciELO, ISI, Scopus and Google Scholar). When available, data regarding the prevalence, mean intensity of infection and mean abundance along with their errors or standard deviations were added to the Table. In cases where these data do not exist but data does exist that enable their calculations, we performed the calculations according to the method described by Bush et al. (1997). Results In the present study, the fish collected in the Paranapanema River showed a total of 357 A. compactum metacercariae, recovered from 43 fish specimens. Thirteen fish species were infected by at least one parasite (56.5% of the fish species analysed), C. kelberi, C. haroldoi, E. trilineata, G. brasiliensis, H. regani, H. littorale, H. malabaricus, I. labrosus, L. amblyrhynchus, P. mesopotamicus, P. maculatus, P. squamosissimus, and S. nasutus, of which, two were non-native species, C. kelberi and P. squamosissimus. Of the thirteen species of fish parasitised (192 specimens), the prevalence was 22.3% (43 fishes). Six freshwater fish species were identified as new hosts for A. compactum metacercariae, C. haroldoi, E. trilineata, H. littorale, I. labrosus, L. amblyrhynchus, and P. mesopotamicus, totalling 46.2% of the infected fish species and 26.1% for all the fish species analysed. Three fish orders, Characiformes, Perciformes, and Siluriformes had four parasitised fish species, and Gymnotiformes had one infected fish species. The Cichlidae family had three infected species (23.1%), followed by Pimelodidae and Anostomidae, with two infected species each (15.4%) (Table 2). The overall prevalence was 10.9%, and the highest prevalence was observed in P. squamosissimus (66.6%), followed by E. trilineata (54.5%) and I. labrosus (11.8%). The mean intensity of infection and mean abundance were low for all fish species, with P. squamosissimus having the highest values (13.1±6.1 and 8.7±4.2, respectively). All other fish species had values less than or equal to 2.0 for the mean intensity of infection and less than 1.0 for the mean abundance (Table 2). Austrodiplostomum compactum metacercariae parasitised 36 Brazilian fish species and two taxa not identified (Cichla sp. and Hypostomus sp.) belonging to 13 families and four orders. The reports identified the fish species as follows: Characiformes (families: Anostomidae, three species; Curimatidae, one species; Erythrinidae, one species; and Serrasalmidae, four species); Siluriformes (families: Auchenipteridae, two species; Callichthyidae, one species; Loricariidae, eight species; and Pimelodidae, three species); Gymnotiformes (families: Gymnotidae, one species; and Sternopygidae, one species); and Perciformes (families: Centropomidae, one species; Cichlidae, 10 species; and Sciaenidae, one species). Eight infected fish species are non-native according to Langeani et al. (2007): Cichla sp., C. kelberi, C. ocellaris, G. proximus, G. surinamensis, Metynnis maculatus, P. squamosissimus and Satanoperca pappaterra (Table 2). Of the 36 fish species parasitised, only eight showed a mean abundance higher than five metacercariae. Of these fishes, six are non-native species of the order Perciformes. The non-native species, P. squamosissimus had the highest mean abundance of all the parasitised species (Table 2). The Paranapanema River showed the highest number of parasitised fish species (21), followed by the Paraná River (nine species), Tietê and Guandu Rivers (seven species each) and Grande River (two species). The other rivers had one fish infected species each (Table 2). Discussion Austrodiplostomum compactum metacercariae have been recorded in a wide variety of Brazilian fishes (Table 2). This study demonstrated that 56.5% of all fish species collected were infected. These fish species belong to four orders, Characiformes, v. 22, n. 4, out.-dez. 2013 513 Ramos, I.P. et al. Rev. Bras. Parasitol. Vet. Table 2. List of fish species reported as an intermediate host of Austrodiplostomum compactum metacercariae in Brazil. Number of specimens examined (N), prevalence (P), mean intensity of infection (MII), mean abundance (MA) and site of infection (SI). Taxa N P(%) MII MA SI State/River References Order Characiformes Family Erythrinidae Hoplias malabaricus (Bloch, 1794)* 9 11.1 1.0 0.1±0.1 E SP/Paranapanema present study Hoplias malabaricus** 198 11.1 1.4±1.3 0.2±0.6 E/CC PR/Paraná Machado et al. (2005) Hoplias malabaricus 7 14.3 9.0 1.3 E SP/Tietê Paes et al. (2010b) Hoplias malabaricus 28 60.7 32.6 19.8 E PR/Paraná Santos et al. (2012) Hoplias malabaricus 10 57.1 2.5 1.4 E MG/Doce Belei et al. (2013) Family Serrasalmidae Metynnis maculatus (Kner, 1858)£ 298 0.3 1 0.003 E SP/Tietê Paes et al. (2010b) Piaractus mesopotamicus (Holmberg, 1887)*§ 3 33.3 6.0 2.0±2.0 E SP/Paranapanema present study Pygocentrus nattereri Kner, 1858* 40 15.0 1.6±0.7 0.1±0.7 M AM/Solimões Morais et al. (2011) Serrasalmus maculatus Kner, 1858 3 33.3 1.0 0.3 E PR/Paranapanema Yamada et al. (2008) Family Anostomidae Leporinus amblyrhynchus Garavello & Britski, 1987*§ 11 9.1 2.0 0.2±0.2 E SP/Paranapanema present study Schizodon borellii (Boulenger, 1900) † - - - - - PR/Paraná Pavanelli et al. (1997) Schizodon borellii 15 6.6 2.0 0.1 E PR/Paranapanema Yamada et al. (2008) Schizodon nasutus Kner, 1858* 17 5.9 2.0 0.1±0.1 E SP/Paranapanema present study Schizodon nasutus 84 4.8 1.2 0.05 E SP/Tietê Paes et al. (2010b) Family Curimatidae Cyphocharax gilbert (Quoy & Gaimard, 1824) 60 1.6 1.0 0.01 E RJ/Guandu Abdallah et al. (2005) Order Siluriformes Family Auchenipteridae Auchenipterus osteomystax (Miranda Ribeiro, 1918) 2 50.0 1.0 0.5 E PR/Paranapanema Yamada et al. (2008) Trachelyopterus striatulus (Steindachner, 1877)* 60 1.6 1.0±0.5 0.02±0.3 E RJ/Guandu Mesquita et al. (2011) Family Callichthyidae Hoplosternum littorale (Hancock, 1828)*§ 11 9.1 1.0 0.1±0.1 E SP/Paranapanema present study Family Loricariidae Hypostomus sp.* 5 40.0 17.5±16.5 7.0±6.8 E SP/Paranapanema Zica et al. (2011) Hypostomus affinis (Steindachner, 1877) 31 - - - - RJ/Guandu Azevedo et al. (2010) Hypostomus hermanni (Ihering, 1905) 1 100 27.0 27.0 E SP/Paranapanema Zica et al. (2011) Hypostomus iheringii (Regan, 1908)* 28 64.3 13.1±3.2 8.4±2.4 E SP/Paranapanema Zica et al. (2011) Hypostomus margaritifer (Regan, 1908) 1 100 35.0 35.0 E SP/Paranapanema Zica et al. (2011) Hypostomus regani (Ihering, 1905)* 4 50.0 21.0±18.0 10.5±9.5 E SP/Paranapanema present study Hypostomus regani 8 25.0 0.5 0.1 E PR/Paranapanema Yamada et al. (2008) Hypostomus regani 1 100 1.0 1.0 E SP/Paranapanema Zica et al. (2009) Hypostomus regani 3 33.3 10.0 3.3±3.3 E SP/Paranapanema Zica et al. (2011) Hypostomus strigaticeps (Regan, 1908)* 45 24.4 10.3±2.4 2.7±0.9 E SP/Paranapanema Zica et al. (2011) Loricariichthys castaneus (Castelnau, 1855)* 30 30 13.6 4.1±10.4 E RJ/Paraiba do Sul Paraguassú and Luque (2007) Family Pimelodidae Conorhynchos conirostris (Valenciennes, 1840)* 24 8.3 7.5±9.2 0.6±0.4 G/E MG/S. Francisco Brasil-Sato and Santos (2005) Iheringichthys labrosus (Lütken, 1874)*§ 17 11.8 1.0±0.0 0.1±0.08 E SP/Paranapanema present study Pimelodus maculatus Lacepède, 1803* 34 5.9 2.0±1.0 0.1±0.1 E SP/Paranapanema present study Pimelodus maculatus† 239 20.5 4.0 0.8 SB/K/G MG/São Francisco Brasil-Sato and Pavanelli (2004) Pimelodus maculatus† 229 1.3 1.0 0.01 SB/K/G PR/Paraná Brasil-Sato and Pavanelli (2004) Pimelodus maculatus**† 28 17.0 1 0.2±0.4 E SC/Itajaí-Açu Bachmann et al. (2007) Pimelodus maculatus 60 16.6 1.1 0.2 E RJ/Guandu Santos et al. (2007) Pimelodus maculatus 40 - - - - RJ/Guandu Azevedo et al. (2010) * The values are presented as the mean and standard error; ** the values are presented as the mean and standard deviation; £ non-native fish species; § new host; † parasite identified as Austrodiplostomum sp. or Diplostomum sp.; E eye; CC cranial cavity; G gills; M muscle; SB swimming bladder; K kidney; CF cage farm; CT control. 514 Austrodiplotomum compactum in Brazilian fishes Taxa N P(%) MII MA SI State/River References Order Gymnotiformes Family Gymnotidae Gymnotus carapo Linnaeus, 1758 30 - - - - RJ/Guandu Azevedo et al. (2010) Family Sternopygidae Eigenmannia trilineata López & Castello, 1966*§ 11 54.5 1.3±0.2 0.7±0.2 E SP/Paranapanema present study Order Perciformes Family Centropomidae Centropomus undecimalis (Bloch, 1792) 31 - - - - RJ/Guandu Azevedo et al. (2010) Family Cichlidae Cichla sp.£ 23 52.2 5.9 3.1 E PR/Paraná Santos et al. (2012) Cichla kelberi Kullander & Ferreira, 2006*£ 42 7.1 2.0±0.6 0.1±0.1 E SP/Paranapanema present study Cichla kelberi (=C. monoculus)£ 136 5.2 2.7 0.1 E PR/Paraná Machado et al. (2000) Cichla kelberi (=C. monoculus)**£ 40 65.0 7.8±13.0 5.1±11.1 E/CC PR/Paraná Machado et al. (2005) Cichla ocellaris Bloch & Schneider, 1801£ 66 10.6 6.3 0.6 E MG/Grande Martins et al. (2002) Cichla ocellaris£ 81 55.5 9.3 5.2 E SP/Paraná Santos et al. (2002) Cichla piquiti£† 27 0.3 13.4 3.5 E PR/Paraná Lacerda et al. (2013) Cichla piquiti† 24 0.1 1.0 0.1 E TO/Tocantins Lacerda et al. (2013) Cichlasoma paranaense Kullander, 1983** 25 12.0 1.0±0.0 0.1±0.3 E PR/Paraná Machado et al. (2005) Crenicichla britskii Kullander, 1982** 44 22.7 6.2±9.0 1.4±4.9 E/CC PR/Paraná Machado et al. (2005) Crenicichla haroldoi Luengo & Britski, 1974§ 1 100 6.0 6.0 E SP/Paranapanema present study Geophagus brasiliensis (Quoy & Gaimard, 1824)* 2 100 8.0±5.0 8.0±5.0 E SP/Paranapanema present study Geophagus brasiliensis* 50 14.0 1.6±1.1 0.2±0.2 E RJ/Guandu Azevedo et al. (2006) Geophagus brasiliensis 1 100 1.0 1.0 E SP/Tietê Novaes et al. (2006) Geophagus brasiliensis* 200 18.0 2.1±1.4 0.4±1.0 E/SB RJ/Guandu Carvalho et al. (2010) Geophagus brasiliensis 64 3.1 4.0 0.1 E PR/several rivers Bellay et al. (2012) Geophagus brasiliensis* 200 18.0 2.1±1.4 0.4±1.0 E/SB RJ/Guandu Carvalho et al. (2012b) Geophagus proximus (Castelnau, 1855)* £ 41 92.7 12.8±5.1 11.8±4.7 E SP/Tietê Zica et al. (2010) Geophagus proximus*£ 116 58.6 3.6±0.5 2.1±0.3 E SP/S. J. Dourados Zago et al. (2013) Geophagus surinamensis (Bloch, 1791)£ 40 45.0 13.8 6.2 E PR/Paraná Santos et al. (2012) Satanoperca pappaterra (Heckel, 1840)£ † - - - - - PR/Paraná Pavanelli et al. (1997) Satanoperca pappaterra (Heckel, 1840)** £ 89 71.9 8.0±8.6 5.8±8.1 E/CC PR/Paraná Machado et al. (2005) Satanoperca pappaterra£ 25 60.0 6.4 3.8 E SP/Tietê Paes et al. (2010b) Family Sciaenidae Plagioscion squamosissimus (Heckel, 1840)* £ 30 66.7 13.1±6.1 8.7±4.2 E SP/Paranapanema present study Plagioscion squamosissimus£ 17 100.0 2-100/eye E PR/Paraná Kohn et al. (1995) Plagioscion squamosissimus£ - - - - - PR/Paraná Pavanelli et al. (1997) Plagioscion squamosissimus£ 68 45.6 7.1 3.2 E MG/Grande Martins et al. (1999) Plagioscion squamosissimus£ 70 52.8 5.3 2.8 E MG/Grande Martins et al. (2002) Plagioscion squamosissimus£ 61 91.8 42.0 38.5 E SP/Paraná Santos et al. (2002) Plagioscion squamosissimus**£ 81 95.1 38.9±64.3 37.0±63.2 E/CC PR/Paraná Machado et al. (2005) Plagioscion squamosissimus£ 378 94.2 21.7 20.4 E SP/Tietê Paes et al. (2010a) Plagioscion squamosissimus£ 213 90.1 20.8 18.7 E SP/Tietê Paes et al. (2010b) Plagioscion squamosissimus£ 61 36.1 - - E PR/Paraná Kohn et al. (2011) Plagioscion squamosissimus**£† 35 88.6 98.8 87.5±153.3 E PR/Paraná Lacerda et al. (2012) Plagioscion squamosissimus**† 35 40.0 10.8 4.3±7.8 E AM/Solimões Lacerda et al. (2012) Plagioscion squamosissimus**† 35 8.3 2.9 0.1±0.5 E TO/Tocantins Lacerda et al. (2012) Plagioscion squamosissimus£ 57 98.0 42.7 41.9 E PR/Paraná Santos et al. (2012) Plagioscion squamosissimus CF*£ 37 86.4 20.3±1.1 17.7±6.3 E SP/Paranapanema Ramos et al. (2013) Plagioscion squamosissimus CT*£ 28 57.1 4.3±7.1 2.3±0.8 E SP/Paranapanema Ramos et al. (2013) * The values are presented as the mean and standard error; ** the values are presented as the mean and standard deviation; £ non-native fish species; § new host; † parasite identified as Austrodiplostomum sp. or Diplostomum sp.; E eye; CC cranial cavity; G gills; M muscle; SB swimming bladder; K kidney; CF cage farm; CT control. Table 2. Continued... v. 22, n. 4, out.-dez. 2013 515 Ramos, I.P. et al. Rev. Bras. Parasitol. Vet. Perciformes, Siluriformes and Gymnotiformes, and six new records of hosts to these metacercariae. Thus, the number of Brazilian fish species infected by A. compactum increased to 36, and the number of families parasitised for 13. Based on these observations, we hypothesise that this larval stage of the parasite has a low specificity for the second intermediate host (fish), similar to that reported by Yamada et al. (2008). In addition, the six new hosts identified in the present study demonstrates that parasitological studies with fish communities should significantly expand the list of fish identified as second intermediate hosts for A. compactum. The mean intensity of infection for the analysed fish species was lower than Höglund and Thulin (1990), who reports that fish harbouring more than 40 Diplostomum metacercariae on their eyes are largely parasitized. According to several authors, the high infection rate with diplostomid metacercariae in fish can cause blindness or visual impairment (EIRAS, 1994), cataracts (SHARIFF et al., 1980; KARVONEN et al., 2004), problems with a food intake and growth (OWEN et al., 1993) and increased susceptibility to predation (CROWDEN; BROOM, 1980; SEPPÄLÄ et al., 2004). However, Karvonen et al. (2004) and Owen et al. (1993) report effects in fish with less than 10 Diplostomum spathaceum metacercariae (Rudolphi, 1819) and correlations between the number of metacercariae and the intensity of the effect. Another study reported that fish heavily infected with D. spathaceum occupied surface waters with more frequency, exposing them to higher levels of predation by birds. Therefore, fish with high infection rates would be subject to the effects of parasitism by A. compactum metacercariae, and fish with low infection show less intense effects of parasitism. Among these effects is the difficulty to detect prey, which results in fitness consequences for the individual (OWEN et al., 1993). The prevalence of A. compactum in the present study is low, with exception of the prevalence in E. trilineata and P. squamosissimus. Studies of the infection of A. compactum in P. squamosissimus showed a prevalence greater than 90% and a mean intensity of infection greater than 20 (KOHN et al., 1995; SANTOS et al., 2002, 2012; MACHADO et al., 2005; PAES et al., 2010a, b), whereas in the current study, the prevalence was 66.6% and the mean intensity of infection was 13.1±6.1. According to Karvonen et al. (2006), the infection dynamics of D. spathaceum in fish is related to the snail population variance. Voutilainen et al. (2009) found a positive correlation between Lymnaea stagnalis (Linnaeus, 1758) density (an intermediate host for Diplostomum spp. in Finland) and Diplostomum sp. prevalence in lakes and ponds in Finland. Additionally, Martins et al. (2002) and Santos et al. (2002, 2012) suggested that high infection rates of A. compactum are dependent on high temperatures. According to Berrie (1960), Diplostomum cercariae emerge in waters only at temperatures greater than 10 °C. Despite the high water temperature observed in the current study location (CARVALHO et al., 2012a), which may lead to a high intensity of infection, the values of water transparency, conductivity and chlorophyll a (Table 1), suggest a small quantity of available nutrients in the local aquatic ecosystem. This can limit the size of the snail populations (first intermediate hosts), leading to the low values observed for the prevalence, mean intensity of infection and mean abundance for the majority fish species analysed. The majority of fish species infected with A. compactum metacercariae in Brazil belong to the Perciformes (12 species), Siluriformes (13 species), and Characiformes (nine species), and the Cichlidae (10 species) and Loricariidae (eight species) families were the most infected. However, the other fish species analysed in this study also live in this habitat and were not infected. Therefore, the absence of A. compactum metacercariae infection in these fish species may be related to species-specific characteristics, which remain unknown. For the fish species with higher mean abundances in Brazil, six are non-native species, and currently, P. squamosissimus has the highest mean abundance. This was also demonstrated by Pojmanska and Chabros (1993), who showed that the prevalence of diplostomids was significantly lower in native fishes than non- native fishes. However, Lacerda et al. (2012) demonstrated an inverse situation in which the native fish H. malabaricus showed a higher abundance of Austrodiplostomum sp. than the introduced P. squamosissimus. Lacerda et al. (2012) also demonstrated that P. squamosissimus in native regions showed a prevalence and abundance of diplostomids that was significantly lower than P. squamosissimus in the region where they were introduced. According to Lacerda et al. (2012), migratory birds, such as P. brasilianus are the final hosts for Austrodiplostomum; therefore, geographic barriers for the parasite may be reduced or eliminated. Rather than introducing a new parasite, P. squamosissimus may be acting as a new and suitable host for a local parasite. This may also occur with other species of fish, such as the six non-native Brazilian fish species, which had higher abundances. The majority of infected fish species are in the Paranapanema River. Specifically, the Paraná basin is the most studied region for A. compactum in Brazil, and this is possibly related to the distribution of researchers in Brazil. Despite the large number of studies, further investigations are necessary to understand the relationship between environmental aspects and life strategies because diplostomiasis causes large aquaculture losses each year worldwide (PAPERNA; DZIKOWSKI, 1995; OVERSTREET; CURRAN, 2004). Acknowledgments The authors are grateful to the Instituto de Biociências de Botucatu (IBB) and Centro de Aquicultura (CAUNESP) – Universidade Estadual Paulista “Júlio de Mesquita Filho” – UNESP, for the use of laboratory facilities and logistics. This study complies with current Brazilian laws. This study was supported by FINEP (Financiadora de Estudos e Pesquisas - process number: 3626/05) and FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo - process number 2008/58792-1). References Abdallah VD, Azevedo RK, Luque JL. Ecologia da comunidade de metazoários parasitos do sairú Cyphocharax gilbert (Quoy e Gaimard, 1824) (Characiformes: Curimatidae) do rio Guandu, estado do Rio de Janeiro, Brasil. Rev Bras Parasitol Vet 2005; 14(4): 154-159. PMid:16445872. Azevedo RK, Abdallah VD, Luque JL. Ecologia da comunidade de metazoários parasitos do acará Geophagus brasiliensis (Quoy e Gaimard, 1824) (Perciformes: Cichlidae) do rio Guandu, Estado do Rio 516 Austrodiplotomum compactum in Brazilian fishes de Janeiro, Brasil. Acta Sci Biol Sci 2006; 28(4): 403-411. http://dx.doi. org/10.4025/actascibiolsci.v28i4.406 Azevedo RK, Abdallah VD, Luque JL. Acanthocephala, Annelida, Arthropoda, Myxozoa, Nematoda and Platyhelminthes parasites of fishes from the Guandu river, Rio de Janeiro, Brazil. Check List 2010; 6(4): 659-667. Bachmann F, Greinert JA, Bertelli PW, Silva HH Fº, Lara NOT, Ghiraldelli L, et al. Parasitofauna de Pimelodus maculatus (Osteichthyes: Pimelodidae) do rio Itajaí-Açu em Blumenau, estado de Santa Catarina, Brasil. Acta Sci Biol Sci 2007; 29(1): 109-114. http://dx.doi.org/10.4025/ actascibiolsci.v29i1.159 Belei F, Ferreira SR, Perin LM, Braga FR, Sampaio WMS, Araújo JV, et al. First report of Austrodiplostomum compactum and Ithyoclinostomum dimorphum in trahira (Hoplias malabaricus) from the middle course of the Rio Doce, Minas Gerais, Brazil. Arq Inst Biol 2013; 80(2): 249-252. http://dx.doi.org/10.1590/S1808-16572013000200017 Bellay S, Ueda BH, Takemoto RM, Lizama MAP, Pavanelli GC. Fauna parasitária de Geophagus brasiliensis (Perciformes: Cichlidae) em reservatórios do estado do Paraná, Brasil. R Bras Bioci 2012; 10(1): 74-78. Berrie AD. Two Diplostomulum larvae (Strigeida, Trematoda) in the eyes of sticklebacks (Gasterosteus aculeatus L.). J Helminthol 1960; 34(3-4): 211-216. http://dx.doi.org/10.1017/S0022149X00021143 Brasil-Sato MC, Pavanelli GC. Digenea de Pimelodus maculatus (Osteichthyes, Pimelodidae) das bacias dos rios São Francisco e Paraná, Brasil. Parasitol Latinoam 2004; 59(3-4): 123-131. Brasil-Sato MC, Santos MD. Metazoan parasites of Conorhynchos conirostris (Valenciennes, 1840), an endemic siluriform fish of the São Francisco basin, Brazil. Rev Bras Parasitol Vet 2005; 14(4): 160-166. Bush AO, Lafferty KD, Lotz JM, Shostak AW. Parasitology meets ecology on its own terms: Margolis et al. revisited. J Parasitol 1997; 83(4): 575-583. PMid:9267395. http://dx.doi.org/10.2307/3284227 Carvalho AR, Tavares LER, Luque JL. Variação sazonal dos metazoários parasitos de Geophagus brasiliensis (Perciformes: Cichlidae) no rio Guandu, Estado do Rio de Janeiro, Brasil. Acta Sci Biol Sci 2010; 32(2): 159-167. http://dx.doi.org/10.4025/actascibiolsci.v32i2.4883 Carvalho ED, Silva RJ, Ramos IP, Paes JVK, Zanatta AS, Brandão H,  et  al. Ecological Features of Large Neotropical Reservoirs and Its Relation to Health of Cage Reared Fish. In: Carvalho ED, David-Silva G, Silva RJ. Health and environment in aquaculture. Rijeka: InTech; 2012a. p. 361-382. http://dx.doi.org/10.5772/2462 Carvalho AR, Azevedo RK, Abdallah VD, Luque JLF. Metacercárias de Diplostomidae (Digenea: Diplostomoidea) em Geophagus brasiliensis (Perciformes: Cichlidae) do rio Guandu, Estado do Rio de Janeiro, Brasil. Acta Sci Biol Sci  2012b;  34(2):  233-239. http://dx.doi.org/10.4025/ actascibiolsci.v34i2.5957 Crowden AE, Broom DM. Effects of the eyefluke, Diplostomum spathaceum, on the behaviour of dace (Leuciscus leuciscus). Anim Behav  1980;  28(1):  287-294. http://dx.doi.org/10.1016/S0003- 3472(80)80031-5 Eiras JC. Elementos de ictioparasitologia. Porto: Fundação Engenheiro Antônio de Almeida; 1994. Eiras JC, Takemoto MR, Pavanelli GC. Métodos de estudo e técnicas laboratoriais em parasitologia de peixes. 2nd ed. Maringá: EdUEM; 2006. Eiras CJ, Takemoto MR, Pavanelli GC. Diversidade dos parasitas de peixes de água doce do Brasil. Maringá: Clichetec; 2010. Höglund J, Thulin J. The epidemiology of the metacercariae of Diplostomum baeri and D. spathaceum in perch (Perca fluviatilis) from the warm water effluent of a nuclear power station. J Helminthol 1990; 64(2): 139-150. PMid:2387975. http://dx.doi.org/10.1017/S0022149X00012050 Karvonen A, Sepällä O, Valtonen ET. Eye fluke-induced cataract formation in fish: quantitative analysis using an ophthalmological microscope. Parasitology  2004;  129(Pt4):  473-478. http://dx.doi. org/10.1017/S0031182004006006 Karvonen A, Savolainen M, Seppälä O, Valtonen ET. Dynamics of Diplostomum spathaceum infection in snail hosts at a fish farm. Parasitol Res  2006;  99(4):  341-345. http://dx.doi.org/10.1007/s00436-006- 0137-8 Kohn A, Fernandes BMM, Baptista-Farias MFD. Metacercariae of Diplostomum (Austrodiplostomum) compactum (Trematoda, Diplostomidae) in the eyes of Plagioscion squamosissimus (Teleostei, Sciaenidae) from the reservoir of the Hydroelectric Power Station of Itaipu, Brazil. Mem Inst Oswaldo Cruz 1995; 90(3): 341-344. http:// dx.doi.org/10.1590/S0074-02761995000300005 Kohn A, Moravec F, Cohen SC, Canzi C, Takemoto RM, Fernandes BMM. Helminths of freshwater fishes in the reservoir of the Hydroelectric Power Station of Itaipu, Paraná, Brazil. Check List 2011; 7(5): 681-690. Lacerda ACF, Takemoto RM, Tavares-Dias M, Poulin R, Pavanelli GC. Comparative parasitism of the fish Plagioscion squamosissimus in native and invaded river basins. J Parasitol 2012; 98(4): 713-717. http://dx.doi. org/10.1645/GE-2882.1 Lacerda ACF, Takemoto RM, Poulin R, Pavanelli GC. Parasites of the fish Cichla piquiti (Cichlidae) in native and invaded Brazilian basins: release not from the enemy, but from its effects. Parasitol Res 2013; 112(1): 279- 288. PMid: 23052767. http://dx.doi.org/10.1007/s00436-012-3135-z Langeani F, Corrêa e Castro RM, Oyakawa OT, Shibatta OA, Pavanelli CS, Casatti L. Diversidade da ictiofauna do Alto Rio Paraná: composição atual e perspectivas futuras. Biota Neotrop 2007; 7(3): 181-197. Machado PM, Almeida SC, Pavanelli GC, Takemoto RM. Ecological aspects of endohelminths paraziting Cichla monoculus Spix,  1831 (Perciformes: Cichlidae) in the Paraná River near Porto Rico, State of Paraná, Brazil. Comp Parasitol 2000; 27(2): 210-217. Machado PM, Takemoto RM, Pavanelli GC. Diplostomum (Austrodiplostomum) compactum (Lutz, 1928) (Platyhelminthes, Digenea) metacercariae in fish from the floodplain of the Upper Paraná River, Brazil. Parasitol Res 2005; 97(6): 436-444. http://dx.doi.org/10.1007/ s00436-005-1483-7 Martins ML, Fujimoto RY, Nascimento AA, Moraes FR. Ocorrência de Diplostomum sp. Nordmann, 1832 (Digenea: Diplostomatidae), em Plagioscion squamosissimus Heckel, 1840, proveniente do Reservatório de Volta Grande, MG, Brasil. Acta Sci 1999; 21(2): 263-266. Martins ML, Paiva AMFC, Fujimoto RY, Schalch SHC, Colombano NC. Prevalência, sazonalidade e intensidade de infecção por Diplostomum (Austrodiplostomum) compactum Lutz, 1928 (Digenea, Diplostomidae), em peixes do reservatório de Volta Grande, Estado de Minas Gerais, Brasil. Acta Sci Biol Sci 2002; 24(2): 469-474. Mesquita RLB, Azevedo RK, Abdallah VD, Luque JL. Ectoparasites as numerical dominant species in parasite community of Trachelyopterus striatulus (Siluriformes: Auchenipteridae) from Guandu River, southeastern Brazil. Braz J Biol 2011; 71(3): 623-627. PMID: 21881785. http://dx.doi.org/10.1590/S1519-69842011000400006 Monteiro CM, Amato JFR, Amato SB. Helminth parasitism in the Neotropical cormorant, Phalacrocorax brasilianus, in Southern Brazil: effect of host size, weight, sex, and maturity state. Parasitol Res  2011;  109(3):  849-855. http://dx.doi.org/10.1007/s00436-011- 2311-x v. 22, n. 4, out.-dez. 2013 517 Ramos, I.P. et al. Rev. Bras. Parasitol. Vet. Morais AM, Varella AMB, Fernandes BMM, Malta JCO. Clinostomum marginatum (Braun,  1899) and Austrodiplostomum compactum (Lutz,  1928) metacercariae with zoonotic potencial on Pygocentrus nattereri (Kner,  1858) (Characiformes: Serrasalmidae) from Central Amazon, Brazil. Neotrop Helminthol 2011; 5(1): 8-15. Noronha D, Sá MR, Knoff M, Muniz-Pereira LC, Pinto RM. Adolpho Lutz e a coleção helmintológica do Instituto Oswaldo Cruz. Rio de Janeiro: Museu Nacional; 2009. Novaes JLC, Ramos IP, Carvalho ED, Silva RJ. Metacercariae of Diplostomum compactum Lutz, 1928 (Trematoda, Diplostomidae) in the eyes of acará Geophagus brasiliensis Quoy & Gaimard, 1824 (Teleostei, Cichlidae) from Barra Bonita Reservoir – São Paulo, Brazil. Arq Bras Med Vet Zootec  2006;  58(6):  1229-1231. http://dx.doi.org/10.1590/ S0102-09352006000600037 Overstreet R, Curran S. Defeating diplostomoid dangers in USA catfish aquaculture. Folia Parasitol 2004; 51(2-3): 153-165. PMid:15357393. Owen SF, Barber I, Hart PJB. Low level infection by eye fluke, Diplostomum spp., affects the vision of three-spined sticklebacks, Gasterosteus aculeatus. J Fish Biol 1993; 42(5): 803-806. http://dx.doi. org/10.1111/j.1095-8649.1993.tb00387.x Paes JVK, Carvalho ED, Silva RJ. Infection by Austrodiplostomum compactum metacercariae in fish from the Nova Avanhandava Reservoir, Tietê River, São Paulo, Brazil. Acta Sci 2010a; 32(3): 273-278. http:// dx.doi.org/10.4025/actascibiolsci.v32i3.5675 Paes JVK, Carvalho ED, Silva RJ. Infection levels of Austrodiplostomum compactum (Digenea, Diplostomidae) metacercariae in Plagioscion squamosissimus (Teleostei, Sciaenidae) from the Nova Avanhandava reservoir, São Paulo State, Brazil. J Helminthol 2010b; 84(3): 284-291. PMid:19889255. http://dx.doi.org/10.1017/S0022149X09990617 Paperna I, Dzikowski R. Digenea (Phylum Platyhelminthes). In: Woo PT. Fish diseases and disorders. Vol. I: protozoans and metazoan infections. Wallingford: CAB International; 1995. p. 345-390. Paraguassú AR, Luque JL. Metazoários parasitos de seis espécies de peixes do reservatório de Lajes, estado do Rio de Janeiro, Brasil. Rev Bras Parasitol Vet  2007;  16(3):  121-128. http://dx.doi.org/10.1590/ S1984-29612007000300002 Pavanelli GC, Machado MH, Takemoto RM. Fauna helmintica de peixes do rio Paraná, região de Porto Rico, Paraná. In: Vazzoler AEAM, Agostinho AA, Hahn NS. A planície de inundação do alto rio Paraná: aspectos físicos, biológicos e sócioeconômicos. Maringá: EdUEM; 1997. p. 307-329. Pinto HA, Melo AL. Biomphalaria straminea and Biomphalaria glabrata (Mollusca: Planorbidae) as new intermediate hosts of the fish eyefluke Austrodiplostomum compactum (Trematoda: Diplostomidae) in Brazil. J Parasitol 2013; 99(4): 729-733. http://dx.doi.org/10.1645/12-13.1 Pojmanska T, Chabros M. Parasites of common carp and three introduced cyprinid fish in pond culture. Acta Parasitol 1993; 38(3): 101-108. Ramos IP, Francheschini L, Zica EOP, Carvalho ED, Silva RJ. The influence of cage farming on infection of the corvine fish Plagioscion squamosissimus (Perciformes: Sciaenidae) with metacercariae of Austrodiplostomum compactum (Digenea: Diplostomidae) from the Chavantes reservoir, São Paulo State, Brazil. J Helminthol 2013; 30: 1-7. http://dx.doi.org/10.1017/S0022149X13000229 Santos RS, Pimenta FDA, Martins ML, Takahashi HK, Marengoni NG. Metacercárias de Diplostomum (Austrodiplostomum) compactum Lutz, 1928 (Digenea: Diplostomidae) em peixes do rio Paraná, Brasil. Prevalência, sazonalidade e intensidade de infecção. Acta Sci Biol Sci 2002; 24(2): 475-480. Santos MD, Lemos-Pita SRLC, Brasil-Sato MC. Metazoan parasite fauna of Pimelodus maculatus La Cépède, 1803 (Siluriformes, Pimelodidae) from the Guandu river, Rio de Janeiro State, Brazil. Acta Sci Biol Sci  2007;  29(1):  101-107. http://dx.doi.org/10.4025/actascibiolsci. v29i1.130 Santos RS, Marchiori N, Santarem VA, Takahashi K, Mourino JLP, Martins ML. Austrodiplostomum compactum (Lutz,  1928) (Digenea, Diplostomidae) in the eyes of fishes from Paraná River, Brazil. Acta Sci Biol Sci 2012; 34(2): 225-231. http://dx.doi.org/10.4025/actascibiolsci. v34i2.9337 Seppälä O, Karvonen A, Valtonen ET. Parasite-induced change in host behaviour and susceptibility to predation in an eye fluke–fish interaction. Anim Behav  2004;  68(2):  257-263. http://dx.doi.org/10.1016/j. anbehav.2003.10.021 Seppälä O, Karvonen A, Valtonen ET. Manipulation of fish host by eye flukes in relation to cataract formation and parasite infectivity. Anim Behav  2005;  70(4):  889-894. http://dx.doi.org/10.1016/j. anbehav.2005.01.020 Shariff M, Richards RH, Sommerville C. The histopathology of acute and chronic infections of rainbow trout Salmo gairdneri Richardson with eye flukes, Diplostomum spp. J Fish Dis 1980; 3(6): 455-465. http://dx.doi. org/10.1111/j.1365-2761.1980.tb00432.x Travassos L, Freitas T, Kohn A. Trematódeos do Brasil. Mem Inst Oswaldo Cruz 1969; 67(fasc. Único): 1-886. Violante-González J, García-Varela M, Rojas-Herrera A, Guerrero SG. Diplostomiasis in cultured and wild tilapia Oreochromis niloticus in Guerrero State, Mexico. Parasitol Res  2009; 105(3): 803-807. http:// dx.doi.org/10.1007/s00436-009-1458-1 Voutilainen A, Van Ooik T, Puurtinen M, Kortet R, Taskinen J. Relationship between prevalence of trematode parasite Diplostomum sp. and population density of its snail host Lymnaea stagnalis in lakes and ponds in Finland. Aquat Ecol 2009; 43(2) 351-357. http://dx.doi. org/10.1007/s10452-008-9203-x Yamada FH, Moreira LHA, Ceschini TL, Takemoto RM, Pavanelli GC. Novas ocorrências de metacercária de Austrodiplostomum compactum (Lutz, 1928) (Platyhelminthes: Digenea) parasito de olhos de peixes da bacia do rio Paraná. Rev Bras Parasitol Vet 2008; 17(3): 163-166. http:// dx.doi.org/10.1590/S1984-29612008000300010 Zago AC, Franceschini L, Zocoller-Seno MC, Veríssimo-Silveira R, Maia AAD, Ikefuti CV, et al. The helminth community of Geophagus proximus (Perciformes: Cichlidae) from a tributary of the Paraná River, Ilha Solteira Reservoir, São Paulo State, Brazil. J Helminthol 2013; 87(2): 203-211. http://dx.doi.org/10.1017/S0022149X12000223 Zica EOP, Santos KR, Ramos IP, Zanatta AS, Carvalho ED, Silva RJ. First case of an infection of the metacercariae of Austrodiplostomum compactum (Lutz, 1928) (Digenea, Diplostomidae) in Hypostomus regani (Ihering, 1905) (Siluriformes: Loricariidae). Panamjas 2009; 4(1): 35-38. Zica EOP, Wunderlich AC, Ramos IP, Silva RJ. Austrodiplostomum compactum (Lutz, 1928) (Digenea, Diplostomidae) infecting Geophagus proximus Castelnau, 1855 (Cichlidae, Perciformes) in the Tietê River, Nova Avanhandava reservoir, Municipality of Buritama, São Paulo State, Brazil. Neotrop Helminthol 2010; 4(1): 9-15. Zica EOP, Brandão H, Zawadzki CH, Nobile AB, Carvalho ED, Silva RJ. The occurrence of Austrodiplostomum compactum (Lutz, 1928) (Digenea: Diplostomidae) metacercariae in the eyes of loricariid fish (Siluriformes: Osteichthyes: Loricariidae) from Brazil. J Helminthol 2011; 85(1): 73-79. http://dx.doi.org/10.1017/S0022149X10000271 518