Biomphalaria stramineaandBiomphalaria glabrata(Mollusca: Planorbidae) as New Intermediate Hosts of the Fish EyeflukeAustrodiplostomum compactum(Trematoda: Diplostomidae) in Brazil

Abstract

Austrodiplostomum compactum has been involved in cases of ocular diplostomiasis in several species of fish in Brazil, but the molluscan intermediate hosts of the parasite remain unknown. In the present study, malacological surveys were carried out at Pampulha Reservoir, Belo Horizonte, Minas Gerais, Brazil, between January 2009 and July 2012. A total of 16,119 specimens of Biomphalaria spp. were collected and examined, of which 68/14,948 specimens (0.45%) of Biomphalaria straminea and 6/541 (1.11%) of Biomphalaria glabrata were found harboring a strigeid cercariae. Groups of 5 specimens of Cyprinius carpio were experimentally infected with these cercariae (100 larvae/fish), and metacercariae were recovered from the eyes of the fish, 65 days after infection, with a mean intensity of infection of 10.4 (8-13) metacercariae/fish. Morphological study on cercariae and metacercariae identified them as A. compactum . This is the first record of cercariae of A. compactum in Brazil, and B. straminea and B. glabrata as new intermediate hosts for the parasite.

Metacercariae of Austrodiplostomum spp. (Digenea: Diplostomidae) infecting the eyes and brains of fish in Brazilian Amazon

“…Austrodiplostomum spp. adults inhabit the digestive tract of piscivorous birds such as Phalacrocorax brasilianus (PINTO; MELO, 2013;MONTEIRO et al, 2016), which has a large presence in the area of the present study, together with Ardea alba, snails, and fish, are believed to maintain the biological cycle of A. compactum in the region of the Amazonian ecosystem investigated here.…”

“…The presence of these metacercariae at heightened levels of abundance can cause exophthalmos, displacement of the retina, opacity of the crystalline lens, blindness, and even the death of host fish (HECKMANN, 1992;BULLARD;OVESTREET, 2008;MONTEIRO et al, 2016;VITAL et al, 2016). The formation of cataracts in infected fish is more intense after the parasites complete their larval development and are ready to infect the definitive host, augmenting the susceptibility of intermediate host fish to predation (SANTOS et al, 2002;PINTO;MELO, 2013;CORRÊA et al, 2014). This is therefore an efficient transmission method for these digeneans (MOURITSEN;POULIN, 2003;VITAL et al, 2016).…”

Metacercarial Infection of Wild Nile Tilapia (Oreochromis niloticus) from Brazil

“…Nevertheless, it had not yet been reported in O. niloticus in the country. Adult parasites were found in Phalacrocorax brasilianus (Gmelin, 1789) in Brazil [ 26 ] and snails of the genus Biomphalaria Preston, 1910, are the first intermediate hosts [ 20 ]. The infection of O. niloticus with A. compactum , including reports of the occurrence of mortality, was previously reported in Mexico [ 28 ] and Panama [ 29 ].…”

Metacercariae of Austrodiplostomum compactum (Trematoda, Diplostomidae) in non-native fish species in Brazil: a possible explanation for the high rate of parasitic infection

“…In South America, diplostomiasis is mainly caused by species of the genus Austrodiplostomum Szidat & Nani, 1951. The adults of Austrodiplostomum compactum (Lutz, 1928) were recorded in several countries from America (Argentina, Brazil, U.S.A., Mexico and Venezuela) inhabit the intestine of the piscivorous birds Nannopterum auritus (Lesson, 1831) (=Phalacrocorax auritus) and Nannopterum brasilianus (Gmelin, 1789) (=Phalacrocorax brasilianus) (Szidat & Nani 1951, Dubois 1968, Ostrowski de Núñez 1982, Dronen 2009, Monteiro et al 2011, O'Hear et al 2014, Garcia-Varela et al 2016, Rosser et al 2016. Although, cercariae emerge from the tegument of gastropods such as: Biomphalaria straminea (Dunker, 1848), Biomphalaria glabrata (Say, 1818) (Pinto & Melo 2013), Biomphalaria prona (Martens, 1873) (Ostrowski de Núñez 1982), Biomphalaria obstructa (Morelet, 1849) (Rosser et al 2016) and larval forms (metacercariae) can inhabit the eyes of several species of freshwater fishes (Yamada et al 2008, Ramos et al 2013). According to Ramos et al (2013Ramos et al ( , 2016 and Campos et al (in press), metacercariae of A. compactum have been reported in 38 Brazilian fish species belonging to 13 families of four orders, highlighting the high infection rates in Plagioscion squamosissimus (Heckel, 1840).…”