Effect of wide spectrum anti-helminthic drugs upon Schistosoma mansoni experimentally infected mice

Mebendazole, albendazole, levamisole and thiabendazole are well known as active drugs against several nematode species, and against cestodes as well, when the first two drugs are considered. None of the drugs have proven activity, however, against trematodes. We tested the effect of these drugs on the fecal shedding of schistosome eggs and the recovering of adult schistosomes, after portal perfusion in Schistosoma mansoni experimentally infected mice. Balb/c mice infected with 80 S. mansoni cercariae were divided into three groups, each in turn subdivided into four other groups, for each tested drug. The first group was treated with each one of the studied drugs 25 days after S. mansoni infection; the second group was submitted to treatment with each one of the drugs 60 days after infection. Finally, the third group, considered as control, received no treatment. No effect upon fecal shedding of S. mansoni eggs and recovering of schistosomes after portal perfusion was observed when mice were treated with either mebendazole or albendazole. Mice treated with either levamisole or thiabendazole, on the other hand, showed a significant reduction in the recovering of adult schistosomes after portal perfusion, mainly when both drugs were given during the schistosomula evolution period, i.e., 25 days after cercariae penetration, probably due to unspecific immunomodulation

Genetic variation between susceptible and non-susceptible snails to Schistosoma infection using random amplified polymorphic DNA analysis (RAPDs)

Susceptibility of snails to infection by certain trematodes and their suitability as hosts for continued development has been a bewildering problem in host-parasite relationships. The present work emphasizes our interest in snail genetics to determine what genes or gene products are specifically responsible for susceptibility of snails to infection. High molecular weight DNA was extracted from both susceptible and non-susceptible snails within the same species Biomphalaria tenagophila. RAPD was undertaken to distinguish between the two types of snails. Random primers (10 mers) were used to amplify the extracted DNA by the polymerase chain reaction (PCR) followed by polyacrylamide gel electrophoresis (PAGE) and silver staining. The results suggest that RAPD represents an efficient means of genome comparison, since many molecular markers were detected as genetic variations between susceptible and non-susceptible snails.

Melanoides tuberculatus (Gastropoda: Thiaridae) as intermediate host of Heterophyidae (Trematoda: Digenea) in Rio de Janeiro metropolitan area, Brazil

In the late 1960s, Melanoides tuberculatus snails were introduced in Brazil from North/East Africa and Southeast Asia. The first records of specimens infected with cercariae were registered in Rio de Janeiro State in 2001. The present study reports the occurrence of M. tuberculatus infected with larval trematodes in Rio de Janeiro City. Bottom sediment was collected with dip nets and sieved through 0.25 inch-mesh screening. Snails were transported to the laboratory in vials with stream water, then measured and individually isolated in glass vials with distilled water. They were exposed to artificial light and temperature to induce cercarial emergence. The most actively emerging cercariae were processed by differential staining and silver nitrate impregnation methods. Negative snails were subsequently dissected. Approximately 700 snails were collected. Snail total lengths ranged from 1.2 to 3.3 cm. The prevalence rate was 15.76% although 53.76% of the snails were found infected in one of the sites. Infected snails were infected with rediae and pleurolophocercous cercariae. Cercarial morphology and chaetotaxy were consistent with those of the family Heterophyidae mostly due to the presence of median dorsal and ventral fins on the tail and the absence of CI dorsal sensory receptors.

EXPERIMENTAL INFECTION OF SWISS AND AKR/J MICE WITH Centrocestus formosanus (TREMATODA: HETEROPHYIDAE)

In order to better understand the biology of Centrocestus formosanus in a definitive host model, mice of Swiss and AKR/J strains were experimentally infected with 100 metacercariae of the parasite. Fourteen days post-infection, the rodents were killed and adult trematodes were recovered from the small intestine. The percentage of parasite recovery from AKR/J mice (11.4%) was significantly higher than that from Swiss mice (5.3%). Moreover, trematodes recovered from the AKR/J strain were more developed and had greater fecundity. Peculiarities concerning the mice’s immune system could explain the difference in susceptibility and in worm development seen in the present study. The data obtained confirm that mice are susceptible to infection with C. formosanus and indicate that the AKR/J strain provides a more favorable environment for parasite development.

The Pampulha reservoir remains a potential urban focus of schistosomiasis mansoni in Brazil: changes in the occurrence patterns of Biomphalaria species and a new record of the parasite

Introduction The Pampulha reservoir has long been a focus of schistosomiasis transmission in Belo Horizonte, State of Minas Gerais, Brazil. The last malacological study conducted in this urban reservoir was more than two decades ago, and thus, an update on the distribution of the species of Biomphalaria as well as new data on the presence of Schistosoma mansoni in this water body are required. Methods The current distribution of Biomphalaria spp. in the Pampulha reservoir and their infection with S. mansoni was evaluated during 55 malacological surveys conducted between 2009 and 2012. Results Biomphalaria straminea displayed a high population density and distribution, and 13.7% (2,233/16,235) of the specimens collected were infected with larval trematodes other than Schistosoma mansoni. Biomphalaria tenagophila and Biomphalaria glabrata, species currently presenting a restricted distribution and small populations, displayed trematode infection rates of 15.2% (98/644) and 13% (83/640), respectively. Thirteen (2%) specimens of B. glabrata were found to be infected with S. mansoni. In addition, a historical review based on previous and new data on the occurrence patterns of Biomphalaria species in this reservoir is presented. Conclusions The results indicate that the Pampulha reservoir remains a potential focus of urban schistosomiasis in Brazil, and significant changes in the occurrence patterns of Biomphalaria species were verified.

Freshwater gastropods of the Baixada Maranhense Microregion, an endemic area for schistosomiasis in the State of Maranhão, Brazil: I - qualitative study

Introduction: The Baixada Maranhense Microregion currently has the highest prevalence of schistosomiasis in the State of Maranhão, likely because this parasitosis is characterized as an occupational disease, and increased contact with water increases the risk of infection by Schistosoma mansoni. This paper reports the results of the first comprehensive freshwater malacological survey performed in the Baixada Maranhense Microregion. Methods: Freshwater mollusks were collected from the twenty-one municipalities of the Baixada Maranhense Microregion and from Bacurituba and Cajapió and were evaluated for infection by trematodes. Results: A total of 9,129 mollusks were collected (sixteen species), which included the first records of six species in the State of Maranhão: Gundlachia radiata, G. ticaga, Hebetancylus moricandi, Plesiophysa guadeloupensis, Pomacea bridgesii diffusa and Omalonyx sp. Biomphalaria glabrata was found in five municipalities, whereas B. straminea was found in nine. Biomphalaria glabrata and B. straminea were observed in syntopy in Pinheiro and São Bento. Of the 990 specimens of B. glabrata and the 2,109 specimens of B. straminea that were exposed to and/or analyzed for the presence of larval trematodes, only a single specimen of B. glabrata (0.1%) from São Bento shed S. mansoni. Other larval trematodes were first observed in mollusks from the State of Maranhão. Conclusions: These results indicate that the study area is epidemiologically important due to the presence of two natural vectors of schistosomiasis and the active transmission of schistosomiasis, which was confirmed in the infected specimen that was collected in this study.

Two new Bucephalidae (Trematoda) from Fishes of the Brazilian Amazon

Two new species of Bucephalidae (Trematoda) are described from fishes of the Brazilian Amazon. Glandulorhynchus turgidus gen. et sp. n. from Hydrolycus sp. differs from all others in the family by having conspicuous glands near the anterior extremity and an expanded uterus used for storing eggs. Prosorhynchus piranhus sp. n. from Serrasalmus rhombeus is characterized as having a small rhynchus and pharynx, and a large cirrus sac.

Two new Haploporidae (Trematoda) of Fishes from the Brazilian state of Rondônia

Two new Haploporidae (Trematoda) are described from fishes of the State of Rondônia, Brazil. Rondotrema microvitellarum gen. et sp. n., an intestinal parasite of Hemiodus microlepis, is characterized as having intercecal vitellaria limited to one small cluster on either side postero-lateral to the ovary. Lecithobotrioides elongatus sp. n., from Prochilodus nigricans, has an elongate, cylindrical body, short thick ceca, a small hemaphroditic sac and extensive vitellaria.

Maritremopsis mariettavogeae sp. n. (Trematoda, Microphallidae) and Amphimerus lancea (Diesing, 1850) (Trematoda, Opisthorchiidae) parasites of Nectomys Squamipes (Rodenta) in Brazil

In this paper two species of trematodes recovered from nectomys squamipes from Goiás State, Brazil, are presented. Maritremopsis mariettavogeae sp. n. is compared to M. proxilum (Caballero & Montero-Gei, 1961) and M. belopolskaiae (Caballero, 1964). Amphimerus lancea originally described from a cetacean host, is for the first time referred in a rodent.

The life cycle of Dendritobilharzia anatinarum cheatum, 1941 (Trematoda, Schistosomatidae)

The life cycle of Dendritobilharzia anatinarum was completed experimentally in the laboratory. Cairina moschata domestica (domestic duck) and Biomphalaria straminea served respectively as definitive and intermediate hosts. Eggs passed in duck faeces hatch miracidia in 10 minutes when placed in water. Eight days after the snail infection, the mother sporocyst contains daughter sporocysts ready to migrate. Cercariae are present within the daughter sporocysts 23 days after infection and emerge from the snail on the 25th day. They actively penetrate the skin of the duck and after a prepatent of 39 days, sexually mature trematodes are present in the blood vessels of the bird. The adult parasite is predominantly in the renal-portal system and to a lesser degree in the lungs and mesentery. A detailed morphological description of the egg. miracidium, sporocyst and cercaria is presented.

Skrjabinoclava tupacincai Freitas, Vicente & Ibáñez, 1970 in Brazil and some other helminths from tyrannidae birds

Brief comments are made on five species of nematodes: Skrjabinoclava tupacincai Freitas, Vicente & Ibáñez, 1970, Deliria gomesae Vicente, Pinto & Noronha, 1980, Ornithofilaria pitangi Vicente, Pinto & Noronha, 1980, Diplotriaena delirae Pinto & Noronha, 1970, Thelazia sp.; three species of trematodes: Lutztrema transversum (Travassos, 1917) Travassos, 1941, Lophosicyadiplostomum nephrocystis (Lutz, 1928) Dubois, 1937, Gynaecotyla jägerskiöldi (Travassos, 1920) Yamaguti, 1939; one species of cestode: Biuterina campanulata (Rudolphi, 1819) and one species of acanthocephala: Centrorhynchus opimus Travassos, 1921, that were studied in order to provide some data concerning the examined samples.

Redescription of the type-material of creptotrema creptotrema travassos, Artigas & Pereira, 1928 (Digenea, Allocreadiidae)

Creptotrema creptotrema Travassos, Artigas & Pereira, 1928, a digenetic trematode parasite of Leporinus elongatus, is redescribed from the type-material with additional morphological data and original figures.

Redescription of Teratotrema dubium, Travassos, Artigas & Pereira, 1928 (Callodistomidae: Digenea)

Teratotrema dubium Travassos, Artigas & Pereira, 1928, a digenetic trematode parasite of Pseudocurimata plumbea (Curimatidae: Pisces) is redescribed with additional morphological data, confirming the presence of a single testis.

The genus lobatostoma (Trematoda: Aspidocotylea) in the pacific coast of South America, with description of Lobatostoma veranoi new species, parasite of Menticirrhus ophycephalus (Teleostei: Sciaenidae)

The presence of three aspidocotyleans trematodes in marine fishes from Perú and Chile is reported. One of them, Lobatostoma veranoi from the intestine of Menticirrhus ophicephalu (Sciaenidae) is considered a new species. Distinct characteristcs of the new species are:a cirrus sac smaller than the pharynx; tail overlapping posteriorly the ventral disk; testis in the last third of the body and the presence of 64-66 marginal alveoli. The two other species are Lobatostoma pacificum Manter, 1940 found in Trachinotus paitensis Cuvier, 1830 from Perú and Chile and Lobatostoma Anisotremum Oliva & Carvajal, 1984 from the intestine of Anisotremus scapularis (Tschudi, 1844) from Perú.

Schikhobalotrema solitaria sp. n. and S. acanthuri Yamaguti, 1970 (Haplosplanchnidae: Digenea) in Brazilian marine fishes

Schikhobalotrema solitaria sp. n. is described from Stephanolepis hispidus (Linnaeus, 1758), and is characterized by the relation between oral sucker and pharynx 1:1,1. This Relation in the other species ranges between 1:0.3-0.6. It is more similar to S. manteri Siddiqi & Cable, 1960 in the distribution of vitellaria, differing from it in the size of vitelline follicles, extension of uterus and in the size of the eggs. S. acanthuri Yamaguti, 1970 is referred for the first time in South America in Mugil liza Valenciennes, 1836 representing a new host record.