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PubMed1994

Attenuation of Schistosoma mansoni cercariae with a molluscicide derived from Millettia thonningii.

A chloroform extract of molluscicidal plant secondary compounds from the seeds of a West African legume Millettia thonningii was used to attenuate cercariae of Schistosoma mansoni prior to infection of NMRI female mice. Exposure of cercariae to 0.3, 0.6, 1.3, 2.5, 10 or 20 mg/l concentrations of extract for 30 min, immediately before standardized infection, was associated with a concentration-dependent decline in worm establishment at 55 days post-infection. The mean numbers of adult worms established declined from about 17 worms/mouse with control cercariae and those exposed to 0.3 mg/l Millettia to 0.1 worms/mouse after 10 mg/l pre-treatment. Mice exposed to cercariae after 20 mg/l pre-treatment had no adult worms at 55 days post-infection. The activities of cercariae 30 min after exposure to Millettia extract at concentrations up to 2.5 mg/l were similar to those of control larvae: none was immobile. Exposure to higher concentrations of Millettia progressively reduced swimming activity and increased the proportion of immobile cercariae. After pretreatment with 20 mg/l Millettia the majority of larvae were immobile. Levels of anti-parasite antibodies (estimated by ELISA assay using an adult worm-based antigen preparation) rose between 21 and 55 days p.i. with control cercariae and those pre-treated with 2.5 mg/l Millettia. After 5 mg/l pre-treatment, cercariae induced a reduced antibody rise, while mice exposed to cercariae after 10 mg/l pre-treatment showed no rise in anti-parasite antibody levels. These results are discussed in the context of protocols which could possibly use Millettia-attenuated cercariae to induce useful levels of protection in mice towards further cercarial challenge.

Animals↗
PubMed1985

Antibody response against schistosomulum surface antigens and protective immunity following immunization with highly irradiated cercariae of Schistosoma mansoni.

The production of antibodies against the schistosomulum surface antigens of Schistosoma mansoni in response to immunization with highly irradiated cercariae was followed. Four antigens were reproducibly identified by 125I surface labelling using Iodogen and immunoprecipitation; they had mol. wts of 38, 32, 20 and 15 kD. In addition a 92 kD antigen was also evident in most experiments. It was demonstrated that the 20 kD antigen was the same as that recognized by the monoclonal antibody NIMP/M.47 and that this antigen like the 38 and 32 kD antigens was thus identified during both chronic infection and following vaccination with irradiated cercariae. Two weeks following immunization with irradiated cercariae antibody was produced only against the 15 kD antigen but at 4 weeks the major response was against the 32 kD antigen. A second immunization with irradiated cercariae boosts the antibody response so that all four antigens were strongly precipitated. Further vaccinations did not lead to the identification of further antigens. Immunization of rats with highly irradiated cercariae also resulted in antibody production against the 38, 32, 20 and 15 kD antigens. Surface labelling of schistosomula transformed from irradiated cercariae resulted in the same four antigens being precipitated as from normal cercariae indicating that irradiation did not affect transformation nor antigen expression on 3h schistosomula. Furthermore, antibodies against the same surface antigens were detectable 4 weeks after immunization with equal numbers of cercariae irradiated with 0, 5, 25 or 50 krad. Vaccination of mice with irradiated, cloned cercariae resulted in identical antibody production and similar levels of immunity directed at both an homologous or heterogeneous challenge. Thus all parasites within our laboratory population appear to express the same antigens and there was no evidence for a genetically defined variation that could account for the partial resistance to reinfection exhibited by mice vaccinated with irradiated cercariae.

Animals↗
PubMed1964

[Studies On The Experimental Mode Of Infections Of Clonorchis Sinensis: II. Experimental Infection Of Clonorchis Sinensis Cercaria To Fry Of Fresh Water Fishes]

Cercariae of Clonorchis sinensis were attempted to penetrate into various fry of fresh water fishes in order to examine the conditions of infection and the further development in the fish. The following conclusions were made. 1. Cercariae of C. sinensis penetrated into the muscle of the fry of Pseudorasbora parva were found to be able to develop. 2. Cercariae penetrated into the fry of Pseudorasbora parva migrated into the organs of the fry to kill their host. 3. From each dead individual of P. parva, more than 10 larvae of C. sinensis could be discovered. 4. Cercariae attached on the Cyprinus carpio, Carassius and gold fish were almost killed before penetration into the body and even one or two cercariae penetrated were also killed as time passed. 5. Cercariae of C. sinensis infected on the fry of Cyprinus Carpio, Carassius auratus and gold fish could not survive more than 60 days. 6. Cercariae penetrated into Cyprinus carpio and Carassius auratus could not develop into complete metacercariae even after 3O days. 7. Cercariae of Clonorchis sinensis penetrated into the fry of Aplocheilus latipes were killed within 10 hours and the cercariae attached on the caudal fin were destroyed in 2 hours. 8. It was found that no cercariae of Clonorchis sinensis could penetrate into the body of the fry of Misgurnus anguillicaudatus.

Journal Article↗
PubMed2003

On the pathogenicity of attenuated Schistosoma mansoni cercariae released from metabolically disturbed Biomphalaria alexandrina.

Biomphalaria alexandrina were treated with sublethal concentrations (LC10) of dry powdered leaves Solanum nigrum or whole dry Ambrosia maritima. The two plants affected the development of schistosome parasite within snails by disturbing the glycolytic flux, the most important metabolic pathway for schistosome-infected snails. Attenuated cercariae released from treated snails were used to infect male albino mice to evaluate their pathogenicity compared to control cercariae shed from untreated snails. The mean number of worms established declined from about 70 +/- 17.6 worms/mouse infected with control cercariae to 23.4 +/- 20.33 and 14.18 +/- 10.06 worms/mouse infected with S. nigrum and A. maritima-attenuated cercariae respectively. Most males and females detected in these animals measured 0.4-0.6 and 0.6-1.2 mm respectively compared to 1.2-1.4 and 1.4-1.7 mm in males and females released from mice infected with normal cercariae. Egg count in the liver and intestine of mice infected with attenuated cercariae was remarkably lower showing reduced fecundity of worms developed from attenuated cercariae. Number and size of granulomatous reactions showed remarkable reduction in attenuated cercariae-infected mice. Biochemical analyses for pathogenicity achieved with attenuated cercariae showed that while serum aspartate and alanine aminotransferases (AST &ALT) were more or less similar, depleted glycogen and elevated lipid peroxides were normalized when compared to those infected with normal cercariae.

Ambrosia↗
PubMedDate not supplied

[Patterns of swimming of cercariae in some trematode species].

Swimming activity of cercariae in the trematode species Cryptocotyle lingua, Himasthla elongata, Maritrema subdolum, and Cercaria parvicaudata (Renicola sp.) is studied using video microfilming. The larvae of C. lingua demonstrate a typical intermittent swimming with regularly alternating periods of active movement and passive floating. The duration of both periods during the first 30 min of cercaria's life retains equal, and later the passive period becomes longer. In 15 h the duration of the active period is 0.5-1 s and the passive one--20-30 s. The cercariae of H. elongata during the first 10-15 min of their free life make short stops (1-2 s) in every 10-15 s of swimming. Later these stops become rare and their duration reduces to 0.5-1 s. The cercariae of M. subdolum and C. parvicaudata are continuous swimmers, having left the molluscan host they move persistently. If stops take place they are very rare (one case in 5-15 min) and very short (0.5-1 s). The movements of cercariae body and their tail during swimming are similar in all species studied. The proximal part of the tail undulates in lateral plane, and the middle and distal parts of this organ in the top view circumscribe a figure of eight. In the side view the middle and distal parts of the tail being rotate form a figure like a screw. The cercariae move along the screw axis. The linear swimming rate in the beginning of cercariae's life is 4.8 mm/s for C. lingua, 2.4 mm/s for H. elongata, and 0.35 mm/s for M. subdolum and C. parvicaudata. By the aging the cercariae swimming rate decreases down to the full cease of swimming activity, and the larvae sediment onto the bottom. The age dynamics of swimming rate is different in cercariae of different species and is determined by the morphological functional features of the larvae.

Animals↗
PubMed1985

Chemically attenuated larvae of S. mansoni as a novel tool in schistosomiasis research: 2. Chemical attenuation of cercariae by diimidoesters.

A novel approach to chemically attenuate cercariae of S. mansoni is presented. The method utilizes the biologically active surface proteins/glycoproteins which are essential for the survival of the organism as a target for inactivation. The inactivation was achieved by reaction with 0.01 M dimethyl adipimidate, dimethyl pimelimidate or dimethyl suberimidate at pH 8.5. The cercariae lost their viability, but retained the ability to exclude trypan blue for up to 2 years when stored at 4 degrees C in a manner similar to live cercariae and in contrast to dead cercariae which took up the dye immediately. In addition, the attenuated cercariae reacted with monoclonal and polyclonal antischistosome antibodies in an indirect immunofluorescence assay indicating the retention and preservation of surface antigens after attenuation. The immunochemical reactivity of the attenuated cercariae was preserved after storage for 2 years at 4 degrees C as shown by reaction with antisera from infected mice and rats in IIF assay. Attenuated cercariae revealed the presence of antischistosome antibodies as early as one week after infection in mice and rats. The presence of receptors for the Fc portion of human IgG on the attenuated cercariae interfered in their use as an immunodiagnostic reagent for human schistosomiasis. The attenuated cercariae were also used to screen cultures for monoclonal antischistosome antibodies. Preliminary results indicated that immunization with attenuated cercariae was capable of imparting protective immunity in mice.

Animals↗
PubMed1996

Pattern of emergence and the effects of temperature and light on the emergence and survival of heterophyid cercariae (Centrocestus formosanus and Haplorchis pumilio).

Production of the cercariae of Centrocestus formosanus and Haplorchis pumilio was not affected by a 10-day starvation of the snail host Melanoides tuberculata, and there was no circadian rhythm in the pattern of cercarial emergence. Daily average cercarial productions from each snail were 1,643 for C. formosanus and 689 for H. pumilio at 25 C and 500 lux illumination. The number of cercariae was moderately correlated with the size of snail host. The heaviest sheddings ever observed from 1 snail in 24 hr were 63,400 cercariae for C. formosanus and 3,470 cercariae for H. pumilio. The cercariae of C. formosanus could emerge in the dark, but the number was much less than in the light. In contrast, the cercariae of H. pumilio emerged equally well with or without light. Within the temperature range tested, the emergence of cercariae occurred at 15-35 C, but not at 10 C. Shedding of C. formosanus cercariae increased with the rise in ambient temperature, whereas the greatest shedding of H. pumilio cercariae occurred at 25 C. Life-span of the cercariae was temperature-dependent. The most favorable temperature for survival of C. formosanus was 15 C, at which some survived for 160 hr, and 20 C for H. pumilio, with the longest survival of 130 hr.

Animals↗
PubMed2006

Schistosoma japonicum and S. mansoni cercariae: different effects of protein in medium, of mechanical stress, and of an intact complement system on in vitro transformation to schistosomula.

The cercariae of Schistosoma japonicum were subjected in vitro to treatments known for Schistosoma mansoni to generate schistosomula-like organisms. As a technical prerequisite to pipette or to otherwise handle the sticky cercariae of S. japonicum, the addition of protein to water or medium was found to abolish the stickiness of cercariae of this species. Shearing forces exerted in vitro by syringe (22 G) passage are known since long to fully transform S. mansoni cercariae, but this treatment was found to be much less efficient with S. japonicum. Thus, even with very narrow needles (27 G), complete transformation of cercariae was not obtained with S. japonicum. Complement, provided by fresh human serum, is also well known to induce rapid transformation of S. mansoni cercariae with subsequent killing of the schistosomula. This treatment of S. japonicum cercariae induced degeneration of the tails and strongly promoted the transformation to schistosomula-like organisms, but at a much slower pace. These effects were absent from sera either heat-inactivated or depleted of factor B or of complement component C8, but were restored after adding the purified respective complement components. The schistosomula-like organisms of S. japonicum were not susceptible to lysis after 1 day of in vitro culture in the presence of 50% fresh human serum, although both cercariae and schistosomula of S. mansoni were killed under these conditions. In conclusion, the dynamics of in vitro transformation of S. japonicum cercariae differ significantly from those of S. mansoni, and complement has a major transformation-promoting activity.

Animals↗
PubMed1987

Schistosoma mansoni: chemical stabilization of cercariae by aldehydes.

Chemically stabilized cercariae of Schistosoma mansoni have been developed by inactivating surface glycoproteins which are essential for their survival. The inactivation was achieved by reaction with 0.01-0.1% glutaraldehyde, 0.1-1% formaldehyde, and 0.37-3.7 microliters citraconic anhydride. The cercariae lost their viability but retained the ability to exclude trypan blue for up to 2 years in a manner similar to live cercariae and in contrast to cercariae killed by other means, which took up the dye immediately. The chemically stabilized cercariae reacted with polyclonal and monoclonal antischistosome antibodies in an indirect immunofluorescence assay for up to 2 years, indicating the retention and preservation of surface antigens. Chemically stabilized cercariae revealed the presence of antischistosome antibodies as early as 1 week after infection when used for immunodiagnosis of mouse and rat infections. The presence of Fc receptors for human IgG on the stabilized cercariae interfered in their use as an immunodiagnostic reagent of human schistosomiasis. The stabilized cercariae were also used to screen cultures for monoclonal antischistosome antibodies. Preliminary results indicated that immunization of mice with glutaraldehyde stabilized cercariae imparted protective immunity to mice.

Aldehydes↗
PubMed1991

Schistosoma mansoni: possible involvement of protein kinase C in linoleic acid-induced proteolytic enzyme release from cercariae.

The possible involvement of protein kinase C and Ca2+ metabolism in the proteolytic enzyme release from schistosome cercariae was studied. Cercariae were placed in dechlorinated tap water containing 0.37 mM calcium in the small glass petri dish and exposed to the stimuli (linoleic acid, phorbol esters, and Ca2+ ionophore) with or without inhibitors of protein kinase C or Ca2+ metabolism. The proteolytic activity of incubation medium of cercariae thus treated was measured by the azocoll assay. The penetration response of cercariae induced by linoleic acid, a physiological stimulus, was mimicked by phorbol esters. When exposed to phorbol esters, 0.02 to 2 microM of 12-O-tetradecanoylphorbol-13-acetate (TPA) and 0.2 to 2 microM of phorbol-12,13-dibutyrate (PDBu), cercariae ceased the swimming movement, began a rhythmic thrusting of the anterior tip of the parasite, and released the proteolytic enzyme, but they did not shed the tails. Lowering Ca2+ in water by addition of 5 mM ethylene glycol-bis(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA), phorbol ester-induced release of enzyme was completely inhibited. Phorbol ester-induced release of enzyme was partially inhibited by 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), an inhibitor of protein kinase C, at a concentration of 100 microM. H-7 alone, at a concentration of 100 microM, did not affect the swimming movement of cercariae. The cercariae were stimulated to release the enzyme by high concentrations (10 and 100 microM) of the Ca2+ ionophore, A23187, but enzyme was not released by low concentrations (0.5 and 1 microM) of this drug. Cercariae exposed to A23187 behaved differently from those exposed to phorbol esters. They ceased swimming, showed strong muscle contraction, and shed their tail. A23187 stimulated cercariae to release the enzyme in the water containing 5 mM EGTA. A23187-induced enzyme release was not inhibited by N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), a calmodulin antagonist, trifluoperazine (TFP), a better calmodulin antagonist on schistosome, or by verapamil, a Ca2+ channel blocker. Linoleic acid-induced release of enzyme was partially inhibited by 0.5 and 5 mM of EGTA and by 1 to 100 microM of H-7. While it was not inhibited by N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide (H-8) and N-(2-guanidinoethyl)-5-isoquinolinesulfonamide (HA-1004), inhibitors of cyclic nucleotide-dependent protein kinase which were used as negative controls of H-7, W-7, TFP, 8-(N,N-diethylamino)octyl 3,4,5-trimethoxybenzoate (TMB-8), an intracellular Ca2+ antagonist, and verapamil.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2005

In vivo and in vitro encystment of Echinochasmus liliputanus cercariae and biological activity of the metacercariae.

In vivo and in vitro encystment of the cercariae of Echinochasmus liliputanus and biological activity of the metacercariae were studied. In vivo encystment of cercariae occurred in the gills of goldfish, the second intermediate host. However, the cercariae also encysted in vitro in Locke solution (0.6x to 1.2x strength), 0.7-1.2% NaCI, artificial gastric juice, and human gastric juice. Locke or NaCI solutions were shown to be appropriate for in vitro encystment to occur within 24 hr; however, full-strength Locke solution was shown to be optimal. The 1-day-old metacercariae formed in vivo and treated in 0.1% sodium deoxycholate excystation medium at 37 C for 1 hr showed 88.5% excystation. The metacercariae formed in vitro, however, showed 88.6% and 85.0% excystation for normal and abnormal ones, respectively. Abnormal cysts at room temperature usually die within 10 days. About 70% of the normal cysts, both in vivo and in vitro, can still excyst after being stored in Locke 0.5x solution at 4 C for 3 mo. Cysts formed in vivo and in vitro were equally infective. The encystment of the cercariae in vitro could be inhibited when the cercariae were treated with 1 micromol silver nitrate. Because silver nitrate binds to the papillae, especially to the ciliated papillae, on the cercaria surface, it is suggested that papillary chemoreceptors may be involved in encystment of the cercariae. The finding of E. liliputanus cercariae encysting in vitro, especially in human gastric juice, might be helpful in elucidating mechanisms of the definitive hosts that are directly infected by the cercariae.

Animals↗
PubMed2002

Effects of exogenous glucose on survival and infectivity of Schistosoma mansoni cercariae.

The effects of exogenous glucose in artificial spring water (ASW) were studied on the survival and infectivity of Schistosoma mansoni cercariae. The mean percent survival of cercariae maintained in 1% glucose in ASW for 36 and 48 hr was significantly greater than that of cercariae maintained identically in ASW. Cercariae maintained in ASW with or without glucose for 24 hr, fixed in neutral buffered formalin, and stained in Oil Red O, showed an accumulation of neutral lipid in the tail. Cercariae maintained as described above and stained in periodic acid-Schiff exhibited depleted glycogen, mainly from the tail. Cercariae maintained in ASW with glucose for 24 hr did not resynthesize glycogen. Cercariae maintained in ASW with glucose for 24 hr were as capable of infecting male FVBN202 mice as were freshly emerged cercariae, and increased the percent of worm recovery. Exogeneous glucose added to ASW prolonged the survival of S. mansoni cercariae and increased infectivity in terms of worm recovery.

Animals↗
PubMedDate not supplied

[Morphological criteria of the species in cercaria of the genus Diplostomum (Trematoda: Diplostomidae) and methods for their study].

Taxonomy values of morphological features used for differential diagnostics of different taxa is considered for cercariae of the genus Diplostomum. It was shown that, as a rule, taxa criteria of superspecies ranks had a qualitative nature and were easily detected in live cercaria studies. In contrast, cercariae species diagnostics (CSD) is based exclusively on less significant, from a taxonomy point of view, quantitative features presenting absolute and relative body dimensions and that of cercariae organs as well as peculiarities of their cuticular armament. All this compels a taxonomist to use for CSD a whole range of diagnostic features of groups mentioned and increase their taxonomy values owing to standardization of cercariae collection, fixation and subsequent processing techniques, as well as broader application of variation-statistic methods of analysis that is possible only in cercariae studies through a use of permanent slices. A complex of methodical devices, which observance will ensure reliable CSD of the genus mentioned, is proposed. It encompasses cercariae collection and fixation as well as mounting of permanent balsame slides with preceding cercariae treatment with acetic-acid carmine (morphometric analysis), acid fuxine Sekki (cuticular armament staining) and silver nitrate (sensory apparatus detection). The reagents mentioned may form a real base for a creation of cercariae museum collections being not inferior in scientific value to existing trematode maritae and metacercariae stocks.

Animals↗
PubMed1988

Schistosoma mansoni: sterol and phospholipid composition of cercariae, schistosomula, and adults.

The sterol and phospholipid composition of cercariae, schistosomula, and adult Schistosoma mansoni was analyzed by gas-liquid chromatography and high-performance liquid chromatography (HPLC). Cercariae and schistosomula contained cholesterol, desmosterol, campesterol, stigmasterol, and beta-sitosterol while adults contained only cholesterol. In all stages cholesterol comprised greater than 50% of the total sterols, and in cercariae and schistosomula desmosterol comprised 38 and 21% of the total sterols, respectively. The other three sterols, campesterol, stigmasterol, and beta-sitosterol, made up approximately 10% of the total. The same five sterols found in cercariae and schistosomula were present in the hepatopancreas of uninfected snails but with a much higher desmosterol concentration in the parasite, 38%, than in the snail, 2%. As in cercariae and schistosomula the three minor sterols comprised approximately 10%. Thus, the sterol composition of cercariae and schistosomula was similar but not identical to that of the snail host. Phosphatidylcholine was the major phospholipid of all three stages (50%) as determined by two HPLC procedures. The remaining phospholipids consisted of phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol. In addition, in adults there were small quantities of sphingomyelin and lysophosphatidylcholine. The percentage of each phospholipid was similar among stages with the exception of a slight increase in phosphatidylserine in adults compared to cercariae and schistosomula. These results show that a characteristic lipid composition is found in cercariae, schistosomula, and adults.

Animals↗
PubMed1990

Temperature effects on survival and excystment of cercariae of Halipegus occidualis (Trematoda).

Survival of the cystophorous cercariae of Halipegus occidualis (Trematoda: Hemiuridae) from naturally infected Helisoma anceps (Gastropoda: Planorbidae) was determined following constant temperature storage at 4, 16, 22, 26 and 30 degrees C. At 4 degrees C, 90% of cercariae survived for 14 weeks and 50% survived for 30 weeks. Survival varied inversely with temperature, and at 30 degrees, 90% survived for 1.5 weeks and 50% survived for 2.5 weeks. At the time of release from snails, cercariae excysted within 0.5 s of stimulation. Excystment times ultimately increased to 1-3 s at all temperatures as length of storage increased, but no connection was detected between excystment time and the activity of the cercaria. Excystment times began increasing while survival was still above 90%. Temperature specific mortality rates of cercariae were estimated, and used to simulate the survival of cercariae released naturally at various times of the year. The results of these simulations suggest that cercariae of H. occidualis are present in the environment at all times of the year, but that cercariae present in late winter (January to mid-March) may have an impaired excystment mechanism that reduces their infectivity.

Animals↗
PubMed2003

Transmission, infectivity and survival of Diplostomum spathaceum cercariae.

The transmission dynamics of the cercariae of Diplostomum spathaceum were investigated under laboratory conditions using cercariae collected from naturally infected Lymnaea stagnalis. Cercariae were kept in a constant temperature of 20 degrees C and the survival and infectivity to naïve young rainbow trout recorded at 3-h intervals until few cercariae were alive. Mortality initially remained constant but increased rapidly after 20 h. While a model of constant mortality fitted the survival data, an age-dependent model provided a better fit and implied that cercariae tended to carry similar quantities of resources and once these were exhausted the cercariae died. Cercarial infectivity also showed an age-dependent pattern although infectivity tended (P = 0.09) to increase with age over the first 6 h of life and then fall. The per capita transmission rate of cercariae was investigated by experimentally infecting rainbow trout under standardized conditions, first with an increasing cercarial density and second, by keeping density constant but increasing numbers of cercariae. The per capita transmission rate was frequency dependent and averaged 0.341/h (+/- 0.036).

Animals↗
PubMed2004

Effects of glucose on survival, infectivity and linear movement of the cercariae of Echinostoma caproni.

The effects of glucose in artificial spring water (ASW) on the survival, infectivity, and linear movement of Echinostoma caproni cercariae were studied. Cercariae maintained at 23 degrees C in 1% glucose in ASW (ASWG) or ASW alone, reached 50% survival at 26 and 23 h, respectively. All cercariae in ASWG and ASW were dead by 50 and 32 h, respectively. Infectivity to juvenile Helisoma trivolvis (Colorado strain) snails was significantly less for cercariae aged 16 h in ASWG compared to cercariae aged 16 h in ASW. Linear movement, i.e. the ability of cercariae to traverse a 1-cm radius, ceased at 16 and 20 h for cercariae maintained in ASWG and ASW, respectively. Glucose added to ASW extended the survival time of E. caproni cercariae but decreased their ability to infect snails or move in a linear direction.

Animals↗
PubMedDate not supplied

Recovery of avian schistosome cercariae from water using penetration stimulant matrix with an unsaturated fatty acid.

Avian schistosome cercariae that emerge from aquatic snails can penetrate human skin causing cercarial dermatitis resulting in serious skin disease in sensitized and immunocompromised people. A trap developed for Schistosoma mansoni cercariae was tested for recovery of avian schistosome cercariae. A matrix with an unsaturated fatty acid, linoleic acid stimulates attachment and penetration of Trichobilharzia spp. cercariae, and the immobilized larvae can be subsequently visualized. The number of trapped cercariae exceeded by 3 to 7 times the number of larvae expected on the surface of the trap, based on their random distribution in the water. Recognition, attachment, and penetration of Trichobilharzia spp. cercariae led to injection of more secretory products into the stimulant matrix than by Schistosoma mansoni cercariae. This method can assist in the identification of waters infected with avian schistosome cercariae so that human exposure to these parasitic larvae can be minimized.

Animals↗