Experimental transmission of Caligus rogercresseyi between two different fish species

Caligus rogercresseyi is the dominant sea louse parasite affecting the salmon and trout industry in southern Chile. This parasite has a wide range of native and endemic fish hosts. The Patagonian blenny Eleginops maclovinus, which is parasitized mostly by the caligid species Lepeophtheirus spp. and C. rogercresseyi, is presumably responsible for the transmission of C. rogercresseyi to salmonids. The aim of this study was to characterize the transmission of parasites between different fish species and parasite cohort development under laboratory conditions. Parasite abundances and intensities were quantified. Transmission of parasites from Patagonian blenny to Atlantic salmon Salmo salar was lower (~9%, mainly corresponding to C. rogercresseyi) than from salmon to Patagonian blenny (14.7-26.9%, where only C. rogercresseyi were observed). This suggests that the transmission of C. rogercresseyi from salmon individuals is higher than the transmission from a native fish. Parasite cohorts developed successfully on both fish species, but apparently under different developmental rates. Water temperature, oxygen, and juvenile abundances were the variables that better explained cohort development success and variation in C. rogercresseyi adult abundances over time.

TaqMan real-time RT-PCR detection of infectious salmon anaemia virus (ISAV) from formalin-fixed paraffin-embedded Atlantic salmon Salmo salar tissues

The objective of this study was to evaluate the application of a TaqMan real-time reverse transcriptase PCR (RT-PCR) assay for the detection of infectious salmon anaemia virus (ISAV) in formalin-fixed paraffin-embedded (FFPE) fish tissues from Atlantic salmon Salmo salar with and without clinical signs of infection, and to compare it with histological and immunohistochemical (IHC) techniques. Sixteen fish samples obtained in 2007 and 2008 from 4 different farms in Chile were examined. The real-time RT-PCR allowed the detection of ISAV in FFPE samples from 9 of 16 fish, regardless of the organs analyzed, whereas 4 of the real-time RT-PCR negative fish were positive as indicated by histological examination and 3 of the real-time RT-PCR positive fish were negative as indicated by immunohistochemistry evaluation. The presence of ISAV in RT-PCR positive samples was confirmed by amplicon sequencing. This work constitutes the first report on the use of real-time RT-PCR for the detection of ISAV in FFPE sections. The assay is very useful for the examination of archival wax-embedded tissues, and allows for both prospective and retrospective evaluation of tissue samples for the presence of ISAV. However, the method only confirms the presence of the pathogen and should be used in combination with histopathology, which is a more precise tool. The combination of both techniques would be invaluable for confirmatory diagnosis of infectious salmon anaemia (ISA), which is essential for solving salmon farm problems.

First description of atypical furunculosis in freshwater farmed Atlantic salmon, Salmo salar L., in Chile

We report the first isolation, identification and characterization of a group of Chilean strains of atypical Aeromonas salmonicida isolated from freshwater farmed Atlantic salmon, Salmo salar. Affected fish showed superficial ulcers and pale liver with or without petechial haemorrhages. Outbreaks of the disease occurred in two farms in the south of Chile about 2200 km apart. Five strains were isolated in pure culture and identified by serological assays and immunofluorescence tests as belonging to Aeromonas salmonicida. Although the bacterial isolates were phenotypically homogeneous, minor differences with the reference strain A. salmonicida subsp. salmonicida ATCC 33658 were noted. Three specific primer sets and partial 16S rRNA gene sequencing allowed the identification of the Chilean isolates as atypical A. salmonicida, with A. salmonicida subsp. achromogenes and A. salmonicida subsp. masoucida as their closest relatives (100% sequence similarity). Molecular typing indicated that the atypical isolates belong to two genetic groups that were associated with the geographical origin.

[Endoscopic ligation plus sclerotherapy in esophageal varices treatment. Experience in active bleeding and in the elective treatment]

BACKGROUND

Endoscopic ligation is the treatment of choice for bleeding esophageal varices. The usefulness of additional sclerotherapy is not clear.

AIM

To assess the effectiveness of ligation followed by sclerotherapy in the treatment of variceal bleeding.

PATIENTS AND METHODS

Forty eight patients with variceal bleeding admitted for emergency treatment and 73 patients admitted for elective treatment were studied. Varices were ligated until a significant reduction in size was achieved. Eradication was completed with the injection of 1% polidocanol.

RESULTS

In 34 of 48 patients admitted for emergency treatment, the site of variceal rupture was identified. In all these subjects, and in 13 of 14 patients in whom the rupture site was not identified, hemorrhage was stopped with the procedure. Varices were eradicated in 108 of the 121 patients. Hemorrhage recidivated in 12.5% of patients admitted for emergency treatment, in a period of 14 months of follow up and in 9.6% of those admitted for elective treatment, in a period of 16 months follow up. Mortality was 14, 18 and 57% among patients classified as Child Pugh A, B or C, respectively.

CONCLUSIONS

Endoscopic ligation is effective in the treatment of variceal bleeding. Adding sclerotherapy, variceal eradication is achieved in a high percentage of patients. Survival depends on hepatic function.

[Esophagogastric varix hemorrhage. Experience with cyanpoacrylate and polidocanol in 68 patients with active hemorrhage]

BACKGROUND

Sclerosis, injection of cianoacrylate and rubber band ligation are the most commonly used endoscopic techniques for the treatment of bleeding esophageal varices.

AIM

To assess the effectiveness of cianoacrylate and polidocanol in the treatment of bleeding esophageal varices.

PATIENTS AND METHODS

Sixty eight patients with active variceal bleeding were studied. Bleeding varices were classified as thin, thick or gastric. Bleeding from thin varices was treated with polidocanol. Bleeding from thick or gastric varices was treated with cianoacrylate. Variceal eradication was done with polidocanol.

RESULTS

Bleeding came from thin esophageal varices in 23% of patients and endoscopic treatment stopped bleeding in 95% of them, from thick esophageal varices in 62% and endoscopic treatment was successful in 94% of these, and from gastric varices in 12% and treatment stopped bleeding in 87% of these (in 3% bleeding was considered subcardial). Twenty-five percent of patients bled again during variceal eradication, 12% died due to uncontrollable bleeding and 20% died due to liver failure. During variceal eradication 59% of patients classified as Child Pugh C, died.

CONCLUSIONS

Treatment of bleeding esophageal varices with cianoacrylate or polidocanol is effective. Patients classified as Child Pugh C have a had prognosis.

Use of a very flexible guide wire to permit dilation of complex malignant strictures of the esophagus

Risk of perforation is a major impediment to the use of polyvinyl bougies in palliative dilation of cancerous strictures of the esophagus. We encountered 23 patients with complex malignant strictures in whom initial dilation with Savary-Gilliard bougies was thwarted because attempts to pass a conventional Eder-Puestow guide wire were unsuccessful. As a recourse, we probed these strictures with a very flexible guide wire of the type used to implant prostheses in the biliary tract. The purpose was to establish a passage through which a standard guide wire could then be inserted. The procedure was successful in all but 4 of the 23 patients. We conclude that in such cases the preliminary use of the very flexible guide, even though time-consuming, improves the chance of effective dilation with minimal added risk.