Now showing items 1-7 of 7

    • Article

      Detection of Vibrio penaeicida in kuruma prawn after transport 

      LD de la Peña, H Koube, T Nakai & K Muroga - Fish Pathology, 1997 - Japanese Society of Fish Pathology
      In Japan, vibriosis caused by Vibrio penaeicida usually occurs in cultured kuruma prawn (Penaeus japonicus) during summer and fall. The causative bacterium can easily be detected from overtly diseased prawns, but from apparently healthy prawns the detection rate is low. The results of the conventional isolation method of the pathogen does not seem to reflect the true carrier rate because more prawns often come into overt infection after collection-transport-acclimation procedures, although such data have not been published.

      In the present study, transport stress was given to apparently healthy prawns to verify the above phenomenon.
    • Article

      The effects of iron compounds on the virulence of Vibrio anguillarum in Japanese eels and ayu 

      T Nakai, T Kanno, ER Cruz & K Muroga - Fish Pathology, 1987 - Japanese Society of Fish Pathology
      When Japanese eels (Anguilla japonica) were injected intramuscularly (IM) with ferric ammonium citrate (FAC) at a sublethal dose of 10 µg/g and followed by IM-injection with various doses of Vibrio anguillarum, FAC injection enhanced greatly the virulence of the pathogen to eels, lowering the LD50 value from 107.9 to 104.2 CFU/100 g. Similar effects were obtained with ferrous sulfate and ferric chloride in eels. However, such a virulence-enhancing effect of FAC was scarcely observed in ayu (Plecoglossus altivelis), which has high susceptibility to the pathogen by nature. It was also found that addition of FAC (10 µg/ml) in fish sera accelerated the bacterial growth in vitro but the effect was much greater in eel serum than in ayu serum. The results of these in vivo and in vitro experiments demonstrated that the availability of free iron in host fish would have a significant influence on the pathogenesis of V. anguillarum infection.
    • Article

      The effects of Vibrio anguillarum extracellular products on Japanese eels 

      MC de la Cruz & K Muroga - Aquaculture, 1989 - Elsevier
      To test the effect of Vibrio anguillarum extracellular products (ECP) on Japanese eels (Anguilla japonica ), test fish were injected intramuscularly with ECP at a dose of 1 mg protein/100 g body weight of fish.At 3,6,12,24 and 36 h post-injection, blood samples were collected for haematocrit, haemoglobin, and serum protein determinations and tissues were fixed in Bouin's solution. Histopathological observations 24 h post-injection revealed that the ECP caused severe damage to muscle tissue, characterized by extensive muscle liquefaction and haemorrhaging. In addition, extensive haemosiderin deposits were observed in the spleen, with lesser deposits occurring in the kidney and liver. Haematocrit, haemoglobin, and serum protein values were lower in ECP-treated fish than in the untreated controls.
    • Article

      Experimental infection of kuruma prawn (Penaeus japonicus) with Vibrio penaeicida 

      LD de la Peña, T Nakai & K Muroga - The Israeli Journal of Aquaculture-Bamidgeh, 1998 - The Society of Israeli Aquaculture and Marine Biotechnology
      To estimate the portal of entry of Vibrio penaeicida in kuruma prawn (Penaeus japonicus), immersion and oral infection experiments were conducted with pre-treated and intact prawns. In immersion challenge, V. penaeicida produced 30% mortality in the shell-removed group at both 108 and 107 CFU/ml doses while in the eye-cut group, mortalities were 44% and 13% at 108 and 107 CFU/ml, respectively. In the intact group, 10% mortality was observed at 108 CFU/ml and no mortality at 107 CFU/ml after two weeks. The pathogen produced high mortalities in the orally incubated group, the median lethal dose (LD50) being 103-104 CFU/animal. In the groups given V. penaeicida-inoculated kuruma prawn meat and V. penaeicida-contaminated commercial pellets, mortalities within 60 days were 10% and 20%, respectively. These results suggest that the main portal of entry of V. penaeicida is the gastro-intestinal tract although the cuticle (epidermis) or wounds can also be portals.
    • Article

      Fate and location of Vibrio anguillarum in tissues of artificially infected ayu (Plecoglossus altivelis) 

      K Muroga & MC de La Cruz - Fish Pathology, 1987 - Japanese Society of Fish Pathology
      Ayu (Plecoglossus altivelis) were infected with Vibrio anguillarum by a water-born method. At 6, 12, 18, 36, 38-45 (moribund stage) and 48 h (dead) after infection, fish were sampled to determine the fate and location of the bacterium in various tissues by viable cell count and the enzyme-labeled antibody technique (ELAT). V. anguillarum was first detected in the skin at 12 h by bacterial isolation. It appeared in the muscle, spleen and liver at 24 h, but was not isolated from the gills or intestine until 36 h or 38-45 h. The same trend in the fate of the pathogen was confirmed by ELAT, and the cells were found in dermal layer of the skin from the early stage (12h) of infection. Based on these observations it was concluded that the first colonization site of V. anguillarum in ayu was the skin.
    • Article

      Mortality in pond-cultured shrimp Penaeus monodon in the Philippines associated with Vibrio harveyi and white spot syndrome virus 

      LD de la Peña, CR Lavilla-Pitogo, A Namikoshi, T Nishizawa, Y Inui & K Muroga - Fish Pathology, 2003 - Japanese Society of Fish Pathology
      Heavy mortalities were observed among pond-cultured Penaeus monodon in the provinces of Bohol, Misamis Occidental, Lanao del Norte and Zamboanga del Sur, Philippines. Vibrio harveyi was isolated purely from the hepatopancreas and lymphoid organs of affected shrimp and histopathological observations indicated a severe bacterial infection in the shrimp. Majority of the samples gave negative results in the one-step PCR for the detection of white spot syndrome virus (WSSV). However, nested PCR produced amplicons specific for WSSV DNA from most of the shrimp tested. These results suggest that shrimp were infected dually with V. harveyi and WSSV, but the major causative agent of the present mortalities was V. harveyi.
    • Article

      Vibrio sp. isolated from milkfish (Chanos chanos) with opaque eyes 

      K Muroga, GD Lio-Po, C Pitogo & R Imada - Fish Pathology, 1984 - Japanese Society of Fish Pathology
      Several milkfish (Chanos chanos) juveniles polycultured with the Indian prawn (Penaeus indicus) in earthen ponds at the Leganes Station of the Aquaculture Department, SEAFDEC, Philippines, manifested eye abnormalities. Signs observed varied from unilateral and bilateral opaque eye coverings/eye balls, exophthalmia and hemorrhagic eyes. A vibrio was predominantly isolated from the opaque eye coverings and eye balls, and it was proved pathogenic to milkfish, Japanese eel (Anguilla japonica) and mouse by injection experiments. The opaqueness of eye coverings of milkfish was likewise reproduced by a combination of injury and contact with the pathogen.

      The bacterium, though seemingly closely related to Vibrio parahaemolyticus or V. alginolyticus, was not identified to any known Vibrio species.