Now showing items 1-17 of 17

    • Article

      Antibiotic resistance of bacteria from shrimp ponds 

      EA Tendencia & LD de la Peña - Aquaculture, 2001 - Elsevier
      The incidence of antibiotic resistance was compared in bacteria isolated from pond water, pond sediment, water and sediment from the receiving environment (area where water from pond drains, which is 0 and 50 m away from the exit gate, in this study) and cultured shrimp from ponds that have not used any antimicrobials, ponds that have previously used antimicrobials and ponds that are currently using oxolinic acid. Most of the bacteria isolated from all sample and pond type were Vibrios. Among the Vibrios, V. harveyi were most commonly isolated. Multiple antibiotic resistance (MAR) to at least two antimicrobials was highest in ponds currently using oxolinic acid (24% of bacteria isolated from such ponds), followed by those that have previously used antimicrobials (19%) and the least was those from ponds that have not used any antimicrobials (17%). The lowest incidence of antibiotic resistance was observed in ponds that have not used any antimicrobials (41% of the isolates from such ponds). Among the individual antibiotics, incidence of resistance to oxytetracycline was highest (4.3% of the total number of isolates) followed by furazolidone (1.6%), oxolinic acid (1%) and chloramphenicol (0.66%).

      Resistance to individual chemotherapeutants did not reflect the pattern of antimicrobial use with ponds that have previously used antimicrobials showing the highest incidence of resistance to one antimicrobial (12% of total isolates from such ponds). Resistance to both oxolinic acid and furazolidone (15% of total number of isolates) was highest compared to other antimicrobial resistance profiles (1–12%). Multiple antimicrobial resistance and intermediate reaction to at least one antimicrobial are associated with antimicrobial use.
    • 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.
    • Book

      Diseases in farmed mud crabs Scylla spp.: Diagnosis, prevention, and control. 

      CR Lavilla-Pitogo & LD de la Peña - 2004 - Aquaculture Dept., Southeast Asian Fisheries Development Center
      Aquaculture production has suffered many set-backs due to the occurrence of diseases. Many of the diseases are caused by infectious organisms that are difficult to detect and need sophisticated instruments for diagnosis, but most disease occurrence and mortality in farmed aquatic animals are related to poor rearing water quality. It is, therefore, important for technicians and farmers to recognize the relationship between the animals they culture and the aquatic environment. The Government of Japan, through the Regional Fish Disease Project, funded research on diseases affecting mud crabs in order to come up with sound prevention and control methods. This book is a collection of observations gathered from various research and commercial culture activities, and gives emphasis on disease recognition using simple techniques and gross observations of affected crabs. However, since many of the diseases are caused by microorganisms, microscopy is an important technique for their diagnosis. The authors of the book encourage active cooperation between farmers and diagnostic laboratories for disease identification, prevention, and control in order to build up more information to increase production. The Regional Fish Disease Project supports sustainable mud crab production and hopes that farmers and other users of this book will attain their production goals.
    • Article

      Distribution of nervous necrosis virus in orange-spotted grouper Epinephelus coioides with asymptomatic infection 

      I Kiryu, LD de la Peña & Y Maeno - Fish Pathology, 2007 - Japanese Society of Fish Pathology
      Distribution of nervous necrosis virus in asymptomatically infected orange-spotted grouper Epinephelus coioides was determined by PCR assay in this study. Fourteen different tissues and organs were collected from apparently healthy groupers including seven individuals of broodstock and 17 juveniles with body weight ranging from 4 to 12 kg and from 2 to 9 g, respectively. No cytopathic effects were found in E-11 cells inoculated with filtrates of sample homogenates. However, all the broodstock and juveniles were positive by nested PCR test except for one juvenile. One hundred percent detection rate of the virus was obtained only from the brain.
    • 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

      Immune responses of Asian sea bass, Lates calcarifer Bloch, against an inactivated betanodavirus vaccine 

      RV Pakingking Jr., R Seron, LD de la Peña, K Mori, H Yamashita & T Nakai - Journal of Fish Diseases, 2009 - Blackwell Publishing
      Asian sea bass, Lates calcarifer (Bloch), exhibited strong immune responses against a single injection of the formalin-inactivated red-spotted grouper nervous necrosis virus (RGNNV), a betanodavirus originally isolated in Japan. Fish produced neutralizing antibodies at high titre levels from days 10 (mean titre 1:480) to 116 (1:1280), with the highest titre at day 60 post-vaccination (1:4480). When fish were challenged with the homologous RGNNV at day 54 post-vaccination, there were no mortalities in both the vaccinated and unvaccinated control fish. However, a rapid clearance of the virus was observed in the brains and kidneys of vaccinated fish, followed by a significant increase in neutralizing-antibody titres. Furthermore, the vaccine-induced antibodies potently neutralized Philippine betanodavirus isolates (RGNNV) in a cross-neutralization assay. The present results indicate the potential of the formalin-inactivated RGNNV vaccine against viral nervous necrosis (VNN) of Asian seabass.
    • Article

      Luminescent vibrios associated with mortality in pond-cultured shrimp penaeus monodon in the Philippines: Species composition 

      LD de la Peña, CR Lavilla-Pitogo & MG Paner - Fish Pathology, 2001 - Japanese Society of Fish Pathology
      Heavy mortalities due to luminescent vibriosis have been observed among pond-cultured Penaeus monodon shrimp in the Philippines. The species composition of luminescent Vibrio associated with mortalities was determined. A total of 189 luminescent bacteria isolated from the hepatopancreas of affected shrimps, rearing water and seawater from different shrimp farms in 11 provinces of the Philippines were examined for their morphological, physiological and biochemical characteristics. Results revealed a varied composition of Vibrio species. The most dominant luminescent Vibrio species was V. harveyi (65.5%) followed by V. logei (7%), Photobacterium sp. (6%) and V. orientalis (1%). Some isolates, based on their characteristics, were identified as V. campbellii (16%), V. mediterranei (3%), V. fluvialis (0.5%), V. cholerae (0.5%) and V. splendidus II (0.5%), which are known as non-luminescent Vibrios. V. harveyi is thought to be the major etiological agent associated with the luminescent vibriosis in pond-cultured P. monodon and its pathogenicity was confirmed through intramuscular injection to shrimp. Experimental infection showed that V. campbellii was also pathogenic to P. monodon.
    • Article

      Mass mortalities associated with viral nervous necrosis in hatchery-reared sea bass Lates calcarifer in the Philippines 

      Y Maeno, LD de la Peña & ER Cruz-Lacierda - Japan Agricultural Research Quarterly, 2004 - Ministry of Tropical Agricultural Research Centre
      Viral nervous necrosis (VNN), also known as viral encephalopathy and retinopathy (VER), is an emerging disease affecting larvae and juveniles of many farmed marine fish species in Asia, Australia, Europe and North America. Mass mortality occurred in 14-day old larval sea bass Lates calcarifer at a hatchery in the Philippines associated with clinical signs such as abnormal swimming behavior and pale-gray discoloration of the body. Histological investigations in moribund fish revealed marked vacuolation in the retina and brain. Cytopathic effects (CPE) were observed in SSN-1 cells inoculated with the tissue filtrate of affected sea bass. A piscine nodavirus, the causative agent of VNN, was detected in the affected tissues and SSN-1 cells inoculated with the tissue filtrate of affected fish by RT-PCR. Electron microscopy revealed non-enveloped viral particles, 22-28 nm in diameter, in the cytoplasm of the brain and retina of affected fish and in the cytoplasm of VNN-infected SSN-1 cells after CPE appeared. These results indicate that mass mortality of sea bass larvae in the Philippines was caused by a piscine nodavirus.
    • Article

      Microsatellite and mitochondrial haplotype diversity reveals population differentiation in the tiger shrimp (Penaeus monodon) in the Indo-Pacific region 

      EM You, TS Chiu, KF Liu, A Tassanakajon, S Klinbunga, K Triwitayakorn, LD de la Peña, Y Li & HT Yu - Animal Genetics, 2008 - International Society for Animal Genetics
      The black tiger shrimp (Penaeus monodon) is an ecologically and economically important penaeid species and is widely distributed in the Indo-Pacific region. Here we investigated the genetic diversity of P. monodon (n = 355) from eight geographical regions by genotyping at 10 microsatellite loci. The average observed heterozygosity at various loci ranged from 0.638 to 0.743, indicating a high level of genetic variability in this region. Significant departures from Hardy–Weinberg equilibrium caused by heterozygote deficiency were recorded for most loci and populations. Pairwise FST and RST values revealed genetic differentiation among the populations. Evidence from the assignment test showed that the populations in the West Indian Ocean were unique, whereas other populations examined were partially admixed. In addition, the non-metric multidimensional scaling analysis indicated the presence of three geographic groups in the Indo-Pacific region, i.e. the African populations, a population from western Thailand and the remaining populations as a whole. We also sequenced and analysed the mitochondrial control region (mtCR) in these shrimp stocks to determine whether the nuclear and mitochondrial genomes show a similar pattern of genetic differentiation. A total of 262 haplotypes were identified, and nucleotide divergence among haplotypes ranged from 0.2% to 16.3%. Haplotype diversity was high in all populations, with a range from 0.969 to 1. Phylogenetic analysis using the mtCR data revealed that the West Indian Ocean populations were genetically differentiated from the West Pacific populations, consistent with the microsatellite data. These results should have implications for aquaculture management and conservation of aquatic diversity.
    • 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

      Mortality of pond-cultured Litopenaeus vannamei associated with acute hepatopancreatic necrosis disease (AHPND) and white spot syndrome virus (WSSV) infection in the Philippines 

      LD de la Peña, NAR Cabillon, EC Amar, DD Catedral, RC Usero, JP Faisan Jr., JI Arboleda, WD Monotilla, AT Calpe, DD Fernandez & CP Saloma - Fish Pathology, 2017 - Japanese Society of Fish Pathology
      Mortalities of up to 60% were observed in pond-cultured Litopenaeus vannamei in Bohol, Philippines. Histopathological examination revealed typical acute hepatopancreatic necrosis disease (AHPND) pathology. PCR test generated 1,269 bp and 230 bp amplicons confirmative for the toxin-producing AHPND strain of Vibrio parahaemolyticus among shrimp sampled from eight ponds. The same samples were subjected to PCR analyses for the presence of other viruses, namely WSSV, IHHNV, IMNV, and TSV. The samples were negative for the viruses except WSSV, which was detected after one-step PCR in six out of eight ponds. These results suggested that shrimp were infected dually with AHPND V. parahaemolyticus and WSSV.
    • Article

      Nodavirus infection in hatchery-reared orange-spotted grouper Epinephelus coioides: First record of viral nervous necrosis in the Philippines 

      Y Maeno, LD de la Peña & ER Cruz-Lacierda - Fish Pathology, 2002 - Japanese Society of Fish Pathology
      Mass mortality occurred in 34-day old larval orange-spotted grouper Epinephelus coioides reared at a hatchery in the Philippines with clinical signs such as anorexia and abnormal swimming behavior. Histopathology of moribund fish demonstrated marked vacuolation of the brain, spinal cord and retina. Cytopathic effects were observed in SSN-1 cells inoculated with the tissue filtrate of affected grouper. Electron microscopy revealed non-enveloped virus particles measuring 20 to 25 nm in diameter in the cytoplasm of degenerated SSN-1 cells. Piscine nodavirus (betanodavirus), the causative agent of viral nervous necrosis (VNN), was detected in the affected tissues and SSN-1 cells inoculated with the tissue filtrate of affected fish by RT-PCR. This is the first record of VNN in the Philippines.
    • Article

      Prevalence of monodon baculovirus (MBV) in wild shrimp Penaeus monodon in the Philippines 

      LD de la Peña, CR Lavilla-Pitogo, CBR Villar, MG Paner & GC Capulos - Aquaculture, 2008 - Elsevier
      Prevalence of monodon baculovirus (MBV) was determined using polymerase chain reaction (PCR) on deoxyribonucleic acid (DNA) extracts from the hepatopancreas of the wild black tiger shrimp, Penaeus monodon collected from 7 sampling sites in the Philippines. These sites are considered as the primary sources of broodstock and spawners used for hatchery operations. MBV was detected from all sites except Palawan during the dry season and Negros Occidental and Bohol during wet season. The prevalence of MBV showed no seasonal, sex and size variations. These results show that MBV is an established viral infection in wild populations of Penaeus monodon in the Philippines. Broodstock collected from the contaminated sites could serve as a reservoir of the virus which could infect the post-larvae used to stock in grow-out ponds.
    • Article

      Prevalence of white spot syndrome virus (WSSV) in wild shrimp Penaeus monodon in the Philippines 

      LD de la Peña, CR Lavilla-Pitogo, CBR Villar, MG Paner, CD Sombito & GC Capulos - Diseases of Aquatic Organisms, 2007 - Inter Research
      Prevalence of white spot syndrome virus (WSSV) was determined using polymerase chain reaction (PCR) methodology on DNA extracted from the gills of wild black tiger shrimp Penaeus monodon collected from 7 sampling sites in the Philippines. These 7 sampling sites are the primary sources of spawners and broodstock for hatchery use. During the dry season, WSSV was detected in shrimp from all sites except Bohol, but during the wet season it was not detected in any site except Palawan. None of the WSSV-PCR positive shrimp showed signs of white spots in the cuticle. Prevalence of WSSV showed seasonal variations, i.e. prevalence in dry season (April to May) was higher than in the wet season (August to October). These results suggest that WSSV has already become established in the local marine environment and in wild populations of P. monodon. Thus, broodstock collected during the dry season could serve as the main source of WSSV contamination in shrimp farms due to vertical transmission of the virus in hatcheries.
    • Book

      Prevention and control measures against viral nervous necrosis (VNN) in marine fish hatcheries 

      LD de la Peña - 2010 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual; No. 44
      An extension manual that describes the clinical signs, behavioral changes, geographical distribution, and species affected by the virus; detection, prevention and control methods especially in the hatchery phase are also included.
    • Article

      Surveillance of emerging fish viral pathogens in some Southeast Asian countries 

      G Lio-Po, E Amar, L de la Peña, ZG Orozco, J Faisan, V Suarnaba & DB Tubo - The Israeli Journal of Aquaculture-Bamidgeh, 2009 - Society of Israeli Aquaculture and Marine Biotechnology
      Preventing the transboundary movement of fish viral pathogens in a global environment requires active surveillance. This study examined the presence of three emerging viral pathogens among koi, common, grass, and silver carp in Cambodia, Lao PDR, Myanmar, Philippines, and Vietnam. The studied viruses included koi herpesvirus (KHV), spring viremia of carp virus (SVCV), and grass carp reovirus (GCRV). Detection methods consisted of virus isolation by cell culture, infection assay in naive fish, polymerase chain reaction (PCR), and reverse-transcriptase PCR (RT-PCR). Tissues were collected and pooled from 193 fish samples in Dec. 2004 to Feb. 2005, 406 in Sep. 2005 to Feb. 2006, and 1302 in Oct. 2006 to Feb. 2007. For cell culture, tissue filtrates were prepared from pooled spleens, kidneys, livers, and gills and inoculated onto koi fin (KF-1), grass carp kidney (GCK), and fat head minnow (FHM) cells. For infection assay, tissue filtrates were injected intraperitoneally to healthy, naive common carp. No virus was detected after three cell culture passages and the infection bioassays. One-step and nested-step PCR was used to detect KHV in gills of fish samples. One-step and semi-nested RT-PCR was used to detect SVCV and GCRV in the spleens, kidneys, and livers of fish samples. Samples from all three years from all five countries yielded negative results for all three viruses, indicating that KHV, SVCV, and GCRV were not present in these five countries during the period of the study although KHV outbreaks had been detected in Indonesia, Taiwan, Japan, Thailand, China, and Malaysia.