Now showing items 1-20 of 22

    • Article

      Anti-luminous Vibrio factors associated with the ‘green water’ grow-out culture of the tiger shrimp Penaeus monodon 

      The ability of the “green water” grow-out culture of the tiger shrimp Penaeus monodon to prevent outbreaks of Luminous Vibriosis was investigated by screening associated isolates of bacteria, fungi, phytoplankton and fish skin mucus for anti-luminous Vibrio metabolites. Among the 85 bacterial isolates tested, 63 (74%) caused +∼+++ inhibition of the Vibrio harveyi pathogen after 24–48 h co-cultivation. The variation in growth inhibition rates of +, ++, and +++ were demonstrated by 15 (18%), 13 (15%), and 28 (33%) isolates, respectively, 24 h after treatment. Eight bacterial isolates showed consistently sustained maximum inhibition of luminous Vibrio after 24 to 48 h exposure. The majority of these luminous Vibrio inhibiting bacterial isolates were obtained from tilapia mucus and gut. In tests with fungi, 4 of 20 (20%) yeast isolates showed intracellular metabolites inhibitory to luminous Vibrio. Among filamentous fungi, 5 of 45 (11%) isolates yielded intracellular metabolites while 3 of 41 (7%) isolates had extracellular metabolites inhibitory to luminous Vibrio. These fungal isolates were identified as Rhodotorula sp., Saccharomyces sp., Candida sp., Penicillium sp., mycelia sterilia, and two unidentified species. The microalgae, Chaetoceros calcitrans and Nitzchia sp., consistently demonstrated complete inhibition of luminous Vibrio from 24 h and 48 h post exposure, respectively, and during the 7-day experiment. Leptolyngbia sp. caused a 94–100% reduction of the luminous Vibrio population from 104 to 101 cfu/ml 24 h post exposure which was sustained throughout the 10-day observation period. In contrast, the inhibitory effects of Skeletonema costatum on luminous Vibrio was bacteriostatic throughout the 7-day exposure while Nannochlorum sp. did not significantly inhibit luminous Vibrio. The skin mucus of jewel tilapia, Tilapia hornorum, had no resident luminous bacteria and inhibited this bacterial pathogen in 6–48 h, which was proportionate to the 103 and 105 cfu/ml test concentrations of luminous Vibrio. This study provides a scientific explanation that the effectiveness of the “green water” culture of tiger shrimp (P. monodon) in preventing outbreaks of luminous Vibriosis among P. monodon juveniles in grow-out ponds can be attributed to the presence of anti-luminous Vibrio factors in the bacterial, fungal, phytoplankton microbiota and the skin mucus of tilapia associated with this novel technique of shrimp culture.
    • Article

      Bacterial flora in the hepatopancreas of pond-reared Penaeus monodon juveniles with luminous vibriosis 

      EM Leaño, CR Lavilla-Pitogo & MG Paner - Aquaculture, 1998 - Elsevier
      Quantification and characterization of bacterial flora in the hepatopancreas (hp) of pond-reared Penaeus monodon juveniles affected with luminous bacteria were conducted in 1994 and 1995. Shrimp samples were taken from 23 grow-out ponds, 14 of which had disease outbreaks. Luminous bacterial (LB) load of the shrimps' hp with (mean=2.4×101 colony forming units (CFU)/hp) and without (mean=0.3×101 CFU/hp) disease outbreaks were comparable during the first 15 days of culture (DOC). During disease outbreaks at 18 to 32 DOC, however, LB load of affected shrimps (mean=9.0×104 CFU/hp) were higher than healthy shrimps (mean=7.0×101 CFU/hp). At 50 to 60 DOC, levels of LB were comparable in older shrimps with or without disease. Total viable and presumptive Vibrio counts were also comparable in both shrimp samples from 1 to 60 DOC. Characterization of the 172 bacterial isolates collected showed that most (90.12%) were Vibrio species dominated by V. harveyi (27.91%), V. splendidus II (13.37%) and V. parahaemolyticus (10.46%).
    • Article

      Bacterial flora of milkfish, Chanos chanos, eggs and larvae 

      RD Fernandez, EA Tendencia, EM Leaño & MN Duray - Fish Pathology, 1996 - Japanese Society of Fish Pathology
      Aerobic bacterial flora of eggs and larvae of milkfish, Chanos chanos, was investigated. Microflora in the incubating water of egg, rearing water of larvae, water source, and larval food was also analyzed.

      Aerobic bacterial flora of milkfish eggs was largely influenced by the bacterial flora in the incubating water. Both in eggs and in the incubating water Pseudomonas species were the dominant bacteria. During milkfish larval rearing, intestinal aerobic bacterial flora was examined at days 1, 3, 7, 10, 15, 18, and 21. Bacterial number in the larvae and rearing water significantly increased during the culture period up to day 18 but dropped significant at day 21. Pseudomonas species were detected from yolk-sac larvae (day 1) as the dominant bacteria, similarly to the normal flora in the rearing water. However, intestinal bacteria were predominated with Vibrio species when the yolk-sac was absorbed on day 3. Larval rearing water, water source, and larval food contained predominantly Pseudomonas species.
    • Article

      Characterization of a virus obtained from snakeheads Ophicephalus striatus with epizootic ulcerative syndrome (EUS) in the Philippines 

      GD Lio-Po, GS Traxler, LJ Albright & EM Leaño - Diseases of Aquatic Organisms, 2000 - Inter Research
      This is the first report of the isolation and characterization of a fish virus from the Philippines. The virus was isolated using snakehead spleen cells (SHS) from severely lesioned epizootic ulcerative syndrome (EUS)-affected snakehead Ophicephalus striatus from Laguna de Bay, in January 1991. The virus induced cytopathic effects (CPE) in SHS cells yielding a titer of 3.02 x 106 TCID50 ml-1 at 25°C within 2 to 3 d. Other susceptible cell lines included bluegill fry (BF-2), catfish spleen (CFS) and channel catfish ovary (CCO) cells. Replication in chinook salmon embryo cells (CHSE-214) was minimal while Epithelioma papulosum cyprini cells (EPC) and rainbow trout gonad cells (RTG 2) were refractory. Temperatures of 15 to 25°C were optimum for virus replication but the virus did not replicate at 37°C. The virus can be stored at -10 and 8°C for 30 and 10 d, respectively, without significant loss of infectivity. Viral replication was logarithmic with a 2 h lag phase; viral assembly in the host cells occurred in 4 h and release of virus occurred 8 h after viral infection. A 1-log difference in TCID50 titer between the cell-free virus and the total virus was noted. Freezing and thawing the virus caused a half-log drop in titer. Viral exposure to chloroform or heating to 56°C for 30 min inactivated the virus. Exposure to pH 3 medium for 30 min resulted in a more than 100 fold loss of viral infectivity. The 5-iododeoxyuridine (IUdR) did not affect virus replication, indicating a RNA genome. Neutralization tests using the Philippine virus, the ulcerative disease rhabdovirus (UDRV) and the infectious hematopoietic necrosis virus (IHNV) polyvalent antisera showed slight cross-reaction between the Philippine virus antiserum and UDRV but established no serological relationship with SHRV and IHN virus. Transmission electron microscopy (TEM) of SHS cells infected with the virus showed virus particles with typical bullet morphology and an estimated size of 65 x 175 nm. The Philippine virus was therefore a rhabdovirus, but the present study did not establish its role in the epizootiology of EUS.
    • Book chapter

      Ecology of straminipiles from mangrove habitats 

      EM Leaño - In KD Hyde (Ed.), Fungi in Marine Environments, 2002 - Fungal Diversity Press
      Series: Fungal Diversity Research Series; 7
      Straminipiles are common inhabitants of marine, estuarine and freshwater aquatic environments. In mangrove habitats, halophytophthorans and thraustochytrids are abundant, both in tropical and sub-tropical areas. Their abundance is attributed to their wide tolerance to environmental parameters such as salinity and temperature, and their ability to produce abundant zoospores. Fallen mangrove leaves supply the bulk of organic material in any mangrove habitat. Straminipiles are one of the initial colonizers of fallen mangrove leaves. The ability of their zoospores to respond chemotactically to nutrients released by the leaves, and to attach firmly on the substrata surface by the release of adhesive materials, make them highly competitive in the colonization process. Thus, they are reported to play significant role in the microbial degradation of fallen mangrove leaves. Moreover, these organisms, especially thraustochytrids, are producers of high amounts polyunsaturated fatty acids (PUFAs). Therefore in the degradation process, they consequently enrich the nutrient content of the leaves for the benefit of other organisms at higher trophic levels, making mangroves an excellent nursery grounds for many fish and crustacean species. Some species of thraustochytrids are also used in the commercial production of PUFAs, for use in aquaculture specifically in larval rearing of marine fish and crustaceans.
    • Article

      Enrichment potential of HUFA-rich thraustochytrid Schizochytrium mangrovei for the rotifer Brachionus plicatilis 

      C Estudillo-del Castillo, RS Gapasin & EM Leaño - Aquaculture, 2009 - Elsevier
      An enrichment experiment was performed to evaluate the changes in lipid and essential fatty acid contents of the rotifer Brachionus plicatilis fed with freeze-dried cells of tropical thraustochytrid Schizochytrium mangrovei (Isolate IAo-1). Rotifers starved for 24 h were fed with S. mangrovei cells at 200, 300, 400, 500, 600 and 700 mg L−1. Enrichment was carried out at two periods (Short-term = 5 h; Long-term = 10 h) to determine the optimum time needed for the maximum enrichment of the rotifers. There was an overall significant increase in the total lipid, arachidonic acid (AA) and docosahexaenoic acid (DHA) contents of rotifers after feeding with freeze-dried S. mangrovei indicating the successful uptake of these nutrients in the rotifer's biochemical composition. On the other hand, docosapentaenoic acid (DPA) did not change significantly in enriched rotifers. Results of the present study indicate that both factors, feeding concentrations and enrichment periods, significantly affected the lipid, AA and DHA contents of rotifers. Uptakes of lipid, AA and DHA significantly increased with increasing feeding concentrations except for those fed the highest feeding concentration of 700 mg L−1 for 10 h. Moreover, lipid and AA contents of enriched rotifers were significantly higher during the short-term enrichment period while DHA contents were significantly higher during the long-term enrichment period. Therefore, it is concluded that the feeding concentration of 700 mg L−1 at an enrichment period of 5 h is optimum in the AA and DHA enrichment of rotifers. The strategic scheme of combining the proper amount of enrichment product and the duration of enrichment in boosting the DHA contents of rotifers will effectively ensure a reliable production of nutritionally superior rotifers at a minimal cost. This will ultimately contribute to the success of rearing marine fish larvae in the hatchery.
    • Article

      Experimental induction of lesions in snakeheads (Ophicephalus striatus) and catfish (Clarias batrachus) with Aeromonas hydrophila, Aquaspirillum sp., Pseudomonas sp. and Streptococcus sp. 

      GD Lio-Po, LJ Albright, C Michel & EM Leaño - Journal of Applied Ichthyology, 1998 - Wiley-Blackwell
      Isolates of Aquaspirilluni sp., Pseudomonas sp., and Streptococcus sp. recovered from epizootic ulcerative syndrome (EUS)-affected snakeheads (Ophicephalus striatus) in Thailand as well as an isolate of Aeromonas hydrophila recovered from EUS-affected snakeheads in the Philippines were characterized and identified. Each isolate was injected intramuscularly (IM) into healthy catfish (Clarias batrachus) and snakeheads (O. striatus). Results showed in tests with C. batraclius that 24 h after injection, Aquaspirillum sp., Pseudomonas sp., Streptococcus sp. and A. hydrophila induced slight, slight, moderate and severe dermomuscular necrotic lesions, respectively. Among O. striatus, only A. hydrophila induced severe lesions. Streptococcus sp. induced slight lesions 2 days post-injection which healed rapidly, while Aquaspirillum sp. and Pseudonionas sp. did not manifest any dermal lesions. Experiments indicated that among the four EUS-associated test bacteria, A. hydrophila was the most pathogenic, inducing severe dermomuscular necrotic lesions in intramuscularly injected catfish (C. batrachus) and snakeheads (O. striatus). Differences in the susceptibility of O. striatus and C. batrachus to Aquaspirillum sp., Pseudomonas sp. and Streptococcus sp. were evident. Furthermore, this is the first evidence of the association between Aquaspirillum sp. and diseased fish.
    • Article

      Experiments on virulence dose and portals of entry for Aeromonas hydrophila in walking catfish 

      GD Lio-Po, LJ Albright & EM Leaño - Journal of Aquatic Animal Health, 1996 - American Fisheries Society
      Aeromonas hydrophila, isolated from chevron snakehead Ophicephalus (=Channa) striatus affected with epizootic ulcerative syndrome (EUS), was injected intramuscularly into healthy walking catfish Clarias batrachus at varying 10-fold serial dilutions from 108 to 0 colony-forming units (cfu) per fish. Only 106 or more cfu/mL induced dermomuscular lesions. Initial healing of lesions was observed by day 7 but complete healing was not apparent until day 16. Experiments were also conducted on possible portals of entry of A. hydrophila into walking catfish: Intramuscular (IM) injection, gastric gavage, fish food, and immersion of injured fish in rearing water inoculated with the test bacteria. Injuries were caused by skin or muscle cut, dermal scraping or incision, fish bite, and cohabitation of fish with golden snails Ampullarius sp. Only IM injection treatment induced dermomuscular pathology in the test catfish. This suggests that a localization of A. hydrophila to a level of 106 cfu/mL in the musculature must be established for dermal lesions to develop.
    • Book chapter

      Fungal diseases 

      EM Leaño - In GD Lio-Po & Y Inui (Eds.), Health Management in Aquaculture, 2010 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Over the past 20 years, aquatic animal mycopathogens have become the focus of considerable research. The many known occurrences of fungal diseases in wild populations and the documented devastating disease outbreaks indicate that fungal and fungal-like pathogens are important in nature. Fungal diseases can act as major limitations on natural and cultured populations of aquatic animals. However, knowledge on fungal diseases is rudimentary consisting primarily of the identification and pathology of etiological agents. Detection of fungal infections relies only on the observation of gross pathology, histological examinations, and standard mycological isolation and identification procedures. As a result, there are some cases where the implicated fungal pathogen cannot be demonstrated as the primary cause of a particular disease. In such cases, the fungal pathogen is usually regarded as secondary invader. Continued research in basic mycology is still an essential resource for fish pathologists in diagnosing diseases caused by fungi. Although fungi reportedly affect very few species, fungal diseases, if not properly controlled or prevented, can still pose a threat to the aquaculture industry.
    • Book chapter

      Fungal diseases 

      EM Leaño - In GD Lio-Po, CR Lavilla & ER Cruz-Lacierda (Eds.), Health Management in Aquaculture, 2001 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Over the past 20 years, aquatic animal mycopathogens have become the focus of considerable research. The many known occurrences of fungal diseases in wild populations and the documented devastating disease outbreaks indicate that fungal and fungal-like pathogens are important in nature. Fungal diseases can act as major limitations on natural and cultured populations of aquatic animals. However, knowledge on fungal diseases is rudimentary consisting primarily of the identification and pathology of etiological agents. Detection of fungal infections relies only on the observation of gross pathology, histological examinations, and standard mycological isolation and identification procedures. As a result, there are some cases where the implicated fungal pathogen cannot be demonstrated as the primary cause of a particular disease. In such cases, the fungal pathogen is usually regarded as secondary invader. Continued research in basic mycology is still an essential resource for fish pathologists in diagnosing diseases caused by fungi. Although fungi reportedly affect very few species, fungal diseases, if not properly controlled or prevented, can still pose a threat to the aquaculture industry.
    • Article

      Growth and fatty acid production of thraustochytrids from Panay mangroves, Philippines 

      EM Leaño, RSJ Gapasin, B Polohan & LLP Vrijmoed - Fungal Diversity, 2003 - Mushroom Research Foundation
      Optimization of culture conditions with regard to the combined effects of salinity and temperature on biomass and fatty acid production of four thraustochytrid isolates were undertaken. Two strains of Schizochytrium mangrovei (IAo-1 and IXm-6), and one isolate each of Schizochytrium sp. (BSn-1) and Thraustochytrium sp. (IRa-8), isolated from fallen mangrove leaves, were used in this study. Results of the physiological study show that the best growth condition for Schizochytrium isolates was at a salinity range of 15-30 ‰ at 20-30°C, while that for Thraustochytrium sp. was at 22.5-30 ‰ at 25°C. Highest biomass production was 350 mg 50 mL-1 for Schizochytrium spp., and 133 mg 50 mL-1 for Thraustochytrium sp. Total lipid content (% freeze-dried biomass) ranged from 16.0-33.2% for S. mangrovei, 13.0-39.1% for Schizochytrium sp., and 11.4-37.5% for Thraustochytrium sp. Highest lipid production was observed at 15-22.5 ‰ salinity (25°C) for S. mangrovei, and at 15 ‰ (25°C) for Schizochytrium sp. and Thraustochytrium sp. Palmitic acid (16:0) and docosahexaenoic acid (DHA; 22:6n3) were the major components of the total fatty acid (TFA) content, comprising about 39-42% and 24-35%, repectively.
    • Article

      Haliphthoros spp. from spawned eggs of captive mud crab, Scylla serrata, broodstocks 

      EM Leaño - Fungal Diversity, 2002 - Springer Verlag
      Monitoring of the fungal flora of spawned eggs of captive mud crab, Scylla serrata, was conducted in several hatchery runs at the Aquaculture Department of Southeast Asian Fisheries Development Center in Iloilo, Philippines. Quantification of the egg mycoflora revealed the dominance of oomycetes, particularly Haliphthoros spp. among spawners which aborted their eggs prior to hatching. Two species of Haliphthoros (H. philippinensis and H. milfordensis) were identified from the 24 isolates collected. Haliphthoros milfordensis was the dominant species. Physiological studies on vegetative growth and sporulation of the two species show that H. philippinensis have wider optimal range for salinity and temperature requirements than H. milfordensis, especially in sporulation. The pathogenicity study showed that only H. milfordensis was pathogenic to spawned eggs of S. serrata, while H. philippinensis was not. Infection of S. serrata eggs by H. milfordensis was observed starting at two days after inoculation of zoospores with 2-5% infection rate, reaching up to 10% at five days post-inoculation.
    • Book chapter

      Important diseases of Penaeid shrimps 

      GD Lio-Po & EM Leaño - In IC Liao, NH Chao & EM Leaño (Eds.), Progress of Shrimp and Prawn Aquaculture in the World, 2016 - National Taiwan Ocean University; The Fisheries Society of Taiwan; Asian Fisheries Society; World Aquaculture Society
      In tropical Asia, the two main species of penaeid shrimps that are widely cultured are the black tiger shrimp (Penaeus monodon) and the Pacific white shrimp (Penaeus (Litopenaeus) vannamei). The former species is indigenous in most Asian countries while the latter is indigenous in the Americas and was introduced to Asian countries in the late 1990s. In this chapter, only details of the economically-important microbial infections in Asia in these two penaeid shrimps are presented and arbitrarily grouped as viral, bacterial, fungal and parasitic diseases. Viral infections are divided further into two groups: DNA viruses; and, RNA viruses. The infections attributed to DNA viruses are: White Spot Disease (WSD) Disease, Penaeus stylirostris densovirus (PstDNV) previously known as Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV) Disease, Penaeus monodon densovirus (PmDNV) formerly known as Hepatopancreatic Parvo-like Virus (HPV) Disease and Penaeus monodon nucleopoly-hedrovirus (PemoNPV) previously known as Monodon Baculovirus (MBV) Disease. The shrimp infections caused by RNA viruses are: Yellow Head Virus (YHV) Disease, Taura Syndrome Virus (TSV) Disease, and Infectious Myonecrosis Virus (IMNV) Disease. For bacterial diseases, the list includes Luminous Bacterial Disease, Non-luminous Vibrio Infections, and Acute Hepatopancreatic Necrosis Disease (AHPND). Fungal disease includes Larval mycosis, while parasitic disease includes the current emerging threat to the shrimp industry, the Hepatopancreatic Microsporidiosis caused by Enterocytozoon hepatopenaei (EHP).
    • Article

      Mortalities of pond-cultured juvenile shrimp, Penaeus monodon, associated with dominance of luminescent vibrios in the rearing environment 

      CR Lavilla-Pitogo, EM Leaño & MG Paner - Aquaculture, 1998 - Elsevier
      Severe mortalities due to luminescent vibrios occurred in pond-cultured Penaeus monodon juveniles particularly in the first 45 days of culture. Luminescent vibriosis epizootics led to reduced shrimp production due to mortalities and slow growth of affected stocks. Monitoring of bacterial population in the rearing water of several ponds was conducted from the time the ponds were flooded with water until 60 days of culture to understand the course of infection. Results showed that the occurrence of mortalities was preceded by a shift of the bacterial profile of the rearing water in infected ponds, notably the dominance of luminescent vibrios. Comparison of bacterial load in the rearing water and water source (river or open sea) showed elevated luminescent Vibrio counts in the former at 12 days to 3 weeks after initial entry of water. Histopathology of affected shrimps showed the hepatopancreas as the target organ of infection where severe inflammatory responses in the intertubular sinuses were seen.
    • Article

      Mycoflora of the 'green water' culture system of tiger shrimp Penaeus monodon Fabricius 

      EM Leaño, GD Lio-Po, LA Nadong, AC Tirado, RB Sadaba & NG Guanzon - Aquaculture Research, 2005 - Blackwell Publishing Ltd
      This study was conducted to quantify and characterize the mycoflora associated with the ‘green water’ culture system of Penaeus monodon. Samples of water, tilapia gut and mucus, and shrimp hepatopancreas from three shrimp farms were collected during 15, 30, 45 and 60 days of culture (DOC). Results showed that high fungal loads were observed in tilapia gut (total: 117–1352 colony forming unit (CFU) 5 cm hind gut−1; yeasts: 0–136 CFU 5 cm hind gut−1) and mucus (total: 12–311 CFU (5 cm2)−1; yeasts: 0–88 CFU (5 cm2)−1), while minimal fungal populations were observed in water samples (total: 0–110CFU mL−1; yeasts: 0–5 CFU ml−1). Shrimp hepatopancreas harboured a very low number of filamentous fungi (0–27 CFU 0.1 g−1) and yeasts (0–7CFU 0.1 g−1) especially at 60 DOC. The filamentous fungal isolates were dominated by Penicillium and Aspergillus species, while the yeast populations were dominated by Rhodotorula and Saccharomyces species. The dominance of these fungi on tilapia mucus and gut and their presence in the rearing water might play an important role in the overall mechanisms involved in the control of luminous Vibrio in the ‘green water’ grow-out culture of P. monodon.
    • Article

      Pathogenicity of the epizootic ulcerative syndrome (EUS)-associated rhabdovirus to snakehead Ophicephalus striatus 

      GD Lio-Po, LJ Albright, GS Traxler & EM Leaño - Fish Pathology, 2001 - Japanese Society of Fish Pathology
      The rhabdoviruses isolated from EUS-affected snakeheads in the Philippines was tested for pathogenicity to healthy, naive snakehead Ophicephalus striatus fry, fingerlings and juveniles. Virus exposure of naive snakehead fry and fingerlings by bath at 20-22.5°C resulted in significant mortalities (p<0.01) with no apparent lesions. Naive snakehead juveniles when injected intramuscularly (IM) with the EUS-associated rhabdovirus at ambient water temperature (28-32°C) did not develop any lesion. However, similarly treated snakehead juveniles at 20-22.5°C developed dermal lesions 3-5 days following treatment. The lesions progressed from slight to moderately advanced lesions by days 10-12 but not to deep ulcers as exhibited by naturally EUS-affected snakeheads. Mean mortalities were higher in the virus-injected fish (72%) compared to those in controls (33%). Moreover, the virus was reisolated from fish in the 20-22.5°C treatment but not from fish in the 28-32°C treatment. Virus from infected tissue filtrate and the virus passaged 3 or 4 times induced similar dermal lesions if the rhabdovirus concentration was 103 TCID50/fish or higher. When administered orally, by bath, by intraperitoneal (IP), IM and subdermal injections to snakehead juveniles, only the latter two viral routes induced dermal lesions. However, IP injection of the rhabdovirus caused 75% mortalities but none in control fish. The results demonstrate the pathogenicity of the rhabdovirus isolates to naive snakeheads at low (20-22.5°C) rearing water temperatures.
    • Conference paper

      Regional response on AHPND and other emerging shrimp diseases in the Asia-Pacific 

      EM Leaño - In RV Pakingking Jr., EGT de Jesus-Ayson & BO Acosta (Eds.), Addressing Acute Hepatopancreatic Necrosis Disease (AHPND) and Other Transboundary Diseases for Improved Aquatic … Diseases for Improved Aquatic Animal Health in Southeast Asia, 22-24 February 2016, Makati City, Philippines, 2016 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Transboundary aquatic animal diseases are among the major concerns for establishing biosecurity measures and strengthening of aquatic animal health (AAH) management capacity (including emergency preparedness) in the region. In aquaculture, biosecurity and AAH management entails protection of fish or shellfish from infectious agents (viral, bacterial, fungal or parasitic) as well as prevention of disease spread from one area to another. Several transboundary aquatic animal diseases have swept the region over the past 25 years causing massive economic and social losses. These include spread and outbreaks of epizootic ulcerative syndrome (EUS) in freshwater fish, viral nervous necrosis (VNN) in marine fish, viral haemorrhagic septicaemia (VHS) in marine and freshwater fish, and several viral diseases in shrimps (e.g. white spot disease [WSD], infectious haematopoietic necrosis [IHHN]). The spread of these transboundary diseases clearly demonstrates the vulnerability of the aquaculture industry to disease emergence where impacts have been aggravated by the lack of effective preparedness and response when diseases emerge.

      Recently, outbreaks of acute hepatopancreatic necrosis disease (AHPND), popularly known as early mortality syndrome (EMS), among cultured shrimps were reported in China and Viet Nam (2010), Malaysia (2011), Thailand (2012), Mexico (2013) and the Philippines (2014). There have been reports of its spread in South American countries but limited report is available in this regard. This disease caused significant losses in the production of Penaeus monodon and P. vannamei in the affected countries. NACA s regional response to this disease during its initial outbreak in Viet Nam, Thailand and Malaysia signified that improved control on transboundary diseases and emergency preparedness are still needed in the region. In collaboration with international organizations (OIE, FAO), NACA has implemented awareness programs, efficient information dissemination, and emergency regional expert consultation to address this disease problem. OIE and FAO also deployed experts to assess the disease and identify the pathogen involved. All of these efforts, together with subsequent studies on prevention and disease management, have paved the way in preventing further spread of this disease to other shrimp-producing countries so far. However, the risk is still very high that this disease will spread, as transboundary movement of live shrimps within and outside the region is inevitable. In addition, other emerging diseases are now affecting production of major cultured shrimps in the region. These include hepatopancreatic microsporidiosis (HPM) caused by Enterocytozoon hepatopenaei (EHP) with confirmed reports from China, Viet Nam, Thailand, Malaysia and Indonesia (unconfirmed reports from India), and viral covert mortality disease (VCMD) which was reported to be affecting cultured shrimps in China.

      By and large, outbreaks of damaging aquatic animal diseases are likely to continue and the potential consequences are likely to increase with the expansion (intensification) of aquaculture systems and introduction of new species for culture. Consequently, the risks associated with emerging and transboundary diseases are shared - shared water bodies and epidemiological links through trade (especially live movement) - thus, a collaborative approach in dealing with these diseases is therefore warranted and necessary.
    • Article

      Resistance to antibiotics of Vibrio spp. and Aeromonas spp. isolated from fish and shrimp tissues and rearing water in Panay island, Philippines 

      EM Leaño, VBM Inglis & IH Macrae - UPV Journal of Natural Science, 1998 - University of the Philippines Visayas
      A survey on the resistance patterns to selected antibiotics of bacterial pathogens of fish and shrimps in Panay Island, Philippines was conducted. One hundred and sixteen (116) bacterial isolates were collected from fish (Chanos chanos, Epinephelus sp. and Lates calcarifer) and shrimp (Penaeus monodon and P. indicus) tissues and rearing water. Among these isolates, only seven were identified as Aeromonas spp., the rest (109 isolates) were Vibrio spp., 42% of which were luminous Vibrio. Results of the sensitivity tests showed that all Aeromonas spp. isolates were resistant to streptomycin, oxytetracycline, and trimethoprim/sulphamethoxazole. Most of the Vibrio spp. isolates (94.5%) were resistant to streptomycin. Multiple resistance to two or more antibiotics was observed in 17 isolates of Vibrio spp. and all isolates of Aeromonas spp.
    • Conference paper

      Siderophore detection among bacteria associated with the epizootic ulcerative syndrome (EUS) 

      EM Leaño, GD Lio-Po & LA Dureza - In M Shariff, JR Arthur & RP Subasinghe (Eds.), Diseases in Asian Aquaculture II : Proceedings of the Second Symposium on Diseases in Asian Aquaculture, 25-29 October 1993, Phuket, Thailand, 1995 - Fish Health Section, Asian Fisheries Society
      Sixteen isolates of Aeromonas hydrophila andone isolate each of Aeromonas sp. n., Aquaspirillum sp., Pseudomonas sp., and Streptococcus sp., isolated from normal, apparently normal and epizootic ulcerative syndrome (EUS)-affected fish were screened for siderophore production at 20, 25, 30, and 37oC. results showed that siderophore production of A. hydrophila and Aeromonas sp. n. isolates decreased with increasing temperature. Among A. hydrophila isolates, 81.2% produced siderophore at 20oC, 50% at 25 and 30oC, and only 37.5 at 37oC. In contrast, Aquaspirillum sp., Pseudomonas ep., and Streptococcus sp., showed higher production of siderophore at 30 and 37oC.
    • Article

      Straminipilous organisms from fallen mangrove leaves from Panay Island, Philippines 

      EM Leaño - Fungal Diversity, 2001 - Springer Verlag
      Fallen senescent mangrove leaves from three marine mangrove sites in Panay island, Philippines were collected for observation and isolation of straminipilous organisms. A total of 11 mangrove species were sampled. Halophytophthora species were observed on 7 out of 11 mangrove species sampled, with H. vesicula as the most abundant species observed. Halphytophthora epistomium also occurred abudantly on fallen leaves of Rhizophora apiculata and Sonneratia sp. Thraustochytrids, on the other hand, were observed on all mangrove leaf samples except Aegiceras corniculatum. Schizochytrium mangrovei was the most abundant species observed. Their association and ecological role on the degradation of fallen mangrove leaves is discussed.