Experimental transmission of malignant catarrhal fever to red deer (Cervus elaphus)

Malignant catarrhal fever was transmitted from affected to recipient red deer (Cervus elaphus) using blood or lymphoid suspension as inoculum. Incubation periods ranged from 11 to 26 days. The disease was also transmitted using lymphoid suspension stored overnight at 4 degrees C or at -70 degrees C for 8 months. The experimental disease was characterised by fever, depression, anorexia, diarrhoea and dysentry. The course of the disease was approximately 96 hours. Major lesions consisted of acute mesenteric lymphadenitis and acute haemorrhagic typhlitis and colitis. Lesions in the caecum and colon started as multifocal mucosal haemorrhages and progressed rapidly to massive mucosal haemorrhage.     

White Spot Syndrome Virus Infection of Cultured Shrimp in China

Abstract

In 1993 and 1994, an epizootic of disease (white spot) occurred among cultured shrimp in China, resulting in mass mortality. During the periods of outbreak epizootiological surveys were undertaken. Based on these surveys it is known that the disease occurred among populations of cultured Penaeus chinensis, P. japonicus, and P. monodon, infecting shrimp from 2.4 cm to adult. The disease presumably spread among farms as a result of transport of contaminated shrimp seedlings and seawater. Water temperatures exceeding 25°C caused the disease to spread more rapidly. Challenge experiments showed the causative agent was highly virulent. Both naturally and experimentally infected shrimp exhibited white spots on the carapace. Moribund shrimp contained turbid hemolymph, hypertrophied lymphoid organ, and a necrotic hepatopancreas. By electron microscopy, viral particles were observed in gills, stomach, lymphoid organ, and hypodermal tissue of infected shrimp. The virions were slightly ovoid with an envelope and averaged 350 × 150 nm and nucleocapsids measured 325 × 120 nm in size. By use of negative stains, complete virions were 375 × 157 nm and unenveloped nucleocapsids averaged 395 × 83 nm.     

A Viral Disease in Larvae and Juveniles of the Japanese Flounder Paralichthys olivaceus

Abstract

From 1985 to 1987, outbreaks of a disease resulting in mass mortality occurred in larvae and juveniles of the Japanese flounder Paralichthys olivaceus cultured at prefectural and private hatcheries in Hiroshima Prefecture, Japan. The disease occurred in 10-30-d-old fish that were reared at about 18–20°C, and mortality usually reached 80–90% in a few weeks. The affected fish had opaque fins and a hyperplastic epidermis on the fins and skin. Electron microscopy revealed hexagonal virus particles in the nucleus (100–140 nm in diameter without an envelope) and cytoplasm (190–230 nm with an envelope) of the affected epidermal cells. Although isolation of the causative agent by the use of five fish-cell cultures was not successful, the disease was transmitted to healthy larval flounder by exposing them to a 0.45-μm filtrate of diseased fish homogenate. The agent's morphological features and its sensitivity to ether, to a pH of 3, and to a 30min exposure to 50°C indicate it is a herpesvirus.     

Equine multisystemic eosinophilic epitheliotropic disease: A case report and review of literature

CASE HISTORY: A 2-year-old Standardbred gelding presented with a history of fever over 1 week, anorexia and skin lesions on all four legs. The lesions were associated with severe pruritus and oedema, and there was no response to therapy.

CLINICAL FINDINGS: The horse was in poor body condition, was lethargic and severely pruritic. Skin lesions consisted of diffuse alopecia and crusting of the distal extremities. Initially it was slightly febrile, but subsequently its temperature increased up to 40°C. Ten days after admission it developed profuse watery diarrhoea and the skin lesions progressed. Skin biopsies revealed superficial and deep perivascular dermatitis with lymphoplasmacytic and eosinophilic predominance. Based on the poor prognosis the horse was subject to euthanasia.

PATHOLOGICAL FINDINGS: The most notable lesions included ulcerative gastritis, typhlitis and colitis with prominent oedema of the intestines, marked subcutaneous oedema and severe thickening of the large bile ducts. Histopathology showed marked eosinophilic and lymphoplasmacytic infiltration of various tissues including the skin, gastrointestinal tract, mesenteric lymph nodes, large bile ducts, pancreatic duct and kidney. Immunohistochemistry revealed a clear predominance of CD3-positive cells in the lymphocytic infiltrations.

DIAGNOSIS: Based on the clinical findings and histopathology a diagnosis of multisystemic eosinophilic epitheliotropic disease (MEED) was made.

CLINICAL RELEVANCE: Multisystemic eosinophilic epitheliotropic disease is rare in horses, and usually chronic. In the current case the horse showed an apparently acute onset with high fever and rapid clinical deterioration. A diagnosis of MEED should be considered in horses presenting with weight loss and skin lesions with or without fever. A final diagnosis is based on histological results of biopsy specimens from affected organs.     

An investigation of ewe to lamb transfer of the itch mite Psorergates ovis

Five outbreaks of acute enteritis and one of myocarditis in 5 to 12-week-old puppies are reported. In cases of enteritis the initial clinical finding of slight malaise was followed within 24 hours by severe vomiting, diarrhoea, dehydration and death in most cases. The lesions of acute necrotizing enteritis and widespread lymphoid depletion were identical to those of feline panleucopaenia. In the outbreak of myocarditis, 3 puppies were founddead and a fourth developed congestive heart failure.

Parvoviral-like particles were found in the faeces of 5 cases of enteritis by electron microscopy and virus was isolated from 2 dogs, using a feline kidney cell line. The isolates demonstrated the physicochemical characteristics of a parvovirus and haemagglutinated porcine red blood cells at 4°C and 22°C but not 37°C. The isolates were antigenically related to feline panleucopaenia virus by immune aggregation, haemagglutination inhibition and immunofluorescence.

Fourteen of 48 sera from local dogs had significant haemagglutination inhibition titres to the virus. The diseases reported here are identical to overseas reports of parvoviral enteritis and myocarditis.     

Optimal Dosage of Erythromycin Thiocyanate in a New Feed Additive to Control Bacterial Kidney Disease

Abstract

An experimental feed additive containing erythromycin thiocyanate was formulated into fish feeds and tested to determine the optimal dosage and length of administration to treat acute infections of Renibacterium salmoninarum in chinook salmon Oncorhynchus tshawytscha. Trials were conducted on groups of yearling salmon acclimated and held in the laboratory at 10°C or 14°C in both the winter and spring. Parametric and nonparametric statistical analyses were used to assess survival rates during the tests and to evaluate the condition of fish alive at the completion of the trials. Survival was highest in trials of fish held at 10°C and among those fish that consumed higher quantities of erythromycin for 28 d of continuous therapy. Because portions of the daily rations were more likely to be refused when target dosages exceeded 100 mg/kg body weight, particularly in winter conditions, we recommend a standard therapeutic dosage of 100 mg/kg for 28 d.     

Experimental Induction of Proliferative Gill Disease in Specific-Pathogen-Free Channel Catfish

Abstract

Specific-pathogen-free channel catfish Ictalurus punctatus were exposed to sediment and mud from a pond containing channel catfish with proliferative gill disease. In one experiment, fish were to exposed to mud and sediment for 2 months in water maintained at 19°C. Fish were necropsied weekly, and certain tissues were examined histologically and ultrastructurally. Four trials were conducted with sediment samples from different epizootics of proliferative gill disease. In a second experiment, fish were exposed to sediment for 7 d in water maintained at 16, 19, or 26°C; the fish were then moved to clean water held at 16, 19, or 26°C. Fish were necropsied before transfer to clean water and weekly thereafter for 2 months. Channel catfish held at 19°C developed proliferative gill disease within 2 d of exposure to sediment. Primary cells of a uninucleate myxosporean parasite were present in the gills at the base of lamellae. These developed into plasmodia with numerous secondary cells, and some primary cells disintegrated, releasing their internal secondary cells. Similar development was observed in internal organs 1 week after appearance of the parasite in gills. Complete sporogony did not occur over the 2 months of this study. Plasmodia became necrotic and were not detected after 60 d. In fish exposed to sediment for 7 d at 16, 19, and 21°C, similar organisms were detected, but clinical disease occurred only at 19 and 26°C. Proliferative gill disease may be attributed to extrasporogonic stages of a myxosporean resembling Sphaerospora spp.     

Relation of Water Temperature to Bacterial Cold-Water Disease in Coho Salmon,Chinook Salmon,and Rainbow Trout

Abstract

The effect of water temperature on the progress of experimentally induced Cytophaga psychrophila infection was investigated in juveniles of coho salmon Oncorhynchus kisutch, chinook salmon O. tshawytscha, and rainbow trout O. mykiss (formerly Salmo gairdneri). A virulent strain of C. psychrophila was administered to fish by subcutaneous injection. Infected fish were held in tanks containing pathogen-free well water at temperatures ranging from 3 to 23°C. Mean times from infection to death of the fish were shortest at 12–15°C, which were the temperatures associated with the shortest time for doubling the population of this bacterium in vitro. Juvenile steelhead (anadromous rainbow trout) injected with viable C. psychrophila cells and held in 22°C water did not become diseased.     

Pharmacokinetics of sulphadimidine in carp (Cyprinus carpio L.) and rainbow trout (Salmo gairdneri Richardson) acclimated at two different temperature levels

Summary

The influence of temperature (10° C and 20° C) on pharmacokinetics and metabolism of sulphadimidine (SDM) in carp and trout was studied.

At 20° C a significantly lower level of distribution (Vd_area ) and a significantly shorter elimination half‐life (T _(½>) β) was achieved in both species compared to the 10° C level. In carp the body clearance parameter (Cl_B (SDM) was significantly higher at 20° C compared to the value at 10° C, whereas for trout this parameter was in the same order of magnitude for both temperatures.

N₄‐acetylsulphadimidine (N₄‐SDM) was the main metabolite of SDM in both species at the two temperature levels. The relative N₄‐SDM plasma percentage in carp was significantly higher at 20° C than at 10° C, whereas there was in trout no significant difference.

In neither species was the peak plasma concentration of N_4‐SDM (C_maxN4‐SDM)) significantly different at two temperatures.

The corresponding peak time of this metabolite (T_{max (N4‐SDM)}) was significantly shorter at 20° C compared to 10° C in both carp and trout.

In carp at both temperatures, acetylation occurs to a greater extent than hydroxylation. Only the 6‐hydroxymethyl‐metabolite (SCH₂OH) was detected in carp, at a significant different level at the two temperatures. Concentrations of hydroxy metabolites in trout were at the detection level of the HPLC‐method (0.02‐μg/ml). The glucuronide metabolite (SOH‐gluc.) was not detected in either species at the two temperatures.     

Effects of Water Temperature on Experimental Transmission of Dermal Sarcoma in Fingerling Walleyes

Abstract

The effects of temperature on experimental transmission of dermal sarcoma, a spontaneous tumor of adult walleyes Stizostedion vitreum to fingerling walleyes was determined. Test temperatures were 10, 15, and 20°C. Three-month-old walleyes were inoculated intramuscularly with a cell-free filtrate from a dermal sarcoma collected from an adult walleye in the spring of the year. Tumors were first grossly visible in fish held at 15°C at 8 weeks postinoculation. At 12 weeks postinoculation, all fish were euthanized and examined for presence of tumors. Tumor transmission was most successful at 15°C, followed by that at 20°C; many fish maintained at these temperatures had grossly visible tumors. Although the majority offish held at 10°C also had tumors, tumors in these fish developed to a lesser degree than those observed in fish held at the higher temperatures.     

The Effect of Temperature and Salinity on the Elimination of Enrofloxacin in the Manila Clam Ruditapes philippinarum

Abstract

The effect of temperature and salinity on the elimination of enrofloxacin (EF) in Manila clams Ruditapes philippinarum was investigated. The clams, cultured under different temperatures and salinities (16°C and 30‰, 22°C and 30‰, or 22°C and 20‰), were exposed to EF at 5 μg/mL of water in a medicated bath. After a 24-h exposure, the concentration of EF in various tissues was measured by high-performance liquid chromatography and the elimination rate of EF in those tissues was investigated by regression analysis. After the treatment, the initial concentrations of EF among tissues were (in decreasing order) plasma > gill > visceral mass > foot > adductor muscle. In all tissues the elimination half-life (t _1/2) of EF in the clams cultured at 22°C and 20‰ and 16°C and 30‰ were markedly longer than in those cultured at 22°C and 30‰, and the t _1/2 at 16°C and 30‰ was slightly longer than that at 22°C and 20‰. Slight differences were also observed in t _1/2 values among various tissues. These data indicate that both temperature and salinity had significant effects on the elimination of EF in the Manila clams and that lower temperature or salinity could result in slower elimination.

Received January 21, 2011; accepted December 2, 2011.     

Streptococcus iniae Associated with Mortality of Tilapia nilotica × T. aurea Hybrids

Abstract

The cause of an ongoing mortality of hybrid tilapias Tilapia nilotica × T. aurea in a Texas fish farm was a biotype of Streptococcus iniae. Identification was based upon classical biochemical and physiological analysis as well as ribosomal RNA gene sequencing. The causative agent, a β-hemolytic Streptococcus species, grew better at 37°C than at 10, 25, or 40°C, and its growth was inhibited at pH 9.6, in 6.5% NaCl, and in 40% bile. The bacterium was resistant to ampicillin and furazolidone but was susceptible to several antibiotics including tetracycline, oxytetracycline, and sulfadimethoxine-ormetoprim (5:1). This is the first record of this bacterial species affecting fish in the USA. External signs of disease in tilapia were loss of orientation, exophthalmia, corneal opacity, and petechia around the mouth, anus, and proximal margins of the pectoral fins. Internally, fluid accumulation in the peritoneal cavity and enlargement of the liver, spleen, and kidney were observed.     

Experimentally Induced Whirling Disease II. Determination of Longevity of the Infective Triactinomyxon Stage of Myxobolus cerebralis by Vital Staining

Abstract

Effects of temperature and aging on viability and infectivity of laboratory-produced actinosporean triactinomyxon spores (infective stage of the organism causing whirling disease) were studied. In vitro staining of triactinomyxon spores with vital fluorescein diacetate correlated with the ability of the spores to infect fry of rainbow trout Oncorhynchus mykiss. The experimentally produced actinosporean stage of Myxobolus cerebralis was short-lived, persisting for only 3–4 d at 12.5°C and for less time at warmer temperatures. The vital staining method has potential for screening therapeutants intended to control myxosporean infection of fish.     

Spatial and Temporal Variation of Whirling Disease Risk in Montana Spring Creeks and Rivers

Abstract

Spring creeks are important spawning and rearing areas for wild trout, but the stable flows, cool temperatures, and high nutrient levels that characterize these unique habitats may also make them highly susceptible to establishment and proliferation of the whirling disease pathogen Myxobolus cerebralis. We evaluated the spatial and temporal dynamics in whirling disease risk by using sentinel rainbow trout Oncorhynchus mykiss fry in nine different spring creeks and their conjoining rivers or reservoirs in Montana over a 20-month period. Whirling disease risk was high in five of the seven pathogen-positive spring creek study sites; at these sites, prevalence levels exceeded 90% and over 50% of sentinel fry had moderate to high infection severity scores. Spring creeks generally had higher disease prevalence and severity than paired river or reservoir sites. Fine sediment levels varied widely among springs creeks with high and low whirling disease risk, and we found no significant association between fine sediment level and infection severity. The low risk measured for some spring creeks was likely attributable to the pathogen invasion being in its early stages rather than to environmental characteristics limiting the severity of infection. High whirling disease risk occurred over a wide range of temperatures at spring creek sites (4.5–13°C) and river sites (1.7–12.5°C). There was an unusual seasonal cycle of infection in spring creeks, with peak infection levels occurring from late fall to early spring and declining to near zero in late spring to early fall. The low infection risk during spring suggests that spring-spawning trout would be at a low risk of infection, even in spring creeks with otherwise high disease severity. In contrast, fry of fall-spawning trout may be much more susceptible to infection in spring creek environments.

Received November 22, 2011; accepted May 7, 2012     

Comparison of Two Biochemical Test Systems with Conventional Methods for the Identification of Bacteria Pathogenic to Warmwater Fish

Abstract

One hundred seven Aeromonas spp., 26 Edwardsiella ictaluri, 6 E. tarda, 12 Plesiomonas shigelloides, and 6 Pseudomonas spp. (131 piscine isolates and 26 reference isolates) were studied with 36 biochemical tests from the Minitek system, 20 tests from the API 20E system, and corresponding standard tube tests. Isolates were incubated at 25°C. Arginine dihydrolase, ornithine decarboxylase, mannose, and citrate showed less than 95% agreement between the Minitek system and the tube tests. Arginine dihydrolase, lysine decarboxylase, nitrite reductase, Voges-Proskauer, and citrate showed less than 95% agreement between the API 20E system and the tube tests. The 26 reference isolates were examined with the three systems and were incubated at both 25 and 37°C. There were no major differences between tests run at 25 and 37°C except with nine Aeromonas spp. that did not grow well at 37°C. Both the Minitek and API 20E systems will reproduce standard biochemical tube test results with at least 95% accuracy when used to test warmwater fish pathogens incubated at 25°C. However, the numerical identification databases for both the Minitek and API 20E systems were not usable for identifying fish pathogens.     

Death of a neonatal lamb due to Clostridium perfringens type B in New Zealand

ABSTRACT

Case history and clinical findings: A flock of 20 sheep was kept within three paddocks on a single property. None of the animals in the flock had been vaccinated against any disease for at least three years. Abdominal bloating and haemorrhagic diarrhoea were observed in Lamb 1 at 24 hours-of-age. The lamb subsequently died within an hour of the onset of clinical signs. Lamb 2 was 3-days-old when observed to be recumbent with opisthotonus. The lamb was treated with dextrose, vitamins B1 and B12, and penicillin G, but died 4 hours later.

Pathological findings: Examination of Lamb 1 revealed markedly increased gas within the peritoneum and within dilated loops of intestine. The intestines were dark red and contained large quantities of haemorrhagic fluid. Histology of the intestines revealed peracute mucosal necrosis with minimal accompanying inflammation. The intestinal lumen contained cell debris, haemorrhage, and myriad large Gram-positive bacilli. The intestines of Lamb 2 did not appear bloated or reddened. However, multiple fibrin clots were visible within the pericardial sac. Histopathological examination revealed small foci of necrosis within the mucosa of the distal intestine. The necrotic foci were often associated with large numbers of large Gram-positive bacilli.

Immunohistochemsitry and molecular biology: Intestinal samples from Lamb 1 were processed for Clostridium perfringens immunohistochemistry, which revealed large numbers of intralesional, positively immunostained rods. Fragments corresponding to the expected sizes for genes encoding alpha, beta, and epsilon C. perfringens typing toxins were amplified by PCR from DNA extracted from formalin-fixed sections of intestine.

Diagnosis: Lamb dysentery due to C. perfringens type B.

Clinical relevance: C. perfringens bacteria have a worldwide distribution, but disease due to C. perfringens type B has only been diagnosed in a small number of countries and has never been reported in New Zealand or Australia. C. perfringens type B produce both beta toxin and epsilon toxins, therefore both haemorrhagic enteritis and systemic vascular damage can develop. As many animals are exposed to C. perfringens without developing disease, there must be additional unknown factors that resulted in disease in these particular sheep. Vaccines that specifically protect against C. perfringens type B are available and may be recommended for use in smaller non-commercial flocks, as in the present case.     

The effects of temperature on the silage microbiology and aerobic stability of corn and vetch-grain silages

Abstract

The purpose of the current work was to extend the study of the effect of temperature on silage microbiology, with or without formic acid, and on the aerobic stability of corn and vetch-grain silages.

The silage samples were ensiled in 1.0-l anaerobic jars, with and without formic acid, at room (20°C) or elevated temperatures (30–37°C). After 45 days of ensiling, the silages were subjected to an aerobic stability test at room (20°C) and elevated (30–37°C) temperatures. The most intensive deterioration occurred at 30–37°C. Samples incubated at 30–37°C had the highest yeast and mould count, most prolific CO₂ production.

The finding of the current study suggests that formic acid may decrease mould growth in silage samples. Unfortunately, formic acid does not reduce aerobic deterioration rate of silages. Applying a 5 g/kg formic acid on corn and vetch-grain silages was not very effective at high temperatures.     

Epizootics of Erythrocytic Inclusion Body Syndrome in Coho Salmon Cultured in Seawater in Japan

Abstract

Epizootics attributable to erythrocyytc inclusion body syndrome (EIBS) occurred among populations of coho salmon Oncorhynchus kisutch cultured in seawater in Japan. Onset of the disease was correlated with water temperatures declining to below 10°C. Symptoms of EIBS were severe anemia with hematocrits of less than 20% and corresponding changes in erythrocyte counts, hemoglobin concentration, and mean corpuscular hemoglobin concentration. Erythrocytes had characteristic inclusion bodies that contained enveloped viral particles with a diameter of approximately 77 nm. The disease was reproduced in artificially induced infections.     

Effects of ambient temperature on growth performance and carcass traits of male growing White Pekin ducks

ABSTRACT

1. An experiment was conducted to investigate the effects of ambient temperature on growth performance and carcass traits in male growing Pekin ducks from 14 to 42 d of age in order to establish their optimal temperature requirements.

2. A total of 216 14 d old male White Pekin ducks were allocated randomly to six environmentally controlled chambers with ambient temperature set at 20°C, 22°C, 24°C, 26°C, 28°C, and 30°C from 14 to 42 d of age, respectively.

3. As ambient temperature increased from 20°C to 30°C, the body weight and weight gain decreased linearly or quadratically (P < 0.05) and was accompanied by linearly decreasing feed intake (P < 0.05). According to broken-line regression, the upper critical level of ambient temperature during the growing period for body weight, weight gain, and feed conversion ratio were 27.4°C, 27.4°C, and 26.0°C, respectively.

4. The weight of breast meat, leg meat, and abdominal fat decreased linearly or quadratically as ambient temperature increased and declined to a minimum when the temperature increased to 30°C (P < 0.05). The percentage of breast meat and abdominal fat showed a linear or quadratic decreasing response to increasing temperature, but leg meat percentage increased as temperature increased and reached maximum at 30°C (P < 0.05). According to broken-line regression, the upper critical ambient temperatures during the growing period for breast meat weight and percentage were 25.5°C and 25.6°C, respectively.

5. It was concluded that both growth performance and breast meat of growing ducks were sensitive to increasing ambient temperature and this should be kept below the upper critical temperature during the growing period in order to optimise growth performance and carcass traits at market age.