Literaturdatenbank
Literaturdatenbank |
|
 |
|
MacNeill, A. L., Uhl, E. W., Kolenda-Roberts, H., & Jacobson, E. R. (2002). Mortality in a wood turtle (clemmys insculpta) collection. Veterinary Clinical Pathology, 31(3), 133–136.
Added by: Admin (14 Aug 2008 20:35:30 UTC) Last edited by: Beate Pfau (09 Nov 2008 08:13:17 UTC) |
| Resource type: Journal Article BibTeX citation key: MacNeill2002a View all bibliographic details  |
Categories: General Keywords: Clemmys, Emydidae, Glyptemys, Glyptemys insculpta, Parasiten = parasites, Schildkröten = turtles + tortoises, Veterinärmedizin = veterinary medicine Creators: Jacobson, Kolenda-Roberts, MacNeill, Uhl Collection: Veterinary Clinical Pathology |
Views: 2/618
Views index: 10% Popularity index: 2.5% |
| Abstract |
|
Case Presentation: A reptile breeder with a collection of 130 turtles began to see high mortality rates among wood turtles (Clemmys insculpta) that had hatched between May and August 2000. The breeder had over 10 years of experience with this species, and historically 2-3% of the breeder's hatchling turtles did not survive to adulthood. In 2000, >40 of the hatchling turtles died between the months of September and October. Lethargy, inactivity, and peri-ocular swelling were noted in several of the affected animals. Few hatchling turtles recovered after showing signs of disease; 5-10% of the adult turtles showed mild signs of illness, but none died. Prior to the epizootic, the only major change in environmental conditions was the water supply. A new well had been installed in July 2000, and all areas of the facility were supplied with water from this well. No new ani-mals had been introduced from outside the facility in the past year. Originally, 10-12 animals were housed together in tanks that were 15 in long, 20 in wide, and 4in deep and contained 1 gal of water. The tanks wereoutdoors and above ground.The temperature remainedbetween 69.8°F and 93.9°F between September 1 andSeptember 30, 2000.1The breeder changed the tankwater daily and routinely cleaned the tanks with a 5%bleach solution. When deaths began, the turtles wereplaced in separate containers. Turtles that became illwere treated by the owner with acriflavine (an antimi-crobial) and were soaked repeatedly in bleach solution,but no improvement was seen.On September 27, 2000, the breeder submitted 2recently deceased wood turtles to the Department ofPathobiology at the College of Veterinary Medicine,University of Florida, for necropsy and histopathologicand microbiologic examination. Significant necropsyfindings included moderate amounts of mucoid dis-charge within the nares of 1 turtle and mildly enlargedmottled pale tan to brown livers in both turtles. Animpression smear of the liver was prepared and stainedwith Wright-Giemsa (Hareleco, EM Science, Gibbstown,NJ, USA) (Figure 1).Based on necropsy and cytology results, survivingturtles were given 20 mg/kg metronidazole (SidmarkLaboratories, East Hanover, NJ, USA) orally once dailyfor 5 days. Five additional deaths occurred the weektreatment was started; however, no other turtles showedsigns of illness subsequently. Cytologic InterpretationThe impression smear of the liver was moderately cellu-lar with large amounts of necrotic debris and moderatenumbers of RBCs in the background. Low numbers ofintact hepatocytes with abundant blue-gray mottled cyto-plasm, moderately indistinct cell borders, round nuclei,somewhat diffuse chromatin, and single prominentnucleoli were observed individually and in cohesive clus-ters. Several hepatocytes contained large distinct cyto-plasmic vacuoles. Low numbers of basophils, het-erophils, and reactive macrophages with cytoplasmicvacuoles were noted. Frequent round unicellular organ-isms 27-32 µm in diameter with basophilic cytoplasmand small eccentrically located round nuclei approxi-mately 5.5 µm in diameter were observed throughoutthe sample (Figure 1).The sample also contained sever-al oval vacuolated cystlike structures approximately 16.5µm wide by 30 µm long. A heterogeneous population ofextracellular bacteria was noted. No intracellular organ-isms or neoplastic cells were observed. The round uni-cellular organisms were most consistent with amoebatrophozoites. Pathogenic amoebae, nonpathogenicamoebae, and some flagellates were considered as dif-ferential diagnoses because of the similar morphologyof these organisms.2Histologic InterpretationMultifocal to focally extensive areas of hepatic necrosiswere observed that occasionally extended to the capsu-lar surface. Small to moderate aggregates of macro-phages, heterophils, and lymphocytes were associatedwith the areas of necrosis. Scattered throughout thehepatic parenchyma, but especially common in thenecrotic areas, were 10-15 µm in diameter round toslightly oval protozoal organisms. The organisms con-sisted predominately of trophozoites and were poorlystained in formalin-fixed sections stained with hema-toxylin and eosin (Figure 2). The organisms had mildlyto moderately vacuolated cytoplasm and nuclei contain-ing chromatin plaques with a small, often indistinctendosome. Amoebae consistent with Entamoebasp wereobserved in trichrome-stained liver samples, which hadbeen emulsified and fixed overnight in polyvinyl alcoholbefore staining (not shown). Based upon these featuresand positive staining with periodic acid-Schiff (PAS)(Figure 3), amoebiasis was diagnosed.Amoebae also were associated with mild to moder-ate diffuse necrotizing pneumonia, severe multifocalnecrotizing enteritis, serositis, and adrenalitis. Crosssections of the head revealed mild to moderate conjunc-tivitis and rhinitis associated with large numbers ofgram-positive bacterial rods detected with Brown-Brenn stain. Moderate to heavy growth of Aeromonassobriawas obtained from samples of the liver andcoelomic cavity.DiscussionInfection with some Entamoebaspecies can cause fataldisease in captive populations of reptiles. The majorpathogenic amoeba in reptiles is E invadens.2-5Epidemicsassociated with E invadenshave been reported in snakes3and red-footed tortoises.4Several amoeba species havebeen isolated from reptiles; however, a specific diagno-sis cannot be made by morphologic examination of tis-sue sections or cytologic smears.The 2 common amoebaspecies isolated from humans are E disparand E histolyt-ica. Differentiation between the nonpathogenic E disparMortality in Wood TurtlesPage 134Veterinary Clinical PathologyVol. 31 / No. 3 / 2002Figure 2. Histologic section of liver tissue from a wood turtle withamoebiasis. Arrows indicate 2 faintly stained 10-15 µm in diame-ter trophozoites within an area of necrosis. Vacuolated hepatocytesalso are visible. Hematoxylin & eosin,250.Figure 3. Histologic section of liver tissue from a wood turtle withamoebiasis. Trophozoites and cysts are stained prominently withperiodic acid-Schiff,250.and the pathogenic E histolyticacan be made using poly-merase chain reaction,6-8DNA hybridization,9immuno-histochemistry,10or ELISA to detect parasite antigens11or antibody12against E histolytica. Any of these methodscould be adapted to diagnose E invadensin reptiles, butnone of them are commercially available. Immunohisto-chemistry using a polyclonal antibody against E invadenshas been reported in snakes.2In the past, differentiationbetween E invadensand other species of amoebae hasbeen based on host range and temperature sensitivity inculture.3Amoebic infections in human beings occur world-wide, although there is increased prevalence of the dis-ease in developing countries.13,14More than 500 millionpeople are thought to be infected with either E disparorE histolytica.14Approximately 40 million people infectedwith E histolyticadevelop disease,14and 70,000 die an-nually.13 Ninety percent of people with intestinal amoe-biasis develop dysentery or bloody diarrhea. Other clin-ical forms of intestinal amoebiasis include fulminating colitis, amoebic appendicitis, and amoebae in thecolon.13The most common extraintestinal form of amoe-biasis is amoebic liver abscessation.13,14This disease ischaracterized by severe radiating pain, cough, andfever.13Other signs that may be associated with the dis-ease include anorexia, nausea, vomiting, and diarrhea.13In snakes, pathogenic and nonpathogenic amoebicinfections are most common in the southeastern UnitedStates.5Amoebiasis in reptiles is associated with anorex-ia, depression, listlessness, diarrhea, and dehydration.3,4In these affected turtles, the classic clinical signs associ-ated with amoebiasis were not observed in the weeksbefore death, however, the large number of amoebae inthe livers, the history of high mortality, and the resolu-tion of the epizootic with metronidazole treatmentpointed to amoebiasis as the primary cause of disease.Diarrhea may have been present but not observed bythe breeder; however, only one-third of humans withamoebic liver abscesses have concurrent diarrhea.13,14Pathogenic amoebae can spread rapidly through areptile collection. Cysts shed in the feces of infected ani-mals contaminate communal water or food and areingested by other animals.3Curators can inadvertentlycarry the cysts from one area to another on cleaningequipment and clothing.3Cysts can develop intotrophozoites and can invade host tissues if favorableconditions exist in the host.4In experimental infectionsin snakes,E invadenscaused disease at 25°C but not at10°C or 30°C.4Also, amoebae are more likely to invadetissues when the availability of nutrients (particularlycarbohydrates) in the gastrointestinal tract is low.4Thetrophozoites penetrate the mucus of the colon, theintestinal epithelium, and the lamina propria.13,14Pathogenic amoebae can migrate to the liver via the por-tal circulation.13,14This invasion may lead to hepatic tis-sue necrosis, abscess formation, and death of the ani-mal. Rupture of amoebic liver abscesses and dissemina-tion of the infection prior to death have been reported inpeople.13,14The bacteria isolated from the liver and coelomiccavity of affected turtles were probably nonpathogenic.A sobriais a gram-negative, facultative anaerobic bacillus that is ubiquitous in fresh and brackish water.15Thisorganism also was cultured from the well water at thefacility. Each turtle had continuous access to a pool ofwater in the tank, and the bacteria could have been iso-lated from any turtle in the facility.A sobriais a putativepathogen of human beings and fish15and has been cul-tured from feces and blood of people with gastroenteri-tis and septicemia.15However, Koch's postulate has notbeen satisfied for this organism.15Oral metronidazole is an effective medical treat-ment for amoebiasis; however, it is often difficult toidentify the disease prior to the loss of several speci-mens in a collection.Typically, several animals die beforea postmortem diagnosis is made.3,4Cytologic examina-tion of a liver aspirate is a simple, relatively noninvasivetechnique that can be used to diagnose hepatic amoebi-asis before death. A combination of Romanowsky-typeand PAS stains is highly recommended to aid in identi-fication of the organisms. Formalin fixation causes theorganisms to appear 2 times smaller in histologic sam-ples compared with cytologic samples. References 1. National Oceanic and Atmospheric Administration. National Weather Service. Available at: http://www.nws.noaa.gov.Accessed February 2002. 2. Jakob W, Wesemeier HH. Intestinal inflammation associatedwith flagellates in snakes.J Comp Pathol.1995;112:417-421. 3. Donaldson M, Heyneman D, Dempster R, Garcia L. Epizooticof fatal amebiasis among exhibited snakes: epidemiologic,pathologic and chemotherapeutic considerations.Am J Vet Res.1975;36:807-817. 4. Jacobson E, Clubb S, Greiner E. Amebiasis in red-footed tor-toises.J Am Vet Med Assoc. 1983;183:1192-1194. 5. Telford SR. Parasitic diseases of reptiles.J Am Vet Med Assoc.1971;159:1644-1652. 6. Romero JL, Descoteaux S, Reed S, et al. Use of polymerasechain reaction and nonradioactive DNA probes to diagnoseEntamoeba histolyticain clinical samples.Arch Med Res. 1992;23:277-279. 7. Som I, Azam A, Bhattacharya A, Bhattacharya S. Inter- andintra-strain variation in the 5.8S ribosomal RNA and internaltranscribed spacer sequences of Entamoeba histolyticaand com-parison with Entamoeba dispar,Entamoeba moshkovskiiandEntamoeba invadens.Int J Parasitol. 2000;30:723-728. 8. Zindrou S, Orozco E, Linder E, Tellez A, Bjorkman A. Specificdetection of Entamoeba histolyticaDNA by hemolysin gene tar-geted PCR.Acta Trop. 2001;78:17-25. 9. Samuelson J, Acuna-Soto R, Reed S, Biagi F, Wirth D. DNAhybridization probe for clinical diagnosis of Entamoeba histolyt-ica.J Clin Microbiol. 1989;27:671-676. 10. Arias-Negrete S, Leon G, Anaya-Velazquez F, et al. Recognitionof carbohydrate epitopes specific for electron-dense granuleantigens from Entamoeba histolyticaby monoclonal antibodiesin the cecal content of infected hamsters.Curr Microbiol.2001;43:403-407. 11. Haque R, Mollah NU, Ali IK, et al. Diagnosis of amebic liverabscess and intestinal infection with the TechLab EntamoebahistolyticaII antigen detection and antibody tests.J ClinMicrobiol. 2000;38:3235-3239. 12. Zaki NR, Ibrahim SA, Atef SM, Omar HM. Evaluation of labo-ratory techniques for differentiation between Entamoeba his-tolyticaand Entamoeba dispar.J Egypt Soc Parasitol. 2001;31:335-344. 13. Espinosa-Cantellano M, Martinez-Palomo A. Pathogenesis ofintestinal amebiasis: from molecules to disease.Clin MicrobiolRev. 2000;13:318-331. 14. Li E, Stanley S. Protozoa. Amebiasis.Gastroenterol Clin NorthAm. 1996;25:471-492. 15. United States Food and Drug Administration Center for FoodSafety and Applied Nutrition. Foodborne Pathogenic Microor-ganisms and Natural Toxins Handbook.Aeromonas hydrophila.Available at: http://cfan.fda.gov/~mow/chapt17.html. Acces-sed May 2001
Added by: Admin Last edited by: Beate Pfau |