R O UNDTAB LI invadens

Entamoeba invadens is a very significant protozoan pathogen affecting several taxons. is often associated with disease in squamates, but can also cause significant morbidity and mortality in chelonians as well. This panel has extensive experience in chelonian medicine and will provide up-to-date information on diagnosing and treating chelonian species with amoebiasis.

Barbara Bonner, DVM, MS The Turtle Hospital of New England 1 Grafton Road, Upton, MA 01568-1569, USA Tufts University School of Veterinary Medicine, North Grafton, MA 01536, USA Downloaded from http://meridian.allenpress.com/jhms/article-pdf/11/3/17/2203726/1529-9651_11_3_17.pdf by guest on 29 September 2021

Mary Denver, DVM Baltimore Zoo Druid Hill Park, Baltimore, MD 21217, USA

Michael Gamer, DVM, DACVP Northwest Zoo Path 18210 Waverly, Snohomish, WA 98296, USA

Charles Innis, VMD VC A Westboro Animal Hospital 155 Turnpike Road, Route 9, Westboro, MA 01581, USA

Moderator: Robert Nathan, DVM

1). Which species of chelonians do you see with Entamoeba Geochelone elegans. We have seen clinical disease in mata invadens? matas, Chelus fimbriatus, and African mud turtles, Pelusios Bonner: I have seen Entamoeba and clinical signs of ill subniger. health that improved upon treatment in Gulf coast box turtle, Garner: Northwest ZooPath has cases of amoebiasis in all Terrapene Carolina major, three-toed box turtle, T. Carolina groups of , including snakes, lizards, chelonians, and triungulis, leopard tortoise, Geochelone pardalis, Travancore crocodilians. Since inception in 1994, we have accumulated tortoise, Indotestudo forsteni, Geoemyda yuwonoi, spiny tur­ 13 cases of amoebiasis in tortoises, and one case in a turtle. tle, also known as the “cog-wheel turtle,” Heosemys spinosa, These cases include the following: hinged back tortoise, H. grandis, Chinese box turtle (yellow-margined box turtle or Kinixys spp. (5), Travancore/Forsten’s tortoise, Indotestudo yellow-rimmed box turtle), Cuora flavomarginata, Malayan forsteni (3), impressed tortoise, Manouria impressa (2), yel­ box turtle, Cuora amboinensis, Indochinese box turtle(flower- low foot tortoise, Geochelone denticulata (1), Indian star back), hundred-flower box turtle, white-fronted box turtle, tortoise, Geochelone elegans (1), elongated tortoise, three-hill box turtle, Cuora galbinifrons, C. serrata, flat shell Indotestudo elongata (1), and black bellied notched turtle, turtle, Notochelys platynota, Geoemyda spengleri, Borneo Graptemys nigrinoda (1). The disease may be more common black leaf turtle, Siebenrockiella crassicollis, serrated hinge- in tortoises than turtles. back tortoise, Kinixys erosa, Bell’s hinge-back, Kinixys Innis: I have found cysts and trophozoites in the belliana, Home’s hinge-back, Kinixys homeana, and others. feces of numerous species of chelonians. My clinical impres­ Denver: We have seen many species of chelonians that test sion is that terrestrial and semiaquatic species seem more positive for the presence of entamoeba by culture but which often infected than very aquatic species, but this may repre­ have no clinical signs. These include eastern box turtles, sent a caseload bias. I have reviewed 34 chelonian necropsies Terrapene c. Carolina, bog turtles, Clemmys muhlenbergi, from the past two years for which I have detailed histopathol- musk turtles, Sternotherus odorata, Indian flapshell turtles, ogy. Amoebiasis was identified in three cases: black-breasted Lissemys punctata, red-footed tortoises, Geochelone car- leaf turtle, Geomyda spengleri, redfoot tortoise, Geochelone bonaria, spotted turtles, Clemmys guttata, gopher tortoises, carbonaria, and Indian star tortoise, Geochelone elegans. Gopherus polyphemus, map turtles, Graptemys geographica, Although this represents a relatively small series of cases, the common mud turtles, Kinosternon subrubrum, Batagur tur­ incidence of amoebiasis is notable. There are a number of tles, Hardella thurjii, diamondback terrapins, Malaclemmys additional case reports in the literature documenting amoebia­ terrapin, Murray river turtles, Emydura macquarrii, sis in a variety of chelonian species (e.g. J Herp Med Surg Siebenrock’s snakeneck turtles, Chelodina siebenrockii, 10.1). I think that any species should be considered suscepti­ Egyptian tortoises, Testudo kleinmanni, and star tortoises, ble. Finally, it is important to note that amoebae, although

Volume 11, No. 3,2001 Journal of Herpetological Medicine and Surgery 17 most often identified in wild-caught animals, can affect cap­ nation of sloughed colonic pseudomembrane, and that animal tive bom animals, particularly young or debilitated specimens; survived with treatment. and may affect saurians more easily than chelonians. Innis: Many animals that are shedding trophozoites and cysts are clinically affected. However, there also seem to be a 2). Are these chelonians clinically ill from Entamoeba significant number of animals that shed small numbers of invade nst cysts and are asymptomatic carriers. It is unclear exactly what Bonner: Clinically ill depends upon how one defines clini­ conditions cause some animals to become ill from Entamoeba, cally normal. It has been my experience that virtually all but a poor immune response is likely to contribute significant­ turtles who have Entamoeba invadens or other pathogenic ly. In the work that Dr. Bonner and I have done in amoeba improve clinically if it is treated. Clinical improve­ rehabilitating a number of species of Southeast Asian cheloni­ ments may be seen as increased strength, increased activity, ans, many of them are severely debilitated due to a lengthy interest in breeding, increased time out of water/resistance to collection and importation process, and seem generally dehydration (for semi-aquatics), increased, improved or more immunosuppressed. Many of those animals suffer from bacter­ consistent appetite (with resultant weight gain or increased ial sepsis, fungal infection, and metazoan ; and

rate of weight gain), formed stool, or just increased tolerance many of them are shedding large numbers of amoeba cysts. Downloaded from http://meridian.allenpress.com/jhms/article-pdf/11/3/17/2203726/1529-9651_11_3_17.pdf by guest on 29 September 2021 of stress. It is also important to consider the time line involved. One 3). What clinical signs are present? could see a single amoeba or a few cysts on one fecal over a Bonner: Clinical signs can vary widely. Aquatics from series of five fecals. At the time of examination, the turtle endemic parts of the world kept with good husbandry can appears to be more or less clinically without symptoms. It has have significant loads with virtually no clinical signs, except been my experience that often four to eight months later that loose stool and slower rates of weight gain/growth compared animal will be back with clinical signs of diarrhea, inap- to like animals without detectable amoeba load. The most petance, and general lethargy. This time the load will be much common universal signs, seen in aquatics, semi-aquatics, ter­ higher, with multiple amoeba and cysts seen on every fecal. restrial species, and tortoises, are diarrhea and irregular In animals that I manage and thus can assure long-term fol­ appetite. Affected chelonians can present withdrawn, dehy­ low-up, the amoeba-positive animals consistently became the drated, weak, emaciated, and anorexic. In my experience, sudden deaths, the poor-doers, or the holding-steady but fail- these signs are more likely to be seen in non-aquatics and ing-to-thrive category of turtle that in certain species, I do not seen most severely in tortoises. I have seen dysenteric diar­ wait for the onset of clinical illness before treating. rhea (loose stool every 15 min) on occasion. Severely ill Denver: As previously stated, only the mata mata and animals may be icteric, anemic, and in varying stages of cir­ African mud turtles seem to be affected clinically. culatory collapse. In my experience with this category of Garner: With one exception, all animals submitted to patient, multiple health issues often need to be addressed Northwest ZooPath had died; and the amoebic infection had simultaneously. It is difficult to be certain that all the clinical contributed significantly to the animals’ demise. One of the signs are solely related to the amoebiasis. impressed tortoises was diagnosed based on histologic exami­ Denver: The mata mata developed lethargy and inap- petance. The African mud turtles presented with sudden death. The presence of blood or mucus in the stool may also be noted. Garner: A history that includes clinical signs was available on 12 of the cases submitted to Northwest ZooPath. Acute clinical signs were seen in four tortoises. The star tortoise was passing gelatinous material in the stool. One impressed tor­ toise was asymptomatic prior to passing a colonic pseudomembrane containing the organisms. The yellow foot tortoise and one hinge back tortoise had a two day history of depression and inappetence. Eight cases had a history of chronic illness. Seven of these had histories of chronic emaci­ ation and/or anorexia; one had a history of chronic necrotizing rhinitis. Innis: Clinical signs in affected animals are often the same vague signs seen with most chelonian illnesses. As discussed below, amoebae can infect a number of organs, and the signs may differ with the location of pathology. In general, affected animals are anorexic and less active than a healthy specimen Figure. 1. Bog turtle (formerly Muhlenberg’s turtle), Clemmys of that species. They may spend long periods of time with­ muhlenbergi, is 3.0 to 4.5 inches; it is a small brown turtle. The head patch sometimes is yellow or split in two parts. Scutes of drawn in their shell. Anecdotally, some specimens appear to the carapace are light brown to mahogany and may have yellow­ be polydypsic. With gastrointestinal involvement, diarrhea is ish or reddish centers. On large scutes, a light-brown or orange often present. With pulmonary involvement, dyspnea, sunburst pattern may be present. The plastron is brownish-black oronasal discharge, and wheezing may be noted. with varying amounts of yellow along the midline. Photo cour­ tesy of Steve Barten, DVM

18 Journal of Herpetological Medicine and Surgery Volume 11, No. 3,2001 4).»What tests do you use to diagnose Entam oeba may need to be evaluated five to ten times to identify inter­ invadens! mittent shedding. A better technique than a simple wet mount Bonner: I use direct fecals to diagnose Entamoeba. I am may be extrapolated from procedures used in human diagnos­ not always sure I am correctly identifying which species is tic labs. Feces is often fixed in polyvinyl alcohol (PVA, present. Particularly in Asian imports, there appear to be mul­ available from human microbiology labs), then dried smears tiple species of amoeba. The presentation of the amoeba also of the preserved material are made and stained with trichrome seems to vary with the nutritional state of the patient. Very and iron hematoxylin stains. These stains allow differentiation often, initial fecals reveal only cysts, particularly in animals of various morphologic features of the amoebae as discussed presenting with anorexia. The most straightforward way to below. Culture of amoebae has been attempted by Dr. Denver and colleagues with rather discouraging results. In the future, it would be useful to develop a fecal ELISA or IFA test for amoebae. Another useful diagnostic tool in human medicine is colonoscopy and biopsy of colonic ulcers. Endoscopy may also be used in chelonians and may be the only way to get a

premortem diagnosis of hepatic or splenic amoebiasis. Downloaded from http://meridian.allenpress.com/jhms/article-pdf/11/3/17/2203726/1529-9651_11_3_17.pdf by guest on 29 September 2021

5). How do you distinguish Entamoeba invadens from nonpathogenic amoeba? Bonner: I feel that Entamoeba invadens is not the only pathogenic amoeba I am seeing, so I treat based on the species of turtle, the patient’s history, and clinical presenta­ tion. In most species I have worked with, turtles that have been treated seem to be hardier and do better over time, so I am not hesitant to treat. Denver: At this point in time, morphological characteris­ tics are the only method widely available. This can be very inaccurate as Entamoeba invadens has nearly identical mor­ phology to two human Entamoebas and several other reptilian and amphibian Entamoebas. Entamoeba invadens cysts are Figure 2. The spotted turtle, Clemmys guttata, is 3.5 to 4.5 inch­ quadrinucleate, as are many non-pathogenic amoeba cysts. es. The carapace is black and contains small round yellow or orange spots. The ventral surface is yellowish outlined by black The trophozoites are variable in size, but will rarely be blotch. The skin color range from gray to black, which some­ observed as they degenerate very shortly after removal from times contain yellow spots on the neck, head, and limbs. The the host organism. I assume any amoebic cysts are head has a broken yellow band near the tympanum. Photo cour­ Entamoeba invadens if the reptile is sick, and that it is proba­ tesy of Steve Barten, DVM bly Entamoeba invadens even if the reptile is not clinically ill. Garner: Histologically, amoebae are occasionally seen in correlate the cyst with the trophozoite is to watch until one the gastric and intestinal lumina of chelonians, in which there transforms into the other enough times to be able to correctly is no associated inflammatory response or other gut lesion. match a given type of cyst with the corresponding amoeba. These may be amoeba other than Entamoeba invadens, or This is, however, enormously time-consuming. they may represent Entamoeba invadens in which conditions Denver: We have found that routine fecal screening rarely in the gut are not conducive to invasion and pathologic detects Entamoeba unless there are many, many trophozoites change. We assume from available literature that the organism present, and the sample is very fresh. For our research project present in the visceral lesions is Entamoeba invadens, based on Entamoeba, we used a culture technique to increase the on morphology of the organism and the morphology of the number of organisms present for detection. The cultures were lesions, but it is also considered possible that other amoebae then centrifuged and the pellets resuspended in a very small could produce pathologic changes. Infectivity studies with volume for microscopic examination. This is impractical for cultured organisms, immunohistochemistry, or in situ DNA routine screening of fecal samples (Cranfield, et al, 1999). hybridization studies would be needed to fully characterize Garner: All cases of chelonian amoebiasis submitted to the spectrum of amoebic species that can cause pathologic Northwest ZooPath were diagnosed histologically from sam­ changes. ples of colon, intestine, or liver. Innis: I do not think that we have a good understanding of Innis: Clinically, I have relied upon simple saline wet- the many possible species of amoebae that affect reptiles. In mount preparations of fresh feces to identify trophozoites and humans there are at least five genera of amoebae that may be cysts. The organisms are typically in the 10-20 pm size found in feces. Within the human Entamoeba group, there are range, as opposed to the 60 pm size range of ascarids or at least four species found in feces, two of which (E. histolyti­ strongyle-type ova. The trophozoites have a typical amoeboid ca and E. dispar) cannot be morphologically differentiated morphology and movement. The cysts are generally spherical from each other. Historically, it has generally been reported and have a variable number of nuclei, possibly related to dif­ that all reptile amoebae have been E. invadens, but I am quite ferent stages of development or indicating different species sure that a motivated parasitologist could identify a large are present. Having said that, I must admit that this method of number of species among the thousands of species of reptiles. diagnosis is lacking in sensitivity. It is likely that wet mounts In general, the human pathogenic forms can be differentiated

Volume 11, No. 3,2001 Journal of Herpetological Medicine and Surgery 19 by differences in the number of nuclei, chromatin staining, wall, with associated areas of hemorrhage. Coelomitis is usu­ cytoplasmic glycogen granules, and cytoplasmic chromatoid ally fibrinous to granulomatous and more often reflects the bodies of cysts on stained fecal smears. In addition, it is concurrent bacterial component than a response to amoebae. reported that the presence of erythrocyte phagocytosis by E. Organisms spread via vessels to other viscera and lesions are histolytica trophozoites is characteristic of that pathogenic most common in the liver, spleen and lung. Changes vary species. I have not seen this in reptiles. Until we have more depending on chronicity of the lesion: acute changes include information in reptiles, I assume that amoebae are pathogens necrosis and hemorrhage with fibrinous or heterophilic and try to eliminate them. inflammation, and amoebae may be found in blood vessels or areas of necrosis. More “chronic” lesions have granuloma for­ 6). What gross and histopathogic changes are seen from mation and the amoebae are usually found admixed with or Entamoeba invade as"! within the macrophages in the rim of the granulomas. Bonner: In theory, E. invadens can migrate and cause It is doubtful that these animals live more than a few days lesions anywhere in the body. Lesions are most commonly to a week after pathologic changes begin in the gut. Based on identified from the liver and the lumen of the intestine. Other the histologic changes, which are acute to subacute, and the

extra-intestinal organs may be affected as well. Lesions can frequent history of chronic clinical disease such as anorexiaDownloaded from http://meridian.allenpress.com/jhms/article-pdf/11/3/17/2203726/1529-9651_11_3_17.pdf by guest on 29 September 2021 cause intestinal erosion, inflammation and ulceration. The gut and wasting, it is reasonable to suggest that pre-existing wall may be thickened and there may be a fibronecrotic stress, inanition and possibly concurrent antibiotic therapy or pseudomembrane overlaying the focal lesions (Frye 1991). other gut-related drug therapy may alter the microenviron­ There may be focal hepatic abscesses with or without fatty ment in the gut, predisposing these animals to amoebiasis. liver changes. However, until the normal amoebic fauna and all pathogenic Denver: Ulcerative or necrotic colitis, thickening of the species are better characterized and understood, the precise intestinal mucosa, hepatic abscesses, thrombic emboli caus­ pathogenesis will not be fully understood. ing necrosis of the liver or portions of the gastrointestinal Innis: I will leave the histopathology details to Dr. Gamer, tract. Organisms may be seen histopathologically, often with but the gross lesions that I have seen have included colonic associated secondary bacterial infections. ulcers, hepatic abscesses (some as small as 2 - 3 mm and Garner: Gross lesions are suggestive of the infection but some as large as 6 cm), splenomegaly, and pulmonary are not specific. The gross findings usually include colonic abscesses. edema with ulceration and mucosal pseudomembrane forma­ tion. Less commonly, similar changes are seen in the small 7). What disinfectants are useful against amoeba? intestine. The serosa of the viscera may be coated with fibril­ Bonner: Ultraviolet sterilization is effective for treating the lar material or may contain mottled nodular foci. The liver water. Although specific studies are lacking, biocides, sub­ frequently is enlarged and contains mottled nodules or dis­ stances that effectively kill all living microorganisms, including creet foci of red to white discoloration. The spleen may be spores, would be preferred over biostats or antiseptics. enlarged and mottled. Some affected animals have red discol­ Denver: Almost anything will kill the trophozoites. I have oration and thickening of the lung, and many are emaciated. not done any research into what will kill the cysts, however, Histologic changes include transmural ulcerative and one paper tested hydrochloric acid and mercuric chloride and necrotizing colitis (and/or enteritis) with intralesional amoe­ found that 0.002% mercuric chloride was effective when bae and bacteria. This process usually extends onto the applied for 24 hr or more. Heat is probably a more effective serosal surface, and amoebae can usually be found in intesti­ and easier to use treatment. The cysts are rendered inactive by nal and serosal lymphatics and blood vessels. Vessels often 7 days of 37°C (98.6°F) temperature (McConnachie, 1955). contain thrombi and have fibrinous necrosis of the vessel Innis: I have not been able to locate any controlled studies that have evaluated this topic. E. histolytica cysts have been reported to survive up to eight days in soil at 28 - 34°C (82 - 93 °F), while the trophozoites generally die quickly once they leave the body. E. histolytica cysts are killed in less than a minute when exposed to temperatures over 52°C (126°F). As such, it is likely that cleaning with very hot water or steam would be effective for enclosures. I have been using a dilute bleach solution (20:1, water: bleach) to disinfect cages, although I have no evidence that this is effective.

8). How do you treat chelonians with amoebiasis? Are there any new treatments you are finding particularly use­ ful? Bonner: I treat with a 20-day sequential combined regimen of and iodoquinol. The specifics vary with the species. In general, aquatics and semi-aquatics receive five days metronidazole and iodoquinol, five days iodoquinol Figure 3. Common map turtle, Graptemys geographica, hatch­ alone, five days of both, and a final five days of iodoquinol. ling. Note the egg tooth below the nostrils. Photo courtesy of Terrestrial turtles and tortoises or strictly vegetarian species Steve Barten, DVM receive three days of metronidazole and iodoquinol, 14 days

20 Journal of Herpetological Medicine and Surgery Volume 11, No. 3,2001 of idlloquinol alone and a final three days of the combination. dosages, iodoquinal and diloxanide furoate. In human medi­ The iodoquinol dose is based on an original allometric dose cine, metronidazole in considered effective for killing but works out to roughly 25 mg/0.75 - 1.0 kg. The metronida­ trophozoites, but not very good at reducing numbers of cysts. zole dose varies from 25 mg/kg to 50 mg/kg depending upon Metronidazole is usually used in conjunction with either the species. The lower end dosages are better tolerated, but iodoquinol or diloxanide furoate, which are more effective for relapse rates are higher. inactivating cysts. Metronidazole and iodoquinal are both I am currently seeing relapses within two years in up to available in the United States. Diloxanide furoate is not avail­ 25% of animals treated at the lower dosages and probably able in the United States, however, in our trials using snakes 10% of animals treated at the higher dosages. It is possible I and box turtles, it was the most effective at reducing the num­ am seeing reinfection due to breaches in husbandry, but I ber of cysts and caused the least amount of histopathological think it more likely that infection was not entirely eliminated changes. None of the drugs completely eliminates the initially and gradually became clinical again. Relapsed ani­ Entamoeba organism from the host (Denver, et al, 1999). That mals that are retreated seem to respond well to retreatment. I would be an unrealistic expectation. Chelonians may be have been using this drug combination for about three years. asymptomatic carriers, and should never be housed or dis­

I tube-feed patients concurrently if the animal is not eating played with snakes or lizards. Treatment of carrier reptiles isDownloaded from http://meridian.allenpress.com/jhms/article-pdf/11/3/17/2203726/1529-9651_11_3_17.pdf by guest on 29 September 2021 either from illness or the stress of treatment. I also put animals probably unwarranted and useless. Good hygiene is most with severe loads or other concurrent illness on ceftazidime or important in reducing of Entamoeba. another broad-spectrum antibiotic with good Gram-negative Innis: Treatment of amoeba infection varies depending on activity. In animals where there is evidence of malabsorption the severity and location of the infection. In theory, one must due to disruption of normal gastrointestinal flora, I treat with a eliminate both the trophozoite stage and the cyst stage, and probiotic for three weeks following treatment. one must use drugs that will reach the site of infection. The I find the regimen I use more useful than any single drug or drug used most commonly to treat reptile amoebiasis in the any historic treatment. The specific modifications for each past has been metronidazole. While metronidazole is effective species that either result in the treatment being better tolerat­ in killing trophozoites, and can reach a wide variety of body ed or result in a lower rate of relapse seem to be continual tissues, it generally is not effective against the cyst stage. As a works in progress. Each species has its own issues and result, metronidazole is often combined with a cyst-cidal drug responds differently to the drugs and to the stress of daily oral in human cases. In light of this, it is likely that combining medication. This fine-tuning by species is unfortunately metronidazole with iodoquinol, paromomycin, or diloxanide, empirical and, consequently, takes time. I find that every six all of which can kill cysts in the gastrointestinal tract, is most months I look back and have made subtle or not-so-subtle effective in treating reptilian amoebiasis and in trying to elim­ alterations in dosages, intervals, duration, or the timing of ini­ inate the carrier state. Initial clinical use of some of these tiating treatment based upon the species I am working with drugs by Dr. Bonner, Dr. Denver, and myself, and initial con­ and my increased base of knowledge. trolled studies by Dr. Denver, Dr. Mike Cranfield, and Dr. Thaddeus Graczyk indicate that they may be useful, but more Denver: We have used metronidazole at many different research is needed. The work done at the Baltimore Zoo has shown that none of these drugs are 100% effective. At this time, I am treating chelonians with metronidazole (20 mg/kg PO QOD) and iodoquinol (50 mg/kg PO SID) for three weeks, with apparently good results. Most clinically affected animals seem to improve with this protocol, but I have not proven complete eradication in any specimen. This can be a long and tedious treatment, especially in very strong patients. One should consider placement of a pharyngostomy tube in some individuals. It is also important to address other health issues of the patient including its nutritional status, tempera­ tures, bacterial infections, etc. Iodoquinol may be difficult to locate at this time, but compounding pharmacies seem to have access to it and can formulate a palatable suspension. Diloxanide is not available in the United States at this time, but should be considered in other countries. Paromomycin has been used in reptiles at doses of 25 mg/kg to 360 mg/kg PO SID to QOD for two weeks, and should be considered as an alternative to iodoquinol. Caution should be exercised with high doses of paromomycin due to the risk of possible sys­ temic absorption from a damaged gastrointestinal tract as Figure 4. Adult female common map turtle, Graptemys geo- graphica, this species has sexual dimorphism. Adult females are recently reported in cats. Finally, one may want to consider large, 17.5 - 27 cm (6.9 - 10.6 inches), and develop huge heads adding injectable chloroquine to the course of treatment. This with massive crushing jaws to eat the molluscs (snails and clams) drug is labeled for use in treatment of human extraintestinal they prefer. Males stay small, 10 - 16 cm (3.9 - 6.3 inches), with amoebiasis and is available in the United States. I have used small heads, and eat aquatic vegetation and insects. Photo cour­ chloroquine in three chelonians at a dose of 50 mg/kg IM tesy of Steve Barten, DVM. once weekly for three doses in combination with iodoquinol

Volume 11, No. 3,2001 Journal of Herpetological Medicine and Surgery 21 and metronidazole with apparently good results, although it is REFERENCES obviously not possible to claim efficacy of the drug under these conditions. Cranfield MR, Graczyk TK, Denver MC, Blank P. 1999. New approaches for the diagnosis of Entamoeba infections in captive reptiles. Proc ARAV, 17-18. Denver MC, Cranfield MR, Graczyk TK, Blank P, Wisnieski A, Poole V. 1999. A review of reptilian amebiasis and current research on the diagnosis and treatment of amebi­ asis at the Baltimore Zoo. Proc AAZV, 11-15. McConnachie EW. 1955. Studies on Entamoeba invadens Rohdain, 1934, in vitro, and its relationship to some other species of Entamoeba. Parasitology, 45: 452-481. Frye FL, 1991. Biomedical and Surgical Aspects of Captive Reptilian Husbandry. Krieger Publishing Co,

Malabar FL. Downloaded from http://meridian.allenpress.com/jhms/article-pdf/11/3/17/2203726/1529-9651_11_3_17.pdf by guest on 29 September 2021

Figure 5. The spiny turtle, Heosemys spinosa, it is 6.8 to 8.66 inches. It is found from Tenasserim through peninsular Thailand and the Malay Peninsula to Sumatra, Borneo, and various small Indonesian Islands. It prefers shallow, clear rainforest streams at alti­ tudes from 170 m up to 100 m where it frequently wanders about on land in cool, humid, shaded areas. It often hides under plant debris or clumps of grass. Photo courtesy of Steve Barten, DVM.

Figure 6. The common musk turtle, Sternotherus odoratus, is 3 to 5 inches. The carapace is brown or black, and has a smooth, oval shape with a high dome. When these turtles are hatchlings, the carapace is usually black and rough. The skin is a dark-olive to black color, and there are two prominent yellow lines that run from the snout to the neck, one on either side of the eye. Photo courtesy of Steve Barten, DVM.

22 Journal of Herpetological Medicine and Surgery Volume 11, No. 3,2001