Ophidascaris in a Reticulated Python (Python reticulatus)

Dana L. Ambrose, Susan E. Little, Kenneth S. Latimer

Department of Medical Microbiology (Ambrose, Little) and Department of Veterinary Pathology (Latimer), College of Veterinary Medicine, The University of Georgia, Athens, GA 30602 (USA)

Abstract: Identification of Ophidascaris attached to a large gastric nodule from an anorexic, debilitated reticulated python is described. Pathogenicity, treatment and control of these parasites of snakes are reviewed.

Keywords: Ophidascaris, Python, Python reticulatus, fibrous nodules, ascaridoid

Case History

An adult reticulated python (Python reticulatus), owned by Zoo Atlanta, presented with a 5 month history of anorexia and weight loss. The python was tube fed and treated for dehydration with oral and subcutaneous fluids. The snake’s condition continued to deteriorate and the referring clinician elected euthanasia.

Figure 1.

Gastric tissue samples and intestinal nematodes were submitted to the University of Georgia Clinical Parasitology Laboratory for parasite identification. The gastric lesion consisted of a hard, fibrous nodule 2.5 cm in diameter. Nine worms were firmly attached by their anterior ends into the lumen of the nodule. The nematodes ranged from 4.5 to 8 cm in length. The anterior end of each nematode consisted of well-developed interlabia and square-shaped lips. The worms were identified as Ophidascaris sp. , an ascaridoid parasite of the esophagus and stomach of snakes, by comparison to published descriptions. ^1-3

Discussion

Ophidascaris has been reported from pythons in India, Southeast Asia, Australia and Africa. ^3-8 Ophidascaris filaria were reported by Robinson (1934) from Malayan reticulated pythons, Python reticulatus. Many uncertainties exist concerning the taxonomic distinctions between species of the genus Ophidascaris. ^{1, 9} The genus has 25 known species, but only two have been studied in any detail. ^8,10 Sprent (1970) reports that four species are known to infect pythons: O. filaria, O. morliae, O. baylise, and O. infundiculum.

Adult Ophidascaris attach to the gut of the definitive host when the host is not feeding but also can be found intertwined with and feeding on ingesta. These parasites are occasionally found in clusters of up to 50 individuals with their heads buried in an elevated gastric nodule. ¹⁰ In pythons, more than one type of ascaridoid may be found attached to a given nodule. The eggs are spherical, measure 28-85 µ x 68-80 µ in size, and are pitted around the surface of the shell. Eggs containing second-stage larvae can remain infective for intermediate hosts for up to seven years. ¹⁰ Intermediate hosts include rats, mice and a variety of small mammals. The eggs hatch in these hosts and the larvae migrate to the liver, lungs and subcutaneous tissues where they molt. When the intermediate hosts are ingested by the python, the third stage larvae migrate to the lungs where they remain for three or more months. After molting the larvae move up the esophagus as fourth-stage larvae. Eventually the larvae migrate to the stomach, undergo a fourth molt, and continue to develop as adults. ^8,10

The pathogenic effects of ascaridoid infections in snakes is generally related to the number of parasites present, the overall health of the host, the availability of food, and the local host tissue reaction to the parasite. Fibrosis of the muscular wall of the intestine and fibrotic nodules protruding into the intestinal lumen have been reported in pythons parasitized by Ophidascaris;^5,6 however, there is little published information on the clinical significance of these lesions. Digestive disturbances in pythons are sometimes associated with Ophidascaris infections and large masses of adult worms may produce obstruction, gastric ulceration, and perforation of the intestinal wall. ^2,11 Some researchers feel that large numbers of Ophidascaris parasites may reduce resistance to other infections in reptilian hosts. ⁵ Fourth stage larvae of Ophidascaris papuanus encysted in the aortic wall were reported to be the cause of aortitis and possible cause of stenosis and vessel obstruction in a python (Liasis papuances). ¹²

Control of Ophidascaris infections depends on parasitological screening and treatment of snakes prior to their introduction into an established population of reptiles. A variety of efficacious and safe anthelmintics are available for treating nematodes in snakes. ² Oxfendazole, at 10 mg/kg, used as part of routine quarantine procedures at the Houston Zoological Gardens in Texas, resulted in the expulsion of one Ophidascaris adult from a spotted night adder imported from Cameroon, West Africa. ⁸ Rodent food sources, which may serve as intermediate hosts, should be checked for parasite infection. Wild rodents should be prevented from entering into rodent breeding colonies and avoided as food sources unless frozen several weeks prior to feeding. ²

References

1. Ash LR, Beaver PC: Redescription of Ophidascaris labiatopallosa Walton, 1927, an ascarid parasite of North American snakes. J Parasitol 49:765-770, 1963.

2. Frye FL: Biomedical and surgical aspects of captive reptile husbandry. Vol. 1. Krieger Publishing Company. Malabar, FL. 1991. pp.292-309.

3. Sprent, JFA: Studies on ascaridoid nematodes in pythons: redefinition of Ophidascaris filaria and Polydelphis anoura. Parasitol. 59: 129-40, 1969.

4. __________: Studies on ascaridoid nematodes in pythons: speciation of Ophidascaris in the Oriental and Australian regions. Parasitol. 59: 937-959, 1969.

5. Elbihari S, Hussein MF: Ophidascaris filaria (Dujardin 1845) from the African Rock Python, Python sebae, in the Sudan, with a note on associated gastric lesions. J Wildlife Dis 9: 171-173, 1973.

6. Brar RS, Gupta PP, Misri J: Observation on the post-mortem lesions in two pythons. Indian Vet J 67(6): 573, 1990.

7. McAllister CT, Freed PS, Freed DA: Ophiotaenia ophiodex and Ophidascaris sp. in a Spotted Night Adder (Causus maculatus) from Cameroon, West Africa. J Wildlife Dis 28(4): 641-642, 1992.

8. Anderson RC: Nematode Parasites of Vertebrates. Their Development and Transmission. University Press, Cambridge. 1992, pp 291-292.

9. Robinson VC: On a collection of parasitic worms from Malay. I. Nematodes (Superfamilies Ascaroidea and Oxyuroidea). Parasitol. 26: 481-488, 1934.

10. Sprent JFA: Studies on ascaridoid nematodes in pythons: the life history and development of Ophidascaris moreliae in Australian pythons. Parasitol. 60: 97-122, 1970.

11. Telford SR: Parasitic diseases of reptiles. J Am Vet Med Assoc 159: 1644-1652, 1971.

12. Hamir AN: Aortitis caused by Ophidascaris papuanus in a python. J Am Vet Med Assoc 189(9): 1129-1130, 1986.

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