Description of a Gastrointestinal Parasite Found in an Iguana (Iguana iguana) in
Brazil
Karin Werther1; Joaquim Júlio Vicente2; Cláudia Brigagão de
Petta1
1 Universidade Estadual Paulista (UNESP) – Campus de Jaboticabal, Department
of Veterinary Pathology, Via de Acesso Prof. Paulo Donato Castellane s/nº, 14870-000
Jaboticabal/SP/Brazil; 2 Laboratório de Helmintos Parasitos de Vertebrados, Departamento de
Helmintologia do Instituto Oswaldo Cruz, Rio de Janeiro/RJ/Brazil
Abstract: This paper describes and classifies a nematode parasite found in the
gastrointestinal tract of a green iguana (Iguana iguana). The parasite was
identified as Ozolaimus megatyphlon.
Key Words: endoparasites, reptiles, Ozolaimus megatyphlon
Introduction
Free-ranging and captive reptiles are infected and infested with a great diversity of
endo- and ectoparasites (Jacobson, 1986). The antemortem diagnosis of parasitism usually
is done by fecal examination and visualizing the ova. Alternatively, parasitism may be
diagnosed in dead animals at necropsy. In the present case report, parasitism was
diagnosed only by fecal examination and evacuation of the parasites. The animal did not
die.
Case Report
A 6-month-old captive iguana (Iguana iguana) weighing 90 g was presented for
physical examination. The physical findings and medical history included a chronic abscess
of the nose, discrete dehydration, and poor nutritional condition. The animal initially
was treated with oral antibiotics to reduce the size of the abscess which was subsequently
removed by surgery. The fecal examination showed eggs from nematode helminths. The iguana
was treated once with fenbendazole (PanacurÒ , 25 mg/kg
orally). Three days later, the animal evacuated many white nematodes in the feces. The
parasites were collected and fixed in 70° alcohol for identification. One week later, the
fecal examination again showed nematode eggs. The iguana was treated for helminthes once
again, prompting the elimination of additional parasites. The following fecal examination
was negative. In addition, the iguana had an improved appetite and appearance.
The preserved parasites were submitted to the Instituto Oswaldo Cruz, Rio de
Janeiro/RJ, Brazil, Department of Endoparasites / Helminthes for identification. Based
upon the morphologic and anatomical characteristics, the nematodes were classified as
being from the Hyperfamily Oxyuroidea, Family Pharyngodonidae Travassos, 1919, Genus
Ozolaimus Dujardin, 1845, species Ozolaimus megatyphlon (Rud., 1819), Dujardin,
1845. Preserved nematodes (alcohol 70°GL) were permanently deposited in the Oswaldo Cruz
Helminthological Collection (CHIOC) as accession #33,893.
Figure 1 shows one example of this parasite.
 |
| Figure 1. Line drawing of a nematode from an iguana . A= an entire male nematode; B= detailed view
of the anterior extremity of the parasite. |
Discussion
These same parasites have been previously described by Pereira, 1935. The genus Ozolaimus Dujardin, 1845 is distinct from the genus Macracis Gedoelst, 1916,
because parasites from the first genus have only two lips. The lips are lateral-ventral;
dorsal lips are not present. Grossly, these nematodes appear white and elongate.
Pereira (1935) described the male nematodes as being 3.9 to 5.1 mm long and 0.43 to 0.5
mm wide. The cuticle has typical striations and pre-cloacal musculature has not developed.
On the anterior extremity, a constriction exists at the anterior esophagus from which two
large lips (0.3 mm high) appear. The lips are located ventrally and laterally. These lips
later unite ventrally, evert, and form a concave board. Dorsally, the lips also unite
without curvature, forming a transverse board in the cranial-caudal direction. Every lip
emits a membranous process that is 0.008 mm high, occupies all the extension of the lip,
and has a small fissure at the highest part of the process. This part of the membrane has
an enlargement which points toward the medial face of the lip. The oral cavity is shallow
and delineated by the lips. The esophageal canal opens into the dorsal part of the oral
cavity. Furthermore, the oral cavity is asymmetric and has a reinforced base. From a
ventral or dorsal perspective, it is easier to observe the different form of unification
of the lips, called the silhouette of the oral cavity. This silhouette is constricted at
the beginning and later enlarges into a lozenge form cavity. The larger axis of this
cavity coincides with the basal level of the lips. Around the esophageal opening 3
denticulate formations exit, one dorsally and two lateral-ventrally. The esophagus is 1.5
to 2.0 mm long and 0.04 mm wide with a characteristic ampoule form, where the greatest
width is 0.14 mm. Thus, the esophagus can be divided in two parts. The anterior segment is
0.8 to 1.0 mm long, while the segment has a variable length ranging from 0.55 to 0.98 mm.
The anterior part composes the ampoule portion while the posterior part extends to the
esophageal bulb. The nervous ring is 0.26 mm wide and is located near the anterior
extremity. The excretory pore connects to a long chamber that is 1.8 mm distant from the
anterior extremity. The intestines are common and rectilinear. The anterior extremity is
separate from the body and has a membranous lamina dorsally. This membranous lamina is
directed caudally, followed by complex laminar formations more ventrally around the
genital cone. The genital cone lacks morphological individualization.
Ventrally to the genital cone are large papilla formations that terminate with a lot of
delicate papillae. The papillae unite throughout most of their length. Around the opening
of the genital cone are 3 fine, elongated, denticulate formations. Posterior and
ventromedial to the genital cone is a unique fan-like formation. Lateral to this structure
are large basal large formations, the tops of which have discrete external curves.
Dorsally, a membrane with the same breadth as the tail of the parasite exists and
terminates with a rhomboid form. At these end parts exist two pairs of papillae, the
smaller papilla is posterior, while the larger papilla is anterior.
The testis and the seminal vesicle per se lack special characteristics. However,
a unique spicule is moved by two retractor muscles. This spicule reduces its diameter in
accordance when close to the parasite’s body and ends with a fine point. The lumen of
the spicule measures 0.98 to 1.10 mm in length.
The adult female nematodes measure approximately 5.8 to 6.2 mm long and 0.7 to 0.76 mm
wide. The cuticle has normal striations. The digestive tract is similar to that of the
male; the anterior part of the esophagus measures approximately 1.0 mm long and 1.2 to 1.3
mm wide. The esophageal bulb is 0.21 mm in diameter and the anus is located 0.24-0.34 mm
distant from the posterior extremity.
The excretory pore and nervous circle are located 1.6 mm and 0.28 mm distant,
respectively, from the anterior extremity. The genital tract has a vulva situated 1.3 to
1.6 mm from the posterior extremity. The vulva is covered anteriorally by lips. The
elonged eggs measure from 0.065 to 0.131 mm in diameter.
The natural habitat of this parasite is the large intestine of reptiles, family
Iguanidae, species Iguana tuberculata, Laurent. Vicente et al., (1993) described
two species of parasites from the genus Ozalaimus (Ozailamus megatyphlon and O.
cirratus), that parasitize the green iguana (Iguana iguana) in the northeast of
Brazil. Of these two parasites, O. megatyphlon also is known as Ascaris
megatyphlon.
References
1. Jacobson, E. Parasitic Diseases of Reptiles. IN: Fowler (ed.) Zoo and Wild Animal
Medicine. 2. Edition, W.B. Saunders, Philadelphia, 162-181, 1986.
2. Pereira, C. Os Oxyurata parasitos de Lacertilia do Nordeste Brasileiro. IN: Archivos
do Instituto Biológico. Secretaria da Agricultura de São Paulo. 6:5-27, 1935.
3. Vicente, J., Rodrigues, H. O., Gomes, D. C., Pinto, R.M. Nematóides do Brasil.
Parte III: Nematóides de répteis. Revista Brasileira de Zoologia. 10:19-168, 199
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