A Rare Case of Gastric Myiasis in a Lion Caused by Gasterophilus intestinalis (Diptera: Gasterophilidae)-Case Report.

Myiasis is the infection caused by a variety of dipterous (fly) larvae in vertebrate's tissue (man and domestic or wild animals). Species of Gasterophilus are obligate parasite of horses, donkeys, zebras, elephants and rhinoceroses. There are records worldwide, but mostly, in tropical and subtropical regions. This case report describes a type of gastric myiasis caused by G. intestinalis in an old lion in a zoo in Sistan, southeast Iran. Myiasis in lions is rarely reported and this is the first report of gastric myiasis in lion.

Introduction

The genus Gasterophilus (Diptera: Gasterophilidae) includes nine species, six of which are reported to cause gastrointestinal myiasis in equid hosts (Wall and Shearer 2001). All species were originally restricted to the Palearctic and Afrotropical Regions (Colwell et al. 2007), but three major species G. nasalis, G. intestinalis, G. haemorrhoidalis have been distributed worldwide (Zumpt 1965). The adult flies are not parasitic and do not feed (Wall and Shearer 2001). They are large, 11–15 mm in length and their body is covered with yellowish hairs. All the species have a similar general life cycle.

The eggs are usually deposited on the hair of the host in a particular body region. After hatching, the larvae burrow into the tissue of the host, the first stage larvae hatch and moult to L2, which can be present in different regions of the gastrointestinal tract, and in L3 remains attached to the mucosa for 8–10 months. The rounded body, hooked mouth-parts and spines enable the larvae to live in the gastrointestinal tract. Species can be distinguished based on pattern of spines on the body (Wall and Shearer 2001). In G. intestinalis, the third instar larvae are relatively large, between 1.27 to 1.91 cm long and spines arranged in two rows (Zumpt 1965, Sweeney 1990).

Here we report a type of gastric myiasis caused by G. intestinalis in an old lion in a zoo in Sistan, southeast Iran.

Case report

The present case aimed to report the finding of G. intestinalis into the stomach of an old lion in a zoo in Sistan, southeast Iran. Larvae were collected during a post-mortem examination of the digestive tract of lion for parasitological purposes (Fig. 1). Twelve larvae were collected from the stomach and preserved in 70% alcohol with 5% glycerin. Samples were taken to the laboratory of Parasitology, Unit of the Veterinary Medicine, University of Zabol, for morphological identification. All the collected larvae were identified under a stereomicroscope using the identification key (Zumpt 1965). The isolated larvae were creamy-white in color, narrow at their anterior end and wide at their posterior end. They measure from 10–15 mm in length and 5–6 mm in width. Spines on the surface of segments are arranged in two rows (Fig. 2). Based on the morphology and size of the larvae, they were identified as G. intestinalis.

Fig. 1.

Gasterphilus larvae on the stomach mucosal membrane of a lion

Fig. 2.

Gasterophilus intestinalis collected from the stomach of a lion

Discussion

The prevalence of Gasterophilus spp. has been reported in different countries. Larvae of most Gasterophilidae causing equine gastric myiasis have been recorded in southern Italy (Otranto et al. 2005). Gasterophilus intestinalis, G. nasalis, G. hemorrhoidalis, G. inermis, G. nigricornis and G. pecorum were detected in Turkey (GÖkcen et al. 2008). Khalifa et al. (2005) obtained G. haemorrohidalis from the stomach of Egyptian equines.

Distribution of species of this genus also has been investigated in Brazil and G. intestinalis reported to be responsible for the majority of myiasis cases (Felix et al. 2007). Iranian equine myasis associated with Gasterophilus spp., have been reported on a few occasions, three species of G. nasalis, G. intestinalis and G. inermis were identified by Tavassoli and Bakht (2012).

Aside from the higher incidence of infection by Gasterophilus larvae in equid hosts, a few reports of infections in pigs, dogs and rabbits are provided by Hall and Wall (1995) and Sayın Ipek (2012).

Besides veterinary importance, Gasterophilidae larvae can be found in humans with at least three cases reported (James 1947, Harwood and James 1979, Royce et al. 1999). In wild animals has been reported rarely. Only, Kumar et al. (2012) reported a case of wound myiasis in a captive lion. Gasterophilus involvement in the gastric myiasis of lion has not been reported, so the present study is the first report.

Conclusion

Further studies are recommended to complete the lack of data on parasite fauna of wild animals.