 Reference Base  Gastric myiasis due to Gyrostigma pavesii Corti (Diptera:... |
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World |
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Diseases - Parasites |
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White Rhino |
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The association of flies with man and their domestic animals has long been appreciated. Besides nuisance and as a carrier of diseases (Schmidt and Roberts. 1977; Service, 1980), some species of flies are also known to cause myiasis in man and animals.
The Malaysian fly fauna has been described by many workers. They seem to occur in various parts of Malaysia in a variety of ecological conditions.
This paper presents a case of Gyrostigma pavesii third stage larvae (an African botfly) in the stomach of a white rhinoceros (Cerathotherium simum),during postmortem examination at Zoo Negera, Hutu Kelang, Malaysia, The animal died of a condition unrelated to gastric myiasis.
Case History and Postmortem
A female white rhino, C. simum, was imported from Belgium by Zoo Negara, Malaysia on 22. Septernber 1982. The animal was approximately 4 years old and was certified fit. On arrival it was quarantined for 30 days and various routine medical examinations were conducted. During quarantaine this animal was observed having a chronic intermittent diarrhoea, and it was treated symptomatically. On the morning of 14 December, the animal was found to be recumbent and dyspnoeic; it was subsequently treated. Death occured within one and a half hour after treatment.
A postmortem was performed by the senior author and the stomach was observed full, without any gross abnormality. On evacuation of food materials, several dipteran larvae were observed lining singly on the stomach wall; a number of similar larvae were also observed in the evacuated food mass. A total of 30 live maggots were recovered from the stomach. Most of these maggots were taken from the non-glandular portion of the stomach. No fresh wounds or ulcers were observed and the only lesion seen was some excoriation of the mucosal layer of the glandular portion.
The maggots were then cleaned and processed for identification as described by Lane (1974) and was subsequently identified according to Zumpt (1965) as G. pavesii Corti. Fig. 1 shows the maggots in situ.
Discussion
The genus Gyrostigma has 3 species. Their larvae causes obligatory myiasis in the alimentary tract of the Asian and African rhinoceroses. The Asian species (G. sumatrensis Brauer), obtained from an Asian rhino (Didemoceros sumatrensis) was desribed based on a single third instar larva in 1884. Since then no other specimens were described (Zumpt, 1965). The two African species Gyrostigma conjugens and Gyrostigma pavesii have been described by many authors. G. conjugens Enderlein was described from a third instar larva found in a black rhino (Diceros bicornis) as early as 1901. Unfortunately, information on its biology and veterinary importance is scarce. The immature stages of G. pavesii have been described in the black and white rhino (C. simum). G. pavesii is widely distributed South of Sahara and is strictly host specific (Klos and Lang, 1982; Zumpt, 1965). Both the African species were never reported to occur naturally outside the African Continent.
A complete account of the genus has been described by Zumpt (1965). The eggs of Gyrostigma are deposited on the host's skin, mainly on the head, at the base of the ears, on the neck and shoulders. It is still unknown under what circumstances the larvae hatch and how they find their way to the stomach. The larvae are present generally in the oesophageal region of the stomach, with some in the glandular portion (Fowler, 1978). Our observations support those of Fowler (1978). The mature larvae are passed witli the feces and pupates on the ground. The pupal stage lasts about six weeks (Zumpt, 1965). The presence of dipteran larvae in the stomach of rhinos do not seem to cause any severe pathological effects. Apart from the tape worm Anophocephala gigantea, intestinal parasites are of little significance in captive rhinoceroses (Klos and Lang, 1982).
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