Rural Industries Research & Development Corporation

Research Compendium 1993 - 1994

Research Project

AETIOLOGY OF GIANT CELL ENTEROHEPATITIS IN FARMED CROCODILES

Objective

To identify the causal agent of giant cell enterohepatitis (GCEH) - a cause of debility, and often death, of crocodile hatchlings on farms.

Background

This disease was diagnosed almost ten years ago in a pathological study of hatchlings that died on one large crocodile farm. Subsequently, the disease, which is characterised by thickening of the intestine by inflammatory cells containing the presumed causal agent, has continued to be observed in hatchlings from this farm and several other farms which had received stock from the initial farm. The disease was also diagnosed in one hatchling crocodile in Papua New Guinea.

Research

Hatchling crocodiles, which were severely emaciated, were obtained from the initial farm then euthanased for detailed post-mortem examination and laboratory study.

Outcome

Pathological examination of up to fifteen emaciated hatchlings submitted on a number of occasions over a two year period revealed that approximately 205 of such animals were infected with the presumed causal organism. Extension of infection to other organs such as the pancreas, liver and lung was confirmed histologically.

Satisfactory electronmicrographs of intestinal lesions of giant cell enteritis were obtained and these indicated that the causal organism was probably a protozoan (Ladds, Donovan, Reynolds and Turton, 1994).

Whereas morphological studies were successful, repeated attempts to isolate the causal agent in tissue culture were unrewarding - even though several crocodile tissue culture cell lines were established.

As the study has progressed, fewer infected cases have been found and such cases have been milder infections than initially. Change in husbandry procedures, and in particular, the now routine chlorination of water for hatchling ponds may be the explanation for this. It is now becoming difficult and largely non-cost effective to identify infected animals.

Implications

Although decreased occurrence of this disease is welcomed, it is unfortunate that investigations and, in particular, isolation of the causal agent, were not completed as planned. it seems likely that GCEH will reappear sometime as crocodile farming expands, and better knowledge of its pathogenesis, diagnosis and epidemiology and, therefore, control would be of great value especially as there will inevitably be movement of (potentially GCEH) infected crocodiles between farms and perhaps interstate.

RIRDC Project No: UJC-3A

ORGANISATION: Dept of Biomedical & Tropical Veterinary Sciences

PHONE: 077 81 4428

Ladds, P W, Donovan, J A, Reynolds, A and Turton, J A, 1994, 'Giant cell enteritis in young crocodiles. Australian Veterinary Journal 71, pp300-301.

Last updated: 10 October 1996
Copyright © RIRDC
Index of RIRDC Projects URL
http://www.rirdc.gov.au/pub/compendium/93-94/index-b.html